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 αW 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.