Partial isothermal sections of Ti–Al–V ternary diagram

The phase equilibria between the titanium aluminides, Ti₃Al and TiAl, and V have been investigated in the temperature range 1473–873 K. Microstructures were characterised using light, scanning electron, and transmission electron microscopy and the nature of the phases present was established via X-ray diffractometry, electron diffraction, and energy dispersive X-ray analysis. A series of isothermal sections have been determined and are compared with those obtained in earlier studies. Ordering of the high temperature bcc β phase to a simple cubic B2 (β₂) structure was observed: the ordering temperature was found to decrease with increasing V content, whereas the opposite effect was observed with Al. The effect of oxygen is to stabilise the α phase and to shift the α₂+β₂+γ field in the V rich direction. The lattice parameters of α₂ and β phases decrease with additions of Al and V: empirical equations have been developed to predict these changes.

MST/1881