High concentration of vacancies induced by β″ phase formation in Al–Mg–Si alloys.

The high concentration of vacancies induced by β″ phase formation in Al–Mg–Si alloys has been observed by positron annihilation lifetime spectroscopy. These vacancies differ from quenched-in vacancies. The induced vacancies are generated inside or at the interface of the β″ phase, i.e. the β″ phase contains a high concentration of vacancies. The induced vacancies survive during the β″-to-β′ phase transformation. The migration energy of the induced vacancies is determined to be 1.83 ± 0.11 eV, which is about three times higher than that of vacancies in pure Al. [ABSTRACT FROM AUTHOR]