Fabrication and optimization of Al(Zn)-/Al2O3- AlxCuy composite by mechanical alloying and combustion synthesis

Aluminum matrix composites due to low cost, high chemical stability, resistance to oxidation, resistance to abrasion and high mechanical strength at relatively high temperatures have a good status among advanced materials. This paper reports the synthesized Al(Zn)/Al2O3-AlxCuy composite by mechanical alloying and combustion synthesis in Al-ZnO-CuO system. A mixture of Al, ZnO, and CuO powders with different composition (Al-10-20wt.%ZnO with 6wt%CuO) are subjected to high-energy milling with different time of 0-60h. The compacted samples were sintered at different temperature (650-1150 ). X-ray diffraction results of ball-milled samples show that the Al2O3 phase is partially formed after sixty hours of ball-milling and the peaks of CuO are disappeared because of becoming amorphous state. By increasing milling time, the grain size is decreased and it is estimated that minimum grain size for sample (20 nanometer). Based on the model of RSM (Response surface methodology is used to optimize mechanical properties through box-behnken design), by increasing of ball-milling time in stationary conditions of sintering temperature and composition, the density of composite samples will be decreased while, the hardness will be increased to 295 Vickers that is accordance with experimental values. Increasing of ZnO content in stationary conditions of sintering temperature and ball-milling time causes increasing of density and hardness of composite samples. Thermal Analysis investigations show that with increasing milling time, due to mechanical activation and entrance of alloy elements into aluminum, melting point of aluminum (from 667 to 622 .) and starting temperature of alumio-thermic reaction (from 661 to 649 .) is reduced.