Abstract:The structure transformation mechanism in Ti-48Al(mole percent) intermetallic alloy was investigated when it was cooled rapidly from singleαphase region. The results showed that the massiveγwas obtained by anα→γmassive transformation during the quenching process in this alloy. A large number of defects, such as anti-phase boundaries (APBs), stacking faults, microtwins and dislocations, were observed to be within the massiveγ.Studies indicate that the massiveγnucleates with coherent interface and grows in a diffusion controlled ledge growth mechanism.

Key words: TiAl alloy　massive transformation　diffusion controlled ledge growth mechanism