Abstract
Eeffects of the addition of a small amount of Mn on the aging process of Al-Cu alloys were studied. The changes in electrical resistance during aging were measured at the liquid nitrogen temperature, and thin foils made from as-quenched alloys were examined by transmission electron microscopy. The results are as follows: (1) The time law of the resistance change is not changed by the addition of Mn, and a low temperature aging is caused by the formation of G. P. zones of the same kind as in Al-Cu. (2) The aging rate is slightly decreased by the addition of Mn. (3) It was observed by transmission electron micrography that the number and diameter of helices and loops of dislocations in specimens containing Mn resemble those observed in Al-Cu alloys of lower copper contents. (4) The binding energy between an Mn atom (or a pair of Mn-Cu) and a vacancy might be smaller than the sum of the binding energy between a Cu atom and a vacancy, and 0.1 eV.
