Climb dissociation on {310} planes in nearly-stoichiometric Ni3Al

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Abstract
In nearly-stoichiometric Ni3Al deformed in compression above the temperature where the flow stress peaks, superdislocations may be dissociated either by glide, on their {001} slip plane, or by climb, prefentially on {310} planes. Conditions that control the choice of these specific configurations are examined. Simple rules are introduced in order to determine the equivalence between antiphase boundaries (APBs) and to identify the occurrence of composition violations. It is shown that non-conservative APBs occur principally for APB configurations where the crystal composition is conserved and at dislocation orientations with a strong edge component. The set of APB energies, which is available in this material, is inconsistent with a pair-wise model limited to second neighbours. The fact that, for a mixed dislocation, the most favourable configurations may not coincide with the plane of lowest APB energy, is explained within the frame of elastic anisotropy, according to the dislocation character and to the relative values of APB energies on {310} and {001}.