Recrystallization Microstructure in Cold-Rolled Aluminum Composites Reinforced by Silicon Carbide Whiskers

Recrystallization behavior has been studied in 50 and 90 pct cold-rolled, silicon carbide whisker-reinforced aluminum composites containing fine aluminum-oxide particles. The micro-structure in the cold-worked state, in the early stage of recrystallization, and after the completion of recrystallization was examined by transmission and scanning electron microscopy and light microscopy.

Recrystallization kinetics were studied by microhardness measurement. In the cold-worked state, it was found that the presence of SiC whiskers reduced the cell size, increased the hardness, and altered the distribution of dislocations. During recrystallization, the SiC whis-kers, often present in groups, showed a strong tendency to stimulate nucleation, increasing the number of nuclei and lowering the recrystallization temperature.

The recrystallization kinetics in the composite were accelerated; however, the grain refinement effect of SiC was limited, apparently due to the presence of the fine aluminum-oxide particles. The structural observation and kinetics have been discussed and related to results from previous studies of dispersion-strengthened aluminum/aluminum-oxide materials and aluminum of commercial purity.