Ideal simple shear strengths of two HfNbTaTi-based quinary refractory multi-principal element alloys

Abstract

Atomistic simulations are employed to investigate chemical short-range ordering in two body-centered cubic refractory multi-principal element alloys, HfMoNbTaTi and HfNbTaTiZr, and its influence on their ideal simple shear strengths. Both the alias and affine shear strengths are analyzed on the {110} and {112} planes in the two opposing 111 directions. In both quinary alloys, local ordering of NbNb, TaTa, HfNb, HfTa, and NbTa is preferred as the annealing temperature decreases from 900 to 300 K. The pair that achieves the highest degree of local ordering is TiTi in HfMoNbTaTi and HfTi in HfNbTaTiZr. Subject to the affine shear, these alloys yield by first phase transformation at the most likely pairs followed by deformation twinning at those sites.