Stress concentration on eutectic Si phase in Al-Si cast alloy by means of image-based FE simulation

Image-based finite element (FE) simulation, which model was build based on 3D image obtained by synchrotron radiation nano-tomography, was performed to investigate a point of preferential damage on Si particles in the early stage of tensile deformation in an Al-10%Si casting alloy. By reproducing stress concentration on Si particles with the FE simulation, the effects of particle parameters such as (1) particle size, (2) particle orientation to loading direction and (3) particle shape on damage were evaluated. The parameters were suggested by nano-tomography observation to influence to damage. Increasing rate of maximum hydrostatic stress was different depending on Si particle size. Larger particles show rapid increment of the stress. That is, the preferential damage can be possibly caused on large particles at early stage of tensile deformation. In the study of the influence of particle orientation, particles whose longitudinal direction are in a nearly parallel to tensile direction tend to also show rapid increment of the stress. However, the most rapid development of the maximum hydrostatic stress was observed in the particles that possess small Gaussian curvature which corresponds to severe necking. After comparisons of particles having specific parameters with the damaging behavior, it was revealed that the most influencing parameter of the particles on stress concentration was particle shape to possess necking.