A grain boundary sliding model for cavitation, crack growth and fracture in polycrystalline copper

A model is presented for cavity growth, crack propagation and fracture resulting from grain boundary sliding (GBS) during high temperature creep deformation. The theory of cavity growth by GBS was based on energy balance criteria on the assumption that the matrix is sufficiently plastic to accommodate misfit strains produced during the growth of the cavities, and that the cavities were caused to grow as a result of GBS and that sliding would not occur without concurrent cavity growth. This condition then allows shear stress acting on the boundary to do work in opening up the cavity. For elongated cavities, the model predicts a critical stress for fracture of the Griffith type. An equation was derived to establish a link between cavitation and the sliding strain, which was found to describe fairly well the two stages of cavity growth as confirmed by experimental results. Journal of Applied Science and Technology, Vol. 4, Nos. 1 & 2, 1999, pp. 5 - 1