Microstructure and mechanical properties of powder metallurgy high temperature titanium alloy with high Si content

Abstract

The service temperature of high temperature titanium alloy has been raised from 400 °C to 650 °C in the last years. In this study, a new near α high temperature titanium alloy with high Si content (Ti–6Al–4Zr-0.5Mo-0.6Si, wt. %) which can serve at 700 °C was developed by powder metallurgy (P/M) method. The microstructure and mechanical properties were investigated. The results show that the P/M titanium alloy exhibits an α + β two-phase microstructure with dispersed fine S2 type silicide ((TiZr)6Si3). The yield strength and ultimate tensile strength are 1023 MPa and 1190 MPa at room temperature, with an elongation of 10%. At 700 °C, the alloy still maintains a yield strength, an ultimate strength, and an elongation of 510 MPa, 651 MPa and 13%, respectively. The high strength is mainly attributed to the precipitation strengthening of the silicide and the formation of fine-grained α′ phase.