Investigation on the 1000, 1150 and 1400°C isothermal section of the Ti-Al-Nb system

The 1000, 1150 and 1400°C isothermal sections of the Ti-Al-Nb system have been determined using a diffusion couple technique. A series of ternary alloys in the single-phase or multi-phase regions has been employed to identify the phase relations shown in these isothermal sections. A new ternary phase γ₁ has been identified. Several of the binary phases were found to have extensive solubilities, which increased with increasing temperature. The binary compounds TiAl₃ and NbAl₃ form a continuous solid solution in the ternary system. Determination of these phase relations was accomplished through the use of electron microprobe analysis (EPMA), X-ray diffraction (XRD) and microstructure observations.