Four examples of the fracture of metal composites are presented. After analysis, it is revealed that the cause of fracture can be attributed to high tensile stress concentration at free boundaries of the metal composite. The tensile stress concentration arises as a result of vastly different thermal expansion (or contraction) properties between the component materials of the composite. As the composite cools from high temperature (where residual stress is negligible) to room temperature, the component materials in the composite tend to contract differently so that tensile stress concentration is created. The fracture examples also demonstrate that high tensile stress concentration can be devastating to high hardness, brittle materials.
