Stress-induced grain growth during high-temperature deformation of nanostructured Al containing nanoscale oxide particles

In this study we analyze the phenomenon of stress-induced grain growth in nanostructured Al containing a high volume fraction of nanoscale oxide particles during high-temperature extrusion. Our results show that in the absence of an externally applied stress, grain growth was essentially inhibited during annealing at 600 °C. In contrast, when the same material was extruded at 400 °C, the grains increased in size by a factor of 2.2 relative to the initial microstructure. The experimental results were analyzed on the basis of the mechanisms that govern grain growth. We discuss the role of grain boundary (GB) migration, grain rotation, discontinuous dynamic recrystallization and geometric dynamic recrystallization on stress-induced grain growth. Finally, the influence of nanoscale oxide particles on GB migration and grain rotation was rationalized on the basis of a theoretical model.