Recovery and recrystallization in cold-rolled Al-SiC_w composites

Recrystallization behavior has been studied in 50, 70, and 90 pct cold-rolled silicon carbide whisker-reinforced aluminum composites containing fine aluminum-oxide particles. The distribution of aluminum-oxide particles in the composites was not uniform. Macrohardness measurement, transmission electron microscopy (TEM), and light microscopy were used in the investigation. It was found that in regions with low aluminum oxide content, the introduction of SiC whiskers resulted in recovery reactions during and after cold rolling and in an increase in the growth rate of subgrains during annealing. These recovery reactions were enhanced by an increase in the degree of deformation. The number density of nuclei varied between areas with different contents of aluminum-oxide particles. The impingement of nuclei and recovery reactions limited the growth of nuclei, resulting in a process where recrystallization (growth of nuclei by high-angle grain boundary migration) and extended recovery (growth of subgrains) took place simultaneously. The relative amounts of recrystallization and extended recovery that occur simultaneously affect the recrystallization kinetics as well as the grain size distribution and texture after recrystallization.