Stability of ordinary dislocations on cross-slip planes in γ-TiAl

Ordinary dislocations in γ-TiAl frequently cross-slip onto various non-primary slip planes at high temperatures. The anomalous hardening in γ-TiAl was believed to be linked to cross-slip behavior. Therefore, the stability of ordinary dislocations and the interaction energy of kink pairs or jog pairs in these cross-slip planes were examined to understand the cross-slip behavior. The energy factors and line tension for 1/2〈110] screw dislocations in γ-TiAl were calculated on the basis of the Sextic formalism. Inverse Wulff plots were applied to determine the instability of dislocations on (111), (110) and (001) glide planes. The dislocations are stable due to the convexity of the plots and always have positive line tension. The interaction energy in kink pairs on the cross-slip planes were calculated. The results show that the interaction energy was highly anisotropic in the cross-slip planes and was found to be the minimum on the (110) plane, which is consistent with the transmission electron microscopy (TEM) observations in the literature. The temperature effects on the stability and interaction energy were also investigated using six independent elastic constants at different temperatures.