Credit: Image courtesy of Karl Sieradzki, Arizona State University
High magnification images of the surface of a crack -- referred to as the fracture surface -- provide information on how cracks are formed and progress through a material as it breaks. For some gold alloys (models for more common materials), corrosion can cause a large amount of internal pores to form, representing the type of structure that might develop in a material after a long time in a nuclear reactor. This type of corrosion-induced structure can result in unpredictable and premature failure of components. Below 1 millimeter, the fracture surface shown does not have any sharp, abrupt edges, demonstrating that the break was not brittle (i.e., not like glass shattering). At this scale, the fracture results in blunt edges similar to fracture from stretching apart taffy (arrow).