Microstructure and tensile properties of a cost-affordable and ultrahigh-strength metastable β titanium alloy with a composition of Ti-6Al-1Mo-1Fe-6.9Cr

A cost-affordable and ultrahigh-strength metastable β titanium alloy with a composition of Ti-6Al-1Mo-1Fe-6.9Cr has been designed by high-throughput diffusion couple technique. The alloy was heat treated along different regimes to investigate the effects of heat treatments on phase transformation, microstructure evolution, and tensile properties. The results showed that the aging strength of the alloy after solution treatment at 840 °C was higher than that at 800 °C due to the more αs precipitation during aging, while solution treatment at 840 °C and aging caused slight decrease of tensile ductility because of the lower αp-phase fraction during solution treatment. Moreover, the formation TiCr2 Laves phase at aging temperatures above 540 °C resulted in remarkable reduction of tensile ductility. Owing to the multiple-hierarchy α precipitations dispersed into the β matrix, two excellent strength-ductility combinations were successfully obtained for the alloys after solution treatment at 800 °C/840 °C and aging at 470 °C with the ultimate tensile strength and tensile elongation values of 1395 MPa/16.0% and 1614 MPa/9.7%, respectively.