Many-body mechanism of Guinier-Preston zones stabilization in Al-Cu alloys

Thermodynamics and atomic structures of pre-precipitates in dilute Al-Cu alloys are studied using Metropolis Monte Carlo simulations with many-body effective cluster interactions that have been systematically derived from ab initio supercell calculations. We show that many-body interactions, including the contributions due to lattice relaxations around the solute atoms, are mainly responsible for the formation of metastable planar atomic arrangements known as Guinier-Preston zones. Interaction terms up to four-body clusters are shown to be necessary to correctly reproduce the structures and temperatures of pre-precipitation in Al-Cu solid solutions.

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