Influence of Mo Content on Microstructure, Wear Resistance, and Corrosion Behavior of NbTiZrMox Refractory High-Entropy Alloys

Abstract:

NbTiZrMo_x alloys were prepared by vacuum arc furnace with high-purity powder mixtures of Nb, Ti, Zr, and Mo as raw materials. The role of element Mo in NbTiZrMo_x alloys and the effect of different Mo content on microstructure, microhardness, wear resistance, and corrosion resistance of NbTiZrMo_x alloys were investigated. Results show that these alloys display a typical dendritic morphology with a single-phase body-centered cubic crystal structure. The microhardness and wear resistance of NbTiZrMo_x alloys are significantly improved with the increase in Mo content, which is attributed to solid-solution strengthening and fine-grain strengthening. With the increase in Mo content, the dominant wear mechanism of the alloy transforms from adhesive wear accompanied by abrasive and oxidative wear to oxidative wear with slight adhesive wear. Electrochemical corrosion tests conducted in a 3.5wt% NaCl solution reveal that the corrosion resistance of NbTiZrM alloys exhibits a trend of initial enhancement followed by deterioration as Mo content rises. The alloy containing 14.29at% Mo achieves the optimal corrosion resistance, demonstrating that an appropriate addition of Mo facilitates the formation of a stable passive film and thereby markedly improves the corrosion resistance of the alloy.