Effect of interfacial reactions of oxide particle-reinforced nickel–matrix composites on thermally induced strains

Abstract Composites were obtained by hot pressing a mixture of pure nickel and alumina (Al 2 O 3 ) or silica (SiO 2 ) powders in a graphite mould at 1400°C. During sintering, nickel oxide surrounding the grains of nickel powder reacts with silica or alumina under reducing atmosphere. In the case of alumina, this reactivity indicates a eutectoidal decomposition, while, in the case of silica, an olivine type silicate layer remains at the interface nickel/silica. Average residual strains of the nickel matrix are measured between room temperature and 240°C by X-ray diffraction. We have extended the results of Lee about a single particle embedded in an infinite matrix in order to take into account the interaction of two neighbouring particles. We compare the experimental results with our calculations and conclude that the way nickel and ceramics are bound across the interface is important for the mechanical state of these materials.