Vacancy concentrations in metals

The experimental techniques available for the measurement of equilibrium vacancy concentrations, vacancy formation enthalpies and entropies are reviewed. Such methods as differential dilatometry, positron annihilation spectroscopy, field-ion and transmission electron microscopy and resistometry are considered in terms of their particular contributions, advantages and limitations in obtaining information regarding these quantities. The present status of our knowledge of these vacancy properties is assessed. Finally, the ability to combine vacancy formation enthalpy data with self-diffusion data in order to obtain quantitative information regarding vacancy migration properties is discussed. (Auth.)