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 mu m 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 degrees C for 1 h. A rod-shaped Al(7)Cu(2)Fe 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 mu m and 1.5-6 mu m for the MMC with initial 8 and 157 mu m 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 mu m) remained intact on the worn surface and continuously protected the composite against the steel ball counterface. (C) 2010 Elsevier B.V. All rights reserved.