An analysis of superplastic flow after processing by ECAP

Processing by equal-channel angular pressing (ECAP), when carried out optimally, produces submicrometer grain sizes, arrays of equiaxed grains and a significant fraction of high-angle grain boundaries. These conditions are appropriate for achieving high strain rate and/or low temperature superplasticity. This paper reviews experimental results describing superplastic flow in an Al–Mg–Sc alloy after ECAP. It is shown that the experimental data are in good agreement with a model for superplasticity developed for conventional superplastic alloys and based on grain boundary sliding accommodated by the intragranular flow of dislocations. In addition, an analysis shows the region of superplastic flow lies very close to, or even exceeds, the predicted transition between the viscous glide of dislocations and the breakaway of dislocations from their solute atmospheres.