Compositional variability in gum metal

ββ-Ti alloy Gum metals were defined as Ti–24(Nb + Ta + V)–(Zr,Hf)–O (at.%) by Saito et al. [T. Saito et al., Science 300 (2003) 464]. Previous work has focused on compositions near Ti–23Nb–0.7Ta–2Zr–O. Here, Ti–24V–28Zr–2O was examined; similar single-crystal elastic constants were observed. However, the alloy was found to be brittle and did not form α″α″ during loading, unlike the Ti–Nb alloy. V-rich body-centred cubic precipitates were also observed. Therefore the ββ stability parameters e/ae/a, Bo and Md alone are insufficient to define the compositional range of Gum metals.