Interaction of hydrogen and vacancies in copper investigated by positron annihilation

Abstract

Doppler broadening measurements have been performed on Cu samples containing vacancies and/or hydrogen. Trapping of hydrogen by vacancies is indicated above about 150K. Vacancies occupied by hydrogen show a strongly reduced positron-trapping probability as compared to hydrogen-free vacancies. Detrapping of hydrogen is not observed below 450K. Therefore, the vacancy-hydrogen binding energy must be greater than 0.4 eV. The positron measurements also show that quenched-in vacancies become mobile at about 273K and form clusters. The close analogy to the annealing behaviour of electron-irradiated Cu confirms the interpretation of annealing stage III by single-vacancy migration.