Study on Mechanical Behaviour of Al-15Si-10Zn/x ZrO2 Composites Synthesized by Stir Cast Method

In this research, the microstructure and mechanical properties of Al-15Si-10Zn-xZrO2 (x = 5, 7 and 10 wt.%) composites synthesized by the stir-casting process have been investigated. The matrix and composite samples were characterized using an X-ray diffraction test (XRD) and their microstructures were studied using optical microscopy and scanning electron microscopy (SEM). The microstructure of different phases was analyzed using energy-dispersive spectroscopy (EDS). The microstructure of the Al-15Si-10Zn/ZrO2 composites consisted of coarse primary Si, needlelike eutectic Si, and Zn-rich phases, with ZrO2 reinforcement particles distributed homogeneously in the composites. The micro-hardness and tensile properties of the matrix and composites were determined at room temperature. The results show significant improvements in the micro-hardness and tensile strength of the composites compared to the matrix alloy. The micro-hardness of the stir-cast composites increased by 24%, 44%, and 58% in the 5, 7, and 10 wt% ZrO2 reinforcement composites, respectively. The ultimate tensile strength (UTS) of the 5, 7, and 10 wt% ZrO2 composites increased by 17%, 30%, and 44%, respectively, compared to the matrix alloy. The increased content of ZrO2 resulted in an increase in hardness, ultimate tensile and yield strengths and a decrease in ductility.