A remarkable enhancement of mechanical and wear properties by creating a dual-scale structure in an Al–Sn–Si alloy

Nanocomposite Al–Sn-based bearing alloys produced by mechanical alloying (MA) exhibit high hardness; however, their poor sintering density and ductility limit their wide spread application. Here, we present a strategy to produce a dual-scale structure in an Al–Sn–Si alloy consisting of coarse and ultrafine grains through a combination of conventional powder sintering and thermomechanical treatment. We found that severe deformation and the presence of an Al–Si eutectic mixture for sample induced abnormal grain growth of Al to create the dual-scale Al–Sn–Si alloy through annealing treatment. An optimum matching of ductility and strength, and optimum wear performance were achieved at annealing temperatures of 500 and 550°C. Detailed investigation of the wear mechanism revealed that the combination of high strength and high ductility provided by the dual-scale structure is a key factor for the improvement of the wear properties.