Structure and wear properties of SiC reinforced Al-Li (8090) alloy in cast and heat treated conditions

Different percentages of SiC particulates (0-15wt-%) were introduced into Al-Li (8090) to produce composites using the vortex technique. Microstructural studies of both Al-Li and Al-Li composites were carried out in the cast and heat treated conditions. The results showed that the cast composite had some degree of porosity especially with a high volume fraction (15% of SiC) of particulates. The examination of SiC reinforced alloys in the cast and heat treated conditions showed an increasing grain refining effect compared to the base alloy. As the volume fraction of SiC particulates increased from 5 to 15%, the hardness also increased from 68 to 108 HB in the cast condition and from 90 to 120 HB in the peak aged condition. This increase in hardness was related to the modified structure and the hard dispersed SiC particulates. Mechanical deformation was applied to the investigated alloys by rolling to a 50% reduction in thickness to study its effect on impact strength and wear properties. Dry sliding wear tests were performed on both cast and heat treated alloys. Experiments were carried out at a constant load of 30 N and variable sliding speeds of 1, 1(.)25, 1(.)5, 1(.)75, 2 and 2(.)25 m s(-1) using a pin-on-ring wear test machine for a duration of 1 h. The deformed alloys showed better wear results than cast alloys as a result of the strain hardening occurring during the rolling process. The minimum wear rate was obtained at 10%SiC in both cast and heat treated conditions.