Structure and properties of cast binary Ti-Mo alloys

Structure and properties of a series of binary Ti-Mo alloys with molybdenum contents ranging from 6 to 20 wt% have been investigated. Experimental results indicated that crystal structure and morphology of the cast alloys were sensitive to their molybdenum contents. The hexagonal α' phase c.p. Ti exhibited a feather-like morphology. When Mo content was 6 wt%, a fine, acicular martensitic structure of orthorhombic α'' phase was observed. When Mo content was 7.5 wt%, the entire alloy was dominated by the martensitic α'' structure. When Mo content was increased to 10 wt% or higher, the retained β phase became the only dominant phase. Among all Ti-Mo alloys, the α'' phase Ti-7.5Mo alloy had the lowest hardness. The bending strength of Ti-7.5Mo was similar to that of Ti-15Mo and Ti-13Nb-13Zr, and higher than c.p. Ti by nearly 60%. The bending modulus of the α''-dominated Ti-7.5Mo alloy was lower than that of Ti-15Mo by 22%, of Ti-6Al-4V by 47%, of Ti-13Nb-13Zr by 17%, and of c.p. Ti by 40%.