Phase equilibria and transformations in titanium aluminides

The phase equilibria in the binary Ti-Al system are reviewed together with the transformations which occur involving aluminide phases of interest for the production of advanced high temperature materials. The difficulties encountered in the experimental determination of phase diagrams are highlighted. The role of ternary alloying elements, notably oxygen and β stabilising elements, is discussed in relation to their effects on the phase equilibria and transformations in aluminide based alloys.