Strong grain-size effect on deformation twinning of an Al_0.1CoCrFeNi high-entropy alloy

Abstract

An Al0.1CoCrFeNi high-entropy alloy (HEA) with a face-centered cubic structure in the as-cast and the recrystallized states is investigated. The mean grain size of the as-cast HEA is 14 times larger than that of the recrystallized HEA. The tension tests reveal that deformation twinning is the main mechanism dominating the plastic deformation of two HEAs. With a decrease in the grain size, twin spacing increases, and twin thickness decreases, which results in a low twinning activity. The twinning activity of the recrystallized HEA is strongly inhibited by grain refinement, which degrades the promotion of twinning on the strain-hardening ability and the tensile ductility.