Sliding wear behaviour of thixoformed AlSiCuFe alloys

The effect of Si content on the wear properties of thixoformed AlSiCuFe alloys was investigated in the present work. Wear rates, which decrease with increasing Si content until 12 wt%, start increasing at hypereutectic Si levels. The inferior wear resistance of thixoformed hypereutectic alloys is linked with the response of the coarse Si particles to severe wear conditions. The primary Si particles fracture and eventually drop out during the wear test leaving large cavities on the surface. The T6 heat treatment provided considerable hardening yet failed to improve wear properties. It is inferred from the wear rates of thixoformed and heat-treated samples that the wear properties of the thixoformed AlSiCuFe alloys is governed largely by the size and distribution of coarse Si particles and that the impact of hardness is only secondary.