| The evolution of the microstructure during ECAP depends upon the shearing deformation paths introduced into the material. Some authors, using selected-area electron diffraction, reported an effectiveness of cell (low-angle boundaries) evolution toward high-angle boundaries on the order Bc > C > A. This study focused on the cell and grain boundary evolution of an AA1200 during ECAP, up to a true strain of E=8.64, in routes A, C, and Bc. TEM Kikuchi bands were used for the quantitative evaluation of boundary misorientation. A different hierarchy of cell evolution to grains was found, and this was as C > Bc > A; while in terms of reducing grain size, the route efficiency remained as Bc ≥ C > A. Thermal stability of the severely deformed alloy was studied by annealing the alloy at 0.5, 0.6, 0.7 TM for 2 hrs. It appeared that, even if route Bc is the one involving a faster microstructure grain refining, route C is likely to be the most stable upon reheating. |
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