Synthesis and corrosion behavior of Mo15Nb20Ta10Ti35V20 refractory high entropy alloy

The Mo15Nb20Ta10Ti35V20 refractory high entropy alloy with BCC structure was prepared by vacuum arc melting. The synthesized Mo15Nb20Ta10Ti35V20 demonstrated better corrosion resistance compared to 316 stainless steel in chloride corrosion environment, whose better corrosion resistance is attributed to the complex passive film structure and shows the characteristics of passivation-transpassivation-secondary passivation on the polarization curve. Mott-Schottky curves analysis and XPS results show that the primary and secondary passive films have different P-N junctions which were composed of different oxides showing bilayer structure characteristics. Through the thermodynamic calculation, the relationship between the competitive growth of multiple principal elements in RHEA were analyzed. The dynamic changes of TiO2 and Ti2O3 contents were responsible for the secondary passivation phenomenon.