Effect of Cr content on microstructure and properties of Mo0.5VNbTiCrx high-entropy alloys

A combination of good mechanical properties, excellent corrosion resistance and superior irradiation resistance made high-entropy alloys (HEAs) as promising nuclear materials. In this work, the Mo0.5VNbTiCrx (x = 0–2.0) HEAs containing elements with low thermal neutron absorption cross-sections were designed and prepared. The alloys were produced by vacuum arc melting, followed by hot isostatic pressing at 1200 °C and 150 MPa for 2 h and annealing at 1200 °C for 72 h. The crystal structure, microstructure, hardness, and mechanical properties of the annealed alloys were investigated. The corrosion resistance in superheated steam was also preliminarily studied. When 0 ≤ x ≤ 0.75, the alloys consist of one body-centered cubic (BCC) phase. When 1.0 ≤ x ≤ 2.0, the alloys are composed of one BCC phase, one C15 Laves phase, and another face-centered cubic (FCC) phase. The effect of Cr content on the phase formation is discussed. The hardness and yield strength increase substantially with increasing Cr content, which could be attributed to the solid-solution-like strengthening. Moreover, the addition of Cr improves the anti-corrosion properties in superheated steam and the studied alloys exhibit better corrosion resistance than a currently used Zr-4 alloy. The Mo0.5VNbTi and Mo0.5VNbTiCr0.25 alloys exhibit the promising potential to be used as nuclear materials, as they show a good combination of mechanical properties and corrosion resistance.