Shear localization of fcc high-entropy alloys

Abstract

Dynamic behavior of the single phase (fcc) Al0.3CoCrFeNi and CoCrFeMnNi high-entropy alloys (HEAs) was examined. The combination of multiple strengthening mechanisms such as solid solution hardening, cutting forest dislocation, as well as mechanical nano-twinning leads to a high work-hardening rate, compared with conventional alloys. The resistance to shear localization was studied by dynamicallyloading hat-shaped specimens to induce forced shear localization. However, no adiabatic shear band could be observed for Al0.3CoCrFeNi HEA at a large shear strain ~1.1. Additionally, shear localization of the CoCrFeMnNi HEA was only found at an even larger shear strain ~7 under dynamic compression. It is therefore proposed that the combination of the excellent strain-hardening ability and modest thermal softening of these two kinds of high-entropy alloys gives rise to remarkable resistance to shear localization, which makes HEAs excellent candidates for impact resistance applications.