Structure-property correlation of alumina/nickel composites for their mechanical and electrical properties

Abstract Al 2 O 3 /nickel (Ni) composites were fabricated via hot-press sintering at 1400 °C to investigate the effects of microstructure on their mechanical and electrical properties. For this purpose, various amounts of Ni metal particles (5–20 vol%) were dispersed in Al 2 O 3 ceramics. All the composites were highly densified, with a theoretical density of over 97%, and microstructural observations revealed elongated Ni phases and strong Al 2 O 3 /Ni interfaces. The Young’s moduli of the composites with 5–15 vol% Ni content were higher than that of the pure Al 2 O 3 matrix. Additionally, all the composites showed higher fracture toughness than the pure Al 2 O 3 ceramic matrix, owing to toughening mechanisms such as crack deflection and bridging between Al 2 O 3 grains. This microstructural evolution also affected the formation of continuous conductive pathways connecting the elongated Ni particles. As a result, the electrical resistivity of the composite dramatically decreased to 3.6 × 10 3 Ωcm at 15 vol% Ni and was further reduced to 1.1 × 10 2 Ωcm when the volume fraction of Ni was increased to 20 vol%. These results suggest that controlling the amount of Ni, which greatly affects the microstructural evolution, can simultaneously enhance the mechanical and electrical properties of Al 2 O 3 /Ni composites.