Co-segregation effect of Si and Zr at Al/L12–Al3Sc interface.

[Display omitted] Reducing the usage of Sc element, as well as improving the thermal stability of nano-precipitate L1 2 –Al 3 Sc are critical in expanding the application field of Al–Sc based alloys. Previous experiments showed that the impurity Si plays a leading role in accelerating the precipitation and strengthening the thermal stability of Al–Sc-Zr alloy, but the micro mechanism of these effects are not be given at atomic and electron scale. Herein, we performed a first-principles calculations to focus on the segregation behaviors of Si and Zr at Al (0 0 1)/L1 2 -Al 3 Sc (0 0 1) interface. The results show that the ahead segregated Si atom, which prefers to occupy the Al site of Al 3 Sc precipitate side, contributes to induce Zr substituting the Sc atom that is the nearest neighbor of Si rather than the Sc site in Al matrix side. A quantitative calculation suggests that the reduction of Sc usage can at least reach 12 % as the concentration of added Si in Al bulk is about 0.06 %. [ABSTRACT FROM AUTHOR]