Metal matrix composites (MMCs) reinforced with nano-particles, known as Metal Matrix nano-Composites (MMnCs), are promising materials with enhanced mechanical, thermal, and electrical properties. These composites consist of a metal matrix reinforced with nano-particles, which can significantly improve wear resistance, damping, and mechanical strength. Common matrix metals include Al, Mg, and Cu, while nano-reinforcements include ceramic particles (e.g., SiC, Al₂O₃, TiC), carbon nanotubes (CNTs), and intermetallic compounds. The main challenge in synthesizing MMnCs is the low wettability of nano-particles by molten metal, which limits conventional casting methods. Alternative techniques such as ultrasonic-assisted casting, mechanical alloying, and equal channel angular pressing (ECAP) have been explored to overcome this issue. The strengthening mechanisms in MMnCs include load transfer, Hall-Petch, Orowan, and mismatch in thermal expansion and elastic modulus. These mechanisms contribute to improved mechanical properties. The mechanical performance of MMnCs is influenced by the size, distribution, and type of nano-reinforcements. For example, CNTs enhance mechanical strength and electrical conductivity, while nano-SiC and nano-Al₂O₃ improve hardness and wear resistance. Various preparation methods, including liquid, semi-solid, and solid processes, have been developed to produce MMnCs. Liquid processes like ultrasonic-assisted casting and high-intensity ultrasonic waves help in achieving uniform dispersion of nano-particles. Solid processes such as ECAP and HIP are effective in producing dense composites with improved mechanical properties. The application of MMnCs is promising in aerospace, automotive, and electronics due to their high strength-to-weight ratio, thermal conductivity, and damping capacity. However, challenges remain in achieving consistent particle dispersion and interfacial bonding, which affect the performance of these composites. Despite these challenges, MMnCs offer significant potential for structural and functional applications in various industries.Metal matrix composites (MMCs) reinforced with nano-particles, known as Metal Matrix nano-Composites (MMnCs), are promising materials with enhanced mechanical, thermal, and electrical properties. These composites consist of a metal matrix reinforced with nano-particles, which can significantly improve wear resistance, damping, and mechanical strength. Common matrix metals include Al, Mg, and Cu, while nano-reinforcements include ceramic particles (e.g., SiC, Al₂O₃, TiC), carbon nanotubes (CNTs), and intermetallic compounds. The main challenge in synthesizing MMnCs is the low wettability of nano-particles by molten metal, which limits conventional casting methods. Alternative techniques such as ultrasonic-assisted casting, mechanical alloying, and equal channel angular pressing (ECAP) have been explored to overcome this issue. The strengthening mechanisms in MMnCs include load transfer, Hall-Petch, Orowan, and mismatch in thermal expansion and elastic modulus. These mechanisms contribute to improved mechanical properties. The mechanical performance of MMnCs is influenced by the size, distribution, and type of nano-reinforcements. For example, CNTs enhance mechanical strength and electrical conductivity, while nano-SiC and nano-Al₂O₃ improve hardness and wear resistance. Various preparation methods, including liquid, semi-solid, and solid processes, have been developed to produce MMnCs. Liquid processes like ultrasonic-assisted casting and high-intensity ultrasonic waves help in achieving uniform dispersion of nano-particles. Solid processes such as ECAP and HIP are effective in producing dense composites with improved mechanical properties. The application of MMnCs is promising in aerospace, automotive, and electronics due to their high strength-to-weight ratio, thermal conductivity, and damping capacity. However, challenges remain in achieving consistent particle dispersion and interfacial bonding, which affect the performance of these composites. Despite these challenges, MMnCs offer significant potential for structural and functional applications in various industries.