J. Ehmann et M. Fahnle, GENERALIZED STACKING-FAULT ENERGIES FOR TIA1 - MECHANICAL INSTABILITYOF THE (111) ANTIPHASE BOUNDARY, Philosophical magazine. A. Physics of condensed matter. Structure, defects and mechanical properties, 77(3), 1998, pp. 701-714
Generalized stacking-fault energies for the (111) and (100) planes of
stoichiometric TiAl are calculated within the framework of density fun
ctional theory in the local-density approximation and the full-potenti
al linearized-augmented-plane-wave method. The most striking result is
the mechanical instability of the (111) antiphase boundary (APB) with
respect to shear along [112] towards the complex stacking fault (CSF)
. Consequently, the energy of the (111) APB is larger than the energy
of the CSF which in turn is about twice the energy of the superintrins
ic stacking fault. Implications for the dissociation of superdislocati
ons in stoichiometric TiAl are discussed.