INTERNAL FRICTION STUDY OF STRAIN AGING IN ALLOYS

Abstract
Internal friction measurements were used to study strain aging in single crystals of Al-Mg and Cu-Al alloys as a function of temperature and aging time. In the absence of deformation-generated vacancies, solute segregation to dislocations starts at 200 and 300 K, respectively. Excess vacancies were generated in pure Al and Al-Mg alloys by in-situ plastic deformation at 120 K. With increasing temperature, solute segregation to dislocations starts in these alloys at 200 K, as in the absence of excess vacancies. The excess vacancies become mobile in pure Al and in the Al-Mg alloys at 250 K. It is concluded that the initial locking of dislocations by solutes occurs through a rearrangement of solutes near the dislocation cores and that in Al-Mg alloys, deformation-generated vacancies have little or no effect in this process.