PLANAR DEFECT ENERGIES BY THE EMBEDDED ATOM METHOD AND DISSOCIATED SUPERDISLOCATION CONFIGURATIONS IN THE L10-TYPE TIAL COMPOUND

The planar defect energies at the ground state in L1(0)TiAl were calculated by the embedded atom method. The results show that the magnitudes of the defect energies in a {111} plane are in descending order, antiphase boundary (APB), complex stacking faults and intrinsic stacking faults. The APB energy varies depending on the plane of the APB. The APB energy decreases when the APB undergoes cross-slip from the (111) plane onto either the (101) plane or the (010) plane. The calculated APB energies in the (111), (101) and (010) planes were found to be 322, 237 and 131 mJ m-2 respectively. The equilibrium energies of various dissociated superdislocations were calculated based on the balance between the repulsive energy among the partial dislocations, and the attractive energy originating from planar defects. The results show that the superdislocations (b=a[101]) dissociated on two different {111} planes or on one {111} plane and one non-{111} plane possess lower energies than those of co-planar dissociation.