STUDY OF SINTERING PROCESSES IN COPPER AND NICKEL BY POSITRON-ANNIHILATION

In the advanced stage of non‐isothermal sintering, vacancy clusters are present as prevailing type of defects. Their concentration considerably decreases at further temperature increase, and it can be concluded that thermally activated conversion of multiple vacancies into climbable dislocations takes place. Hence, in conformity with recent experiments, coincidence of intensive material transport (\documentclass{article}\pagestyle{empty}\begin{document}$ \dot \varepsilon $\end{document} e‐maximum) and decrease of defect concentration (recovery) can be understood. Copyright © 1990 WILEY‐VCH Verlag GmbH & Co. KGaA