Microstructural characterisation of interpenetrating nickel/alumina composites

Interpenetrating phase composites (IPCs) are a new class of composite materials in which both phases are three-dimensionally (3D) continuous. Such interpenetrating microstructures offer improved combinations of mechanical and physical properties and enhanced damage tolerance. However, identifying those composites containing interpenetrating phases has been a challenge. A study was performed on the microstructures of some nickel/alumina composites that had been produced by hot pressing powder blends of various volume fractions of nickel and alumina. The composite microstructures were characterised in terms of grain size and contiguity to establish the distribution of the phases. Two different techniques, preferential etching and resistivity measurements, were used to determine which compositions displayed interpenetrating phases.