Design and microstructure-mechanical properties of a novel metastable β titanium alloy with excellent strength-plasticity matching

Based on the d-electron theory, a new type of high strength metastable β alloy Ti-5.2Mo-5.2Cr-4.0Al-4.4V-2.4Nb (Ti-542) alloy was developed which presented excellent strength-plasticity matching. In solution state, the yield strength can reach 871 MPa, where the fracture elongation is as high as 23.6 %. The twining and martensitic transformation have been founded which contributes to achieve a superhigh plasticity. After aging treatment, the yield strength of Ti-542 can increase to 1256 MPa and the fracture elongation is still reach 8.7 % which is obviously better than other commercial alloys at the same strength level. The multiple twins of α_W produced during deformation are expected to improve the synergistic deformation ability of micro-zone and enhance the plasticity of the alloy. The strengthening mechanism was also thoroughly discussed based on microstructures and strengthening models. This work provides a valuable choice for structural materials on new generation of aviation equipment.