Recent developments in the field of carbon nanotube (CNT) have attracted attentions on a new development of aluminum matrix composite (AMC). Homogenous dispersion and interfacial bonding of CNT/metal matrix are the two main problems yet to have sound solutions. In general, to ensure uniform dispersion, the overall process can be divided into three steps: preprocessing, mixing and post processing. This paper summarizes previous works on solid and liquid processing techniques which some are more successful than others by looking at the improvement of the composite tensile strengths. On the other hand the interfacial bonding depends on the existance of Al₄C₃ phase and physical conditions of CNT. Both elements must be controlled for the optimized results. The review presented here would be used as references in the future works to fabricate higher strength CNT/aluminum composites.

Thixoforming is a promising method that offers several advantages over both liquid and solid processing. This process utilizes semi-solid behaviour and reduces macrosegregation, porosity and forming forces during the shaping process. Microstructural and mechanical characterization of 0.3, 0.5 and 1.0 wt% graphene nanoplatelet (GNP) reinforced A356 aluminium alloy composite fabricated by thixoforming was investigated. Stir casting was employed to fabricate feedstocks before they were thixoformed at 50% liquid. The microstructure was characterized and evaluated by field emission scanning electron microscopy with an energy dispersive X-ray detector and X-ray diffraction. Mechanical testing, such as microhardness and tensile testing, was also performed to estimate the mechanical properties of the composites. The incorporation of 0.3 wt.% GNPs in Al alloy increased by about 27% in ultimate tensile strength and 29% in hardness. The enhancement in tensile strength is primarily attributed to load transfer strengthening due to the uniform dispersion of these GNPs within the Al matrix, which promotes effective load transfer during tensile deformation, and GNPs’ wrinkled surface structure. Simultaneously, the addition of GNPs enhances the grain refinement effect of the Al alloy matrix, resulting in a grain size strengthening mechanism of the GNPs/Al composites. The results reveal that thixoformed composite microstructure consists of uniformly distributed GNPs, α-Al globules and fine fibrous Si particles. The composites’ grains were refined and equiaxed, and the mechanical properties were improved significantly. This study creates a new method for incorporating GNPs into Al alloy for high-performance composites.

MATEC Web of Conferences, open access proceedings in Materials science, Engineering and Chemistry

Cutting force attenuation in AWJ induces surface defects (high Ra, large theta) in metals and delamination in composites, especially in thick sections that limiting industrial adoption and requiring post-processing. A robust Taguchi experimental design was employed to optimize AWJ cutting parameters to minimize these issues when cutting thick aluminium blocks. An L8 orthogonal array with three factors; waterjet pressure (WP), stand-off distance (SOD), and traverse speed (TS), each at two levels, was used and analyzed via Minitab software. Other parameters remained constant: nozzle diameter (1.0 mm), abrasive size (80 mesh), and abrasive flow rate (0.3 kg/min). Traverse speed was found to be the most critical factor affecting Ra and theta, though waterjet pressure and stand-off distance also had significant impacts. The optimal parameters, higher waterjet pressure (315 MPa), lower traverse speed (38 mm/min), and lower stand-off distance (3 mm), yielded the best results for both Ra (4.2 µm) and theta (1.24°). In conclusion, the interaction of optimized AWJ parameters enhances kinetic energy and momentum transfer, improving material removal efficiency and cutting surface quality. The study systematically evaluates critical abrasive waterjet parameters to optimize cutting strategies, demonstrating applicability for thick aluminium and diverse material types.