Effects of annealing on hardness, yield strength and dislocation structure in single crystals of the equiatomic Cr-Mn-Fe-Co-Ni high entropy alloy

We report that in contrast to the anticipation, the macroscopic mechanical strength of single crystals of the face-centered-cubic single-phase equiatomic Cr-Mn-Fe-Co-Ni high entropy alloy is not influenced by thermal annealing during which short-range ordering is expected to develop. Experimental evidence shows that hardness at room temperature, critical resolved shear stress at room temperature and at 77 K and activation volume values of the alloys do not significantly vary with the annealing temperature in the range from 900 to 1200 degrees C. The stacking fault energies in the specimens deformed at 77 K following annealing at 1000 and 1200 degrees C respectively are essentially identical to each other. These results clearly indicate that the impact of the formation of chemical short-range order on the macroscopic yield strength of the equiatomic Cr-Mn-Fe-Co-Ni high entropy alloy is insignificant, even if it exists. (C) 2020 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

Automated summary

Research shows that the macroscopic mechanical strength of single crystals of equiatomic Cr-Mn-Fe-Co-Ni high entropy alloy, which are expected to develop short-range ordering during thermal annealing, is not affected. The hardness, critical resolved shear stress, and activation volume values of the alloy do not significantly vary with the annealing temperature.