Effect of α-Al2O3 coatings on the mechanical properties of Ni/SiC composites prepared by electrodeposition

α-Al2O3-coated SiC particles were used as reinforcement for the fabrication of nickel matrix composites by electrodeposition. Homogeneous coatings were obtained by the sol–gel method with a thickness of about 80 nm. Both of the Ni/α-Al2O3-coated SiC (Ni/CSp) and Ni/uncoated SiC (Ni/UCSp) composites were heated at 600 °C to study the reactivity of nickel with SiC as well as the resulting interface, microstructure and mechanical properties. The results showed that the α-Al2O3 coatings protected the SiC particles from interfacial reaction, inhibited the formation of defects and nickel silicide, and thus improved the interface performance and achieved excellent mechanical properties for the Ni/CSp composite. The microhardness, yield strength and tensile strength of the Ni/CSp composite were all increased by 40%, 63% and 83%, respectively, compared with the Ni/UCSp composite. Moreover, the α-Al2O3 coatings also changed the fracture mechanism of the composites with heat treatment.