Phase Equilibria of the Ti-Al-Nb System at 1000, 1100 and 1150 °C

1000, 1100 and 1150 °C isothermal sections of the Ti-Al-Nb system were studied using x-ray diffraction, scanning electron microscopy and electron probe microanalysis. A small island-like region of single β0 is present at 1000, but absent at 1100 and 1150 °C. γ1 is not a stable phase at 1000 and 1150 °C. Three three-phase fields (α2 + β0 + σ, β0 + σ + γ and α2 + β0 + γ) are identified in the 1000 °C isothermal section (30-60 at.% Ti content). The 1100 °C isothermal section is firstly studied completely. It includes six three-phase and thirteen two-phase fields. Two three-phase fields β + α2 + γ and β + σ + γ are identified in the isothermal section (30-60 at.% Ti content) at 1150 °C. These data are helpful to the fabrication of the TiAl and Ti2AlNb intermetallics.