Ta/Zr-Alloyed V–Cr–Ti Alloys via a Cluster-Plus-Glue-Atom Model for BCC Solid Solutions

A cluster formula of [M − V14]M1 was formed for vanadium alloys based on a cluster-plus-glue-atom model for BCC solid solutions, where the clusters [M − V14] were centered by one solute M and surrounded by fourteen solvent atoms V, and M could also be served as a glue atom to link clusters. The [M − V14]M1 formula with M = V1/3Cr1/3Ti1/3, an equal-molar combination of V, Cr and Ti, corresponded to the typical V–4Cr–4Ti alloy (wt.%). Based on this formula, a series of new alloys with Ta and Zr substitution for V and Ti respectively in M, were designed and molded into ϕ3 mm rods by copper-mold suction-cast method. These alloys were solid-solutioned at 1273 K for 2 h followed by water-quenching. For Zr-added alloys, the second phase V2Zr was prone to be precipitated, that made alloys much brittle and worse corrosion-resistant in Cl− solution. While Ta-alloyed alloys exhibited a single BCC structure, the Vickers hardness HV of alloys were enhanced obviously. Among them, the Ta-added alloy with M = Ta1/3Cr1/3Ti1/3 (V79.21Ta13.4Cr3.85Ti3.54 wt.%) displayed both higher microhardness and better corrosion-resistance in Cl− solution.