The direct observation of lattice defects by field ion microscopy

Observations of Mo and W in the field ion microscope have revealed the structure of edge dislocations and a grain boundary in molybdenum. Tungsten has been irradiated with 5 MeV α-particles and the production of vacancies at the surface observed. It is shown that this technique can be used to investigate the atomic structure at a grain boundary and around the core of a dislocation while it can be applied to the study of radiation damage to give information about the distribution and range of the damage produced by a single high-energy impact.