Modulating the prestrain history to optimize strength and ductility in CoCrFeMnNi high-entropy alloy

CoCrFeMnNi high-entropy alloy (HEA) exhibits excellent combination of strength and ductility, but low yield strength. In order to ameliorate the mechanical properties, prestrain was applied in this work. The HEA prestrained at 77 K possesses higher yield strength and uniform elongation than the HEA prestrained at 293 K, indicating that the trade-off relationship between strength and ductility can be broken by modulating the prestrain history. Furthermore, the yield point phenomenon was disappeared after prestrained at 77 K. This can be related to the density and distribution of dislocations as imposed in the prestrain process at 293 K and 77 K. (C) 2019 Acta Materialia Inc Published by Elsevier Ltd. All rights reserved.