ABSTRACT
Dislocations and the other imperfections in 99.9999 % aluminum single crystals with a low dislocation density were examined by X-ray topography during the heating and cooling processes. Vacancies in thermal equilibrium at high temperature convert to various type dislocations during the cooling process, and thus formed dislocations reversely convert to vacancies during the heating process. In the heating process of the crystal, dislocation loops of the interstitial type are formed as vacancy source and convert to tangled dislocations. In these conversion processes between dislocation and vacancy, the residual impurities in such a high purity metal affect the final configuration of these imperfections sensitively.
