The effect of palm kernel shell ash reinforcement on microstructure and mechanical properties of Al-Mg-Si metal-matrix composites

Abstract

Aluminium is one of the lightweight materials that have a major contribution in numerous applications globally and it is also considered less expensive compared with other lightweight metals such as titanium and magnesium. As a result of some engineering applications’ requirements of better hardness and strength of material with lesser weight, researchers’ attention is drawn to the enhancement of the mechanical properties of accessible aluminium alloys. This study was conducted to study the microstructure and mechanical properties of a composite Al-Mg-Si matrix with varying weight percentages (0, 4, 6 and 8 wt. %) of palm kernel ash (PKSA) reinforcement, which were denoted correspondingly as C1–C4. The PKSA was obtained at a calcination temperature of 850 °C, XRD and XRF analyses were conducted to characterize it. The formulated samples were then ball-milled using two roll mills for about 60 hours to achieve a near homogeneity of the composites. The SEM image of the reinforced samples (C2 and C3) revealed that there were many networks of coalesced or necked particles while individual particles are hardly found, which is an indication of a high degree of densification ratio percentage of PKSA. The results also showed that there was an increase in hardness (44.4%), modulus of rupture (37.4%) and impact strength (252.03%) of Al-Mg-Si matrix composites (C3) in comparison with the unreinforced matrix material.