Effect of ZrO2 additions on the microstructure, mechanical and wear properties of ZrO2/7075 aluminium alloy composite

Abstract

In this study, to improve the comprehensive performance of aluminium matrix composites, a 7075 aluminium alloy reinforced with ZrO2 particles was successfully fabricated via spark plasma sintering (SPS). Moreover, the effects of ZrO2 addition on the micromorphology, mechanical and wear properties of the composites were investigated. Microstructural analysis revealed that the pinning effect of the ZrO2 particles restrained grain growth and induced a more significant grain size reduction. The addition of ZrO2 resulted in an initial increase and subsequent decrease in density, hardness, ultimate tensile strength and elongation. The fracture surface of the composites was characterised by homogeneous dimples, indicating that the fracture mode of materials is ductile fracture mode. When 4 wt% ZrO2 was added, the density, hardness, tensile strength, elongation and wear rate of the composites were higher than those of 7075Al aluminum alloy., reaching 97.23 %, 152.54 Hv, 376 MPa, 14 % and 0.9 × 10−3 mm3/N·m, respectively. A significant increase in the dislocation density relative to the aluminium alloy was obtained by adding ZrO2. With the addition of ZrO2, the wear resistance of ZrO2/7075Al composites is superior to 7075 matrix alloy. The wear mechanism changed from adhesive to abrasive wear.