Experimental and theoretical characterization of Al3Sc precipitates in Al–Mg–Si–Cu–Sc–Zr alloys

Abstract

Abstract The structure of Al3Sc precipitates in Al –Mg– Si–Cu – Sc –Zr alloys annealed at 450 °C was investigated using transmission electron microscopy and energy-dispersive X-ray spectroscopy. The Al3Sc particles contain mainly Sc and small amounts of Zr, Si, and Cu. The addition of Zr limits the size of the Al3Sc precipitates to about 10– 30 nm, and these precipitates are coherent with the matrix. Density functional energy calculations showed that exceptionally small energies are required to dissolve Zr and Cu in Sc and Al sublattices, respectively. On the contrary, Cu, Mg, and Si are difficult to be dissolved in the Sc sublattice.