Further Studies of Dislocation-Loop Annealing in Aluminium-Base Alloys

Abstract

Abstract The detailed annealing behaviour of large faulted dislocation loops in aluminium and aluminium-base alloys has been studied by quantitative electron microscopy. Changes in loop shrinkage rates, loop character and dislocation pinning have been observed and used to derive information on solute clustering and vacancy/solute interactions. Although generally small, differences between the measured shrinkage rates of loops in pure Al and A1-base alloys were found to be dependent upon the state of solute dispersion. The results are consistent with a model in which extensive clustering occurs during quenching and ageing, and the differences in apparent activation energies are attributed to binding between vacancies and solute atom clusters, or zones. The apparent discrepancy between the large solute atom/vacancy binding energies measured in quenching studies and the much smaller ones measured in equilibrium studies is thus partially explained.