Synthesize and characterization of hybrid aluminium alloy (AA6063) metal matrix composite (HAMMC) with corn cob ash and alumina (Al2O3) reinforcements

Abstract The use of aluminium matrix composites (AMCs) in advanced engineering applications has increased due to their improved mechanical properties, such as hardness, ultimate tensile strength, toughness, wear, and corrosion resistance. Although synthetic ceramic particles enhance the mechanical properties of aluminium matrix composites, they also increase weight and cost due to their high density. Using inexpensive and lightweight reinforcements like industrial and agro-waste can reduce cost and weight, but may compromise some mechanical properties. This study investigates the mechanical properties and microstructure of AA6063 aluminium alloy reinforced with corn cob ash (CCA) and Al2O3 particles. The composites were produced using the two-step stir casting method, incorporating varying weight fractions of CCA and Al2O3 (ranging from 5% to 15% in 5% intervals). Optimal properties were achieved using Taguchi with grey relational analysis. Mechanical testing was carried out, such as tensile, compression, and hardness. Microstructural analysis and phase identification were performed using an optical microscope and X-ray diffraction (XRD), respectively. The findings demonstrate that incorporating CCA and Al2O3 reinforcements leads to significant improvements in the mechanical properties of AA6063 aluminium alloy, with ultimate tensile strength increasing by 49% at 10% CCA and Al2O3, compressive strength by 44.4% at 15% CCA and Al2O3, and hardness by 31% at 15% CCA and Al2O3. Although there was a slight decrease in ultimate tensile strength at 15% CCA and Al2O3, it remained higher than that of the unreinforced AA6063 alloy. The microstructural analysis images revealed the uniform distribution of the reinforcements and the positive influence of Al2O3-CCA reinforcements on the mechanical properties. Furthermore, XRD confirmed the presence of reinforced Al2O3-CCA particles in the produced composite samples. Therefore, the mechanical properties of AA6063 aluminium alloy were significantly improved by incorporating Al2O3-CCA reinforcements, suggesting its potential for enhanced applications in engineering.