In this investigation, the extensive wear behaviour of materials was studied using SiC reinforced magnesium alloy composites fabricated through the stir casting process. The wear properties of AZ91 alloy composites with a small variation (i.e., 3%, 6%, 9% and 12%) of SiC particulates were evaluated by varying the normal load with sliding velocity and sliding distance. The worn surfaces were examined by scanning electron microscope to predict the different wear mechanisms on the pin while sliding on the hard disk in the dry sliding wear test condition. The microhardness of the SiC reinforced AZ91 composites was found to be more than the un-reinforced AZ91 alloy. Pins tested at load 19.62 N, and 2.6 m/s exhibited a series of short cracks nearly perpendicular to the sliding direction. At higher speed and load, the oxidation and delamination were observed to be fully converted into adhesion wear. Abrasion, oxidation, and delamination wear mechanisms were generally dominant in lower sliding velocity and lower load region, while adhesion and thermal softening/melting were dominant in higher sliding velocity and loads. The wear rate and coefficient of friction of the SiC reinforced composites were lower than that of the unreinforced alloy. This is due to the fact of higher hardness exhibited by the composites. The wear behaviour at the velocity of 1.39 m/s was dominated by oxidation and delamination wear, whereas at the velocity of 2.6 m/s the wear behaviour was dominated by abrasion and adhesion wear. It was also found that the plastic deformation and smearing occurred at higher load and sliding velocity.

The present work deals with powder metallurgical processing of AA 6082 Al matrix composite reinforced with non-equiatomic AlSiCrMnFeNiCu high-entropy alloy (HEA). The structure, microstructure, morphology, and phase composition of these Al-HEA nanocomposite powders were discerned through XRD and TEM, SEM–EDS, respectively. The AlSiCrMnFeNiCu HEA used as reinforcement was found to have a two-phase microstructure with a major and minor fraction corresponding to the B2-type (a = 0.29 nm; cP2) and Cr₅Si₃-type (a = b = 0.9165 nm, c = 0.4638 nm; tI32) phases, respectively. Mechanical milling (MM) imparts significant refinement, and nanostructuring of grains (~ 10–12 nm) for Al-HEA for nanocomposite powder was observed. These powders of Al-HEA was found to be thermally stable up to 650 ℃. Further, these Al-HEA nanocomposite powders were consolidated through pressure-less sintering at 560 ℃, which led to the formation of a thin ~ 400–500 nm transitional layer at the interface. The microhardness of these Al-HEA composites were tuned in the range of ~ 0.90 to 1.81 GPa. Graphical abstract

In this study, the processing of SiC particulate-strengthened magnesium alloy metal matrix composites via vacuum supported inert atmosphere stir casting process is presented. The effects of small variations in the SiC particulate (average size 20 µm) reinforcement in magnesium alloy AZ91 were examined. It was found that with the addition of SiC particulate reinforcement, the hardness improved considerably, while the ultimate tensile and yield strength improved slightly. The density and porosity of the magnesium alloy-based composites increased with the increase in the wt.% of SiC particulates. The tensile and compressive fracture study of the fabricated composites was also performed. The tensile fractures were shown to be mixed-mode fractures (i.e., ductile and cleavage). The fractured surface also disclosed tiny dimples, micro-crack, and cleavage fractures which increases with increasing reinforcement. For the compression fracture, the surface microstructural studies of AZ91 displayed major shear failure and demonstrated the greater shear bands when compared to AZ91/SiC composites, which instead revealed rough fracture surfaces with mixed-mode brittle and shear features.