Effects of flow stress and grain size on the evolution of grain boundary microstructure in superplastic 5083 aluminum alloy

Abstract

The effects of flow stress and grain size on the evolution of gain boundary character distribution (GBCD) at elevated temperatures were investigated using a superplastic aluminum 5083 alloy. In the superplastic region, the percentage of random boundaries was high and was almost unchanged during deformation. In addition, stress and grain-size dependencies on the variation of GBCD were not observed during superplastic deformation. On the other hand, in the dislocation creep region, the percentage of low-angle boundaries gradually increased with increasing strain. Stress and grain-size dependencies on the variation of GBCD were observed and the degree of increase in low-angle boundaries increased with increases in both stress and grain size. This microstructural change could be considered to be influenced by grain boundary sliding (GBS). The degree of increase in low-angle boundaries increased with a decrease in the contribution of GBS.