Fabrication and characterization of Cu/B₄C surface dispersion strengthened composite using friction stir processing

Friction stir processing has evolved as a novel method to fabricate surface metal matrix composites. The feasibility to make B₄C particulate reinforced copper surface matrix composite is detailed in this paper. The B ₄C powders were compacted into a groove of width 0.5 mm and depth 5 mm on a 9.5 mm thick copper plate. A tool made of high carbon high chromium steel; oil hardened to 63 HRC, having cylindrical profile was used in this study. A single pass friction stir processing was carried out using a tool rotational speed of 1500 rpm, processing speed of 40 mm/min and axial force of 10 kN. A defect free interface between the matrix and the composite layer was achieved. The optical and scanning electron micrographs revealed a homogeneous distribution of B₄C particles which were well bonded with the matrix. The hardness of the friction stir processed zone increased by 26% higher to that of the matrix material.