Microstructural effects on the dry wear resistance of powder metallurgy Al–Si alloys

Wear resistance of a new powder metallurgy (P/M) Al–Si alloy was studied at two successive development stages, with marked microstructural differences. Wear tests were conducted by a pin-on-disk tribometer, without lubricant, at different loads. Microstructural observations of the alloy at the first stage of development revealed the existence of a porous superficial layer, that directly affects the mechanical and wear behaviour. Dimensions of such layer must be minimised to optimise wear resistance, by an accurate control of material processing parameters. Wear mechanism in P/M alloys was identified as superficial particle removal, which forms semi-elliptical cavities in the worn surfaces. Taking this into account, a high fracture toughness is desired, by properly controlling processing parameters, in order to tailor wear resistance in Al–Si P/M alloys. Obtained results in the alloy in the final stage of the development show enhanced wear behaviour due to such a microstructural control.