Effect of ZrO2 Addition on Mechanical Properties and Microstructure of Al-9Zn-6Mg-3Si Matrix Composites Manufactured by Squeeze Casting

Abstract

Steel is used because of its high strength and toughness, but it has high density, therefore lighter material with comparable toughness is developed. One alternative is aluminum matrix composite with zirconia (ZrO2) as the reinforcement with high fracture toughness. Al-9Zn-6Mg-3Si (wt. %) composites were developed with addition of 2.5, 5, and 7.5 vol. % ZrO2 through squeeze casting. To improve toughness, the composite was solution treated at 450 °C for 1 h, then aged at 200 °C for 1 h. Materials characterization included Optical Emission Spectroscopy (OES), Rockwell B hardness testing, impact testing, fractography analysis, microstructure analysis using Optical microscope (OM) and Scanning Electron Microscope (SEM) / Energy Dispersive X-Ray Spectroscopy (EDS), as well as X-Ray Fluorescence (XRF). The results showed that the more ZrO2 particles, the higher porosity and the lower the hardness and the impact values, both in as-cast condition and after ageing at 200 °C at 1 h.