Fracture surface analysis is a very reliable method to identify the causes of a material failure, since the crack propagation path allows the identification of the crack origin and the propagation direction, the stress state at the moment of the fracture, the causes of fracture initiation, interaction of the crack with the microstructure and the crack propagation sequence. In glasses and ceramics, the most important morphologic features of the fracture surface are the fracture origin, the fracture mirror, the mist and the hackle. Along with these fracture marks, other important surface features can be present too, for instance: "Wallner" lines, scarps, twist hackle, gull wings and the wake hackle. The above fracture surface features are very well defined in glasses, since these materials are homogeneous, isotropic and do not have a crystal structure that can interfere with the crack propagation.
fractography; glasses; fracture surface
