Reaction mechanism in high Nb containing TiAl alloy by elemental powder metallurgy
(1. State Key Laboratory for Advanced Metals and Materials,
University of Science and Technology Beijing, Beijing 100083, China;
2. State Key Laboratory of Powder Metallurgy, Central South University,
Changsha 410083, China)
University of Science and Technology Beijing, Beijing 100083, China;
2. State Key Laboratory of Powder Metallurgy, Central South University,
Changsha 410083, China)
Abstract: High Nb containing TiAl alloy was fabricated in argon atmosphere by reactive hot pressing process. Reaction mechanism was investigated by means of microstructural analyses and thermodynamic calculations. The results show that it is feasible to prepare high Nb containing TiAl alloy with fine lamellar colonies by reactive hot pressing process. The reaction between Ti and Al powders is dominant in Ti-Al-Nb system. Nb powders dissolve into the Ti-Al matrix by diffusion. Pore nests are formed in situ after Nb powders diffusion. The hot pressing atmosphere is optimized by thermodynamic calculations. Vacuum or argon protective atmosphere should be adopted.
Key words: TiAl based alloy; high Nb containing TiAl alloy; powder metallurgy; reaction mechanism; thermodynamics