2012 年 52 巻 9 号 p. 1655-1660
Ternary β-type Ti–10Cr–(V, Fe, Mo) alloys with self-tunable Young's moduli were subjected to solution treatment and cold rolling, and their microstructures and mechanical properties were investigated. During cold rolling, a band-like structure, which is considered to be {332}β<113>β mechanical twin, and deformation-induced ω phase are formed in alloys with certain chemical compositions. The number of bands increases with an increase in the cold-rolling reduction ratio and V content as well as with a decrease in Mo content. On the other hand, the Young's modulus increases during cold rolling, and the increase in Young's modulus is considered to be caused by the deformation-induced ω phase transformation. Furthermore, the tensile strength decreases slightly and the elongation tends to increase with an increase in the alloying element contents, while the effect of the V and Mo contents on the trend in changing the number of mechanical twin is opposite. These tensile properties are derived from the complicated factors among the plastic deformation mode, the type of mechanical twinning, and deformation-induced ω phase transformation, depending on the β stability and the kind of alloying element.
