Effect of nano-SiC particles on grain orientation and hardness of friction stir processed aluminum matrix composite

The present work concentrates on exploiting electron backscatter diffraction (EBSD) and transmission electron microscope (TEM) to investigate the effect of nano-SiC on the microstructure of Al-SiC composites fabricated by friction stir processing (FSP). With the introduction of nano-SiC, the average grain size and the proportion of low angle grain boundaries (LAGBs) decreased to 3.9 mu m and 19.3 %, respectively, while the proportion of n-ary sumation 3 and n-ary sumation 9 grain boundaries increased slightly. The intensity of the main texture components in Al-SiC composite is reduced compared to FSPed Al. The Schmid factor of the Al-SiC composite decreased to 0.455, and the microhardness increased from 80.0 HV of FSPed Al to 100 HV. During the FSP process, the introduction of nano-SiC not only generates more randomly oriented grains in the composite, but also facilitates the occurrence of dynamic recrystallization.