Enhanced yielding strength of near-α Ti–Al–Zr–Sn high temperature alloys

The effect of Si3N4 addition on the mechanical properties and microstructure of Ti–Al–Zr–Sn based near-α Ti alloys has been systematically investigated at both room temperature and high temperature (650 °C). Minor Mo and Ta (β stabilizing elements) together with Si3N4 addition have significantly improved the compressive yielding strength at both room temperature and 650 °C. The strengthening effect was mainly due to the precipitation of TiN, α2-Ti3Al and the retained β phase. High compressive yielding strength together with pronounced ductility can be obtained by only adding minor Si3N4 into Ti–Al–Zr–Sn alloys. The enhanced ductility is probably due to the depression of the brittle α2 intermetallic phase, which did not precipitate out even after long time ageing (750 °C for 500 h).