Effect of Zr on the Microstructure, Friction Coefficient, and Contribution to the Strengthening Mechanisms of Al10Sn4Si1Cu(1Zr) Alloys

The performance of internal combustion engines strongly depends on the surface properties of the materials they are made of. Over the last 20 years, significant efforts have been undertaken to improve Al-Sn alloys, which are widely used in crankshaft and connecting rod bearings. Advanced combustion engines and hybrid systems require both wear reduction and increased load-carrying capacity for these alloys. To address these needs, Al10Sn4Si1Cu and Al10Sn4Si1Cu1Zr (wt%) ribbons were produced by single-roller melt spinning at low speeds and laminated by co-rolling with 99.9% pure aluminum. Microstructure, hardness, and wear characterization tests were conducted to analyze the ribbons and the co-rolled samples. The melt-spun alloys consist of a matrix of homogeneously distributed alpha-Al, beta-Sn, and Al3Zr. The addition of Zr influences the microstructure by reducing the grain size of alpha-Al and altering the distribution and size of Sn particles. This results in increased hardness and a reduced friction coefficient, in reference with the industrial alloy Al-20 wt% Sn.