Effects of alumina-rich waste (valoxy) as an alternative sustainable material to alumina on the morphology, mechanical and wear behavior of Al-6063 alloy by stir casting

Abstract

In recent years, the quest to improve sustainability and cut costs has shifted focus to the use of waste materials as reinforcement in metal matrix composites. The current study aimed to evaluate the effects of valoxy as an alternative material to alumina on Al-6063 based composites for the first time. Al-composites containing 10 wt.-% Al2O3: Valoxy in the steps of 0, 10:0, 7.5:2.5, 5:5, 2.5:7.5, and 0:10 were fabricated using a double stir casting approach, while representative samples from each composition were studied for microstructure, mechanical, and wear properties, respectively. The results of the chemical composition showed that valoxy contains 70 wt.-% Al2O3 alongside other oxides like SiO2 and MgO, making it a potential sustainable alternative to traditional alumina. The density of the composites decreases with an increase in valoxy content, which is attributed to the density of valoxy (1.4 g/cm3) compared to alumina (3.89 g/cm3), which it replaces. There is also a general improvement in all the properties tested across the composites containing valoxy compared with the base alloy and Al-6063/Al2O3 samples. Composite samples 7.5:2.5 and 5:5 (Al2O3:Valoxy) showed consistent results with better hardness of 46.45 and 46.21 HB, tensile strength of 209.2 and 184.8 MPa, and fracture toughness of 6.54 and 4.67 MPam1/2, respectively.