Experimental equilibria of several β/βo-Ti-Al-Nb alloys containing ωo phase

The phase equilibria of several (6, 8, 10) at % Nb-TiAl alloys are experimentally determined by the morphologic, crystallographic and thermal analysis methods. The thermodynamically determined phase equilibria reveal that ω_o phase transforms from α₂ phase, having no β/β_o phase retained at ambient temperature. While, the β/β_o phase are experimentally observed in the samples annealed at 1400 °C followed by a slow cooling rate (∼10 °C min^-1). Furthermore, the transformation of β_o ⇆ ω_o, as well as the disorder-order transition of β ⇆ β_o, is unambiguously detected, within the certain transformation temperatures.