Enhanced diffusion in α-brass during cyclic straining

Abstract

α-brass was subjected to low amplitude cyclic straining at 20 cycles per second at a series of temperatures. The electrical resistivity decreased with increasing number of cycles up to about 2 × 10⁴, the higher temperature runs showing the greater decrease. The interpretation is based on an excess number of vacancies enhancing the diffusion rate and hence the degree of short-range order. The kinetics indicate a bimolecular loss of defects which is interpreted as the recombination of equal numbers of interstitials and vacancies. Equilibrium resistivity is not achieved at the measured temperatures and a model is proposed in which the number of potential defects depends solely on the initial preparation of the material and in which diffusion enhancement stops when these are exhausted by recombination.