Ductile and strong aluminium-matrix titanium aluminide composite formed in situ from aluminium, titanium dioxide and sodium hexafluoroaluminate

An aluminium-matrix TiAl₃-particle (1-2 μm) composite exhibiting high tensile ductility (22%), high tensile strength (235 MPa) and a grain size of 50 μm was made by a new in situ method involving reactions between Al, TiO₂ and Na₃AlF₆, which were subjected to stir casting at 900 °C. The strength and ductility were higher than those of an aluminium-matrix TiAl₃-particle Al₂O₃-particle composite made in situ by reacting Al with TiO₂ (without Na₃AlF₆). This is due to the ability of Na₃AlF₆ to enhance the reduction of TiO₂ and Al₂O₃, thus resulting in more TiAl₃ and a smaller grain size.