High-temperature deformation experiments were performed on two non-stoichiometric Ni2AlTi compounds lying roughly on the NiAl-NiTi quasi-binary line in the Ni-Al-Ti ternary system. The results were compared with those for the stoichiometric compound. Marked effects of non-stoichiometry upon the deformation behaviour were observed only in the Al-rich compound. The deviation from stoichiometry on the Al-rich side produced considerable strengthening of Ni2AlTi. The (001) superlattice dislocations in the Al-rich compound were found to be dissociated into two ½(001) superlattice partial dislocations coupled by a ribbon of antiphase boundary. From the separation of the superlattice partial dislocations, the energy of the antiphase boundary on (110) in the Al-rich compound was found to be about 115mJ/m2. Assuming that the excess Al atoms in the Al-rich compound were all on the Ti sub-lattice, the energy of the antiphase boundary for the stoichiometric composition was estimated to be higher than 155mJ/m2.

Effects of Non-Stoichiometry on the High-Temperature Deformation of Ni2AlTi. Y.Umakoshi, M.Yamaguchi, T.Yamane: Philosophical Magazine A, 1985, 52[3], 357-67