Interface diffusion-induced creep and stress relaxation in unidirectional metal matrix composites under biaxial loading

• We consider the creep rate and stress relaxation in MMC under biaxial loading.
• Interfacial stresses responsible for the interface diffusion are solved.
• The creep and stress relaxation are strongly dependent on the biaxial load ratio.
• The scale effect of the unit cell mode is modified by finite elemental analysis.

Analytical solutions are developed for interface diffusion-induced creep and stress relaxation in unidirectional metal matrix composites under biaxial transverse loading. The driving force for the interface diffusion is the normal stress acting on the interface, which is obtained from rigorous Eshelby inclusion theory. The solutions are a function of the applied stress, volume fraction and radius of the reinforced-fiber, the modulus ratio between the fiber and the matrix, specially, exhibit a strong dependence of creep rate and stress relaxation behavior on the biaxial stress ratio. Moreover, the solution for the interface stress presented in this study also gives some insight into the relationship between the interface diffusion and interface slip. For the application of the solutions in the realistic composites, the scale effect is taken into account by detailed finite element analysis based on a unit cell model.