Dislocation behavior in initial stage of plastic deformation for CoCrNi medium entropy alloy

Abstract

The effects of crystal orientation on the plastic deformation behavior for typical CoCrNi medium entropy alloy under tensile and compressive loading were investigated by molecular dynamics simulations. The Lomer-Cottrell (L-C) structure and parallel hexagonal close packed (HCP) bands are produced in the [111] and [11̅0] orientations at the initial stage of tensile deformation, respectively. However, perfect dislocations and two types of non-slip dislocations (Hirth and Stair-rod) are generated in the [111] and [11̅0] orientations during compressive deformation, respectively. The L-C structure produced by tensile loading in the [111] orientation and Hirth/Stair-rod dislocations produced in the [11̅0] orientation under compression act as a dislocation pinning and limit the continued glide of the dislocations. The dislocation reactions under various conditions were analyzed, which is helpful to understand the plastic deformation mechanism of CoCrNi alloy.