Composition dependence of Young's modulus in Ti-V, Ti-Nb, and Ti-V-Sn alloys

The Young's modulus of Ti-V and Ti-V-Sn alloys quenched from the β-phase region after solution treatment and cold rolling was investigated in relation to alloy compositions, microstructures, and constituent phases. The composition dependence of the Young's modulus for quenched Ti-V binary alloys shows two minima of 69 GPa at Ti-10 mass pct V and 72 GPa at Ti-26 mass pct V. Between the two compositions, athermal ω or stress-induced ω is introduced in retained β phase and increases Young's modulus. That is, a low Young's modulus is attained unless alloys undergo ω transformation. In Ti-5 and -8 mass pct V, which undergo α′ (hcp) martensitic transformation on quenching, the Young's modulus further decreases by cold rolling, which can be reasonably explained by the formation of α′ rolling texture. Comparing Young's modulus in Ti-V binary alloy with that in Ti-Nb binary alloy, it is found that Young's modulus is remarkably increased by athermal- or stress induced ω phase, and it shows a minimum when both martensitic and ω transformation are suppressed during quenching in metastable β alloys. The Sn addition to Ti-V binary alloy retards or suppresses athermal and stress-induced ω transformation, thereby decreasing Young's modulus. Young's modulus exhibits minimum values of 51 GPa in quenched (Ti-12 pct V)-2 pct Sn and of 57 GPa in cold-rolled (Ti-12 pct V)-6 pct Sn.