The Effect of Hot Deformation on Dispersoid Evolution in a Model 3xxx Alloy

The influence of hot deformation on the evolution of size, shape, and fraction of dispersoids has been studied in a simple 3xxx aluminium alloy by means of hot torsion testing. It has been shown that at high strain rates, deformation leads to spheroidization of the dispersoids, an increase in number density, and an increase in volume fraction. The increase in number density and volume fraction are associated with precipitation of new particles. The enhancement of manganese diffusion is a key factor in promoting rapid dispersoid evolution during deformation. A model has been developed to estimate the effect of deformation induced vacancies and dislocations on diffusion. This predicts that an order of magnitude increase in diffusion coefficient between may occur under typical hot deformation conditions, consistent with the rapid microstructural changes measured experimentally.