Enhanced grain growth in an Al-Mg alloy with ultrafine grain size

A submicrometer-grained (SMG) microstructure, with an average grain size of ∼0.2 μm, was introduced into an Al-3% Mg solid solution alloy by equal-channel angular pressing. The SMG structure was heterogeneous with regions of equiaxed and elongated grains and with grain boundaries in a non-equilibrium configuration. Samples were annealed for various times at a temperature of 473 K and then examined using transmission electron microscopy. The results show that the grain boundaries evolve with time into an equilibrium condition and some limited grain growth occurs primarily in the grains where recovery has taken place. The results establish that the SMG structure is reasonably stable in the Al-3% Mg alloy at a temperature of 473 K.