Studies of dislocations by field ion microscopy and atom probe tomography

Alan Cottrell was among the first to recognize the potential of field ion microscopy for the atomic-scale study of crystal defects. The study of atomic configurations at the core of dislocations by this method proved to be unexpectedly difficult, because of the mechanical stresses imposed on the specimen by the high electric field. The development of atom probe tomography revitalized such studies. In particular, the atom probe technique permitted the first direct observations of solute atom distributions in the region of dislocations and confirmed the existence of so-called Cottrell Atmospheres' which are of great importance in the understanding of phenomena such as strain ageing. Atom probe studies of dislocation-solute interactions in a diverse range of alloy systems are outlined.