An in-situ study of the fracture mechanisms of SiCw/AZ91 magnesium matrix composites

摘要

In this paper, the fracture processes of squeeze cast SiCw/AZ91 magnesium matrix composites were studied with in-situ scanning electron microscope (SEM) and transmission electron microscope (TEM) tensile techniques. When the composite was loaded, plastic deformation took place in local stress concentration regions, then developed into microcrack. A large unmber of microcracks initiated in the matrix and these cracks linked abruptly resulting in catastrophic fracture of the composite. The results indicated that the poor ductility of the composites was attributed to the local stress concentration because of the addition of the whiskers and the low inherent ductility of the matrix magnesium alloy. The fracture processes of the composites was matrix-controlled.