@article{witharamage_christudasjustus_walunj_borkar_gupta_2024, title={Effect of V Content on Corrosion Behavior of Al-V Alloys Produced by Mechanical Alloying and Subsequent Spark Plasma Sintering}, volume={171}, ISSN={["1945-7111"]}, url={https://doi.org/10.1149/1945-7111/ad2d1b}, DOI={10.1149/1945-7111/ad2d1b}, abstractNote={
 Al-V alloys produced via high-energy ball milling have been reported to show simultaneous improvement of corrosion resistance and mechanical properties compared to traditional Al alloys. In these alloys, V content plays a crucial role in increasing or decreasing corrosion resistance. Therefore, the effect of V and microstructure on corrosion of high-energy ball milled and subsequently spark plasma sintered Al-xV alloys (x = 2, 5, 10 at.%) has been studied. Cyclic potentiodynamic polarization tests and electrochemical impedance spectroscopic analysis revealed that increments of V content up to 5 at. % enhanced the corrosion resistance of the alloy. However, highly heterogeneous microstructure in Al-10 at.%V resulted in significant localized corrosion over the immersion time. The electrochemical impedance spectroscopy studies over 14 days of immersion revealed underlying corrosion mechanisms.}, number={3}, journal={JOURNAL OF THE ELECTROCHEMICAL SOCIETY}, author={Witharamage, Chathuranga Sandamal and Christudasjustus, J. and Walunj, G. and Borkar, T. and Gupta, R. K.}, year={2024}, month={Mar} }
 @article{christudasjustus_felde_witharamage_esquivel_darwish_winkler_gupta_2023, title={Age-hardening behavior, corrosion mechanisms, and passive film structure of nanocrystalline Al-V supersaturated solid solution}, volume={135}, ISSN={["1941-1162"]}, url={https://doi.org/10.1016/j.jmst.2022.06.044}, DOI={10.1016/j.jmst.2022.06.044}, abstractNote={The effect of age-hardening on microstructure, hardness, and corrosion of an Al-5at.%V alloy, produced using high-energy ball milling and subsequent cold compaction, has been investigated. The alloy exhibited a grain size below 100 nm and extremely high solid solubility of V in Al (3.1 at.%). The age-hardening was carried out at 150, 200, and 250 °C. The peak-aged condition of 150 °C demonstrated the highest hardness—transpired from grain refinement, precipitation, and solid solution hardening. The corrosion resistance of the Al-5at.%V alloy was studied as a function of aging conditions. The peak-aged condition retained the corrosion resistance while it deteriorated in the over-aged condition. Nonetheless, the corrosion resistance of the ball-milled Al alloys in all the aging conditions was superior to that of pure Al. The passive film structure and origin of corrosion were studied using scanning/transmission electron microscopy (S/TEM). The high corrosion resistance of the alloy was attributed to the V enrichment at the film/metal interface and deposition of V on the cathodic phases, which suppresses the dissolution of Al within the pit and therefore promotes repassivation in the early stages of corrosion.}, journal={JOURNAL OF MATERIALS SCIENCE & TECHNOLOGY}, author={Christudasjustus, J. and Felde, M. R. and Witharamage, C. S. and Esquivel, J. and Darwish, A. . A. . and Winkler, C. and Gupta, R. K.}, year={2023}, month={Feb}, pages={1–12} }
 @article{christudasjustus_witharamage_vukkum_walunj_borkar_gupta_2023, title={Surface Film Formation on Al-V Alloys with Far-From-Equilibrium Microstructure}, volume={170}, ISSN={["1945-7111"]}, url={https://doi.org/10.1149/1945-7111/acc7ce}, DOI={10.1149/1945-7111/acc7ce}, abstractNote={
 Nanocrystalline supersaturated Al-V alloys produced by high-energy ball milling have been reported to exhibit enhanced corrosion resistance and mechanical properties compared to commercial Al alloys. Corrosion of passive alloys such as Al-V alloy relies on the characteristics of the surface film, which is studied using scanning/transmission electron microscopy and time-of-flight secondary ion mass spectrometry. The effect of microstructure and composition on the surface film has been investigated after different immersion periods (30 min, 2 hours, and 1 day) in 0.1 M NaCl. The surface film was complex and composed of oxidized Al and V. The heterogeneous surface film was observed due to the presence of secondary phases and initiation of localized corrosion. The void formation was observed beneath the surface film that would potentially cause pitting corrosion. The generation of nano-sized voids was dependent on grain orientation. Compared to pure Al, the chloride penetration is suppressed in Al-V alloys. The effect of composition and microstructure on surface film formation and attendant corrosion behavior is discussed herein.}, number={3}, journal={JOURNAL OF THE ELECTROCHEMICAL SOCIETY}, author={Christudasjustus, J. and Witharamage, C. S. and Vukkum, V. B. and Walunj, G. and Borkar, T. and Gupta, R. K.}, year={2023}, month={Mar} }
 @article{ozdemir_witharamage_darwish_okuyucu_gupta_2022, title={Corrosion behavior of age hardening aluminum alloys produced by high-energy ball milling}, volume={900}, ISSN={["1873-4669"]}, url={http://dx.doi.org/10.1016/j.jallcom.2021.163488}, DOI={10.1016/j.jallcom.2021.163488}, abstractNote={The influence of high energy-ball milling (HEBM) on corrosion and hardness of age hardening aluminum alloys was investigated. Nanocrystalline age hardening (AA2024, AA6061 and AA7075) alloys were produced by HEBM of pre-alloyed powder and subsequent cold compaction under uniaxial pressure of 3 GPa. Cyclic potentiodynamic polarization and immersion tests were conducted in 0.6 M NaCl solution which revealed significantly increased pitting and protection potentials in the HEBM alloys compared to wrought alloys of same composition. X-ray diffraction analysis and transmission electron microscopy indicated grain refinement below 100 nm in the ball milled alloys which was the major strengthening mechanism in the age hardening HEBM alloys. The superior corrosion resistance and hardness of the age hardening ball milled alloys were attributed to nanocrystalline structure, extended solid solubility and homogenous microstructure- free from coarse intermetallic phases.}, journal={JOURNAL OF ALLOYS AND COMPOUNDS}, publisher={Elsevier BV}, author={Ozdemir, Furkan and Witharamage, Chathuranga Sandamal and Darwish, Ahmed Abdelazim and Okuyucu, Hasan and Gupta, Rajeev Kumar}, year={2022}, month={Apr} }
 @article{witharamage_christudasjustus_smith_gao_gupta_2022, title={Corrosion behavior of an in situ consolidated nanocrystalline Al-V alloy}, volume={6}, ISSN={["2397-2106"]}, url={https://doi.org/10.1038/s41529-022-00225-5}, DOI={10.1038/s41529-022-00225-5}, abstractNote={Abstract Supersaturated solid solutions of Al and corrosion-resistant alloying elements (M: V, Mo, Cr, Ti, Nb), produced by non-equilibrium processing techniques, have been reported to exhibit high corrosion resistance and strength. The corrosion mechanism for such improved corrosion performance has not been well understood. We present a fundamental understanding of the role of V in corrosion of an Al-V alloy, which will provide a theoretical background for developing corrosion-resistant Al alloys. High-energy ball milling of the elemental powder of Al and V produced an in situ consolidated Al-V alloy, which exhibited high solid solubility of V. The corrosion resistance of Al-V alloy was significantly higher than that of pure Al, which was attributed to the (1) enrichment of V at the passive film/substrate interface, (2) incorporation of V into the passive film, and (3) deposition of V on the iron-containing cathodic particles and therefore, retardation of cathodic reaction.}, number={1}, journal={NPJ MATERIALS DEGRADATION}, author={Witharamage, C. S. and Christudasjustus, J. and Smith, J. and Gao, W. and Gupta, R. K.}, year={2022}, month={Feb} }
 @article{witharamage_alrizqi_chirstudasjustus_darwish_ansell_nieto_gupta_2022, title={Corrosion-resistant metallic coatings for aluminum alloys by cold spray}, volume={209}, ISSN={0010-938X}, url={http://dx.doi.org/10.1016/j.corsci.2022.110720}, DOI={10.1016/j.corsci.2022.110720}, abstractNote={An Al-V alloy powder produced by high-energy ball milling has been cold sprayed on an AA2024-T3 substrate. The corrosion resistance of cold sprayed alloy, represented by the corrosion current density and pitting potential, was significantly higher than the substrate. Furthermore, a zero-resistance ammeter test revealed that the coating was anodic to the substrate, which would provide cathodic protection in any event of coating breakdown. The wear resistance of the coating was almost four times higher than that of the substrate.}, journal={Corrosion Science}, publisher={Elsevier BV}, author={Witharamage, Chathuranga S. and Alrizqi, Mohammed A. and Chirstudasjustus, Jijo and Darwish, Ahmed A. and Ansell, Troy and Nieto, Andy and Gupta, Rajeev K.}, year={2022}, month={Dec}, pages={110720} }
 @article{christudasjustus_witharamage_walunj_borkar_gupta_2022, title={The influence of spark plasma sintering temperatures on the microstructure, hardness, and elastic modulus of the nanocrystalline Al-xV alloys produced by high-energy ball milling}, volume={122}, ISSN={["1005-0302"]}, url={https://doi.org/10.1016/j.jmst.2022.02.008}, DOI={10.1016/j.jmst.2022.02.008}, abstractNote={• Synthesis of Al-V alloys from high-energy ball milling and spark plasma sintering. • Al-V alloys with far-from-equilibrium microstructure: V solubility 6 orders of magnitude higher than equilibrium value. • Elastic modulus of Al-V alloys is much higher than that of any commercial Al alloy. • Effect of spark plasma sintering temperature on the microstructure, hardness and elastic modulus of Al-V alloys. Al- x V alloys ( x = 2 at.%, 5 at.%, 10 at.%) with nanocrystalline structure and high solid solubility of V were produced in powder form by high-energy ball milling (HEBM). The alloy powders were consolidated by spark plasma sintering (SPS) employing a wide range of temperatures ranging from 200 to 400 °C. The microstructure and solid solubility of V in Al were investigated using X-ray diffraction analysis, scanning electron microscope and transmission electron microscope. The microstructure was influenced by the SPS temperature and V content of the alloy. The alloys exhibited high solid solubility of V―six orders of magnitude higher than that in equilibrium state and grain size < 50 nm at all the SPS temperatures. The formation of Al 3 V intermetallic was detected at 400 °C. Formation of a V-lean phase and bimodal grain size was observed during SPS, which increased with the increase in SPS temperature. The hardness and elastic modulus, measured using nanoindentation, were significantly higher than commercial alloys. For example, Al-V alloy produced by SPS at 200 °C exhibited a hardness of 5.21 GPa along with elastic modulus of 96.21 GPa. The evolution of the microstructure and hardness with SPS temperatures has been discussed.}, journal={JOURNAL OF MATERIALS SCIENCE & TECHNOLOGY}, publisher={Elsevier BV}, author={Christudasjustus, J. and Witharamage, C. S. and Walunj, Ganesh and Borkar, T. and Gupta, R. K.}, year={2022}, month={Sep}, pages={68–76} }
 @article{esteves_witharamage_christudasjustus_walunj_o'brien_ryu_borkar_akans_gupta_2021, title={Corrosion behavior of AA5083 produced by high-energy ball milling}, volume={857}, ISSN={["1873-4669"]}, url={http://dx.doi.org/10.1016/j.jallcom.2020.158268}, DOI={10.1016/j.jallcom.2020.158268}, abstractNote={The corrosion, microstructure, and hardness of nanocrystalline AA5083 were compared to that of conventional AA5083-H116 and consolidated gas atomized powder. The nanocrystalline AA5083 was produced by consolidating high-energy ball milled gas atomized powder with two methods: cold compaction and spark plasma sintering. Electrochemical impedance spectroscopy, cyclic potentiodynamic polarization, Mott-Schottky analysis, and immersion tests followed by surface analysis were used to evaluate the corrosion behavior in 0.6 M NaCl solution. Pitting corrosion resistance of the nanocrystalline AA5083 was superior to that of commercial AA5083-H116. The improved corrosion resistance was primarily attributed to the homogenous microstructure and significant grain refinement below 100 nm.}, journal={JOURNAL OF ALLOYS AND COMPOUNDS}, publisher={Elsevier BV}, author={Esteves, L. and Witharamage, C. S. and Christudasjustus, J. and Walunj, G. and O'Brien, S. P. and Ryu, S. and Borkar, T. and Akans, R. E. and Gupta, R. K.}, year={2021}, month={Mar} }
 @article{esteves_christudasjustus_o'brien_witharamage_darwish_walunj_stack_borkar_akans_gupta_2021, title={Effect of V content on corrosion behavior of high-energy ball milled AA5083}, volume={186}, ISSN={["1879-0496"]}, url={https://doi.org/10.1016/j.corsci.2021.109465}, DOI={10.1016/j.corsci.2021.109465}, abstractNote={AA5083 alloys with V additions were produced in the powder form by high-energy ball milling and consolidation by spark plasma sintering and cold compaction. X-ray diffraction and energy dispersive X-ray spectroscopy analysis indicated the formation of supersaturated solid solution and grain refinement below 100 nm. Corrosion behavior was investigated using electrochemical impedance spectroscopy, cyclic potentiodynamic polarization, and immersion corrosion tests followed by surface analysis. The composition of the passive film was obtained via X-ray photoelectron spectroscopy. The corrosion resistance of the AA5083 was significantly improved due to the addition of V and high-energy ball milling.}, journal={CORROSION SCIENCE}, publisher={Elsevier BV}, author={Esteves, L. and Christudasjustus, J. and O'Brien, S. P. and Witharamage, C. S. and Darwish, A. A. and Walunj, G. and Stack, P. and Borkar, T. and Akans, R. E. and Gupta, R. K.}, year={2021}, month={Jul} }
 @article{witharamage_christudasjustus_gupta_2021, title={The Effect of Milling Time and Speed on Solid Solubility, Grain Size, and Hardness of Al-V Alloys}, volume={30}, ISSN={["1544-1024"]}, url={http://dx.doi.org/10.1007/s11665-021-05663-x}, DOI={10.1007/s11665-021-05663-x}, number={4}, journal={JOURNAL OF MATERIALS ENGINEERING AND PERFORMANCE}, publisher={Springer Science and Business Media LLC}, author={Witharamage, C. S. and Christudasjustus, J. and Gupta, R. K.}, year={2021}, month={Apr}, pages={3144–3158} }
 @inproceedings{witharamage_maddumage_weragoda_2018, title={Determination of Thermal Conductivity of LDPE Using Dual Hot Wire Probe Method}, ISBN={9781538644171}, url={http://dx.doi.org/10.1109/mercon.2018.8421899}, DOI={10.1109/mercon.2018.8421899}, abstractNote={Thermal conductivity is the one of most significant parameters in materials when it comes to the industrial applications, it is important to know the thermal conductivity of materials for materials selection, especially when thermal insulation is required. However, the techniques available in laboratory scale to measure the thermal conductivity of poor thermal conductors like polymers, meeting reliability and economy are not available. This research focuses on developing an instrument to measure the thermal conductivity of polymers that overcome the inherent problems in the existing methods. Measuring of the thermal conductivity can be done either at the steady state conditions or transient conditions. The temperature measurements of the polymer specimen in the transient state were done based on the well-known “Transient Hot-Wire Probe Theory”. Here, basically the temperature of a linear heat source embedded in the specimen, which is read at different time intervals and supplied energy to the heat element were the interested quantities and a programmed micro-controller was used to control the sensing elements of the system (thermocouples, current and voltage sensors) by performing pre-defined or user intended functions. Likewise microcontroller then reads out the sensor signals accordingly, to process and produce results in a useful manner (temperature vs time behavior) so that the thermal conductivity can be calculated according to the theory.}, booktitle={2018 Moratuwa Engineering Research Conference (MERCon)}, publisher={IEEE}, author={Witharamage, C.S. and Maddumage, M.M.B.S. and Weragoda, V.S.C.}, year={2018}, month={May} }