It was argued that decomposition of the a<111> dislocation was controlled by its mobility relative to that of the a<101> segment. Therefore, if the mobility of the latter was higher for the stoichiometric composition, then decomposition might occur at a lower temperature. Contrary to this idea was the fact that few a<101> dislocations were observed above the so-called knee, in the stoichiometric case. Another suggestion was that decomposition of the a<111> dislocation into three a<101> dislocations occurred directly; without any intermediate state that involved a<101> dislocations. The former situation was expected to be favored in the case of high vacancy diffusivity. Recent data suggested that vacancy motion was initiated at about 600K, and that the stoichiometric compound contained a higher density of vacancies.

Decomposition of a<111> and a<101> Dislocations in Hard-Oriented NiAl Single Crystals R.Srinivasan, M.F.Savage, M.S.Daw, R.D.Noebe, M.J.Mills: Scripta Materialia, 1998, 39[4-5], 457-64