Evaluation of microstructure evolution and mechanical properties of Al-10Zn-1.63Si/ particulates alloy composites

Abstract

This study demonstrates the feasibility of using Irvingia gabonensis shell particulates (IGSp) as alternative reinforcing materials in the development of aluminium-based composites. In this experimental study, the microstructure, phase composition, and mechanical behaviour of Al-10Zn-1.63Si/xIGSp (wt%, x = 1, 3, 5 and 7) composites were investigated. The Al-10Zn-1.63Si based composites were fabricated using the stir-casting technique. Different weight percentages (1, 3, 5 and 7) of IGSp were added to the Al-10Zn-1.63Si matrix. The chemical constituents of the IGSp were determined using X-ray fluorescence (XRF). The grain characteristics and phase(s) compositions were determined using Scanning Electron Microscopy (SEM) and X-ray diffractometer (XRD). The ultimate tensile strength, hardness, and impact strength of the developed composites were also determined. The SEM and XRD results revealed the presence of different phases: aluminium phosphate (Al 16 P 16 O 64 ), gahnite (ZnAl 2 O 4 ), andalusite (Al 2 SiO 5 ), Quartz (SiO 2 ) and aluminium silicate (Al 2 O 3.5 .SiO 2 ). Results show that addition of IGSp led to an increase in ultimate tensile strength, with the highest value (128 MPa) obtained at 3 wt% IGSp. The hardness of the composites increased with increasing concentrations of IGSp, reaching a maximum value of 285 HV after adding 7 wt% IGSp. The impact strength improved with the addition of IGSp, with the highest value (30 J) obtained at 1 wt% IGSp. The improvements in mechanical properties were attributed to the dispersion of three major phases: aluminium silicate (Al 2 O 3.54. SiO 2 ), Al 16 P 16 O 64 and Al 2 O 3.54. SiO 2 . These phases contributed to the enhanced strength and hardness of the composites. The study noted a sudden decrease in ultimate tensile strength with higher concentrations of IGSp due to the increase in the intensities of Al 16 P 16 O 64 and precipitation of hard but brittle new phase; Al 2 Si 60. 6O126.33. The study concludes that IGSp has the potential to serve as an alternative reinforcing material for aluminium-based composites.