| In determining limits to ductility of highly-stressed plastic materials such as aeroengine components, one of major importance is the establishment of a criterion for local microcavity initiation condition in terms of evolving stress and plastic strain. In this paper, critical conditions leading to microcavity initiation by local interfacial debonding between elastic carbide particles and the plastic matrix during straining were determined for two cases by considering the states of stress and strain, namely uniaxial tension and uniaxial tension with elevated triaxiality. The continuum analysis was first employed to calculate the critical interfacial strength, σ_c, in order to permit comparison to earlier calculations. Secondly, σ_c was estimated by incorporating local microstructural variables into a microscopic dislocation model, based on a critical stress criterion. The progress of microcavity initiation was also described with local interfacial stress, assuming that the microcavity initiation rate has a normal distribution about a mean interfacial stress, σ_M. |
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