Mechanical and microstructure behaviour of aluminum nanocomposite fabricated by squeeze casting and ultrasonic aided squeeze casting: A comparative study

Abstract

In the search for novel, affordable and efficient reinforcement, it is challenging to identify rare materials that seek to agree and enrich each other. The spent catalyst waste exhausted from the oil refinery industries has been examined as a reinforcement for recycling and reuse. In this investigation, aluminum composites were fabricated through two distinct casting processes: ultrasonic-aided squeeze casting and conventional squeeze casting. The aluminum composites were generated by reinforcing them with two different concentrations of waste spent catalyst (WSC) and silicon carbide (SiC) (1.0 wt. % and 2 wt. %) with an average particle size of 288 and 272 nm, respectively. The reinforcing particle was introduced into the matrix by a novel powder injection technique. The mechanical and microstructural characteristics of aluminum nanocomposites obtained by both techniques were studied and compared. The composite microstructure produced by the squeeze casting with ultrasonic vibration enhances the homogenous dispersion of reinforcing particles. X-ray diffraction (XRD) and energy dispersive x-ray analysis (EDAX) reveal no sign of oxide and impurities formations or secondary phase in the composites. Optical microscopy revealed that the addition of reinforcement particles and aggressive ultrasonic vibration resulted in grain refinement of the α-Al dendrites. The tensile strength and hardness of the aluminum composites fabricated with ultrasonic vibration increased by 64.47 % and 65.59 % compared to the composite obtained without ultrasonic vibration. Different strengthening mechanisms have been used to determine the strength of the aluminum composites. The strengthening contribution, mainly due to the thermal mismatch between the matrix and the reinforcement particles, considerably enhanced the strength of the composites. Moreover, the entire test results reveal that the ultrasonic-aided squeeze-casting improves the microstructure and mechanical characteristics of the composites compared to the squeeze-casting approach.