High-resolution electron microscopy observations of grain boundary structures in submicrometer-grained Al-Mg alloys

An Al-3%Mg solid solution alloy with submicrometer grain size was produced by imposing intense plastic strain through a torsion straining technique. The grain boundary structures of the alloy were examined using high-resolution electron microscopy. The grain boundaries were mostly curved or wavy along their length, and there were some portions which were corrugated with regular or irregular arrangements of facets and steps. Grain boundary migration occurred to reduce the number of grain boundary facets and steps during exposure to high-energy electrons for the experimental observations. The observed features demonstrate that the grain boundaries in the submicrometer-grained material are in a high-energy non-equilibrium configuration.