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

Defect Recovery and Ordering in Ni3Al+B. Karnthaler, H.P., Kozubski, R., Pfeiler, W., Rentenberger, C.: Materials Research Society Symposium – Proceedings, 1995, 364[1], 309-14