Density Functional Theory Studies of Precipitate Interfaces in Aluminium Alloys, with Focus on Theta'-Al2Cu

Abstract

The atomic structure of bulk crystal of aluminium and the precipitate phase $\theta^\prime$ connected to age-hardening of Al-Cu alloys have been studied using Density Functional Theory (DFT). The lattice constant of $\theta^\prime$ at \SI{0}{\kelvin} having a coherent interface with the aluminium is found, for thicknesses up to six unit cells. Five different interface-configurations have been studied in four alloys: Al-Cu, Al-Cu-Ag, Al-Cu-Li and Al-Cu-Mg-Si. The interface stucture of these is found. The lattice misfit of the precipitate with the aluminium matrix around is found for different thicknesses in each of the four alloys, and compared to the strain length and interface energy. The interfacial energies are computed for each thickness taking into acount the strain energy.