ZrC particle reinforced Al–4 wt.% Cu alloy composites fabricated by mechanical alloying and vacuum hot pressing: Microstructural evaluation and mechanical properties

A metal–matrix composite composed of Al–4 wt.% Cu and 10 wt.% of particulates of ZrC with average initial particle sizes of 8 and 157 μm were mechanically alloyed (MA’ed) for 90, 120, 150, 180 and 210 min. Steady-state conditions were obtained after 180 min of MA’ed time. These powders were consolidated by vacuum hot pressing under 70 MPa at 550 °C for 1 h. A rod-shaped Al7Cu2Fe intermetallic phase was observed in the sintered samples due to the reaction of Al–Cu matrix with Fe from balls and/or vials during MA process. The particle size of the ZrC particles in the consolidated samples were 0.3–1.5 μm and 1.5–6 μm for the MMC with initial 8 and 157 μm ZrC powders, respectively. Composite samples comprising the smaller ZrC particles exhibited higher hardness and lower wear resistance compared to those reinforced with coarser ZrC particles. The larger reinforcement particles (1.5–6 μm) remained intact on the worn surface and continuously protected the composite against the steel ball counterface.