Atomistic studies of segregation and diffusion in Al-Cu grain boundaries

The segregation of Cu atoms at Al [110] Σ11 and [001] Σ5 tilt grain boundaries was studied. Cu atoms were found to segregate to asymmetric sites at the Σ11 boundary and form zig-zag planar aggregates at the interface. Segregation is dominated by atomic size and local hydrostatic stress. Cu atoms prefer to occupy the prime diffusion path sites at both grain boundaries. Cu segregation raises the vacancy formation and diffusion activation energies at Σ11 grain boundaries, thus slowing the rate of atomic diffusion.