Optical substructure and serrations in hot deformed Al-5.8 at.% Mg alloy

The substructures developed during the high temperature deformation of Al-5.8 at.% (5.2 wt.%) Mg are observed by optical and electron microscopies in samples tested over a wide range of strains (up to ε = 7.2) in the range of T from 335 to 545 °C and #x003B5; = 0.0014 to 2 s−1, embracing both the region with power law stress exponent n = 3 and n > 5. Although solute atmosphere interaction with dislocations strongly affects dislocation glide throughout the range, subgrain boundaries begin to form and become a complete system of obstacles to dislocation motion at about twice the strain at the peak. Serrations of the grain boundary form with large amplitude and lead to geometric dynamic recrystallizaton.