Simultaneously improved modulus, thermal expansion coefficient and wear resistance of a Mg–6Zn–1Gd–0.3Ca matrix composite by adding high volume fraction SiC particles

Abstract

In this paper, three sizes (5, 20 and 50 μm) SiC particles (SiCp) were selected, and the SiCp/Mg–6Zn–1Gd-0.3Ca (SiCp/ZG61X) composites with ∼50 vol.% were successfully prepared by squeeze casting. The effect of particle size on the properties of the composites was studied, while the wear resistance and the wear mechanism of composites were investigated. The results showed that compared with the matrix alloy, the addition of SiCp can significantly improve the properties of the composites, in which the strength increased from 175.2 to 326.5 MPa and the modulus increased from 45.0 to 159.6 GPa. At the same time, the coefficient of thermal expansion and friction were significantly reduced. In addition, the smaller the particle size, the higher the strength and modulus of the composite. However, for the coefficient of friction and thermal expansion, the larger particle size was conducive to the reduction of the two coefficients. The analysis of friction and wear behavior showed that the wear mechanism of the matrix alloy was mainly abrasive wear and adhesive wear, while the wear mechanism of the composites was abrasive wear and layered wear.