Size Effect of Flow Stress in CoCrNi Medium Entropy Alloy Ultrathin Strips

Abstract:

A constitutive model considering the size effect was established to investigate the behavior of CoCrNi medium entropy alloy ultrathin strip in different deformation stages during the uniaxial quasi-static tensile test. Results show that when the t/d value is lower than 10.62, the CoCrNi alloy ultrathin strip shows an obvious size-dependent property in the elastic deformation stage. With the decrease in t/d value, the volume fraction of the surface layer grains is increased, leading to the linear decrease in flow stress. In the plastic deformation stage, the material stiffness is correlated with the t/d value. Specifically, as the t/d value increases, the work-hardening capacity of the material is enhanced. When the t/d value increases to 10, the work-hardening capacity reaches a maximum state; when the t/d value is beyond 10, the work-hardening capacity weakens.