OPTICAL SUBSTRUCTURE AND SERRATIONS IN HOT DEFORMED AL-5.8 AT.PERCENTMG ALLOY

The substructures developed during the high temperature deformation of Al-5.8 at.% (5.2 wt.%) Mg are observed by optical and electron micros copies in samples tested over a wide range of strains (up to epsilon = 7.2) in the range of T from 335 to 545 degrees C and (epsilon) overdo t = 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 obs tacles to dislocation motion at about twice the strain at the peak. Se rrations of the grain boundary form with large amplitude and lead to g eometric dynamic recrystallizaton. (C) 1997 Elsevier Science S.A.