Grain refinement in an Al-Mg-Sc alloy: Equal channel angular pressing versus friction-stir processing

In contrast to ECAP, the fine-grained material produced by FSP was found to be characterized by a coarser grain- and dispersoid size, lower dislocation density, more irregular texture, higher high-angle boundary fraction and lower strength. The comparatively low efficiency of FSP for grain refinement and enhancement of strength was attributed to the relatively high processing temperature and the relatively low cooling speed.