Effect of sintering temperature on microstructure and mechanical properties of WMoTaVTi refractory high entropy alloys

Refractory high entropy alloys(RHEAs) have broad application prospect in ultra-high temperature filed such as aerospace because of its high service temperature and excellent thermal stability. However, RHEAs are facing the problems of insufficient comprehensive mechanical properties and further application is limited. In order to solve these problems, a kind of WMoTaVTi RHEA was prepared by introducing Ti element on the basis of WMoTaV RHEA, and the effect of sintering temperature on sintering densification, microstructure and mechanical properties of WMoTaVTi RHEAs were systematically investigated. The results show that the grain size of the alloy increases gradually and the yield strength of the alloy increases first and then decreases with the increase of sintering temperature. When the sintering temperature is 1 500 ℃, the alloy exhibits the optimal comprehensive properties at room temperature and its relative density exceeds 99%, with compressive yield strength of 1 672 MPa and a fracture strain of 16.6%, and the fracture morphology is mainly intergranular fracture. Compared with WMoTaV RHEA, the yield strength of WMoTaVTi RHEA increases by 18%. Through the multi-dimensional analysis, due to the introduction of a small amount of O into the powder metallurgy process, the alloy mainly consists of BCC matrix phase and a small amount of TiO precipitation phase with FCC structure. With the increase of sintering temperature, the solid solubility of the matrix increases, and the volume fraction of TiO phase decreases gradually. The improvement of strength can be attributed to the solid solution strengthening and precipitation strengthening. © 2024 Central South University of Technology. All rights reserved.