Change in Si morphology by T6 heat treatment and its effect on tribological properties of Al-Si alloys

Abstract

The effect of heat treatment on microstructural and mechanical properties of three different Al-Si alloys was investigated. Both sand and permanent molds were used to produce Al7Si, Al-12Si and Al-17Si alloy samples. Changes in microstructure, hardness, wear and surface roughness were evaluated. In T6 heat treatment, two different temperatures (425 degrees C and 500 degrees C) and three different durations (5, 15, and 30 h) were selected, and after quenching, aging was carried out at 190 degrees C for 16 h. It was found that increasing the heat treatment temperature and duration resulted in smaller silicon phases for all three alloys. This case positively affected the hardness, wear and surface roughness of the alloys. The best parameter for the morphology of Al7Si and Al-12Si alloys in sand casting samples was 500 degrees C solution temperature and 30 h. 425 degrees C solutionizing temperature was found to be insufficient for Si modification.