Dual mechanisms of grain refinement in a FeCoCrNi high-entropy alloy processed by high-pressure torsion

• DOI: 10.1038/srep46720
• Publication Date: 2017-04-21T09:40:33Z
• Authors: Wenqian Wu; Min Song; Song Ni; Jingshi Wang; Yong Liu; Bin Liu; Xiaozhou Liao
• Keywords: Equiaxed crystals; High-Entropy Alloys; Nanocrystalline material; Stacking-fault energy

Abstract An equiatomic FeCoCrNi high-entropy alloy with a face-centered cubic structure was fabricated by powder metallurgy route, and then processed high-pressure torsion. Detailed microscopy investigations revealed that grain refinement from coarse grains to nanocrystalline occurred mainly via concurrent nanoband (NB) subdivision deformation twinning. NB–NB, twin–NB twin–twin interactions contributed the process. The resulted in severe lattice distortion accumulation of high densities dislocations interaction areas. With increasing strain, NB between primary twins inclined secondary stacking faults (SFs)/nanotwins occurred. Secondary nanotwins divided into many equiaxed parts, leading further refinement. SFs/nanotwins associated presence Shockley partials also transformed twin boundaries incoherent high-angle boundaries.