Dislocation sources in an aluminium alloy

A complete study has been made of one type of dislocation source found in Al-Mg alloys. The source, which is characterised by the unusual geometry of the dislocation loops, is interpreted in terms of the Bardeen-Herring mechanism for the multiplication of dislocations by a process of climb. The shape of the loops is due to the high jog energy, ~1.2 eV, in Al-Mg alloys which is caused by the segregation of Mg atoms to dislocations. The vacancy concentration at 550°C is ~10−2 which implies the existence of a binding energy between Mg atoms and vacancies of 0.3–0.4 eV.