|About this Abstract
||2016 TMS Annual Meeting & Exhibition
||Ultrafine Grained Materials IX
||Peculiar Mechanical Properties and Microstructures of CoCrFeNiMn High Entropy Alloy after High Pressure Torsion at 300 K and 77 K
||Aleksey V. Podolskiy, Elena D. Tabachnikova, Erhard Schafler, Christian Rentenberger, Bertalan Joni, Stefan Maier, M. A. Tikhonovsky, A. S. Tortika, Tamas Ungar, Michael Josef Zehetbauer
|On-Site Speaker (Planned)
The high entropy alloy CoCrFeNiMn was cast to purely one-phase solid solution state and subsequently processed by high-pressure torsion (HPT) at 300 K and 77 K, by pressures between 4 to 8 GPa till shear strains of 140. Measurements of mechanical properties аfter HPT at 300 K at compression temperatures 4.2-350 K showed extremely high values of yield strength (2 GPa at 300 K, and 3 GPa at 4.2 K) while maintaining reasonable plasticity, both correlated with a homogeneously nanocrystalline structure. Samples processed by HPT at 77 K, however, showed only partially nanocrystalline structures which, surprisingly, exhibited lower strength values than samples processed by HPT at 300 K. These unusual results are explained in terms of competing strength contributions arising from variations of grain size, dislocation density, twin fraction and HPT-induced phase formation, all of them in dependence on HPT-strain, HPT-temperature and HPT-hydrostatic pressure.