Abstract:Powder metallurgy Ti-45Al-10Nb alloys was successfully fabricated by reactive sintering of milled powders at 1350 °C for 2 h in vacuum. The microstructure, in particular, constituent phases, grain size, precipitates of the product was investigated in detail. The results indicate that a double phase γ+α₂ microstructure containing Ti₂AlC precipitate is obtained under the sintering condition, and the alloy exhibits a fine and homogenous microstructure compared with traditional TiAl base. In fine grain structure, the average grain sizes for the γ and α₂ phases are (2.3±0.05) and (5.6±0.05) μm, respectively. Additionally, numerous dislocations are observed in the alloy, and the dislocation density in γ phase is significantly higher than that in α₂ phase. The formation mechanisms of the dislocation in the present alloy were also discussed in detail.

Key words: high Nb-TiAl alloy; powder metallurgy; microstructure; dislocation