Investigation of vacancy trapping by solutes during quenching in aluminum alloys

In aluminum alloys, excess vacancies often form pairs or clusters with solute atoms. This is commonly referred to as vacancy trapping by solutes. Such trapping results in a change in the number of mobile or free vacancies, which in turn affects solute diffusion and precipitate formation during heat treatment. In the current work, such trapping is investigated indirectly in the Al-Sn binary model alloy via studying the dependence of Frank loop formation on the availability of free vacancies. Current experimental results show that the addition of 100 at. ppm. Sn to aluminum leads to a significant reduction in the number density of quenched-in Frank loops. Modeling of mono- and divacancy trapping by solutes during quenching demonstrates the influences of the vacancy-solute binding energy, solute concentration, and temperature on the trapping process. The results reveal that the binding between vacancies and solutes significantly reduces the concentration of free vacancies after quenching in Al-Sn.