Effect of High Temperature Heat Treatment on the Structure and Properties of FeCoCrNiZr Alloy

FeCoCrNiZr high-entropy alloy was melted by vacuum arc melting. The alloys were vacuum annealed at 873, 1073, and 1273 K, respectively. The microstructure, compressive mechanical properties, thermal stability, and hardness of as-cast and annealed FeCoCrNiZr alloys at different annealing temperatures were investigated by using X-ray diffractometry (XRD), scanning electron microscopy (SEM), microhardness tester and universal material testing machine. The results reveal that it has no noticeable change in the phase composition of the alloy after high temperature annealing. The as-cast FeCoCrNiZr alloy is composed of the body-centred cubic phase and Laves phase. In the 1073 K annealed state, the s -phase was detected in the alloy, and the alloy's hardness reached a maximum value of 915.94 HV0.2. The hardness of the alloy in the annealed state is obviously higher than that of the as-cast alloy, and the increased compressive strength is the result of the combined effect of the hardening of the C15 Laves phase and the solid solution strengthening of the Zr atoms.