A model for creep cracking by diffusion-controlled void growth

Grain boundary cracks at elevated temperatures propagate by the nucleation and growth of cavities ahead of the crack tip. A model is presented for crack propagation controlled by the diffusional growth of an interdependent array of cavities. In the model a variety of possible cavity shapes and the different mechanisms controlling the nucleation of cavities are treated. The dependence of the crack growth rate on such parameters as the cavity spacing and the number of cavities which grow simultaneously is predicted. In addition the crack growth rate varies as a power of the stress intensity factor K, the power varying between 1 and 4 for different situations.