@article{darling_guduru_reynolds_bhosle_chan_scattergood_koch_narayan_aboelfotoh_2008, title={Thermal stability, mechanical and electrical properties of nanocrystalline Cu3Ge}, volume={16}, ISSN={0966-9795}, url={http://dx.doi.org/10.1016/j.intermet.2007.11.005}, DOI={10.1016/j.intermet.2007.11.005}, abstractNote={The intermetallic ɛ1 compound Cu3Ge was produced through a mechanical alloying procedure that enables the formation of a nanograined microstructure. There is a dependence of grain size (20–11 nm) on milling conditions. The microstructure remained very stable even at temperatures up to 500 °C for 5 h which is a minimum of 76% of the melting temperature. The materials produced by these methods were in the form of powders with particle size ranging from 200 nm to 10 μm. The morphology of the particles varied with the largest being rough and irregular and the smallest being spherical. Preliminary resistivity measurements showed low resistivity, 8.8 μΩ cm, which is comparable to that previously reported for thin films with grain sizes thousands of times larger. Nanoindentation was also performed, yielding an elastic modulus of ∼110 GPa.}, number={3}, journal={Intermetallics}, publisher={Elsevier BV}, author={Darling, Kris A. and Guduru, R.K. and Reynolds, C. Lewis, Jr and Bhosle, Vikram M. and Chan, Ryan N. and Scattergood, Ronald O. and Koch, Carl C. and Narayan, J. and Aboelfotoh, M.O.}, year={2008}, month={Mar}, pages={378–383} }
 @article{guduru_wong_darling_koch_murty_scattergood_2007, title={Determination of Activation Volume in Nanocrystalline Cu Using the Shear Punch Test}, volume={9}, ISSN={1438-1656 1527-2648}, url={http://dx.doi.org/10.1002/adem.200700181}, DOI={10.1002/adem.200700181}, abstractNote={The mechanical behavior of nanocrystalline metals has been a research topic of interest for the past two decades. The current understanding is summarized in several recent reviews. Researchers have been investigating the deformation mechanisms in nanocrystalline metals and alloys through experimental and modeling routes. Modeling results indicate that there is a transition from dislocation generation at sources within grains to grain-boundary mediated dislocation generation in the grain size range between about 100 to 10 nm. Below 10 nm, grain boundary deformation modes (sliding, rotation, etc.) become dominant and inverse Hall-Petch effects have been reported. Experimental evidence to confirm these predictions is an active area of research. Two important experimental parameters that are useful in characterizing the deformation kinetics of materials are the strain rate sensitivity m and the activation volume V*. 11, 12] These are related by m = kT/V*r where k is Boltzmann’s constant, T is temperature (K) and r is the stress. There is a limited amount of data available on m and V* measurements for nanocrystalline metals. 5, 11–14] One aspect of this is the fact that research-scale synthesizing techniques often produce small quantities of material and mechanical testing procedures suited to small sample sizes are required. 5, 7, 13–18] In addition to this fact there is a tremendous scarcity of testing methodologies for testing the materials at small scales such as Micro-Electro-Mechanical-Systems (MEMS) where micro tensile and nanoindentation tests are used for understanding the deformation behaviour. 20] The aim of the present work was to extend the shear punch test (SPT) technique to the measurement of activation volumes on small scale specimens of few millimeters (∼ 1 mm to 3 mm). The advantage of SPT over nanoindentation and micro tensile tests is the deformation zone where a large number of grains undergo deformation within the shear zone and overcomes the problem of strain gradient plasticity effects, gain size effects as well as the specimen size effects. The SPT has been used for evaluating the yield and ultimate stress by numerous researchers, including us. The SPT shear yield or ultimate strength value s can be correlated with its tensile test counterpart r using the relation r = as. The correlation factor a depends upon the testing setup and data analysis methods. The Von Mises (VM) yield criterion predicts a = 3 if the SPT approximates pure shear loading conditions. This was the case in where the details and standardization of the SPT technique used in the present research work are given. The stress relaxation method has been used to determine activation volumes and dislocation dynamics in coarse-grain metals and alloys and in nanocrystalline Ni. The tests are normally done using uniaxial loading conditions. In the present study, we use the stress relaxation method in conjunction with the SPT technique. As far as we are aware, this is the first time that the full implementation of this method has been reported.}, number={10}, journal={Advanced Engineering Materials}, publisher={Wiley}, author={Guduru, R. K. and Wong, P. Z. and Darling, K. A. and Koch, C. C. and Murty, K. L. and Scattergood, R. O.}, year={2007}, month={Oct}, pages={855–859} }
 @article{guduru_darling_scattergood_koch_murty_2007, title={Mechanical properties of electrodeposited nanocrystalline copper using tensile and shear punch tests}, volume={42}, ISSN={["0022-2461"]}, DOI={10.1007/s10853-006-1095-3}, number={14}, journal={JOURNAL OF MATERIALS SCIENCE}, author={Guduru, Ramesh Kumar and Darling, Kristopher A. and Scattergood, Ronald O. and Koch, Carl C. and Murty, K. L.}, year={2007}, month={Jul}, pages={5581–5588} }
 @article{nagasekhar_tick-hon_guduru_ramakanth_2007, title={Multipass equal channel angular extrusion of MgB2 powder in tubes}, volume={466}, ISSN={["1873-2143"]}, DOI={10.1016/j.physc.2007.07.006}, abstractNote={In the current study multipass equal channel angular extrusion (ECAE) is adopted for the first time to study the applicability of the process to compact magnesium boride (MgB2) powder in tubes (PITs). The influence of number of ECAE passes on MgB2 PITs was also analyzed in terms of microstructure, density and mechanical properties. MgB2 PITs with iron tube were processed up to six ECAE passes. X-ray analysis of the compacts showed no other phases, other than MgO, in MgB2 compacts even after large mechanical working and annealing. Simple shear stresses predominant in ECAE constantly rendered compaction of the hard brittle MgB2 powders.}, number={1-2}, journal={PHYSICA C-SUPERCONDUCTIVITY AND ITS APPLICATIONS}, author={Nagasekhar, A. V. and Tick-Hon, Yip and Guduru, R. K. and Ramakanth, K. S.}, year={2007}, month={Nov}, pages={174–180} }
 @article{guduru_nagasekhar_scattergood_koch_murty_2007, title={Thickness and clearance effects in shear punch testing}, volume={9}, ISSN={["1438-1656"]}, DOI={10.1002/adem.200600255}, abstractNote={Shear punch testing (SPT) is a miniaturized specimen testing technique and is often used to predict the tensile properties of metals and alloys by testing a small amount of material. In order to rationalize the testing methodology it is necessary to understand the effect of different testing procedure parameters such as specimen thickness and die-punch clearance on the evaluated mechanical properties. We present our understanding of the above parameters on the SPT yield strength using finite element modeling studies in conjunction with our previous experimental results.}, number={3}, journal={ADVANCED ENGINEERING MATERIALS}, author={Guduru, Ramesh K. and Nagasekhar, Anumalasetty V. and Scattergood, Ronald O. and Koch, Carl C. and Murty, Korukonda L.}, year={2007}, month={Mar}, pages={157–160} }
 @article{guduru_nagasekhar_scattergood_koch_murty_2006, title={Finite element analysis of a shear punch test}, volume={37A}, ISSN={["1543-1940"]}, DOI={10.1007/s11661-006-0092-0}, number={5}, journal={METALLURGICAL AND MATERIALS TRANSACTIONS A-PHYSICAL METALLURGY AND MATERIALS SCIENCE}, author={Guduru, R. K. and Nagasekhar, A. V. and Scattergood, R. O. and Koch, C. C. and Murty, K. L.}, year={2006}, month={May}, pages={1477–1483} }
 @article{guduru_scattergood_koch_murty_guruswamy_mccarter_2006, title={Mechanical properties of nanocrystalline Fe-Pb and Fe-Al2O3}, volume={54}, ISSN={["1359-6462"]}, DOI={10.1016/j.scriptamat.2006.02.014}, abstractNote={Fe, Fe–Al2O3, and Fe–Pb nanocrystalline alloys were prepared using ball milling. Fe–Al2O3 forms a nanocomposite and rule-of-mixtures hardening occurs with an additional contribution due to grain size reduction during milling. Fe–Pb forms a non-equilibrium solid solution where hardening appears to be modulated by Pb clustering and segregation to grain boundaries.}, number={11}, journal={SCRIPTA MATERIALIA}, author={Guduru, RK and Scattergood, RO and Koch, CC and Murty, KL and Guruswamy, S and McCarter, MK}, year={2006}, month={Jun}, pages={1879–1883} }