Aluminum matrix composites (AMCs) are widely used in the automotive industry as engine cylinders, pistons, and brake discs. It is due to its ability that better mechanical performance and physical properties are exhibited. Recently, hypereutectic Al-Mg2Si in-situ composite with a large amount of hard Mg2Si particles has attracted considerable attention due to the beneficial features of Mg2Si particles. However, there are some limitations in the application of this composite due to its low tensile and machinability properties. Therefore, the purpose of this study was to fabricate and characterize the microstructure and tensile properties of Al/(15Mg2Si+xYSZ) hybrid composites by using an in-situ reinforcement, namely magnesium silicide (Mg2Si), and ex-situ reinforcement, yttria-stabilized zirconia (YSZ). The effect of different YSZ concentrations (i.e., 3, 6, and 9 wt. %) on the size, shape, and distribution of Mg2Si particles was analyzed accordingly. Microstructure characterization was carried out by using optical microscope (OM), scanning electron microscopy (SEM), and X-ray diffraction (XRD). The microstructure examinations showed that with increasing YSZ concentrations, the size of primary Mg2Si particles was reduced from 74.4 μm (i.e., without YSZ) to 65.2 μm (with 9 wt. % YSZ addition). Similarly, the tensile properties were enhanced parallel to the increasing concentrations from 53.54 to 85.65 MPa with 6 wt. % of YSZ
