Precipitation strengthening in a hot-worked TiNbTa0.5ZrAl0.5 refractory high entropy alloy

Abstract

A TiNbTa0.5ZrAl0.5 refractory high entropy alloy was prepared by powder metallurgy and subsequently subjected to hot forging and annealing. Precipitation behavior and mechanical properties of the hot-worked TiNbTa0.5ZrAl0.5 alloy were investigated. Results show that the hot forging leads to a formation of (Zr, Al)-rich HCP precipitates in the initial BCC matrix. The precipitates have significant strengthening effect on the TiNbTa0.5ZrAl0.5 alloy after annealing at 1000 °C for 2 h. Owing to the precipitation strengthening, the hot-worked TiNbTa0.5ZrAl0.5 alloy exhibits a high compressive yield strength of 1740 MPa with a compressive stain of 20%. It is interesting that annealing at lower or higher temperatures than 1000 °C causes a degradation in compression properties, mainly due to the decomposition of the BCC matrix and the coarsening of the HCP precipitates.