Fracture in complex microstructures

This paper reviews fracture features of a variety of conventional and advan ced materials which consist of more than two different phases in terms of c omposite material. To be concrete, the materials include ductile cast irons , carburized steels, aluminum alloys, and several kinds of discontinuously- reinforced composites. all of which have been studied by the present author s to date. Firstly, features on fracture of the above-mentioned three conve ntional materials are introduced. Those have constructions common to artifi cial composites: particle reinforced composite and layered composites. In t he latter half of this paper, the detailed mechanisms of deformation and fr acture in artificial composites and those analyses mainly on the basis of c ontinuum mechanics and fracture mechanics are shown. Deformation and fractu re behaviors of "natural" (or in-situ) and artificial composites are discus sed in terms of their similarities and discrepancies both from metallurgica l and mechanical points of view in order to bring systematic understanding of the materials having complex microstructures. In addition, it is shown t hat certain phenomena that already constitute common knowledge in the field of composite materials, should be strongly considered in the field of conv entional materials.