Experimental investigation of Ti–Al–Si phase equilibria at 800–1200 °C

Five partial isothermal sections of the Ti–Al–Si system up to 70 at% Al and 40 at% Si have been determined experimentally between 800 and 1200 °C. Seven alloys were heat-treated for 24–1504 h and characterized utilizing scanning electron microscopy, electron probe microanalysis, X-ray diffraction, and differential thermal analysis. No ternary phase was found and αTi, βTi, Ti3Al, TiAl, TiAl(1d-APS), TiAl2, TiAl3 are in equilibrium with Ti5Si3. A partial vertical section at 9 at% Si shows that all determined data are consistent with each other. •Si is beneficial in improving the creep and high-temperature oxidation resistance of TiAl-alloys.•Phase equilibria and phase transformations in the Ti—Al—Si system at 800–1200 °C have been experimentally established.•The solid solubilities of Al in Ti5Si3 and Si in TiAl, TiAl2, and Ti3Al do not change in dependence on temperature.•Lattice constants of Ti5Si3 for all heat-treated samples showboth lattice constants increase with increasing Al content.•The established partial vertical section at 9 at% Si shows that data are consistent.