Characterization of boron carbide particulate reinforced in situ copper surface composites synthesized using friction stir processing

Friction stir processing has evolved as a novel solid state technique to fabricate surface composites. The objective of this work is to apply the friction stir processing technique to fabricate boron carbide particulate reinforced copper surface composites and investigate the effect of B4C particles and its volume fraction on microstructure and sliding wear behavior of the same. A groove was prepared on 6 mm thick copper plates and packed with B4C particles. The dimensions of the groove was varied to result in five different volume fractions of B4C particles (0, 6, 12, 18 and 24 vol.%). A single pass friction stir processing was done using a tool rotational speed of 1000 rpm, travel speed of 40 mm/min and an axial force of 10 kN. Metallurgical characterization of the Cu/B4C surface composites was carried out using optical microscope and scanning electron microscope. The sliding wear behavior was evaluated using a pin-on-disk apparatus. Results indicated that the B4C particles significantly influenced the area, dispersion, grain size, microhardness and sliding wear behavior of the Cu/B4C surface composites. When the volume fraction of B4C was increased, the wear mode changed from microcutting to abrasive wear and wear debris was found to be finer.