Effect of T6 Heat Treatment in the Microstructure and Mechanical Properties of A356 Reinforced with Nano Al2O3 Particles by Combination Effect of Stir and Squeeze Casting

Hypoeutectic aluminum silicon alloys as (A356) exhibit several specific and interesting properties that qualify them to be used in many automotive and aeronautical applications, aluminum matrix composites have good physical and mechanical properties, when reinforced with nano sized Al2O3 particle, they have high tensile, compressive and fatigue strengths along with superior wear resistance and thermal stability. In this work, the number of cast samples of A356 alloy was prepared by combination effect of stir and squeeze casting, specially designed and built furnace unit allowing for the addition of Al2O3 nano- particles (30 nm). The percentage inclusions were varied from 0.5 to 1.5wt% into the molten Al-Si alloy in the liquid state with stirring at 400 rpm and squeeze casting at 750 ̊C and pressure of 600 MPa. The microstructural features and the mechanical properties of the as cast and T6 heat treated samples were investigated. The results obtained in the work showed enhance in the mechanical properties of the Al2O3 nano-dispersed alloys. Optical microscopic examination revealed uniform distribution of nano particles. Measurements of hardness, compressive strength and double shear strength showed an increase with increase in percentage addition of these nano particles.