The effect of Sr on the microstructure and wear properties of AlSi5Cu1Mg alloy

Abstract

The effect of different amounts (0 wt%, 0.02 wt%, 0.04 wt%, 0.06 wt%) of Sr modification on the microstructure of AlSi5Cu1Mg alloy was investigated. The wear resistances of the alloys were tested using an MMD-1 pin-on-disk wear-testing apparatus. Worn surfaces were examined using a scanning electron microscopy equipped with an energy-dispersive spectrometer. The relationship between the microstructure and wear properties of the alloy was discussed. The results show that the addition of Sr caused the grain refinement and AlSi5Cu1Mg with 0.04 wt% Sr has short rod-like Fe-rich intermetallic, minimal size of α-Al phase and secondary dendrite arm spacing, and granular or fibrous eutectic Si phase distributed uniformly at grain boundaries. Compared to the matrix alloy, the tensile strength, Brinell hardness, and elongation of the AlSi5Cu1Mg with 0.04 wt% Sr increased by 15%, 48%, and 73%, respectively. Both the lowest friction coefficient and the best wear resistance were achieved by the AlSi5Cu1Mg with 0.04 wt% Sr. Compared to the matrix alloy, the wear mass loss and friction coefficient of the AlSi5Cu1Mg with 0.04 wt% Sr increased by 42% and 18%, respectively. The adhesive wear and abrasive wear are the main wear mechanisms.