Defect recovery and long-range ordering (LRO) in Ni76Al24+0.19at.%B (400 wt.ppm) were studied by means of residual resistometry, TEM methods and microhardness testing. The material was cold-rolled with intermediate annealings and the samples were prepared from sheets exhibiting effective thickness reductions of 8 and 14%, respectively, achieved in the final rolling step.
By TEM two recovery processes were observed. Firstly, superlattice intrinsic stacking faults (SISF) of large density recovered almost completely in the temperature regime between 443 and 700 K showing that they are bounded by dislocations of opposite sign. This indicates that most of the SISF are formed by pulling out dipoles and not by dislocation interactions as recently suggested. Secondly, the recovery of antiphase-boundary (APB) dissociated superlattice dislocations occurred by the annihilation of dipoles within the whole temperature regime leading finally to a loss of all dislocations at 1273 K.
Despite some excess disorder caused by cold-rolling, the mechanical deformation did not influence qualitatively the LRO processes.