Observation of point defect production and clustering by high voltage electron microscopy: Interaction of point defect with solutes

Abstract

Excess point defects are generated in metals during irradiation by high energy particles such as electrons, ions and neutrons. Especially in the case of electron irradiation, the only point defects introduced are vacancies and interstitials. These defects develop to form defect clusters of dislocations, stacking faults and voids; when solutes atoms or impurities are contained in metals, the defects interact with the solutes and the defect clustering process is often modified. For the observation of these defect clustering processes and fundamental analysis of defect behaviour, high voltage electron microscopy (HVEM) is utilized; it provides advantages such as strong irradiation intensity with a focussed electron beam, easy control of electron energy, and easy control of temperature during in situ observation. This paper reviews the clustering process of point defects and the interaction of point defects with solute atoms and/or impurities; we concentrate the effect of helium atoms on defect clustering under electron irradiation in HVEM.