Anelastic effects in cold-worked nickel

Abstract

The relaxation peaks P X and P Y , observed at low temperature in high purity cold-worked nickel, have been studied after deformation at various temperatures. Their behaviour after annealing have been analysed. It is shown that they present all the features of Bordoni peaks. The study of the secondary characteristics of the peaks leads to results in agreement with Engelke's developments of Seeger's theory of double-kink relaxation. The justification of the existence of two Bordoni peaks in nickel is grounded on Beshers' hypothesis according to which, in nickel, dislocations are not split into partials during the first stages of deformation, but split at the onset of stage III, when cross-slips develop. It is concluded that nickel has an intermediate position among the f.c.c. metals, between the metals with low stacking fault energies and the metals with high stacking fault energies.