Fig. 5.

Deformation modes in coarse-grained and fine-grained specimens. Schematic diagrams showing microstructure a before, and b after compression at room temperature. The dominant deformation mechanism is intra-granular dislocation slip and twinning in a coarse-grained microstructure that is produced by 400 °C extrusion, and inter-granular mechanisms (grain boundary sliding, which is accommodated by grain rotation, and dynamic recrystallisation) in a fine-grained microstructure resulting from near room temperature extrusion. Scale bars for coarse-grained and fine-grained microstructures indicate ~80 and ~5 µm, respectively