@article{jung_conrad_2022, title={Effects of an electric field applied during the solution heat treatment of the Al-Mg -Si-Cu alloy AA6111 on the subsequent natural aging kinetics and tensile properties}, volume={97}, ISSN={["2195-8556"]}, DOI={10.3139/ijmr-2006-0025}, abstractNote={Abstract The effects of an external dc electric field of 0 – 5 kV/cm, applied at 475 – 550 °C during solution heat treatment (SHT) to AA6111, on the subsequent natural aging kinetics and volume fraction of precipitated clusters were determined employing resistivity. The field increased the asquenched resistivity and that during natural aging, the effect being significant from 0 to ≈0.5 kV/cm and increasing only slightly, if at all, thereafter. An Avrami-type analysis of the natural aging kinetics gave n = 0.59 ± 0.2 and k = (1.2 ± 0.8) · 10– 2 min –1, relatively independent of SHT temperature and field strength. The field increased the volume fraction of precipitated clusters which occurred during natural aging. This was attributed to the increase in solubility during SHT produced by the field. Tensile properties equivalent to those obtained by the SHT at 550 °C without a field were obtained at 500 °C with a field of only 200 V/cm, representing a reduction of 50 °C in the nominal SHT temperature.}, number={2}, journal={INTERNATIONAL JOURNAL OF MATERIALS RESEARCH}, author={Jung, Jung and Conrad, Hans}, year={2022}, month={Jan}, pages={145–149} }
 @article{conrad_jung_2022, title={Effects of an external electric field applied during the solution heat treatment of the Al-Mg-Si-Cu alloy AA6111}, volume={95}, ISSN={["2195-8556"]}, DOI={10.3139/ijmr-2004-0074}, abstractNote={Abstract The application of an external dc electric field during the solution heat treatment (SHT) of AA6111 Al alloy increased the as-quenched resistivity ρ and hardness Hv. The increases represented reductions in SHT of 10–20 K required for a constant ρ or Hv. Analysis of the results gave that the field reduced both the enthalpy and entropy of solution. The resulting reduction in Gibbs free energy gave increases of 0.03–0.04 at.% in solubility of Mg2Si (or Al –Mg– Si – (Cu)-vacancy complexes) at 400 –600 °C, amounting to a factor of 33% increase in solubility at 400 °C and 6% at 600 °C.}, number={5}, journal={INTERNATIONAL JOURNAL OF MATERIALS RESEARCH}, author={Conrad, Hans and Jung, Kang}, year={2022}, month={Feb}, pages={352–355} }
 @article{jung_conrad_2022, title={Influence of electric field strength applied during the solution heat treatment of the Al-Mg-Si-Cu Alloy AA6111}, volume={97}, ISSN={["2195-8556"]}, DOI={10.3139/ijmr-2006-0006}, abstractNote={Abstract In the present paper, the effect of electric field strength in the range E = 0.1 – 5.0 kV/cm applied during the solution heat treatment (SHT) of the AA6111 alloy at 475° –550 °C has been determined employing resistivity. An increase in the as-quenched resistivity ρw occurred for all field strengths, the increase being relatively rapid up to E ≈ 1 kV/cm and only slight, if at all, for higher fields. Analysis of the results gave that the field reduced the enthalpy, entropy and Gibbs free energy of solution, the amount of reduction increasing with field strength. The electric current, which occurred with application of the field during SHT, ranged from (7 × 10 –3 to 4 × 102) μA, increasing with field strength and SHT temperature, but decreasing with time during the SHT. The role of the current in the enhancement of ρw by the field is not clear.}, number={1}, journal={INTERNATIONAL JOURNAL OF MATERIALS RESEARCH}, author={Jung, Kang and Conrad, Hans}, year={2022}, month={Jan}, pages={35–38} }
 @article{wang_du_conrad_2016, title={Effect of a weak DC electric field on the grain size distribution in isothermally-annealed yttria-stabilized zirconia (3Y-TZP)}, volume={42}, ISSN={["1873-3956"]}, DOI={10.1016/j.ceramint.2015.09.135}, abstractNote={The grain size distributions (GSDs) in 3 mol% yttria-stabilized zirconia (3 Y-TZP) which had been isothermally annealed for various times at 1300 °C and 1400 °C without and with a weak DC electric field E0*=18 V/cm were determined. The GSDs for all test conditions fit a single curve whose form is in accord with the Bitti–Di Nunzio model, and moreover is in accord with the GSDs for sintering and plastic deformation. The results for all three processes suggest the GSD to be a unique function of the mean linear intercept grain size.}, number={1}, journal={CERAMICS INTERNATIONAL}, author={Wang, J. and Du, A. and Conrad, H.}, year={2016}, month={Jan}, pages={2091–2093} }
 @misc{wang_conrad_2016, title={On the dynamic compared to static grain growth rate in 3 mole% yttria-stabilized tetragonal zirconia polycrystals (3 Y-TZP)}, volume={3}, number={3}, journal={AIMS Materials Science}, author={Wang, J. and Conrad, H.}, year={2016}, pages={1208–1221} }
 @article{wang_conrad_2015, title={Grain Boundary Curvatures Measurements in Annealed Yttria-Stabilized Zirconia (3Y-TZP) and Their Relation to Mean Grain Size}, volume={98}, ISSN={["1551-2916"]}, DOI={10.1111/jace.13868}, abstractNote={It was determined that the mean grain boundary radius of curvature r¯b in 3 mol% yttria-stabilized zirconia isothermally annealed without and with a DC electric field E0∗ = 18 V/cm was uniquely proportional to the mean linear intercept grain size d¯, the proportionality constant α = 3/2 being in accord with the Rios-Fonseca stereological model.}, number={12}, journal={JOURNAL OF THE AMERICAN CERAMIC SOCIETY}, author={Wang, Jun and Conrad, Hans}, year={2015}, month={Dec}, pages={3628–3630} }
 @article{pang_wu_liu_zhang_zhang_conrad_ding_2015, title={Influence of pouring temperature on solidification behavior, microstructure and mechanical properties of sand-cast Mg-10Gd-3Y-0.4Zr alloy}, volume={25}, ISSN={["2210-3384"]}, DOI={10.1016/s1003-6326(15)63612-3}, abstractNote={Influence of the pouring temperature ranging from 680 to 780 °C on the solidification behavior, the microstructure and mechanical properties of the sand-cast Mg−10Gd−3Y−0.4Zr alloy was investigated. It was found that the nucleation undercooling of the α-Mg phase increased from 2.3 to 6.3 °C. The average α-Mg grain size increased from 44 to 71 μm, but then decreased to 46 μm. The morphology of the eutectic compound transformed from a continuous network into a discontinuous state and then subsequently into an island-like block. The volume fraction of β-Mg24RE5 phase increased and its morphology transformed from particle into rod-like. The increase in pouring temperature increased the solute concentration. YS increased from 138 to 151 MPa, and UTS increased from 186 to 197 MPa. The alloy poured at 750 °C had optimal combining strength and ductility. The fracture surface mode transformed from quasi-cleavage crack into transgranular fracture, all plus the dimple-like fracture, with the micro-porosity and the re-oxidation inclusion as major defects. The average α-Mg grain size played a main role in the YS of sand-cast Mg−10Gd−3Y−0.4Zr alloy, besides other factors, i.e. micro-porosity, morphology of eutectic compounds, re-oxidation inclusion and solute concentration.}, number={2}, journal={TRANSACTIONS OF NONFERROUS METALS SOCIETY OF CHINA}, author={Pang, Song and Wu, Guo-hua and Liu, Wen-cai and Zhang, Liang and Zhang, Yang and Conrad, Hans and Ding, Wen-jiang}, year={2015}, month={Feb}, pages={363–374} }
 @article{wang_conrad_2014, title={Contribution of the space charge to the grain boundary energy in yttria-stabilized zirconia}, volume={49}, ISSN={["1573-4803"]}, DOI={10.1007/s10853-014-8331-z}, abstractNote={A model based on the effect of a modest applied dc electric field on grain growth is proposed for the contribution of the space charge to the grain boundary (GB) energy in 3 mol % yttria-stabilized zirconia (3 YSZ). The model considers that the total GB energy $$ \gamma_{\text{b}}^0 $$ (the capillary driving force for grain growth) consists of three major components: (a) $$ \gamma_{\text{b}}^\varSigma $$ due to the misorientation between neighboring grains, (b) $$ \gamma_{\text{b}}^{\text{s}} $$ due to the size misfit between the segregated solute and the solvent cations, and (c) $$ \gamma_{\text{b}}^{\text{e}} $$ the electrostatic (space charge) component, which results from the segregation of the aliovalent yttrium ions to the grain boundaries. The former two components combined comprise 40 % of the total GB energy in 3 YSZ and the electrostatic component 60 %. Based on the model, the calculated magnitudes of the three components were in qualitative accord with theoretical considerations and with values reported in the literature. A reduction in $$ \gamma_{\text{b}}^{\text{e}} , $$ and in turn in $$ \gamma_{\text{b}}^0 , $$ results from the bias exerted by the applied field on the space charge potential that occurs with the segregation of the yttrium ions to the grain boundaries. The observed reduction of grain growth in 3 YSZ by an applied electric field is attributed mainly to the reduction in $$ \gamma_{\text{b}}^{\text{e}} $$ by the field.}, number={17}, journal={JOURNAL OF MATERIALS SCIENCE}, author={Wang, Jun and Conrad, Hans}, year={2014}, month={Sep}, pages={6074–6080} }
 @article{conrad_wang_2014, title={Equivalence of AC and DC electric field on retarding grain growth in yttria-stabilized zirconia}, volume={72-73}, ISSN={["1359-6462"]}, DOI={10.1016/j.scriptamat.2013.10.010}, abstractNote={It is shown that the full-cycle mean value of a 60 Hz AC field is equivalent to a DC field in its effect on retarding grain growth in 3 mol.% yttria-stabilized zirconia. This equivalence is in keeping with the proposed physical mechanism for the retardation at E < ∼30 V cm−1. A second decrease in the grain size with field occurs at a mean AC field of ∼100 V cm−1, which may be the precursor for “flash” sintering.}, journal={SCRIPTA MATERIALIA}, author={Conrad, Hans and Wang, Jun}, year={2014}, month={Feb}, pages={33–34} }
 @article{pang_wu_liu_zhang_zhang_conrad_ding_2014, title={Influence of cooling rate on solidification behavior of sand-cast Mg-10Gd-3Y-0.4Zr alloy}, volume={24}, ISSN={["2210-3384"]}, DOI={10.1016/s1003-6326(14)63484-1}, abstractNote={The effect of the cooling rate ranging from 1.4 °C/s to 3.5 °C/s on the solidification behavior of the sand-cast Mg–10Gd–3Y–0.4Zr alloy was studied by computer aided cooling curve analysis (CA-CCA). With the increase in cooling rate, the nucleation temperature (Tα,N) increases from 634.8 °C to 636.3 °C, the minimum temperature (Tα,Min) decreases from 631.9 °C to 630.7 °C, the nucleation undercooling (ΔTN) increases from 2.9 °C to 5.6 °C, the beginning temperature of the eutectic reaction (Teut,N) increases, the time of the eutectic reaction shortens, solidus temperature decreases from 546.0 °C to 541.4 °C, and solidification temperature range (ΔTS) increases by 6.1 °C. The increased nucleation rate () is supposed to be the main reason for the increased ΔTN. Increased value (Teut,N–Teut,G) and shortened time of the eutectic reaction cause the change in the volume fraction and morphology of the second phase.}, number={11}, journal={TRANSACTIONS OF NONFERROUS METALS SOCIETY OF CHINA}, author={Pang, Song and Wu, Guo-hua and Liu, Wen-cai and Zhang, Liang and Zhang, Yang and Conrad, Hans and Ding, Wen-jiang}, year={2014}, month={Nov}, pages={3413–3420} }
 @article{conrad_yang_2013, title={Effect of the strength of an AC electric field compared to DC on the sintering rate and related grain size of zirconia (3Y-TZP)}, volume={559}, ISSN={["1873-4936"]}, DOI={10.1016/j.msea.2012.08.146}, abstractNote={The influence of the strength of an initial 60 Hz AC field Eo=1–50 V/cm on the sintering rate and corresponding grain size of yttria-stabilized zirconia (3Y-TZP) was determined and compared with an equivalent DC field. For both field types the sintering rate increased and the grain size decreased with field strength up to a critical value, beyond which no further effect occurred. The AC field however had a greater effect than the DC field over the entire field strength range. The major factor responsible for the enhanced sintering rate with both field types was concluded to be retardation of grain growth by the field. The retardation was in turn attributed to a reduction in the grain boundary energy by the interaction of the field with the space charge. Analysis of the results employing the absolute reaction rate theory gave magnitudes of the space charge potential and corresponding grain boundary energy in accord with reported values, but were larger with AC field than with DC. Factors which could contribute to the greater effect of an AC field compared to DC are suggested.}, journal={MATERIALS SCIENCE AND ENGINEERING A-STRUCTURAL MATERIALS PROPERTIES MICROSTRUCTURE AND PROCESSING}, author={Conrad, Hans and Yang, Di}, year={2013}, month={Jan}, pages={591–594} }
 @inproceedings{wang_conrad_2013, title={Grain boundary resistivity in yttria-stabilized zirconia}, volume={240}, booktitle={Processing and properties of advanced ceramics and composites v}, author={Wang, J. and Conrad, H.}, year={2013}, pages={175–188} }
 @article{obare_wang_conrad_2013, title={Grain size distribution in 3 mol.% yttria-stabilized zirconia sintered with a small AC electric field}, volume={68}, ISSN={["1359-6462"]}, DOI={10.1016/j.scriptamat.2012.09.018}, abstractNote={The grain size stereology in 3 mol.% yttria-stabilized zirconia sintered with a small AC field was essentially the same as in specimens sintered without field or with an equivalent DC field. With the DC field there was no clear difference adjacent to the positive electrode compared to near the negative electrode. Thus, neither polarization nor stereology are major factors in the greater retarding effect of an AC field on grain growth compared to an equivalent DC field.}, number={2}, journal={SCRIPTA MATERIALIA}, author={Obare, J. and Wang, J. and Conrad, H.}, year={2013}, month={Jan}, pages={111–113} }
 @article{plunkett_imam_rath_conrad_2013, title={Resistance of a commercial magnetorheological fluid to penetration}, volume={412}, ISSN={["1742-6596"]}, DOI={10.1088/1742-6596/412/1/012023}, abstractNote={The stress, σ, required to penetrate a commercial magnetorheological (MR) fluid exposed to an applied magnetic field, B, in the range of 0 – 0.25 Tesla was determined for: (a) a constant, continuous field and (b) on-off field. With constant field application, it was found that σ vs. the penetration depth, x, of the cylindrical indenter into the MR fluid at a constant rate of 0.12–0.18 mm/s was parabolic in form, namely σ = σoxn where σ0 = AH, A = 1.7 kPa/(kA/m) and n = 0.3–0.5. The magnitude of σo is approximately six times that of the shear yield stress, τy, of the MR fluid. A model is proposed to explain the resistance to penetration into the MR fluid with the constant field. The results obtained in the on-off field tests and the in-out tests are in keeping with the model.}, journal={13TH INTERNATIONAL CONFERENCE ON ELECTRORHEOLOGICAL FLUIDS AND MAGNETORHEOLOGICAL SUSPENSIONS (ERMR2012)}, author={Plunkett, K. F. and Imam, M. A. and Rath, B. and Conrad, H.}, year={2013} }
 @article{wang_yang_conrad_2013, title={Transient-regime grain growth in nanocrystalline yttria-stabilized zirconia annealed without and with a DC electric field}, volume={69}, ISSN={["1359-6462"]}, DOI={10.1016/j.scriptamat.2013.05.001}, abstractNote={Grain size exponents considerably larger than normally reported occurred for grain growth in nanoscale 3 mol.% yttria-stabilized zirconia annealed without and with a DC electric field at 1300 and 1400 °C. It is shown that the large exponents correspond to the transition regime predicted by solute drag theory. The observed smaller grain growth rate with an electric field compared to without is in keeping with a reduction in the capillary driving force.}, number={5}, journal={SCRIPTA MATERIALIA}, author={Wang, J. and Yang, Di and Conrad, H.}, year={2013}, month={Sep}, pages={351–353} }
 @article{wang_conrad_2012, title={Effect of electric field on solute solubility in Al alloys measured by hardness}, volume={28}, ISSN={["1743-2847"]}, DOI={10.1179/1743284711y.0000000121}, abstractNote={ The influence of dc electric field on pertinent solute solubility during the solution heat treatment of Al–Mg–Si–Cu AA 6111 Al alloy was determined by employing Vickers hardness and resistivity. Thermodynamic analysis of the results showed that the field decreased both entropy Δ Ss and enthalpy Δ Hs of the solution, but still gave a reduction in the Gibbs free energy Δ Gs = Δ Hs– TΔ Ss and in turn an increase in solubility. The reduction in Δ Gs obtained from the hardness tests was similar to that from the resistivity measurements. The decrease in Δ Gs by the field suggests that there exists an electronic aspect to the Gibbs free energy of the solution in addition to the size misfit. The solid solution strengthening corresponding to the increase in solubility by the field was in accord with the Mott–Nabarro model. Considering several Al–Mg2Si alloys, the solubility increase by an electric field was proportional to the difference in valence between the pertinent solute and the Al host. }, number={9-10}, journal={MATERIALS SCIENCE AND TECHNOLOGY}, author={Wang, J. and Conrad, H.}, year={2012}, month={Oct}, pages={1198–1201} }
 @article{obare_griffin_conrad_2012, title={Effects of heating rate and DC electric field during sintering on the grain size distribution in fully sintered tetragonal zirconia polycrystals stabilized with 3% molar yttria (3Y-TZP)}, volume={47}, ISSN={["1573-4803"]}, DOI={10.1007/s10853-012-6391-5}, number={13}, journal={JOURNAL OF MATERIALS SCIENCE}, author={Obare, John and Griffin, William D. and Conrad, Hans}, year={2012}, month={Jul}, pages={5141–5147} }
 @article{conrad_yang_2011, title={Dependence of the sintering rate and related grain size of yttria-stabilized polycrystalline zirconia (3Y-TZP) on the strength of an applied DC electric field}, volume={528}, ISSN={["1873-4936"]}, DOI={10.1016/j.msea.2011.08.022}, abstractNote={The sintering rate of 3Y-TZP increased with increase in initial applied DC electric field strength up to 20 V/cm; no further effect however occurred at 50 V/cm. Analysis of the data confirmed the earlier finding that the increase in sintering rate by the field resulted mainly from a retardation of grain growth. It was further determined that the retardation resulted from a reduction in the grain boundary energy, which provides the driving force. The initial field of 20 V/cm reduced the grain boundary energy to essentially nil, thereby accounting for the fact that no further decrease in grain size occurred at the higher field strength. The reduction in the grain boundary energy by the field is attributed to the interaction of the field with the space charge.}, number={29-30}, journal={MATERIALS SCIENCE AND ENGINEERING A-STRUCTURAL MATERIALS PROPERTIES MICROSTRUCTURE AND PROCESSING}, author={Conrad, Hans and Yang, Di}, year={2011}, month={Nov}, pages={8523–8529} }
 @article{yang_conrad_2011, title={Enhanced sintering rate and finer grain size in yttria-stablized zirconia (3Y-TZP) with combined DC electric field and increased heating rate}, volume={528}, ISSN={["1873-4936"]}, DOI={10.1016/j.msea.2010.10.041}, abstractNote={The influence of heating rate dT/dt = 2–25 °C/min on sintering of yttria-stabilized ZrO2 (3Y-TZP) powder without and with a small initial DC electric field (E0 = 13.9 V/cm) was determined. An increase in dT/dt and the application of electric field reduced both the sintering time and the grain size at a given density. Employing the master sintering curve approach it was determined that the apparent activation energy Q for sintering was 500 ± 5 kJ/mole, essentially independent of dT/dt and E. A major factor in the effects of dT/dt and E on the sintering rate is their reduction of the grain size. It is proposed that retardation of grain growth by the field results from the interaction of the field with the space charge at the grain boundaries.}, number={3}, journal={MATERIALS SCIENCE AND ENGINEERING A-STRUCTURAL MATERIALS PROPERTIES MICROSTRUCTURE AND PROCESSING}, author={Yang, Di and Conrad, Hans}, year={2011}, month={Jan}, pages={1221–1225} }
 @article{conrad_wang_2011, title={Influence of the nature of an electric field applied during the solution heat treatment of the Al-Mg-Si-Cu Alloy AA6111 on subsequent natural aging}, volume={102}, ISSN={["2195-8556"]}, DOI={10.3139/146.110590}, abstractNote={Abstract}, number={11}, journal={INTERNATIONAL JOURNAL OF MATERIALS RESEARCH}, author={Conrad, Hans and Wang, Jun}, year={2011}, month={Nov}, pages={1331–1335} }
 @article{conrad_2011, title={Space Charge and Grain Boundary Energy in Zirconia (3Y-TZP)}, volume={94}, ISSN={["1551-2916"]}, DOI={10.1111/j.1551-2916.2011.04823.x}, abstractNote={An analytical procedure is developed which provides the magnitudes of the space charge potential and the corresponding grain boundary energy in ionic oxides from the effect of an applied dc electric field on grain growth. Reasonable agreement occurred between the calculated values and expectations or other measurements. The agreement indicates that the physical mechanism governing the retardation of grain growth by an electric field in 3Y‐TZP is through reduction in the grain boundary energy by the interaction of the field with the space charge.}, number={11}, journal={JOURNAL OF THE AMERICAN CERAMIC SOCIETY}, author={Conrad, Hans}, year={2011}, month={Nov}, pages={3641–3642} }
 @article{sarma_jian_wang_conrad_zhu_2010, title={Effect of rolling temperature on the evolution of defects and properties of an Al-Cu alloy}, volume={45}, ISSN={["0022-2461"]}, DOI={10.1007/s10853-010-4484-6}, number={17}, journal={JOURNAL OF MATERIALS SCIENCE}, author={Sarma, V. Subramanya and Jian, W. W. and Wang, J. and Conrad, H. and Zhu, Y. T.}, year={2010}, month={Sep}, pages={4846–4850} }
 @article{yang_raj_conrad_2010, title={Enhanced Sintering Rate of Zirconia (3Y-TZP) Through the Effect of a Weak dc Electric Field on Grain Growth}, volume={93}, ISSN={["0002-7820"]}, DOI={10.1111/j.1551-2916.2010.03905.x}, abstractNote={ We show, for the first time, that a dc electric field of 20 V/cm shifts the densification curve to a lower temperature in constant heating rate experiments with yttria‐stabilized tetragonal zirconia powder (3Y‐TZP). The enhanced sintering rate is ascribed, at least in part, to the reduced rate of grain growth under the applied field, consistent with earlier experiments on the influence of such fields on grain size in superplastic deformation and isothermal grain growth in zirconia polycrystals. }, number={10}, journal={JOURNAL OF THE AMERICAN CERAMIC SOCIETY}, author={Yang, Di and Raj, Rishi and Conrad, Hans}, year={2010}, month={Oct}, pages={2935–2937} }
 @article{yang_conrad_2010, title={Enhanced sintering rate of zirconia (3Y-TZP) by application of a small AC electric field}, volume={63}, ISSN={["1359-6462"]}, DOI={10.1016/j.scriptamat.2010.04.030}, abstractNote={A small initial electric field E0 = 13.9 V cm−1 enhanced the sintering rate of zirconia (3Y-TZP) powder, with a 60 Hz AC field having a greater effect than a DC field. The enhancement with both fields was in accord with the retardation of grain growth observed directly by scanning electron microscopy and with that which occurred during grain growth and plastic deformation. Some factors which could contribute to the observed behavior are given.}, number={3}, journal={SCRIPTA MATERIALIA}, author={Yang, Di and Conrad, Hans}, year={2010}, month={Aug}, pages={328–331} }
 @article{conrad_yang_2010, title={Influence of an applied dc electric field on the plastic deformation kinetics of oxide ceramics}, volume={90}, ISSN={["1478-6443"]}, DOI={10.1080/14786430903304137}, abstractNote={A modest dc electric field markedly reduced the tensile flow stress at high temperatures in three polycrystalline oxides, i.e. MgO, Al2O3 and yttria-stabilized tetragonal ZrO2 (Y-TZP). The reduction in flow stress ΔσE in Y-TZP consisted of three components: (i) ΔσT due to Joule heating, (ii) a rapid, reversible component obtained in on-off and electric field step tests and (iii) the cumulative effect of the field on microstructure. Only ΔσT and occurred in MgO and Al2O3. It is concluded that results from a reduction in the electrochemical potential for the formation of vacancies corresponding to the diffusion of the rate-controlling ion in the space-charge at the grain boundary. The calculated magnitude of the space-charge zone width and its temperature and solute composition dependence are in accord with theory and experiment; is attributed mainly to the retardation of grain growth by the field. The retardation could be due to one or more of the following effects of the field on the space-charge zone: (i) an increase in the segregated solute ions, (ii) a decrease in grain boundary energy and (iii) a decrease in solute ion mobility.}, number={9}, journal={PHILOSOPHICAL MAGAZINE}, author={Conrad, Hans and Yang, Di}, year={2010}, pages={1141–1157} }
 @article{conrad_yang_2010, title={On the rate-controlling mechanism during the plastic deformation of nanocrystalline Cu}, volume={45}, ISSN={["1573-4803"]}, DOI={10.1007/s10853-010-4703-1}, number={22}, journal={JOURNAL OF MATERIALS SCIENCE}, author={Conrad, Hans and Yang, Di}, year={2010}, month={Nov}, pages={6166–6169} }
 @article{sarma_wang_jian_kauffmann_conrad_freudenberger_zhu_2010, title={Role of stacking fault energy in strengthening due to cryo-deformation of FCC metals}, volume={527}, ISSN={["1873-4936"]}, DOI={10.1016/j.msea.2010.08.015}, abstractNote={The effectiveness of the cryogenic (CT) rolling vis-à-vis room temperature (RT) rolling on strengthening is significantly affected by stacking fault energy (SFE) and there is an optimum SFE at which CT rolling is most effective. Studies on Al, Al alloy AA6061, Cu, Cu–4.6Al, Cu–9Al and Cu–15Al (in at.%) alloys revealed that in metals with very high and very low SFEs, the strength difference between CT and RT rolled samples is <10%. The Cu–4.6Al alloy with an intermediate SFE revealed maximum enhancement of strength (25–30%). These results are explained by changes in deformation mechanisms with SFE and temperature. High SFE metals deformed by dislocation slip and low SFE metals deformed by twinning during CT and RT rolling. Metals with intermediate SFEs deformed by twinning during CT rolling but by dislocation slip during RT rolling, and this makes the CT rolling most effective over RT rolling in enhancing the strength.}, number={29-30}, journal={MATERIALS SCIENCE AND ENGINEERING A-STRUCTURAL MATERIALS PROPERTIES MICROSTRUCTURE AND PROCESSING}, author={Sarma, V. Subramanya and Wang, J. and Jian, W. W. and Kauffmann, A. and Conrad, H. and Freudenberger, J. and Zhu, Y. T.}, year={2010}, month={Nov}, pages={7624–7630} }
 @article{yang_conrad_2009, title={Effect of electropulsing on the tensile flow stress of ultrafine-grained 3Y-TZP at 1400 degrees C}, volume={100}, ISSN={["2195-8556"]}, DOI={10.3139/146.101784}, abstractNote={Abstract}, number={1}, journal={INTERNATIONAL JOURNAL OF MATERIALS RESEARCH}, author={Yang, Di and Conrad, Hans}, year={2009}, month={Jan}, pages={76–80} }
 @article{conrad_yang_2008, title={Effect of an alternating current electric field on the plastic deformation of ultrafine-grained 3Y-TZP at 1400 degrees C and 1500 degrees C}, volume={39A}, ISSN={["1073-5623"]}, DOI={10.1007/s11661-007-9396-y}, number={2}, journal={METALLURGICAL AND MATERIALS TRANSACTIONS A-PHYSICAL METALLURGY AND MATERIALS SCIENCE}, author={Conrad, Hans and Yang, Di}, year={2008}, month={Feb}, pages={272–278} }
 @article{conrad_yang_becher_2008, title={Effect of an applied electric field on the flow stress of ultrafine-grained 2.5Y-TZP at high temperatures}, volume={477}, ISSN={["1873-4936"]}, DOI={10.1016/j.msea.2007.05.057}, abstractNote={Application of a dc electric field (E = 46 V/cm) during the tensile deformation of an ultrafine-grained 2.5Y-TZP (d = 350 nm) at 1450 °C resulted in a significant reduction in the flow stress σ, which reversed upon removal of the field. At strains ϵ ≤ 0.6, the reduction in flow stress ΔσE consisted of two components: (a) a rapid initial decrease in stress (ΔσE*) due to the effect of the field on the deformation mechanism(s) and (b) a longer-time decrease in stress (ΔσT) due to Joule heating, giving ΔσE=ΔσE*+ΔσT. At ϵ > 0.6, an additional contribution (ΔσEstr) occurred, which was attributed to a change in defect structure, e.g., grain growth and cavitation. It was concluded that the rate-controlling mechanism in the present tests is grain boundary sliding accommodated by lattice diffusion of the Zr ions with a threshold stress σo, giving an acting effective stress σe = σ − σo. It was determined for this case that ΔσE* contained reductions in both the effective stress (Δσe,E*) and in the threshold stress (Δσo,E). Analysis of the behavior in terms of an electrochemical potential for vacancy formation showed that Δσe,E* and Δσo,E are related to changes in the electric field potential pertaining to the space charge at the grain boundaries. The calculated width of the space charge region acted on by the electric field was 3–5 nm in the temperature range of 1450–1550 °C.}, number={1-2}, journal={MATERIALS SCIENCE AND ENGINEERING A-STRUCTURAL MATERIALS PROPERTIES MICROSTRUCTURE AND PROCESSING}, author={Conrad, H. and Yang, Di and Becher, P.}, year={2008}, month={Mar}, pages={358–365} }
 @article{starnes_conrad_2008, title={Grain size distribution in ultrafine-grained yttria-stabilized zirconia deformed without and with an electric field}, volume={59}, ISSN={["1359-6462"]}, DOI={10.1016/j.scriptamat.2008.07.025}, abstractNote={Grain size distributions were determined in the grip ( e  ≈ 0) and near fracture ( e  ≈ 1.0) of yttria-stabilized zirconia ( d ¯ 0 = 0.44  μm) specimens deformed in tension at 1450–1600 °C without and with an electric field. The mean grain size increased with temperature, but decreased with field, with no clear effect of strain. The distributions for all test conditions fit a single curve based on the Bitti–Nunzio model, showing that the field had no significant effect on the grain size distribution.}, number={10}, journal={SCRIPTA MATERIALIA}, author={Starnes, Stephen and Conrad, Hans}, year={2008}, month={Nov}, pages={1115–1118} }
 @article{conrad_yang_becher_2008, title={Plastic deformation of ultrafine-grained 2.5Y-TZP exposed to a dc electric field with an air gap}, volume={496}, ISSN={["0921-5093"]}, DOI={10.1016/j.msea.2008.07.012}, abstractNote={Abstract The influence on the tensile flow stress of ultrafine-grained 2.5Y-TZP at 1450 °C by a dc electric field with an air gap between the negative electrodes and the positive specimen was determined in two test procedures: Type a, in which the field is applied continuously from the very beginning up to a fixed strain ɛ  ≈ 0.2 and Type b, in which the field is alternately applied and removed following the prestrain ɛ  ≈ 0.2 without and with the field. A larger reduction in the flow stress by the field occurred in the Type a test compared to the Type b. Moreover, a larger reduction occurred in the Type b test when the prestrain was with a field applied compared to without. Both of these behaviors are attributed to a retardation of dynamic grain growth by the field. The reduction in the flow stress by the field in the Type b test was in accord with a decrease in the electrochemical potential for the formation of vacancies corresponding to the lattice diffusion of the rate-controlling Zr ions. The results in the present tests were in general accord with those obtained previously in which both the positive and negative electrodes made direct contact with the specimen. This indicates that neither the orientation of the field nor the presence of an air gap has significant influence on the electric field dependence of the flow stress.}, number={1-2}, journal={MATERIALS SCIENCE AND ENGINEERING A-STRUCTURAL MATERIALS PROPERTIES MICROSTRUCTURE AND PROCESSING}, author={Conrad, H. and Yang, Di and Becher, P.}, year={2008}, month={Nov}, pages={9–13} }
 @article{yang_conrad_2008, title={Retardation of grain growth and cavitation by an electric field during superplastic deformation of ultrafine-grained 3Y-TZP at 1,450-1,600 degrees C}, volume={43}, ISSN={["0022-2461"]}, DOI={10.1007/s10853-008-2653-7}, number={13}, journal={JOURNAL OF MATERIALS SCIENCE}, author={Yang, Di and Conrad, Hans}, year={2008}, month={Jul}, pages={4475–4482} }
 @article{conrad_yang_2007, title={Effect of DC electric field on the tensile deformation of ultrafine-grained 3Y-TZP at 1450-1600 degrees C}, volume={55}, ISSN={["1873-2453"]}, DOI={10.1016/j.actamat.2007.08.032}, abstractNote={Two test types were employed to determine the effect of DC electric field E = 5–8.3 V cm−1 applied in the loading direction on the tensile flow stress of 3Y-TZP (do = 0.44 μm) at 1450–1600 °C. In type a, the field was applied continuously throughout the tensile test; in type b, the field was alternately applied and removed during the course of the tensile test. The field reduced the flow stress in both test types, but with an appreciably larger effect in the type a tests. The field, however, had no discernable effect on the stress exponent n=∂logε˙/∂logσ determined by strain rate change tests. The reduction in flow stress in the type b tests reversed upon removal of the field. It was interpreted to result from both Joule heating and a decrease in the energy to form the rate-controlling Zr4+ vacancies in the space charge zone adjacent to the grain boundaries. The calculated width of the space charge zone λ (=1.5–7.8 nm) and the ratio of the applied electric potential to the reduction in stress Δϕa/Δσ (=18–19 μV/MPa) were in accord with predictions. The larger reduction in the flow stress in the type a tests is attributed to a greater retardation of grain growth by the field.}, number={20}, journal={ACTA MATERIALIA}, author={Conrad, H. and Yang, D.}, year={2007}, month={Dec}, pages={6789–6797} }
 @article{conrad_jung_2007, title={Effect of an electric field applied during the solution heat treatment of the Al-Mg-Si alloy AA6022 on the subsequent natural aging kinetics}, volume={42}, ISSN={["1573-4803"]}, DOI={10.1007/s10853-006-0850-9}, number={4}, journal={JOURNAL OF MATERIALS SCIENCE}, author={Conrad, Hans and Jung, Kang}, year={2007}, month={Feb}, pages={1299–1303} }
 @article{conrad_2007, title={Plastic deformation kinetics in nanocrystalline FCC metals based on the pile-up of dislocations}, volume={18}, ISSN={["1361-6528"]}, DOI={10.1088/0957-4484/18/32/325701}, abstractNote={Experimental data on the effect of grain size in the nanocrystalline range (d = 20–500 nm) on the plastic deformation kinetics of fcc metals representing a wide range in stacking fault energy are evaluated to determine the governing mechanism. Special consideration is given to the anomalous temperature dependence of the strain rate sensitivity of the flow stress expressed by the apparent activation volume . It is shown that the anomalous temperature dependence of υ is consistent with the mechanism of grain boundary shear promoted by the pile-up of dislocations, which gives for the shear rate , where the subscript c refers to the stress concentration τc* resulting from the pile-up of dislocations at the grain boundaries. Furthermore, the experimental values of the Helmholtz free energy ΔFo,c*, the true activation volume υc* and the pre-exponential are in accord with theoretical predictions, i.e. ΔFo,c*≈ΔFb, the activation energy for grain boundary diffusion, υc*≈1−10b, where b is the Burgers vector and . Although it is well established that the stacking fault energy γSF has a significant influence on the plastic deformation kinetics of fcc metals with grain size in the micron range, no clear effect of γSF was detected for the submicron grain size range considered in the present analysis.}, number={32}, journal={NANOTECHNOLOGY}, author={Conrad, Hans}, year={2007}, month={Aug} }
 @article{jung_conrad_2007, title={Retardation of grain growth in electrodeposited Cu by an electric field}, volume={42}, ISSN={["0022-2461"]}, DOI={10.1007/s10853-006-0177-6}, number={11}, journal={JOURNAL OF MATERIALS SCIENCE}, author={Jung, Kang and Conrad, Hans}, year={2007}, month={Jun}, pages={3994–4003} }
 @article{jung_conrad_2006, title={Effects of an electric field applied during the solution heat treatment of the Al-Mg-Si-Cu alloy AA6111 on the subsequent natural aging kinetics and tensile properties}, volume={97}, ISSN={["0044-3093"]}, DOI={10.3139/146.101216}, abstractNote={Abstract}, number={2}, journal={ZEITSCHRIFT FUR METALLKUNDE}, author={Jung, K and Conrad, H}, year={2006}, month={Feb}, pages={145–149} }
 @article{conrad_jung_2006, title={Effects of grain size from millimeters to nanometers on the flow stress of metals and compounds}, volume={35}, ISSN={["0361-5235"]}, DOI={10.1007/BF02692540}, number={5}, journal={JOURNAL OF ELECTRONIC MATERIALS}, author={Conrad, H and Jung, K}, year={2006}, month={May}, pages={857–861} }
 @article{jung_conrad_2006, title={Influence of electric field strength applied during the solution heat treatment of the Al-Mg-Si-Cu Alloy AA6111}, volume={97}, number={1}, journal={Zeitschrift fur MetallkundeAmerican Journal of Physiology}, author={Jung, K. and Conrad, H.}, year={2006}, pages={35–38} }
 @article{ramachandran_jung_narayan_conrad_2006, title={Regular and high resolution transmission electron microscopy observations on the precipitates in a naturally aged Al-Mg-Si alloy AA6022}, volume={435}, journal={Materials Science & Engineering. A, Structural Materials: Properties, Microstructure and Processing}, author={Ramachandran, S. and Jung, K. and Narayan, J. and Conrad, H.}, year={2006}, pages={693–697} }
 @article{conrad_ramachandran_jung_narayan_2006, title={Transmission electron microscopy observations on the microstructure of naturally aged Al-Mg-Si alloy AA6022 processed with an electric field}, volume={41}, ISSN={["1573-4803"]}, DOI={10.1007/s10853-006-0840-y}, number={22}, journal={JOURNAL OF MATERIALS SCIENCE}, author={Conrad, H. and Ramachandran, S. and Jung, K. and Narayan, J.}, year={2006}, month={Nov}, pages={7555–7561} }
 @article{chia_jung_conrad_2005, title={Dislocation density model for the effect of grain size on the flow stress of a Ti-15.2 at.% Mo beta-alloy at 4.2-650 K}, volume={409}, ISSN={["1873-4936"]}, DOI={10.1016/j.msea.2005.03.117}, abstractNote={Hall–Petch (H–P) plots of the effect of grain size d = 4.6–22 μm on the flow stress σ at 4.2–650 K of a β-Ti–15.2 at.% Mo alloy gave that the parameter σi increased with strain ɛ and with decrease in temperature T. In contrast, the parameter KH–P was relatively independent of ɛ and T. The corresponding dislocation density ρ increased with ɛ and with decrease in d, giving the well-known relation σ/M ≈0.5 μbρ1/2, where M is the Taylor factor. The magnitudes of σi and KH–P calculated from ρ were in reasonable agreement with those obtained from the H–P plots. The grain size dependence of σ was in accord with Li's grain boundary ledge mechanism.}, number={1-2}, journal={MATERIALS SCIENCE AND ENGINEERING A-STRUCTURAL MATERIALS PROPERTIES MICROSTRUCTURE AND PROCESSING}, author={Chia, KH and Jung, K and Conrad, H}, year={2005}, month={Nov}, pages={32–38} }
 @article{conrad_jung_2005, title={Effect of grain size from millimeters to nanometers on the flow stress and deformation kinetics of Ag}, volume={391}, ISSN={["0921-5093"]}, DOI={10.1016/j.msea.2004.08.073}, abstractNote={Data on the effects of grain size, d = 9 nm to 0.26 mm on the flow stress and plastic deformation kinetics of Ag at low homologous temperatures were evaluated. Two regimes were identified for this grain-size range: Regime I (d > 500 nm) and Regime II (d ≈ 10–500 nm). The effect of grain size on the flow stress in both regimes could be described by a Hall–Petch equation. KH–P was however significantly smaller and σi larger for Regime II compared to I. Dislocation activity occurred in both regimes; dislocation cells were observed in Regime I, but not reported for II. The available data suggest that the dislocation density model governs the grain-size dependence of the flow stress in Regime I and that dislocation pile-up applies in Regime II. The rate-controlling mechanism(s) in each of the two regimes are discussed.}, number={1-2}, journal={MATERIALS SCIENCE AND ENGINEERING A-STRUCTURAL MATERIALS PROPERTIES MICROSTRUCTURE AND PROCESSING}, author={Conrad, H and Jung, K}, year={2005}, month={Jan}, pages={272–284} }
 @article{conrad_jung_2005, title={Effect of grain size from mm to nm on the flow stress and plastic deformation kinetics of Au at low homologous temperatures}, volume={406}, ISSN={["1873-4936"]}, DOI={10.1016/j.msea.2005.06.051}, abstractNote={Three grain size regimes were identified: Regime I (d > ∼0.5 μm), Regime II (d ≈ 10–500 nm) and Regime III (d < ∼10 nm). Grain size hardening in accord with the Hall–Petch (H–P) equation occurred in Regimes I and II, grain size softening with the flow stress proportional to d−1 occurred in III. The rate-controlling mechanism in Regime I was concluded to be the intersection of dislocations, that in II grain boundary shear promoted by the pile-up of dislocations and that in III grain boundary shear without pile-ups. The transition from I to II occurred when the dislocation cell size became larger than the grain size, that from II to III when the dislocation elastic interaction spacing became larger than the grain size. The H–P behavior in Regime I is in accord with the dislocation density model, that in II with the dislocation pile-up model. The general behavior of Au is similar to that reported previously for Cu and Ag.}, number={1-2}, journal={MATERIALS SCIENCE AND ENGINEERING A-STRUCTURAL MATERIALS PROPERTIES MICROSTRUCTURE AND PROCESSING}, author={Conrad, H and Jung, K}, year={2005}, month={Oct}, pages={78–85} }
 @article{mcneish_jung_balik_conrad_2005, title={Effects of preparation procedure and electric field frequency on the dielectric constants and electrorheology of a zeolite/silicone oil suspension}, volume={19}, ISSN={["1793-6578"]}, DOI={10.1142/s0217979205030050}, abstractNote={ Determined were the effects of preparation procedure and electric field frequency f = dc to 105 Hz on the dielectric constants and ER response (shear rate [Formula: see text]) of a suspension in silicone oil of 23 wt.% zeolite particles originally containing 19 wt.% H 2 O . Heating the oil and the zeolite particles at 110°C both prior to, and following, mixing decreased the conductivity of the suspension more than simply heating the suspension following mixing. The double heating procedure reduced the complex dielectric constant [Formula: see text] of the particles and the complex mismatch parameter β*. The ER shear stress τ E  was proportional to [Formula: see text] for the single heating and [Formula: see text] for the double heating, where [Formula: see text] is the complex dielectric constant of the silicone oil. The lower exponent corresponds to a higher water content and in turn higher conductivity of the suspension. Erratic ER response occurred for f =10 Hz in tests with [Formula: see text], but not in tests with [Formula: see text]. }, number={7-9}, journal={INTERNATIONAL JOURNAL OF MODERN PHYSICS B}, author={McNeish, D and Jung, K and Balik, CM and Conrad, H}, year={2005}, month={Apr}, pages={1191–1197} }
 @article{conrad_2005, title={Enhanced phenomena in metals with electric and magnetic fields: I Electric fields}, volume={46}, ISSN={["1347-5320"]}, DOI={10.2320/matertrans.46.1083}, abstractNote={The effects of an externally-applied electric field on the equilibria and kinetics of solid state transformations in metals and alloys are reviewed. Regarding equilibria, electric fields have been found to affect the solubility of solutes and the composition as well as volume fraction of phases present. Regarding kinetics, electric fields have been shown to affect recovery and recrystallization, precipitation, phase coarsening, hardenability and sintering. Electric fields thus offer an additional means of controlling microstructure and in turn properties. Our understanding of the effects of an electric field on solid state transformations in metals and alloys is very meager. It appears that most of the observed effects on kinetics are through its influence on vacancies.}, number={6}, journal={MATERIALS TRANSACTIONS}, author={Conrad, H}, year={2005}, month={Jun}, pages={1083–1087} }
 @article{conrad_narayan_jung_2005, title={Grain size softening in nanocrystalline TiN}, volume={23}, ISSN={["0263-4368"]}, DOI={10.1016/j.ijrmhm.2005.04.016}, abstractNote={The effect of grain size d on the hardness H of TiN is considered, with focus on the nanometer grain size range. H increases from ∼22 GPa to ∼32 GPa with decrease in d from single crystals to d = 50 nm. Three sets of data show that H decreases with further reduction in d below 50 nm, i.e., grain size softening occurs. The softening is not in complete or unequivocal accord with any of the three models normally proposed for such softening, namely Coble creep, grain boundary shear and dislocation line tension modification. Factors which could have contributed to the softening are: (a) changes in texture and in turn the corresponding value of the Taylor orientation factor M and (b) the presence of weakening imperfections produced during fabrication.}, number={4-6}, journal={INTERNATIONAL JOURNAL OF REFRACTORY METALS & HARD MATERIALS}, author={Conrad, H and Narayan, J and Jung, K}, year={2005}, pages={301–305} }
 @article{conrad_jung_2005, title={On the strain rate sensitivity of the flow stress of ultrafine-grained Cu processed by equal channel angular extrusion (ECAE)}, volume={53}, ISSN={["1359-6462"]}, DOI={10.1016/j.scriptamat.2005.04.030}, abstractNote={The strain rate sensitivity of the flow stress of ultrafine-grained Cu processed by ECAE is compared with that of vapor-deposited and electrodeposited Cu. The results for all three processing methods were in accord with the model of grain boundary shear promoted by the pile-up of dislocations.}, number={5}, journal={SCRIPTA MATERIALIA}, author={Conrad, H and Jung, K}, year={2005}, month={Sep}, pages={581–584} }
 @article{conrad_jung_2004, title={Effects of an electric field and current on phase transformations in metals and ceramics}, volume={19}, ISSN={["1532-2475"]}, DOI={10.1081/LMMP-200028063}, abstractNote={Abstract Theoretical and experimental results on the effects of an electric field or current on solid state phase transformations in metals and ceramics are reviewed. Examples are given of the effects on both equilibria and kinetics, and the mechanisms are considered. The available results provide a foundation, but indicate the need for more work. They do, however, indicate that electric fields and currents provide additional parameters for controlling microstructure, and offer the potential for reducing processing costs and related environmental pollution.}, number={4}, journal={MATERIALS AND MANUFACTURING PROCESSES}, author={Conrad, H and Jung, K}, year={2004}, pages={573–585} }
 @article{conrad_jung_2004, title={Effects of an external electric field applied during the solution heat treatment of the Al-Mg-Si-Cu alloy AA6111}, volume={95}, ISSN={["0044-3093"]}, DOI={10.3139/146.017965}, abstractNote={Abstract The application of an external dc electric field during the solution heat treatment (SHT) of AA6111 Al alloy increased the as-quenched resistivity ρ and hardness Hv. The increases represented reductions in SHT of 10–20 K required for a constant ρ or Hv. Analysis of the results gave that the field reduced both the enthalpy and entropy of solution. The resulting reduction in Gibbs free energy gave increases of 0.03–0.04 at.% in solubility of Mg2Si (or Al –Mg– Si – (Cu)-vacancy complexes) at 400 –600 °C, amounting to a factor of 33% increase in solubility at 400 °C and 6% at 600 °C.}, number={5}, journal={ZEITSCHRIFT FUR METALLKUNDE}, author={Conrad, H and Jung, K}, year={2004}, month={May}, pages={352–355} }
 @article{jung_conrad_2004, title={External electric field applied during solution heat treatment of the Al-Mg-Si alloy AA6022}, volume={39}, ISSN={["1573-4803"]}, DOI={10.1023/B:JMSC.0000044886.66798.95}, number={21}, journal={JOURNAL OF MATERIALS SCIENCE}, author={Jung, K and Conrad, H}, year={2004}, month={Nov}, pages={6483–6486} }
 @article{conrad_2004, title={Grain-size dependence of millimeters to nanometers}, volume={35A}, ISSN={["1543-1940"]}, DOI={10.1007/s11661-004-0214-5}, number={9}, journal={METALLURGICAL AND MATERIALS TRANSACTIONS A-PHYSICAL METALLURGY AND MATERIALS SCIENCE}, author={Conrad, H}, year={2004}, month={Sep}, pages={2681–2695} }
 @article{jung_conrad_2004, title={Microstructure gradient in 60Sn40Pb solder joints annealed under an external electric field}, volume={39}, ISSN={["0022-2461"]}, DOI={10.1023/B:JMSC.0000016189.01285.35}, number={5}, journal={JOURNAL OF MATERIALS SCIENCE}, author={Jung, K and Conrad, H}, year={2004}, month={Mar}, pages={1803–1804} }
 @article{antolovich_conrad_2004, title={The effects of electric currents and fields on deformation in metals, ceramics, and ionic materials: An interpretive survey}, volume={19}, ISSN={["1042-6914"]}, DOI={10.1081/LMMP-200028070}, abstractNote={Abstract The experimental and theoretical results of 50 years of research on the effects of electrical fields on deformation at high and low temperatures are reviewed. Application of currents to metals above a threshold in the range of about 3 × 102 to about 3 × 103 amp/cm2 (depending on material) increases the strain rate (i.e., decreases the stress). Above that threshold, the relationship between current density and strain rate is log-linear with a slope of about 3, independent of material. Many of the experiments were done in a “pulsed” mode to reduce Joule heating. The amount of Joule heating was measured and analytically eliminated from the results. Careful analysis of the data showed that the major effect of a field was to increase the frequency term . Reductions in the activation enthalpy and energy reductions due to the wind force were modest in terms of their effect on increasing the strain rate. The wind force on dislocations may be viewed as resulting from drift of the electron cloud; at low dislocation velocities the effect is to push the dislocation, while at high dislocation velocities the electron cloud acts as a drag. Thus the concept of a “push” and “drag” coefficient arises. Analysis is done in this paper to compute the electron wind force as a function of the orientation between the current density, Burgers, and unit normal vectors. The effects of fields in the range of 1–100 kV/cm are considered on ceramics, halides, and metals. The effect of a field on the deformation of ceramics and halides at high temperatures is generally to increase the strain rate. This is accomplished in a number of ways, such as changing the rate-controlling diffusion mechanism (e.g., from grain boundary to bulk in the case of Al2O3) or affecting the Peierls force (NaCl). The application of a field to metals might be expected, based on Gauss’ Law, to be nonexistent. However, significant effects are in fact observed. In the superplasticity regime for 7475 Al, a reduction of ∼20% in the flow stress, an increase of ∼20% in the strain hardening exponent, a significantly reduced cavitation, reduced grain growth, increased dispersoid-free zone (DFZ) thickness along the grain boundaries, and an alteration of the DFZ chemistry are all observed. Analysis of the data has revealed that the activation energy corresponds to that of bulk diffusion without the field and that there is a reduction of about 20% in the activation energy, which implies that there is either significant assistance from the field or that the field has changed the mechanism of diffusion. Understanding the basic mechanisms of deformation in the presence of fields and currents will allow these factors to be used intelligently in manipulating processes for improved structures and properties. Acknowledgment H. Conrad wishes to acknowledge that his participation was sponsored by the U. S. Army Research Office Award DAAD190210315 with Dr. William Mullins as technical monitor. Notes aThe initial yield in face centered cubic (FCC) or basal hexagonal close pack (HCP) (i.e., soft group metals) may be due to overcoming of long-range stress fields of dislocation groups distributed randomly in the material. Such a mechanism cannot benefit from thermal activation. However, once yielding has occurred, subsequent deformation is controlled by dislocation intersections and as such is thermally activated. Thus, even soft group metals exhibit thermal activation of the flow stress. bThere would be expected to be two competing effects: (1) a push effect based on the “electron wind” and (2) a drag effect based, to a first approximation, on the drag associated with free electrons. cIn these experiments the field was applied by making the specimen one of the electrodes of an electrostatic circuit. In this setup the polarity could easily be varied. dScrew dislocations acquire jogs only by screw/screw interactions; hence they do not have a charged vacancy cloud and should be relatively unaffected by the imposition of a field. eNote that the units of field strength on the abscissa may be converted to kV/cm by dividing by 100. fThis is the force arising from the applied shear stress resolved in the slip plane of the dislocation acting in the direction of the Burgers vector. It is normal to the unit tangent vector at the point of interest. gThe effective field is that component which acts in the direction of the Burgers vector and which produces a force normal to the dislocation.}, number={4}, journal={MATERIALS AND MANUFACTURING PROCESSES}, author={Antolovich, SD and Conrad, H}, year={2004}, pages={587–610} }
 @article{jung_conrad_2003, title={Effect of an electric field on microstructure coarsening in 60Sn40Pb solder joints}, volume={356}, ISSN={["1873-4936"]}, DOI={10.1016/s0921-5093(02)00851-1}, abstractNote={The influence of an electrostatic field E=15 and 25 kV cm−1 on the microstructure coarsening in 60Sn40Pb solder joints annealed at 150 °C was determined. Without a field the following were found: (a) the eutectic Pb and Sn phase size distributions (PSDs) fit the Bitti–DiNunzio model, (b) the phase size coarsening time exponent m=0.25 and (c) the intermetallic compound (IC) growth time exponent p=0.33. The field had only a slight effect on the PSDs and on the time exponents m or p; it, however, retarded significantly the rates of phase coarsening and of IC growth. The mechanism by which the field produced the retarding effects is not clear. A likely possibility is that it reduced the governing diffusion coefficient.}, number={1-2}, journal={MATERIALS SCIENCE AND ENGINEERING A-STRUCTURAL MATERIALS PROPERTIES MICROSTRUCTURE AND PROCESSING}, author={Jung, K and Conrad, H}, year={2003}, month={Sep}, pages={8–16} }
 @article{conrad_2003, title={Grain size dependence of the plastic deformation kinetics in Cu}, volume={341}, ISSN={["1873-4936"]}, DOI={10.1016/s0921-5093(02)00238-1}, abstractNote={Data on the effect of grain size d in the range of nm to mm on the plastic deformation kinetics of Cu at 77–373 K are analyzed to determine the influence of grain size on the strain rate-controlling mechanism. Three grain size regimes were identified: Regimes I (d≈10−6–10−3 m), II (d≈10−8–10−6 m) and III (d<∼10−8 m). A dislocation cell structure characterizes Regime II, which no longer occurs in Regime II. The absence of all intragranular dislocation activity characterizes Regime III. The following mechanisms were concluded to be rate-controlling for ε̇≈10−5–10−3s−1: (a) Regime I, intersection of dislocations; (b) Regime I, grain boundary shear promoted by dislocation pile-ups; and (c) Regime III, grain boundary shear. The major effect of grain size on the intersection mechanism in Regime I is on the mobile and forest dislocation densities; the effect in Regime II is on the number of dislocations and on the number of grain boundary atom sites; the effect in Regime III is on the number of grain boundary atom sites. The transition grain size from one regime to another depends on the strain rate and temperature. Crystallographic texture is also important.}, number={1-2}, journal={MATERIALS SCIENCE AND ENGINEERING A-STRUCTURAL MATERIALS PROPERTIES MICROSTRUCTURE AND PROCESSING}, author={Conrad, H}, year={2003}, month={Jan}, pages={216–228} }
 @article{conrad_yang_2002, title={Effect of an electric field on the plastic deformation kinetics of electrodeposited Cu at low and intermediate temperatures}, volume={50}, ISSN={["1873-2453"]}, DOI={10.1016/S1359-6454(02)00109-X}, abstractNote={The plastic deformation kinetics of electrodeposited (EP) Cu foil with grain size d=0.6μm was determined at 293–448 K without and with a concurrent electrostatic field E=2.5kV/cm and compared with that for vapor-deposited (VP) Cu foil tested at 77–473 K without a field. The electric field produced a 20–25% decrease in the flow stress of the EP Cu. The apparent activation volume v=kT∂lnε̇/∂σ both without and with electric field, exhibited a minimum at 350–375 K. The strain rate-controlling mechanism at T≤350K was concluded to be grain boundary shear promoted by the pile-up of dislocations at grain boundaries, while that at T=373–473K was concluded to be the intersection of dislocations. The major effect of the electric field was to give a reduction in the dislocation density produced by straining, which was related to the electric charge density at the specimen surface.}, number={11}, journal={ACTA MATERIALIA}, author={Conrad, H and Yang, D}, year={2002}, month={Jun}, pages={2851–2866} }
 @article{conrad_narayan_2002, title={Mechanism for grain size softening in nanocrystalline Zn}, volume={81}, ISSN={["0003-6951"]}, DOI={10.1063/1.1507353}, abstractNote={A technique (laser deposition of Zn/W multilayers) for producing stable nanocrystalline (nc) Zn films free of undesirable imperfections down to a grain size of d=6 nm is presented. These films exhibited grain size softening (inverse Hall–Petch effect) for d⩽11 nm, providing support that this can be a real phenomenon in nc solids. The mechanism responsible for the softening was concluded to be thermally activated grain boundary shear.}, number={12}, journal={APPLIED PHYSICS LETTERS}, author={Conrad, H and Narayan, J}, year={2002}, month={Sep}, pages={2241–2243} }
 @article{conrad_narayan_2002, title={Mechanisms for grain size hardening and softening in Zn}, volume={50}, ISSN={["1873-2453"]}, DOI={10.1016/S1359-6454(02)00357-9}, abstractNote={An analysis of the rate-controlling mechanisms corresponding to effect of grain size d=10−9 to 10−3 m on the flow stress of Zn at 300K and ϵ̇=10-4-10-3 s−1 was performed. Three grain size regimes were indicated: Regime I, d≈10−6–10−3 m, Regime II, d≈10−6–10−8 m and Regime III, d<10−8 m. Grain size hardening occurred in Regimes I and II and grain size softening in Regime III. The intersection of pyramidal forest dislocations by basal dislocations was concluded to be the rate-controlling mechanism in both Regimes I and II, the major effect of the grain size being on the forest and gliding dislocation densities. The absence of twinning and a dislocation cell structure distinguished Regime II from I. The grain size softening observed in Regime III is in better accord with grain boundary shear than with grain boundary diffusion creep.}, number={20}, journal={ACTA MATERIALIA}, author={Conrad, H and Narayan, J}, year={2002}, month={Dec}, pages={5067–5078} }
 @article{conrad_yang_2002, title={Plastic deformation kinetics of electrodeposited Cu foil at low and intermediate homologous temperatures}, volume={31}, ISSN={["0361-5235"]}, DOI={10.1007/s11664-002-0148-x}, number={4}, journal={JOURNAL OF ELECTRONIC MATERIALS}, author={Conrad, H and Yang, D}, year={2002}, month={Apr}, pages={304–312} }
 @article{yang_conrad_2002, title={Plastic deformation kinetics of fine-grained MgO in tension}, volume={37}, ISSN={["0022-2461"]}, DOI={10.1023/A:1013734011298}, number={3}, journal={JOURNAL OF MATERIALS SCIENCE}, author={Yang, D and Conrad, H}, year={2002}, month={Feb}, pages={615–620} }
 @article{conrad_2002, title={Thermally activated plastic flow of metals and ceramics with an electric field or current}, volume={322}, ISSN={["0921-5093"]}, DOI={10.1016/s0921-5093(01)01122-4}, abstractNote={The effects of high density electric current pulses (103–106 A cm−2) on the flow stress of metals at low homologous temperatures and of a modest external electric field on the flow stress of fine-grained oxides at high temperatures is presented. The results in both cases are evaluated in terms of thermally-activated plastic deformation processes. In the case of the metals, the influence of an electron wind on each of the parameters in the equation for the thermally-activated motion of dislocations was determined, the largest effect being on the pre-exponential. The derived electron wind push coefficient was one or more orders of magnitude larger than the value normally accepted for the electron drag coefficient. In the case of the oxides, the substantial effect of an applied electric field on the flow stress was evaluated in terms of its influence on the electrochemical potential of vacancies in the space-charge cloud adjacent to the grain boundaries. Both the derived space-charge cloud width and the electric potential/stress parameter Δ∅/Δσ are in reasonable accord with theoretical predictions.}, number={1-2}, journal={MATERIALS SCIENCE AND ENGINEERING A-STRUCTURAL MATERIALS PROPERTIES MICROSTRUCTURE AND PROCESSING}, author={Conrad, H}, year={2002}, month={Jan}, pages={100–107} }
 @article{fahmy_conrad_2001, title={Electrosintering of iron powder compacts}, volume={32}, DOI={10.1007/s11661-001-0097-7}, number={3A}, journal={Metallurgical and Materials Transactions. A, Physical Metallurgy and Materials Science}, author={Fahmy, Y. and Conrad, H.}, year={2001}, pages={811–819} }
 @article{yang_conrad_2001, title={Exploratory study into the effects of an electric field and of high current density electropulsing on the plastic deformation of TiAl}, volume={9}, ISSN={["0966-9795"]}, DOI={10.1016/S0966-9795(01)00094-2}, abstractNote={The effects of an external electric field (2 kV/cm) and of high density electric current pulsing (2×104 A/cm2, 60 μs duration and 20 pulses per second) on the stress–strain curve of TiAl in compression at 600 °C were determined. The field gave a significant reduction in yield stress followed by a moderate increase in strain hardening. In contrast, electropulsing increased the yield stress and gave a smaller increase in strain hardening. The effects of the electric field and of electropulsing developed during the early stages of plastic deformation (ε<∼2%) and were retained upon subsequent straining without the field or current. Moreover, initial straining (ε<∼2%) without an electric field gave a microstructure which did not respond to the electric field applied during subsequent straining. The results suggest that the electric field and the electropulsing had an influence on the microstructure which developed at small strain through an effect on one or more of the following: (a) stacking fault energy, (b) twinning energy or (c) antiphase boundary energy.}, number={10-11}, journal={INTERMETALLICS}, author={Yang, D and Conrad, H}, year={2001}, pages={943–947} }
 @article{zheng_lu_conrad_2001, title={Influence of an external electric field during quenching on the hardenability of steel}, volume={44}, ISSN={["1359-6462"]}, DOI={10.1016/S1359-6462(00)00608-4}, abstractNote={Deep cryogenic heat treatment is a supplementary process, which is performed in tool steels after quench and before temper regularly. In this study, the effect of the electric current flow through the deep cryogenically treated samples was investigated via the X-ray diffraction (XRD), scanning electron microscope (SEM), energy dispersive spectroscope (EDX), hardness test, and pin-on-disk wear testing machine. Results showed that the deep cryogenic heat treatment improves the carbide percentage, distribution, hardness and wear resistance of the 1.2080 tool steel, as compared with those of the conventionally treated. Further improvement in the wear resistance and hardness were also observed due to the formation of some newly formed nano-sized carbides in the structure. It was also observed that the electric current flow leads to a decrease in this improvement due to its effect on the as-quench vacancies, which were ignored as powerful places for carbide nucleation during the deep cryogenic heat treatment. It was also shown that the predominant wear mechanism is a combination of adhesive and tribo-chemical wear.}, number={2}, journal={SCRIPTA MATERIALIA}, author={Zheng, M and Lu, XP and Conrad, H}, year={2001}, month={Feb}, pages={381–385} }
 @article{jung_conrad_2001, title={Microstructure coarsening during static annealing of 60Sn4OPb solder joints: I stereology}, volume={30}, ISSN={["0361-5235"]}, DOI={10.1007/s11664-001-0114-z}, number={10}, journal={JOURNAL OF ELECTRONIC MATERIALS}, author={Jung, K and Conrad, H}, year={2001}, month={Oct}, pages={1294–1302} }
 @article{jung_conrad_2001, title={Microstructure coarsening during static annealing of 60Sn4OPb solder joints: II eutectic coarsening kinetics}, volume={30}, ISSN={["0361-5235"]}, DOI={10.1007/s11664-001-0115-y}, number={10}, journal={JOURNAL OF ELECTRONIC MATERIALS}, author={Jung, K and Conrad, H}, year={2001}, month={Oct}, pages={1303–1307} }
 @article{jung_conrad_2001, title={Microstructure coarsening during static annealing of 60Sn4OPb solder joints: III intermetallic compound growth kinetics}, volume={30}, ISSN={["0361-5235"]}, DOI={10.1007/s11664-001-0116-x}, number={10}, journal={JOURNAL OF ELECTRONIC MATERIALS}, author={Jung, K and Conrad, H}, year={2001}, month={Oct}, pages={1308–1312} }
 @article{conrad_2001, title={Space charge and the dependence of the flow stress of ceramics on an applied electric field}, volume={44}, ISSN={["1359-6462"]}, DOI={10.1016/S1359-6462(00)00589-3}, abstractNote={Spark plasma sintering (SPS), also known as pulsed electric current sintering (PECS) or field-assisted sintering technique (FAST), belongs to a class of powder metallurgy techniques. In SPS, the sample is simultaneously subjected to a uniaxial pressure and electrical current in a vacuum or protective atmosphere. Although the fundamental principles of this procedure were first proposed over 50 years ago, SPS acquired major importance only within the last 20 years. Scholars come to realize that SPS technique enables control of the powder surface condition, atomic diffusion behavior, and phase stability and crystal growth behavior, as well as accelerating densification of hard-to-sinter materials. This review summarizes the latest research findings with respect to experimental procedures, densification behaviors, microstructural characteristics, and mechanical properties of various traditional and novel materials synthesized using SPS, mainly highlighting the heating mechanisms in SPS and the effects induced by multi-physical fields on materials. In addition, influences of operating parameters containing current, voltage, and uniaxial pressure on product characteristics are reviewed for a wide range of materialsincluding hard-to-sinter materials, carbon-containing materials, nanocrystalline materials, non-equilibrium materials, gradient materials, interconnect materials, complex shape materials, and advanced functional materials.}, number={2}, journal={SCRIPTA MATERIALIA}, author={Conrad, H}, year={2001}, month={Feb}, pages={311–316} }
 @article{tang_conrad_2000, title={An analytical model for magnetorheological fluids}, volume={33}, ISSN={["0022-3727"]}, DOI={10.1088/0022-3727/33/23/304}, abstractNote={Two- and three-dimensional analytical models for the yield stress of magnetorheological (MR) fluids as a function of magnetic field and total volume fraction of particles are developed, which are in accord with experimental data. Important factors are the packing density of the particles in the aggregates, their magnetization saturation and the enhanced field between the particles. Our calculations indicate that the torsional force components due to the anisotropic magnetizability of the entire MR suspension may contribute up to 20% of the resultant shear force. Further, when the particles are completely saturated the yield stress is proportional to the square of the saturation magnetization.}, number={23}, journal={JOURNAL OF PHYSICS D-APPLIED PHYSICS}, author={Tang, XL and Conrad, H}, year={2000}, month={Dec}, pages={3026–3032} }
 @article{conrad_2000, title={Effects of electric current on solid state phase transformations in metals}, volume={287}, ISSN={["1873-4936"]}, DOI={10.1016/s0921-5093(00)00780-2}, abstractNote={The influence of an electric current on the following solid state transformations in metals are considered: (1) intermetallic compound formation and growth in diffusion couples, (2) precipitation, (3) crystallization of amorphous alloys and (4) recrystallization and grain growth of cold worked metals. The formation and growth of intermetallic compounds were in qualitative accord with electromigration theory. Regarding precipitation, an electric current can either enhance or retard the precipitation rate, depending on the alloy, the current density and its frequency. Important factors appear to be the effect of current on the quenched-in vacancies and the presence of an internal stress. Both a continuous d.c. current and high current density electropulsing enhanced the crystallization rate of amorphous alloys. The effects are greater than can be explained by simple electromigration theory and suggest the cooperative motion of a larger number of atoms. Electropulsing enhanced the recrystallization rate of cold worked metals, but retarded subsequent grain growth. Enhancement of the recrystallization rate resulted mainly from an increase in the pre-exponential factor of the Arrhenius rate equation, which is considered to refer to the nucleation rate. Retardation of subsequent grain growth resulted from a lower residual dislocation density within the newly-formed grains.}, number={2}, journal={MATERIALS SCIENCE AND ENGINEERING A-STRUCTURAL MATERIALS PROPERTIES MICROSTRUCTURE AND PROCESSING}, author={Conrad, H}, year={2000}, month={Aug}, pages={227–237} }
 @article{conrad_2000, title={Electroplasticity in metals and ceramics}, volume={287}, ISSN={["1873-4936"]}, DOI={10.1016/s0921-5093(00)00786-3}, abstractNote={The influence of an electric field or corresponding current on the plastic deformation of metals and ceramics is reviewed. Regarding metals, the following are considered: (a) the effects of high density electric current pulse on the flow stress at low to intermediate homologous temperatures; and (b) the effects of an external electric field on superplasticity at high temperatures. The major effect of the current pulses was to reduce the thermal component of the flow stress. This resulted from the combined action of an electron wind force, a decrease in the activation enthalpy for plastic deformation and an increase in the pre-exponential, the last making the largest contribution. Besides giving a reduction in the flow stress during superplastic deformation, an external electric field reduced cavitation and grain growth. The influence of the external field appears to be on the migration of vacancies or solute atom-vacancy complexes along grain boundaries to the charged surface. In the case of ceramics, the effects of an internal electric field on the plastic deformation of polycrystalline NaCl at 0.28–0.75TM and on the superplasticity of fine-grained oxides (MgO, Al2O3 and ZrO2) at T>0.5TM are considered. Regarding NaCl, at T≤0.5TM an electric field E≥10 kV cm−1 is needed to enhance dislocation mobility in single crystals. However, a field of only 1 kV cm−1 significantly reduced the flow stress in polycrystals, which is concluded to result from an enhancement of cross slip. At T>0.5TM, there occurred a decrease in the flow stress of polycrystalline NaCl along with a reduction in the rate-controlling diffusion activation energy. Regarding the fine-grained oxides at T>0.5TM, an internal electric field E≤0.3 kV cm−1 gave an appreciable, reversible, reduction in the flow stress by an enhancement of the rate-controlling diffusion process. Limited work suggests that a field may also retard grain growth and cavitation in ceramics.}, number={2}, journal={MATERIALS SCIENCE AND ENGINEERING A-STRUCTURAL MATERIALS PROPERTIES MICROSTRUCTURE AND PROCESSING}, author={Conrad, H}, year={2000}, month={Aug}, pages={276–287} }
 @article{conrad_yang_2000, title={Influence of an electric field on the plastic deformation of fine-grained MgO at high homologous temperatures}, volume={48}, ISSN={["1359-6454"]}, DOI={10.1016/S1359-6454(00)00203-2}, abstractNote={The effect of a dc electric field up to 385 V/cm on the stress–strain behavior in tension of fine-grained MgO (do=5.3 μm) was determined at 1500–1600°C. The field produced a decrease in the flow stress and an increase in the elongation. The reduction in flow stress was reversible and proportional to the field strength, amounting to ∼50% of the flow stress for E=220 V/cm. The field had only little, if any, influence on the stress exponent n=∂lnε̇/∂lnσ, which had a value of ∼1.0, indicating that it did not change the rate-controlling mechanism. The decrease in flow stress produced by the field is given byΔσ∗E=ZeExsc/Ωwhere Z=+2 is the charge on the rate-controlling Mg2+ ions, e is the electron charge, E is the field strength, xsc is the width of the space charge region and Ω is the atomic volume. The present results are the first of their kind which provide experimental support for the use of an electrochemical potential in diffusion flux equations pertaining to the plastic deformation of ceramic materials.}, number={16}, journal={ACTA MATERIALIA}, author={Conrad, H and Yang, D}, year={2000}, month={Oct}, pages={4045–4052} }
 @article{conrad_2000, title={Influence of an electric or magnetic field on the liquid-solid transformation in materials and on the microstructure of the solid}, volume={287}, ISSN={["0921-5093"]}, DOI={10.1016/s0921-5093(00)00777-2}, abstractNote={The influence of an electric or magnetic field on the liquid–solid transformation in materials and the microstructure of the resulting solid is reviewed. In the case of metals, electromigration in the liquid produced substantial changes in composition due to differences in ionic mobility. Further, both a small, continuous d.c. current (∼0.1 A cm−2) and high density (∼103 A cm−2) electropulsing refined the microstructure of castings. A magnetic field (>1 T) applied during directional solidification significantly reduced the convective flow in the melt and distorted the cellular array, but did not affect the dendritic array, nor the macrosegregation. The mechanisms by which these effects on the microstructure occur are not clear. In the case of electropulsing, the influence of the current appears to be to enhance the nucleation rate and at the higher current densities to deform and fracture dendrites by the pinch effect. The influence of a magnetic field appears to be largely due to the Lorentz forces which are established between the motion of the conductive melt and the applied field. Regarding semiconductors, an electric current of 1–10 A cm−2 enhanced the growth rate of GaAs single crystals on a substrate and reduced the dislocation density in the product. Theoretical treatments of these effects are in good accord with the experimental results. In the case of polymers, an electric field of ∼1 V cm−1 ‘pulled’ a camphor single crystal from a solution of camphor in CCl4. The mechanism by which this interesting phenomenon occurs still needs to be established.}, number={2}, journal={MATERIALS SCIENCE AND ENGINEERING A-STRUCTURAL MATERIALS PROPERTIES MICROSTRUCTURE AND PROCESSING}, author={Conrad, H}, year={2000}, month={Aug}, pages={205–212} }
 @article{lai_conrad_teng_chao_2000, title={Nanocrystallization of amorphous Fe-Si-B alloys using high current density electropulsing}, volume={287}, ISSN={["0921-5093"]}, DOI={10.1016/s0921-5093(00)00781-4}, abstractNote={Amorphous Fe–Si–B ribbons were nanocrystallized by using high current density dc electropulsing instead of the usual annealing. The microstructural changes were investigated by TEM, SAD, XRD, and Mössbauer spectral analysis. It was found that current pulsing promotes crystallization at a lower temperature than the usual annealing temperature. The primary crystallization temperatures of Metglas 2605 S-2 and Finemet were significantly lowered by pulsing. This enabled us to obtain 20–30 vol.% of single phase, α-Fe(Si) with a grain size of 15–20 nm in Metglas 2605 S-2. As a consequence, certain magnetic properties of this material are improved with respect to the as-quenched state. A preliminary interpretation is given for the phenomenon of electro-nanocrystallization.}, number={2}, journal={MATERIALS SCIENCE AND ENGINEERING A-STRUCTURAL MATERIALS PROPERTIES MICROSTRUCTURE AND PROCESSING}, author={Lai, ZH and Conrad, H and Teng, GQ and Chao, YS}, year={2000}, month={Aug}, pages={238–247} }
 @article{conrad_narayan_2000, title={On the grain size softening in nanocrystalline materials}, volume={42}, ISSN={["1359-6462"]}, DOI={10.1016/S1359-6462(00)00320-1}, abstractNote={In this study, Cu-Cr-Mg alloy wires were prepared by up-drawing continuous casting and multi-pass drawing. The effect of the solid solution process on the strength and electrical conductivity of the Cu-Cr-Mg alloy was investigated. The solid solution degree of Cu-Cr-Mg alloys with different solid solution processes was evaluated by XRD. The types and morphologies of nanoprecipitates of the two alloys during different thermomechanical treatments were compared by selected area electron diffraction in TEM, and the degree of recrystallization of the peak-aged Cu-Cr-Mg alloy was analyzed by EBSD. The results showed that the degree of supersaturated solid solution of the as-cast Cu-Cr-Mg alloy was comparable to that of the as-cast Cu-Cr-Mg alloy after holding at 950 ℃ for 1 h and water quenching. Meanwhile, the strength of the as-cast Cu-Cr-Mg alloy was 52.2 MPa higher than that of the solution-treated Cu-Cr-Mg alloy, and the decrease in conductivity was only 6.3% IACS. The microstructure results showed that a large number of dispersed nanoscale precipitates existed in the matrix of both alloys, and the precipitates were close in size. The results of the strengthened model calculations are also close to the experimental results.}, number={11}, journal={SCRIPTA MATERIALIA}, author={Conrad, H and Narayan, J}, year={2000}, month={May}, pages={1025–1030} }
 @article{conrad_2000, title={Preface - Enhanced synthesis, processing and properties of materials with electric and magnetic fields}, volume={287}, ISSN={["0921-5093"]}, DOI={10.1016/s0921-5093(00)00764-4}, number={2}, journal={MATERIALS SCIENCE AND ENGINEERING A-STRUCTURAL MATERIALS PROPERTIES MICROSTRUCTURE AND PROCESSING}, author={Conrad, H}, year={2000}, month={Aug}, pages={VII-VII} }
 @article{conrad_wu_tang_1999, title={Conductivity in electrorheology}, volume={13}, ISSN={["0217-9792"]}, DOI={10.1142/s0217979299001739}, abstractNote={ Analytical models for the quasi-static ER behavior of suspensions have been developed which take into consideration both the conductivity and dielectric mismatches between the components and the supra-ohmic behavior of the host liquid. Included are models for: (a) slightly conducting particles, (b) insulating particles with a conducting film and (c) highly conducting particles with an insulating film. Both dc and ac fields are treated. Good agreement between predicted and experimental results occur. The models indicate that promising ER suspensions for use over a wide frequency range are those which contain highly conducting particles coated with an "insulating" film which has a hihg dielectric constant and a high electrical breakdown strength. It is conceivable that with proper desigh a yield strength of 20–100 kPa may be obtained with an acceptable current density. }, number={14-16}, journal={INTERNATIONAL JOURNAL OF MODERN PHYSICS B}, author={Conrad, H and Wu, CW and Tang, X}, year={1999}, month={Jun}, pages={1729–1738} }
 @article{wu_conrad_1999, title={Electrorheology of suspensions of si particles with an oxide film in silicone oil}, volume={13}, ISSN={["0217-9792"]}, DOI={10.1142/s0217979299001715}, abstractNote={ The electrorheological (ER) behavior of suspensions of oxidized Si partices in silicone oil was determined with dc electric field E 0. The yield stress decreased with the thickness of the surface oxide film and was proportional to E01.7 when the surface film thickness δ=0.2 μ m . The current density and the field dependent exponent decreased with the surface film thickness. When the surface film thickness δ=0.05μ m , the current density was proportional to E001.3. The results are in accord with our recent non-ohmic conduction model for the influence of an oxide film on conducting particles on ER response. The ER response of highly conducting particles with a low conductivity coating with ac field is also discussed. }, number={14-16}, journal={INTERNATIONAL JOURNAL OF MODERN PHYSICS B}, author={Wu, CW and Conrad, H}, year={1999}, month={Jun}, pages={1713–1720} }
 @article{boissy_wu_fahmy_conrad_1999, title={Experimental study of the yield stress of electrorheological suspensions under AC field: Comparison with a theoretical model}, volume={13}, ISSN={["0217-9792"]}, DOI={10.1142/s0217979299001788}, abstractNote={ Recently a model describing the interaction between the particles of an electrorheological suspension and the resulting properties (yield stress, current density) has been proposed by Wu and Conrad. This model takes into account both the conductivity and the permittivity of each constituent of the suspension and predicts the behavior under DC and AC fields. The goal of the present work is to compare the predictions of this model with data available in the literature and with additional experiments using DC and AC fields at frequencies up to 2000 Hz. The ER fluids used in our experiments are suspensions of different ceramics particles ( Al 2 O 3, ZrO 2, TiO 2, CaTiO 3, BaTiO 3) in silicone oil. These particles cover a wide range of permittivity and conductivity, which allows us to study the ER effect with varying values of the conductivity and/or permittivity mismatch between the particles and the liquid. The model is in reasonable accord with experiment. }, number={14-16}, journal={INTERNATIONAL JOURNAL OF MODERN PHYSICS B}, author={Boissy, C and Wu, CW and Fahmy, Y and Conrad, H}, year={1999}, month={Jun}, pages={1775–1782} }
 @article{campbell_fahmy_conrad_1999, title={Influence of an electric field on the plastic deformation of fine-grained Al2O3}, volume={30}, ISSN={["1073-5623"]}, DOI={10.1007/s11661-999-0119-4}, number={11}, journal={METALLURGICAL AND MATERIALS TRANSACTIONS A-PHYSICAL METALLURGY AND MATERIALS SCIENCE}, author={Campbell, J and Fahmy, Y and Conrad, H}, year={1999}, month={Nov}, pages={2817–2823} }
 @article{conrad_guo_fahmy_yang_1999, title={Influence of microstructure size on the plastic deformation kinetics, fatigue crack growth rate, and low-cycle fatigue of solder joints}, volume={28}, ISSN={["0361-5235"]}, DOI={10.1007/s11664-999-0184-x}, number={9}, journal={JOURNAL OF ELECTRONIC MATERIALS}, author={Conrad, H and Guo, Z and Fahmy, Y and Yang, D}, year={1999}, month={Sep}, pages={1062–1070} }
 @article{campbell_fahmy_conrad_1999, title={Plastic deformation kinetics of fine-grained alumina}, volume={30}, ISSN={["1543-1940"]}, DOI={10.1007/s11661-999-0118-5}, number={11}, journal={METALLURGICAL AND MATERIALS TRANSACTIONS A-PHYSICAL METALLURGY AND MATERIALS SCIENCE}, author={Campbell, J and Fahmy, Y and Conrad, H}, year={1999}, month={Nov}, pages={2809–2816} }
 @article{yang_conrad_1999, title={Plastic deformation of fine-grained Al2O3 in the presence of an electric field}, volume={41}, ISSN={["1359-6462"]}, DOI={10.1016/S1359-6462(99)00126-8}, abstractNote={The effect of electric field/current on creep deformation was examined in fine-grained 8 mol% Y2O3 stabilized cubic ZrO2 (8Y-CSZ) under direct and alternative current (DC and AC) conditions. Even at similar sample temperature of 1160–1170 °C, although the electric fields/currents accelerate the deformation of 8Y-CSZ, the acceleration effect (athermal effect), which cannot be explained by an increase of the sample temperature due to Joule heating, is much pronounced in AC than in DC. Under the deformation without the electric field/current, the creep behavior can be characterized by diffusional creep processes with a stress exponent of n ≈ 1, whereas under DC and AC, the predominant mechanism changes to grain boundary sliding (GBS) with n ≈ 2. This indicates that the athermal effect under the electric field/current changes the deformation mechanism from diffusional creep to GBS mechanisms by enhancing GBS and its rate controlling process of cation diffusivity, especially in AC.}, number={4}, journal={SCRIPTA MATERIALIA}, author={Yang, D and Conrad, H}, year={1999}, month={Jul}, pages={397–401} }
 @article{conrad_yang_1999, title={The rate-controlling mechanism(s) during plastic deformation of polycrystalline NaCl at 0.28-0.75 T-M}, volume={34}, DOI={10.1023/A:1004537300154}, number={4}, journal={Journal of Materials Science}, author={Conrad, H. and Yang, D.}, year={1999}, pages={821–826} }
 @article{fahmy_hare_tooke_conrad_1998, title={Effects of a pulsed magnetic treatment on the fatigue of low carbon steel}, volume={38}, ISSN={["1359-6462"]}, DOI={10.1016/S1359-6462(98)00046-3}, abstractNote={Results of cavitation erosion tests for EN8 steel, nickel-aluminium bronze (NAB), 70/30 brass and aluminium alloy AA2014-T6 following alternating magnetic field (AMF) treatment are presented. These alloys were selected because of their magnetic nature; EN8 steel is ferromagnetic, NAB and 70/30 brass are diamagnetic and AA2014 alloy is paramagnetic. The indirect cavitation erosion tests (ASTM G32–10 standard) were fulfilled at a frequency of 20 kHz in deionized water which was maintained at room temperature and ambient pressure for a predetermined time. The results show significant decrease in the mass loss for all samples that had underg1 AMF treatment. The eroded samples were characterised by means of scanning electron microscopy, while microhardness measurements showed an increase in the surface hardness as a result of the AFM treatment. The results of X-ray diffraction indicated formation of more compressive residual stresses following treatment, while examination by transmission electron microscopy showed evidence of dislocation movement away from grain boundaries. In the case of the NAB and 20014-T6 alloys, there was evidence of new precipitation. By considering the deformed state and the magnetic nature of each alloy, mechanisms explaining the increase in the cavitation erosion resistance due to the treatment are proposed and discussed.}, number={9}, journal={SCRIPTA MATERIALIA}, author={Fahmy, Y and Hare, T and Tooke, R and Conrad, H}, year={1998}, month={Apr}, pages={1355–1358} }
 @article{li_conrad_1998, title={Electric field strengthening during superplastic creep of Zn-5 wt% Al: A negative electroplastic effect}, volume={39}, ISSN={["1359-6462"]}, DOI={10.1016/S1359-6462(98)00268-1}, abstractNote={The effect of an electric field on the microstructure and mechanical properties of an Al-Cu-Li alloy was investigated by optical microscopy (OM), scanning electron microscopy (SEM), transmission electron microscopy (TEM), microhardness tests, electric conductivity tests, and tensile tests. The results show that the field-aged sample exhibited a shorter stable hardening plateau period and an earlier peak-aged stage than the field-free-aged sample. Also, the hardness and conductivity of the field-aged sample during the hardening plateau interval were generally greater than that of the field-free-aged sample. This might be due to the fact that the electric field promoted the precipitation of the β'/δ' phase and accelerated the growth of the θ' phase. The improvement in mechanical properties of the field-aged sample was caused by the segregation of the T1 phase at the subgrain boundaries and the grain boundaries. A vacancy-atom complex diffusion model successfully explains the microstructure evolution and the change in mechanical properties of the alloy during the ageing process accompanied by an electric field.}, number={7}, journal={SCRIPTA MATERIALIA}, author={Li, SC and Conrad, H}, year={1998}, month={Sep}, pages={847–851} }
 @article{wu_conrad_1998, title={Electrical properties of electrorheological particle clusters}, volume={255}, ISSN={["0921-5093"]}, DOI={10.1016/s0921-5093(98)00777-1}, abstractNote={The electrical conductivity of static clusters of ∼220-μm diameter humidified glass beads in silicone oil arranged in a rectangular or cubic lattice was determined under d.c. electric field. The current density flowing through the cluster increased with field strength. It was independent of the number of glass spheres forming a chain in the cluster but increased with the number of chains comprising the cluster. The conductivity of a single chain was about twice the saturation conductivity of the silicone oil. Some possible reasons for the enhanced current density of a cluster of particles compared to an equal number of single-row chains are proposed.}, number={1-2}, journal={MATERIALS SCIENCE AND ENGINEERING A-STRUCTURAL MATERIALS PROPERTIES MICROSTRUCTURE AND PROCESSING}, author={Wu, CW and Conrad, H}, year={1998}, month={Oct}, pages={66–69} }
 @article{wu_chen_conrad_1998, title={Electrorheology of a zeolite silicone oil suspension with dc and ac fields}, volume={31}, ISSN={["0022-3727"]}, DOI={10.1088/0022-3727/31/8/006}, abstractNote={The electrorheology of a zeolite/silicone oil suspension with direct current (dc) and alternating current (ac) electric fields was determined at room temperature. The shear yield stress changed only slightly with the field frequency, but the current density increased considerably. Good agreement occurs between the experimental results and those predicted by our model for both the shear yield stress and the current density. This study shows that there is a significant electrorheological (ER) effect over a large frequency range when a suspension has both a high conductivity ratio and a high dielectric ratio of the particles to the host oil.}, number={8}, journal={JOURNAL OF PHYSICS D-APPLIED PHYSICS}, author={Wu, CW and Chen, Y and Conrad, H}, year={1998}, month={Apr}, pages={960–963} }
 @article{yang_conrad_1998, title={Grain size dependence of electroplastic effect in NaCl}, volume={97}, number={6}, journal={British Ceramic Transactions}, author={Yang, D. and Conrad, H.}, year={1998}, pages={263–267} }
 @article{yang_conrad_1998, title={Influence of an electric field on grain growth in extruded NaCl}, volume={38}, ISSN={["1359-6462"]}, DOI={10.1016/S1359-6462(98)00042-6}, abstractNote={Spark plasma sintering (SPS), also known as pulsed electric current sintering (PECS) or field-assisted sintering technique (FAST), belongs to a class of powder metallurgy techniques. In SPS, the sample is simultaneously subjected to a uniaxial pressure and electrical current in a vacuum or protective atmosphere. Although the fundamental principles of this procedure were first proposed over 50 years ago, SPS acquired major importance only within the last 20 years. Scholars come to realize that SPS technique enables control of the powder surface condition, atomic diffusion behavior, and phase stability and crystal growth behavior, as well as accelerating densification of hard-to-sinter materials. This review summarizes the latest research findings with respect to experimental procedures, densification behaviors, microstructural characteristics, and mechanical properties of various traditional and novel materials synthesized using SPS, mainly highlighting the heating mechanisms in SPS and the effects induced by multi-physical fields on materials. In addition, influences of operating parameters containing current, voltage, and uniaxial pressure on product characteristics are reviewed for a wide range of materialsincluding hard-to-sinter materials, carbon-containing materials, nanocrystalline materials, non-equilibrium materials, gradient materials, interconnect materials, complex shape materials, and advanced functional materials.}, number={9}, journal={SCRIPTA MATERIALIA}, author={Yang, D and Conrad, H}, year={1998}, month={Apr}, pages={1443–1448} }
 @article{yang_conrad_1998, title={Influence of an electric field on the plastic deformation of polycrystalline NaCl at elevated temperatures}, volume={46}, ISSN={["1359-6454"]}, DOI={10.1016/S1359-6454(97)00431-X}, abstractNote={Abstract The effect of a d.c. electric field of 1 kV/cm on the plastic deformation of polycrystalline 99.9% NaCl was determined in compression at 23–532°C (0.28–0.75  T M ) and strain rate e =8.3×10 −4  s −1 . Upon removing the effect of Joule heating it was found that the reduction in the flow stress produced by the field increased with temperature from 0.28 to 0.4  T M , reached a maximum at 0.4  T M and then decreased, becoming nil at 0.75  T M . It is proposed that the reduction in flow stress resulted from an enhancement of cross-slip due to an increase in stacking fault energy. The field had no detectable effect on the plastic deformation kinetics at constant structure in the temperature range 0.28–0.6  T M (cutting of forest dislocations), nor did it appear to have a significant influence on dislocation glide and climb at 0.75  T M .}, number={6}, journal={ACTA MATERIALIA}, author={Yang, D and Conrad, H}, year={1998}, month={Mar}, pages={1963–1968} }
 @article{wu_conrad_1998, title={Influence of mixed particle size on electrorheological response}, volume={83}, ISSN={["0021-8979"]}, DOI={10.1063/1.366621}, abstractNote={Two sizes (6 and 100 μm average diameter) glass spheres suspended in silicone oil (volume fraction φ=0.3) were used to investigate the influence of particle size on electrorheological response at a shear rate 2 s−1. The larger particles gave a higher shear yield stress but a lower current density at zero shear than the smaller ones. When the two particle sizes were mixed together, the shear yield stress decreased, reaching a minimum when the volume fraction of the small particles equals that of the large particles. The minimum in the current density occurred when the ratio of the volume of small to large particles was ∼1/3.}, number={7}, journal={JOURNAL OF APPLIED PHYSICS}, author={Wu, CW and Conrad, H}, year={1998}, month={Apr}, pages={3880–3884} }
 @article{wu_conrad_1998, title={Multi-coated spheres: recommended electrorheological particles}, volume={31}, ISSN={["0022-3727"]}, DOI={10.1088/0022-3727/31/22/021}, abstractNote={This paper considers the design of electrorheological (ER) particles. Multi-coated particles suspended in insulating (very weakly conducting) oil are recommended for obtaining high-performance ER suspensions. Only the outer two coatings determine the ER strength. The outermost coating should be a material with high dielectric constant, high electrical breakdown strength and a reasonable level of conductivity. The coating immediately below should be a highly conducting material. The inner coatings, including the core (which can be void), can be of any material having such a density that the composite particle has substantially the same density as the host liquid. Our analysis gives that multi-coated particles can have an ER shear strength as high as 29 kPa when the volume fraction of particles is 0.4 and the applied field is 5 kV . Results in the literature provide support for the concept and analysis.}, number={22}, journal={JOURNAL OF PHYSICS D-APPLIED PHYSICS}, author={Wu, CW and Conrad, H}, year={1998}, month={Nov}, pages={3312–3315} }
 @article{wu_conrad_1998, title={On the prediction of the shear stress of electrorheological suspensions}, volume={13}, ISSN={["0884-2914"]}, DOI={10.1557/JMR.1998.0449}, abstractNote={Several common methods used for calculating the shear stress and shear modulus of electrorheological (ER) suspensions are reviewed. It is found that when the mismatch ratio of the particle dielectric constant to that of the host liquid in an ac electric field or the ratio of the particle conductivity to that of the host fluid in a dc electric field is >300, no significant difference exists between the predictions of the various methods employed to-date. However, when Λ < 300 the several methods give different estimates for the shear yield stress and shear modulus. Empirical equations are given for a simple estimate of the shear yield stress and the shear modulus when Λ < 300.}, number={11}, journal={JOURNAL OF MATERIALS RESEARCH}, author={Wu, CW and Conrad, H}, year={1998}, month={Nov}, pages={3299–3303} }
 @article{hacke_fahmy_conrad_1998, title={Phase coarsening and crack growth rate during thermo-mechanical cycling of 63Sn37Pb solder joints}, volume={27}, ISSN={["0361-5235"]}, DOI={10.1007/s11664-998-0125-0}, number={8}, journal={JOURNAL OF ELECTRONIC MATERIALS}, author={Hacke, PL and Fahmy, Y and Conrad, H}, year={1998}, month={Aug}, pages={941–947} }
 @article{conrad_1998, title={Properties and design of electrorheological suspensions}, volume={23}, ISSN={["0883-7694"]}, DOI={10.1557/S0883769400030803}, abstractNote={Although electrorheological (ER) fluids are presently being used in some commercial devices, their full potential has yet to be realized. The maximum shear stress (~2 kPa) of commercial ER fluids is not sufficient for most pertinent applications, especially in regard to the automotive industry. However, recent theoretical studies indicate that a shear stress of at least an order of magnitude greater than 2 kPa might be attained by the proper design of the ER suspension. This article reviews the status of the understanding of ER behavior which leads to this possibility.}, number={8}, journal={MRS BULLETIN}, author={Conrad, H}, year={1998}, month={Aug}, pages={35–42} }
 @article{wu_conrad_1998, title={Shear strength of electrorheological particle clusters}, volume={248}, ISSN={["0921-5093"]}, DOI={10.1016/s0921-5093(98)00497-3}, abstractNote={The electrorheological shear strength of clusters of small, humidified glass spheres with an average diameter ∼220 μm in silicone oil forming a rectangular or cubic lattice was determined with d.c. electrical field. The arrangement, shearing, and the yield and fracture processes of the clusters were observed. The shear strength of the cluster increased with the number of chains in a cluster and with the applied electrical field. The shear modulus was essentially independent of the number of chains in a cluster, but increased with applied field.}, number={1-2}, journal={MATERIALS SCIENCE AND ENGINEERING A-STRUCTURAL MATERIALS PROPERTIES MICROSTRUCTURE AND PROCESSING}, author={Wu, CW and Conrad, H}, year={1998}, month={Jun}, pages={161–164} }
 @article{conrad_1998, title={Some effects of an electric field on the plastic deformation of metals and ceramics}, volume={2}, ISSN={["1432-8917"]}, DOI={10.1007/s100190050053}, abstractNote={The external parameters generally considered in the plastic deformation of metals and ceramics are the temperature, pressure or stress and time. Usually neglected are the effects of electric and magnetic fields. However, such fields can often have a significant influence, especially when applied concurrently with the more common parameters. Some examples of the effects of an electric field on the plastic deformation of metals and ceramics found by the author and his coworkers are presented. Included are the following: (a) the influence of electropulsing on the flow stress of metals at 78–300 K, (b) the effect of an external electric field (surface charge) on the superplastic deformation of the 74754 Al alloy, (c) the influence of an electric field on the flow stress and ductility of polycrystalline NaCl at 0.28–0.75 TM and (d) the effect of an electric field on the super-plastic deformation of 3Y-TZP. Mechanisms responsible for the observed effects are considered.}, number={1}, journal={MATERIALS RESEARCH INNOVATIONS}, author={Conrad, H}, year={1998}, month={May}, pages={1–8} }
 @article{wu_conrad_1998, title={The temperature dependence of the conductivity of silicone oil and related electrorheology of suspensions containing zeolite particles}, volume={31}, ISSN={["0022-3727"]}, DOI={10.1088/0022-3727/31/23/015}, abstractNote={The effect of temperature (22-) on the conductivity of silicone oil was determined employing three heating-cooling schedules. In all cases the conductivity was super-ohmic with a good fit to the equation based on Onsager's dissociation theory, namely where is the conductivity at low electric field and A and are constants which define the field-enhanced ionic dissociation. The parameters , A and varied with temperature; however, the major effect of the heating-cooling schedules was on the parameter A. An analysis of the dissociation process gave that the valence of the conducting ions was in the range 1-2. The observed anomalous effect of temperature on the conductivity of the silicone oil was attributed to the gain and loss of water which occurred during a given heating-cooling schedule. We found good agreement between the measured anomalous temperature dependence of the yield stress (in dc field) of a zeolite-silicone oil suspension and that predicted by the conduction model when the variation of the conductivity of the oil with temperature was taken into account.}, number={23}, journal={JOURNAL OF PHYSICS D-APPLIED PHYSICS}, author={Wu, CW and Conrad, H}, year={1998}, month={Dec}, pages={3403–3409} }
 @article{wu_conrad_1997, title={Dielectric and conduction effects in ohmic electrorheological fluids}, volume={30}, ISSN={["0022-3727"]}, DOI={10.1088/0022-3727/30/18/019}, abstractNote={Dielectric and conduction effects in electrorheological (ER) fluids with ohmic conductivity of the host liquids and with an applied AC electric field are considered. It is found that the conductivity ratio , the dielectric constant ratio and the applied field frequency f are three important parameters which determine the ER effect. If , a stronger ER response is obtained with a low applied field frequency than with a high frequency. If , the opposite occurs. Empirical equations are given for the attractive force between the particles in an ER fluid and for the shear yield stress. The calculated current density is independent of the applied field frequency when the frequency is smaller than a critical value, but becomes a linear function of the frequency beyond the critical value. The predicted attractive force of two nearly touching polymer spheres in mineral oil is in good agreement with that measured; also the predicted shear yield stress of some common ER suspensions is in accord with measurements.}, number={18}, journal={JOURNAL OF PHYSICS D-APPLIED PHYSICS}, author={Wu, CW and Conrad, H}, year={1997}, month={Sep}, pages={2634–2642} }
 @article{yang_conrad_1997, title={Effect of an electric field on the plastic deformation and fracture of polycrystalline NaCl}, volume={225}, ISSN={["0921-5093"]}, DOI={10.1016/s0921-5093(96)10846-7}, abstractNote={The influence of an electric field E ≤ 0.1 MV/m on the plastic flow and fracture of cast polycrystalline NaCl was determined in compression at room temperature. Without an electric field the major slip system was deduced to be 110 〈 110 〉, with impurity-cation-vacancy dipoles being the short-range obstacles to dislocation motion. The initial strain hardening rate was similar in magnitude to that for Stage II in single crystals; its decrease with strain was attributed to cross slip. Plastic flow preceded fracture, which was intergranular without an electric field. The yield, flow and fracture stresses and the strain hardening coefficient decreased with electric field, an approximately 50% decrease occurring at E = 0.1 MV/m. This field is one-to-two orders of magnitude lower than had previously been found to produce significant effects in NaCl single crystals. The fracture mode with the field was mixed cleavage and intergranular. It is concluded that the major effect of the electric field was to enhance cross slip, thereby reducing the rate of strain hardening and in turn the flow and fracture stresses.}, number={1-2}, journal={MATERIALS SCIENCE AND ENGINEERING A-STRUCTURAL MATERIALS PROPERTIES MICROSTRUCTURE AND PROCESSING}, author={Yang, D and Conrad, H}, year={1997}, month={Apr}, pages={173–183} }
 @article{yang_conrad_1997, title={Electroplastic effect in cast polycrystalline NaCl with various orientations of the electric field}, volume={80}, DOI={10.1111/j.1151-2916.1997.tb02996.x}, abstractNote={The influence of various orientations and configurations of an electric field on the flow and fracture stresses in compression of cast polycrystalline NaCl was determined at room temperature. An electric field of }0.1 MV/m reduced the flow and fracture stresses by }50%, relatively independent of the orientation of the field. This field is one to two orders of magnitude lower than those previously reported to enhance {110} (110) dislocation motion in NaCl single crystals. It is concluded that in the present tests on polycrystals the electric field enhanced cross slip. Several mechanisms by which this might occur are proposed.}, number={6}, journal={Journal of the American Ceramic Society}, author={Yang, D. and Conrad, H.}, year={1997}, pages={1389–1396} }
 @article{yang_conrad_1997, title={Enhancement of the ductility of polycrystalline NaCl by an electric field}, volume={37}, ISSN={["1359-6462"]}, DOI={10.1016/S1359-6462(97)00161-9}, abstractNote={Abstract The influence of an electric field E ≈ IkV/cm on the plastic deformation in tension of polycrystalline ( d o = 30 μm ) 99.9% NaCl was determined at 532°C (0.75T m ) using two electrode configurations. The following is a summary of the results and the conclusion derived therefrom: 1. 1. The field produced a decrease in the flow stress and an appreciable increase in the ductility. 2. 2. The magnitude of the stress exponent n from strain rate cycling tests was 9.5, independent of strain and electric field. This suggests that the rate-controlling mechanism did not change with the field. 3. 3. Dynamic grain growth occurred during the tests without a field; grain refinement (dynamic recrystallization) occurred with the field. 4. 4. Turning the field “on” and “off” during the course of a test gave an increase in strain hardening when the field was turned “on” and a decrease when it was turned “off ”. The difference decreased with strain. 5. 5. The results suggest that the field led to the development of a dislocation structure which was conductive to the nucleation of new grains. Moreover, the field retarded the growth of the new grains [10] .}, number={6}, journal={SCRIPTA MATERIALIA}, author={Yang, D and Conrad, H}, year={1997}, month={Sep}, pages={767–771} }
 @article{wu_conrad_1997, title={Influence of a surface film on conducting particles on the electrorheological response with alternating current fields}, volume={81}, ISSN={["0021-8979"]}, DOI={10.1063/1.365412}, abstractNote={A method was developed for the frequency dependence of the electrorheological (ER) response of suspensions of highly conducting particles with a low conducting surface film. At dc or low frequency ac field, the shear yield stress of the ER fluids considered is determined by the conductivity ratio σI/σf of the film to the host oil; at high frequency ac field it is determined by the permittivity ratio εI/εf. The critical frequency separating the conduction domain from the dielectric domain is proportional to σf/εf, the ratio of the conductivity to the permittivity of the host oil. To obtain a high shear yield stress at high frequency ac field, a high ratio of the permittivity of the surface film to the oil is desired and a reasonably thin surface film. Too thin a film increases the possibility of electrical breakdown in the film especially at a small ratio of εI/εf. An effective method for overcoming electrical breakdown in the surface film is to increase the permittivity of the film. Good agreement exists between the measured shear yield stress, current density, and the applied breakdown field for oxidized aluminum particles suspended in silicone oil and those predicted by the present model. Recommendations are given for the design of ER fluids with high yield strength and reasonable current density.}, number={12}, journal={JOURNAL OF APPLIED PHYSICS}, author={Wu, CW and Conrad, H}, year={1997}, month={Jun}, pages={8057–8063} }
 @article{wu_conrad_1997, title={Influence of a surface film on the particles on the electrorheological response}, volume={81}, ISSN={["0021-8979"]}, DOI={10.1063/1.364123}, abstractNote={A conduction model is developed for the dc electrorheological (ER) response of highly conducting particles (e.g., metal particles) suspended in a weakly conducting oil. The numerical analyses show that a surface film with some conductivity is desired, but not a completely insulating film as previously proposed. Increasing the film conductivity leads to an increase in the ER yield stress. However, too high a conductivity will give an unacceptable level of current density. The film should also have an intermediate thickness. A small thickness increases the possibility of electrical breakdown in the film; too large a thickness decreases the ER effect. Good agreement exists between the yield stress and the current density predicted by our model and those measured.}, number={1}, journal={JOURNAL OF APPLIED PHYSICS}, author={Wu, CW and Conrad, H}, year={1997}, month={Jan}, pages={383–389} }
 @article{yang_conrad_1997, title={Influence of an electric field on the superplastic deformation of 3Y-TZP}, volume={36}, ISSN={["1359-6462"]}, DOI={10.1016/S1359-6462(97)00045-6}, abstractNote={The effect of electric field/current on creep deformation was examined in fine-grained 8 mol% Y2O3 stabilized cubic ZrO2 (8Y-CSZ) under direct and alternative current (DC and AC) conditions. Even at similar sample temperature of 1160–1170 °C, although the electric fields/currents accelerate the deformation of 8Y-CSZ, the acceleration effect (athermal effect), which cannot be explained by an increase of the sample temperature due to Joule heating, is much pronounced in AC than in DC. Under the deformation without the electric field/current, the creep behavior can be characterized by diffusional creep processes with a stress exponent of n ≈ 1, whereas under DC and AC, the predominant mechanism changes to grain boundary sliding (GBS) with n ≈ 2. This indicates that the athermal effect under the electric field/current changes the deformation mechanism from diffusional creep to GBS mechanisms by enhancing GBS and its rate controlling process of cation diffusivity, especially in AC.}, number={12}, journal={SCRIPTA MATERIALIA}, author={Yang, D and Conrad, H}, year={1997}, month={Jun}, pages={1431–1435} }
 @article{hacke_sprecher_conrad_1997, title={Microstructure coarsening during thermo-mechanical fatigue of Pb-Sn solder joints}, volume={26}, ISSN={["0361-5235"]}, DOI={10.1007/s11664-997-0251-0}, number={7}, journal={JOURNAL OF ELECTRONIC MATERIALS}, author={Hacke, PL and Sprecher, AF and Conrad, H}, year={1997}, month={Jul}, pages={774–782} }