The creep rate induced by interface diffusion in particulate composite materials

Aclosed-form solution for creep rate induced by interface diffusion is developed for particulate reinforced composites. The driving force for diffusional mass transport along the interface is the normal stress acting on the interface, which is obtained from the Eshelby inclusion theory. For the application of the present solution to the realistic composites, the scale effect is taken into account by finite element analysis based on a three-dimensional unit cell under uniaxial tension. The closed-form solution is an explicit function of the applied stress, reinforcement volume fraction and size, as well as the modulus ratio between the reinforcement and the matrix. It is noted that although the present solution is derived under the assumptions of free interface slip and the composites of a linearly elastic matrix, it is approximately applicable for the case of interface slip, and gives an upper bound of the creep rate for a composite of nonlinear matrix.