Al2O3/ADC12 Composites Fabricated by Decomposition-Synthesis Method and their Mechanical Behaviors
Aluminium matrix composites reinforced by Al2O3 particles has been produced by adding NH4AlO(OH)HCO3 into molten ADC12 Al-Si alloy, where the γ-Al2O3 reinforcement particles are formed by decomposing reaction of NH4AlO(OH)HCO3 during stirring. The results show that the Al2O3 particles are distributed more uniformly in the matrix than that by direct adding of Al2O3 particles. Hardness and wear properties have also been examined and the results show that the hardness of the composites increases with increasing volume fraction of the reinforced particles. Wear rate of the composites decreases with increasing volume fraction of the reinforced particles and increases with the applied load. The mechanical properties of the composites prepared by adding of NH4AlO(OH)HCO3 are superior and more wearable than that prepared by direct adding of Al2O3 particles. Wearing mechanism of the surfaces of the unreinforced alloy and composites is dominantly abrasive.