Abstract: A method of reducing wear between the radial faces of a piston ring and the radial faces of the co-operating piston ring groove in an aluminium alloy piston is described. The method comprises the steps of locally alloying the region in which the piston ring groove radial faces are located to increase the concentration of at least one strengthening element and coating at least the co-operating radial faces of a piston ring with a compatible material. Nickel has been found to be particularly advantageous and an example is described of a piston which is locally alloyed by electron-beam melting wherein the nickel content is raised to about 12%. The co-operating piston ring was electroless plated with a nickel-phosphorus alloy.