An examination of strain ageing in a Mg–Y–Zn alloy containing Gd

摘要

Dynamic strain ageing has been observed on straining a Mg–Y–Zn–Gd alloy in both the quenched and the annealed states, where long-period-structural-order phase and solution or precipitation of Gd is found. Deformation mechanisms are analysed in terms of solute diffusion to mobile dislocations, the role of excess vacancies and the presence of a Taylor dislocation network. In quenched material, the operation of multiple deformation modes leads to the creation of a three-dimensional (Taylor) dislocation network such that pipe diffusion along forest dislocations can readily lead to pinning of a moving dislocation. The many planar precipitates present in annealed material inhibit non-basal flow such that the Taylor dislocation network does not form and bulk diffusion of solute is required for flow serrations to appear.