Hardening in quenched aluminium

Abstract

The variation in yield stress, (σy), with testing temperature of quenched polycrystalline aluminium has been investigated as a function of quenching temperature. Transmission electron microscopy studies were performed on the same specimens to correlate the defect structure and the mechanical properties. A strong temperature sensitivity of σy is observed when the quenching treatment introduces a high uniform density of dislocation loops. On the other hand, when the quenching conditions favour void formation a small temperature dependence of σy is observed, similar to that for annealed aluminium. The results are compared with presently available theories and the best agreement for the void hardening is obtained with Coulomb's theory, while a modified version of Fleischer's theory may account for the hardening observed when dislocation loops are present.