Deformation behavior and microstructure evolution of FCC high entropy alloy under dynamic loading

Abstract

In recent years, new solid solution alloy called High Entropy Alloy (HEA) has been attracting attention. CoCrMnNiFe equiatomic alloy is expected as a new structural material because of its excellent mechanical property. However understanding of the deformation mechanismin the CoCrMnNiFe alloy is still not sufficient. In this study, CoCrMnNiFe alloy was loaded at room temperature quasi-statically or dynamically by Split-Hopkinson Pressure Bar (SHPB) method at the strain rate of 10³ s^-1. CoCrMnNiFe alloy showed higher yield stress under the dynamic loading than that at the quasi-static rate. Therefore, it is suggested that this alloy possesses the strain rate dependence of the yield stress. Deformation twining was not observed in the dynamically deformed micro structure. It suggests that the dominant deformation mechanism of CoCrMnNiFe is dislocation slip