Microstructure and sliding wear behavior of AA6360/(TiC+B4C) hybrid surface composite layer synthesized by friction stir processing on aluminum substrate

► Fabrication of AA6360/(TiC+B4C) hybrid surface composite layers using FSP. ► Homogeneous distribution of TiC and B4C particles in the surface composite layers. ► Little or no comminution of ceramic particles during stir processing. ► Hybrid surface composite exhibited highest wear resistance. ► TiC and B4C particles changed the morphology of wear debris. Friction stir processing (FSP) has evolved as a viable technology to fabricate surface composite layers. Hybrid composites have attracted the attention of researchers to minimize the wear of counterface materials. In this work, AA6360/(TiC+B4C) hybrid surface composite layers (SCLs) with various volume ratios of TiC and B4C were synthesized by FSP. The particles were compacted into a groove of width 0.5mm, depth 5.5mm and length 100mm cut on the surface of the aluminum plate. The FSP was carried out at a tool rotational speed of 1600rpm, traverse speed of 60mm/min and axial force of 8kN. Two passes were applied in opposite directions. The microstructure and sliding wear behavior of the fabricated SCLs were evaluated. TiC and B4C particles were distributed homogeneously in the SCLs. Both the particles behaved as one type of reinforcement particle during FSP. There was little or no comminution of ceramic particles. Addition of TiC and B4C particles enhanced the wear resistance of AA6360. 50%TiC+50% B4C hybrid SCL exhibited lowest wear rate due to the formation of a thin tribo film. Detailed characterization of the worn surfaces and the wear debris was also reported.