Microstructural evolution in an aluminum solid solution alloy processed by ECAP

Samples of an Al–1% Mg solid solution alloy were processed by equal-channel angular pressing (ECAP) at room temperature for totals of 1–12 passes and the microstructures of the processed samples were examined using orientation imaging microscopy. The results demonstrate the alloy achieves a reasonably stable microstructure after 6 passes through the ECAP die with an ultimate equilibrium grain size of ∼700 nm. Measurements show both the fraction of high-angle boundaries and the average boundary misorientation increase with increasing numbers of passes up to 6 passes but thereafter there is only a minor additional increase up to 12 passes.