Recovery of quenched Cu-Ge alloys studied by positron annihilation

The migration stages of single vacancies and vacancy-Ge atom pairs, and their clustering process are studied in quenched Cu-Ge alloys. The decrease in h parameter is observed from about -700C to about 00C in quenched Cu-1.0 at.%Ge alloy, and two mechanisms are proposed for this phenomenon. The increase of h parameter is observed by the aging from about 2500C to about 4000C. The stage can be deduced to be the growth of clusters of Ge atoms and vacancies, and gaseous bubbles. The presence of three dimensional small clusters of Ge atoms and vacancies, and stability of the clusters are discussed. (author)