Micromechanical modelling of crack initiation in hard two-phase materials

Due to the fact that hard two-phase alloys frequently fail by brittle fracture, special interest is devoted to the research of the fracture mechanisms of these materials. It is known that the fracture behaviour strongly depends on the properties of their microstructure. In particular, the mismatch of mechanical properties between the hard phases (HP) and the metal matrix (MM) favours crack initiation in/at HP by interfacial failure or particle fracture. The ongoing research project of our group intends to qualify and to quantify these effects by parameter studies using the finite-element method. Besides the mechanical property mismatches between HP and MM (Youngs modulus, yield strength, hardening), geometrical aspects (size, shape, distribution of HP) influence crack initiation and propagation. In this paper failure criteria for interfacial failure and particle fracture will be suggested Numerical illustrations show how the developed FE-code CRACKAN automatically simulates crack initiation in HP.