Influence of particle shape and aspect ratio on thermally activated viscoplastic (time-dependent) response of ceramic (zirconia)–metal (NiCoCrAlY) particulate composites

The effect of particle shape and aspect ratios on the thermally activated viscoplastic response (time-dependent behavior) of ceramic (zirconia)–metal (NiCoCrAlY) particulate composites is investigated. Finite element analyses are performed using axisymmetric unit-cell models, in which the composite is represented by spherical or cylindrical inclusions of one phase embedded in a matrix of the other. Response of the unit-cell to a high temperature compression creep test is simulated. The effects of inclusion shape on the deformation of the composite are studied. The results show that a composite with spherical inclusions exhibits a softer response that one with cylindrical inclusions. Further, for the case for cylindrical inclusions, the effect of inclusion aspect ratio is investigated and is found to have a significant effect on the overall viscoplastic behavior of the composite. It is observed that the effects of inclusion aspect ratio on the viscoplastic response of the composite depend on the volume fractions of the constituent phases. Further, for a given composition, the influence of inclusion aspect ratio varies with the applied loads and the resulting deformation rate.