NUMERICAL AND EXPERIMENTAL-STUDY OF EARLY STAGES OF THE FAILURE OF ALSI-CAST ALLOYS

The failure mechanisms in different AlSi-cast alloys with varying micr ostructures of the Si-eutectic are studied by in-situ tensile tests in a scanning electron microscope. Failure criteria for the matrix and t he Si-particles as well as the macroscopic fracture behaviour are dete rmined on the basis of these observations. The critical failure stress of Si-particles is calculated by Finite Elemente modelling of the fra cture behaviour of a large grained model alloy. Crack initiation and s ubsequent crack propagation in the real microstructure of the technica l alloys is then simulated using the recently introduced method of mul tiphase elements and an automatic element elimination technique. Exper iment and simulation are in very satisfactory agreement.