A parametric study on mechanical properties of aluminum–silicon/SiO 2 nano-composites by a solid–liquid phase processing

In this article, different aluminum–silicon matrix nano-composites which reinforced by SiO2 nano-particles were developed. The stir casting was used as a solid–liquid phase processing to make such nano-composites. Pouring temperatures and stir times were two parameters which were varied from 700 to 850 °C and 2–4 min, respectively. In addition to microstructural evaluations, the mechanical and tribological properties of different nano-composites were compared to the aluminum alloy without any reinforcement agent. Obtained results showed that the hardness of nano-composites increased significantly when the pouring temperature was 850 °C with respect to the aluminum alloy. The wear resistance was also increased obviously when nano-particles were distributed homogenously in the aluminum matrix. Besides, the ratio of the hardness to the elastic modulus was a compatible parameter to predict the wear rate of most specimens. FESEM images demonstrated that the nano-particles distribution was reasonably uniform. The elastic modulus for all nano-composites increased. The ultimate compressive strength also increased for nano-composites which made at the pouring temperature of 750 °C for both stirring times. The presence of more intermetallic phase especially Al–Ni phase and the micro-cracks were responsible for lowering the toughness of nano-composites which made at higher pouring temperatures.