The present study investigates the synthesis, characterization, and machinability evaluation of copper matrix composites reinforced with silicon nitride (Si₃N₄₎ and aluminum nitride (AlN) particles in both micro and nano forms. Composites containing 5 wt.% of each reinforcement were fabricated using a powder metallurgy route involving ball milling, cold compaction, and sintering at 800 °C. The resulting composites were characterized for density, porosity, and microhardness in accordance with ASTM standards. SEM and EDS analyses confirmed uniform distribution and high purity of the reinforcements without evidence of interfacial reaction products. Among all compositions, the Si₃N₄ micro-particle reinforced composite exhibited the highest hardness (68 HV) and density (6.24 g/cc), indicating superior particle-matrix bonding. In contrast, AlN-reinforced samples exhibited better dispersion and ductility but lower mechanical strength, with densities around 5.57 g/cc. Machinability was assessed using wire electrical discharge machining (WEDM), where Si₃N₄ based composites demonstrated finer surface finishes (minimum Ra ~2.5 µm), while AlN reinforced composites with micro particles exhibited rougher surfaces and higher oxide formation. These findings highlighted the effectiveness of Si₃N₄ micro-particle reinforcement in enhancing the mechanical and machining performance, making it suitable for copper composites to be utilized in frictional and structural applications.

Keywords: Copper matrix composites, Silicon nitride, Aluminum nitride, Micro/nano reinforcement, Powder metallurgy, WEDM, Surface roughness.