A numerical study of plastic strain localization and fracture across multiple spatial scales in materials with metal-matrix composite coatings

摘要

The mechanisms of stress concentration and plastic strain localization operating in an aluminum substrate with an aluminum-matrix composite coating subjected to uniaxial loading are investigated. The plane strain deformation of the coated material across micro-, meso- and macroscales is simulated numerically by the finite-difference method. The constitutive models used in the study include the elastic-brittle and isotropic elastic-plastic responses of ceramic particles and metal matrixes/substrates, respectively. The experimentally observed microstructure of the coated material is explicitly taken into account in the calculations. The formation of local regions experiencing bulk tension under compression of the composite material is simulated in order to control crack initiation and growth in ceramic particles, with the irregular geometry of matrix-particle and coating-substrate interfaces being a major factor of stress concentration. The influence of the coating thickness, distance between ceramic particles, mechanical properties of the constituents, and matrix-particle interfacial strength on the macroscopic strength of the composite and coated materials are studied.