Cryogenic deformation mechanism of CrMnFeCoNi high-entropy alloy fabricated by laser additive manufacturing process

Abstract

Well-formed equimolar CrMnFeCoNi high-entropy alloy (HEA) bulk samples with good tensile properties are fabricated by laser additive manufacturing (LAM) processing. To elucidate the deformation mechanism, tensile tests are performed on at 77 K and 293 K and interrupted at different strains. Electron backscatter diffraction and X-ray diffraction indicate that the large initial dislocation density introduced by LAM processing increases the yield strength significantly and dislocation motion is the dominant deformation mechanism. In addition, deformation twinning is a large addition at large strain levels under cryogenic conditions. These two mechanisms and their interaction produce the excellent mechanical properties of bulk HEA. Keywords: High-entropy alloys, Laser additive manufacturing, Cryogenics, Dislocation density, Deformation twinning