The utilization of agricultural and industrial waste in the synthesis of AA7075-based novel lightweight composite

Fly ash (FA) and coconut shell ash (CSA) are solid byproducts of industrial and agricultural waste, respectively, that are produced in enormous amounts around the world. It is considered to be a contaminant in the environment. Because of the negative impacts on the environment, research on the use of FA and CSA is being undertaken all over the world. The current study focuses on the use of FA and CSA as reinforcement in an AA7075 alloy matrix through two-step stir casting. The present study also reported on the characteristics of newly developed novel composites and their environmental effects using leaching tests. The inclusion of ceramic particles can enhance the microstructure, mechanical, and corrosion characteristics of AA7075 alloys. Optical and scanning electron microscopes were used to evaluate the homogenous distribution of FA and CSA particles in the matrix. Contrasting with the homogeneous alloy, the hybrid composite, composed of 5 wt% FA and 5 wt% CSA, exhibited a remarkable surge of 27% in maximum hardness and a 19% increase in tensile strength. To explore the corrosion resistance of these newly created composites, polarization tests and AC impedance spectra were employed. Immersing the meticulously crafted specimens in a 3.5% sodium chloride solution, the corrosion assessment revealed that the composite with 5 wt% FA and 5 wt% CSA outperformed the traditional monolithic AA7075 alloy in terms of corrosion resistance. Graphical Abstract