STOICHIOMETRIC NBTIAL3 (GAMMA(1) PHASE) ALLOY IN TI-AL-NB TERNARY-SYSTEM

The microstructure and phase constitution in stoichiometric NbTiAl3 (g amma(1) phase) alloy treated at 1000 degrees C were examined by metall ography and X-ray diffraction. The alloy microstructure is mainly gamm a(1) phase containing eta second phase [(Ti,Nb)Al-3] less than 1%. DTA analysis shows no phase transformation from room temperature to 1200 degrees C. In the diffusion couple of NbTiAl3 with gamma-TiAl compound , clear phase boundary and composition jump exist. between gamma(1) an d gamma phase, These results further confirm the existence of gamma(1) single phase at 1000 degrees C in Ti-Al-Nb ternary system.