Phase dissolution strengthens and ductilizes a high-entropy alloy

Abstract

Annealing is widely used in the thermomechanical processing of metallic alloys. Usually, ductility enhances while strength decreases because defects annihilate with the increase in annealing temperature. Here, we report a simultaneous improvement in strength and ductility of a TiZrNbTa high-entropy alloy by promoting phase dissolution with increasing annealing temperature. When annealing is performed from 800 to 1250°C, the tensile yield strength increases by 40% to 1003 ± 16 MPa, and the elongation is nearly doubled to 16.79% ± 1.03%. The annealing-induced phase dissolution promotes lattice distortion, contributing to enhanced lattice friction stress and yield strength. The correspondingly decreased interface mismatch alleviates stress concentration, and the stimulated formation of local chemical orders encourages coplanar slip and dislocation multiplication. Both occurrences boost ductility. These results not only expand our understanding of the phase dissolution and annealing effect in metallic materials, but also provide an insight into designing strong and ductile alloys.