Microstructural evolution and mechanical behavior of metastable β-type Ti–30Nb–1Mo–4Sn alloy with low modulus and high strength

Abstract

A metastable β-type Ti–30Nb–1Mo–4Sn alloy with ultralow elastic modulus and high strength was fabricated. Under the solution treatment state, the Ti–30Nb–1Mo–4Sn alloy possesses low yield strength of about 130MPa owing to the presence of the coarse α′′ martensitic laths. Upon a cold rolling and annealing process, the martensitic transformation from β to α′′ is significantly retarded due to the inhibitory effect of grain boundaries and dislocations. As a result, the metastable β phase with low total amount of β-stabilizers is retained to room temperature, giving rise to a low modulus of 45GPa. Meanwhile, nano-sized α precipitates and dislocation tangles play a key role in strengthening the Ti–30Nb–1Mo–4Sn alloy, resulting in a high tensile strength of ~1000MPa. With low elastic modulus and high strength, the metastable β-type Ti–30Nb–1Mo–4Sn alloy could be a potential candidate for biomedical materials.