Phase transformation in the γ-TiAl alloy induced by Ar ions

Intermetallic γ-TiAl alloy specimens were irradiated with 25 keV Ar ions at room temperature. The defect formation and structural changes were investigated by conventional and high-resolution transmission electron microscopy. The defects observed in low-dose irradiated specimens are planar defects, which may be stacking faults or dislocation loops. A phase transformation was induced in high-dose irradiated specimens. The results suggest that the induced phase has a relation with the planar defects in the early stage of the ion irradiation. The induced phase was found to be of the same structure as the induced phase in Xe-irradiated γ-TiAl. The features of the ion irradiation induced structure changes are compared with reported results. The mechanism of the phase transformation is discussed.