Microstructure and wear characterization of rice husk ash reinforced copper matrix composites prepared using friction stir processing

Rice husk ash (RHA) is an economical reinforcement to improve the poor wear behavior of pure copper. This work concentrates on the preparation of Cu/RHA (0,6,12,18 vol.%) copper matrix composites (CMCs) by friction stir processing (FSP). Grooves were machined on the copper plates to deposit RHA particles and were friction stir processed at a chosen set of process parameters. The microstructure was studied using optical, scanning and transmission electron microscopy. The wear behavior was estimated using a pin-on-disc apparatus. The micrographs revealed a uniform dispersion of RHA particles in the copper matrix. Neither aggregation nor segregation was observed. The variation in the dispersion of RHA particles at different regions within the stir zone was negligible. A good interfacial bonding between RHA particles and the copper matrix was realized. Many RHA particles encountered break up. A remarkable grain refinement was achieved due to dynamic recrystallization and pinning effect of RHA particles. The wear behavior under dry sliding condition was presented in detail.