Effect of copper and iron on the wear properties of spray formed Al–28Si alloy

Abstract

In the present study the effect of copper (Cu) and iron (Fe) on the wear behavior of spray formed Al–28Si alloy has been investigated. The spray formed Al–28Si alloy exhibited equiaxed grain morphology with fine and uniform distribution of Si particles in Al matrix and spray formed Al–28Si–5Cu–4Fe alloy exhibited similar morphology with small needles of β-Al4FeSi intermetallics and globular shaped θ-Al2Cu precipitates spread along the boundaries and junctions of grains. Hot pressing has considerably reduced the porosity in spray formed alloys. On the contrary the microstructure of as-cast Al–28Si alloy consisted of coarse primary and eutectic Si unevenly distributed in Al matrix and that of as-cast Al–28Si–5Cu–4Fe alloy consisted of coarse Si particles, long needles of β-Al4FeSi2 and θ-Al2Cu phases in Al matrix. Spray formed and hot pressed Al–28Si–5Cu–4Fe alloy exhibited higher value of hardness compared to the other alloys. The wear behavior of these alloys under dry sliding conditions showed that the spray formed and hot pressed Al–28Si–5Cu–4Fe alloy exhibited maximum wear resistance and minimum coefficient of friction, while as-cast Al–28Si alloy showed minimum wear resistance and maximum coefficient of friction over the entire range of loads. The high wear resistance of spray formed and hot pressed Al–28Si–5Cu–4Fe alloy is explained in light of its microstructural modifications induced during spray forming and the topography of worn surfaces.