Elastic and plastic anisotropy in a refractory high entropy alloy utilizing combinatorial instrumented indentation and electron backscatter diffraction

Abstract

A comprehensive study was carried out to predict the elastic and plastic anisotropy of the non-equiatomic Mo15Nb35Ta35V5W10 Refractory High Entropy alloy (RHEA) using a high throughput combinatorial approach employing instrumented micro-indentation with electron backscatter diffraction (EBSD). The Levenberg–Marquardt optimization algorithm was utilized to determine elastic stiffness constant (C11= 267, C12= 115 and C44= 52 GPa) for accessing elastic anisotropy. The anisotropy in plastic deformation of<001>,<011> and<111> orientated grains can be attributed to the activation of the different {112}<111> slip system along with cross slip and the conservative movement of jogs on the screw dislocation. The spatial distribution of misorientation on <001>, <011> and <111> orientated grains as well as slip plane trace analysis, indicates that symmetry in misorientation pattern results from the flow of material along <111> slip direction on the indented surface. The results of the present investigation clearly indicate that the anisotropy in the elastoplastic behavior of novel RHEA is distinct from its constituent elements and that simple rule of mixtures is not sufficient to determine elastic modulus and lattice friction stress of RHEAs. Thus, high throughput experimental techniques are necessary to establish the structure-property linkages in novel multicomponent multi-principal RHEA compositions.