MAPAA · MULTISCALE ANALYSIS OF PRECIPITATE IN Al-Cu ALLOYS

MULTISCALE ANALYSIS OF PRECIPITATE IN Al-Cu ALLOYS

The equilibrium phase diagrams are at the core of novel design strategies to discover new materials or to optimize existing ones through integrated computational material engineering. So far, the determination of phase diagrams has been achieved through the CALPHAD (CALculation of PHAse Diagrams) method. Notwithstanding the huge success of the CALPHAD methodology, the accuracy of the predicted phase diagrams is not always as good as required because of the difficulties imposed by kinetics and metastability to determine experimentally accurate thermodynamics and thermochemical parameters, together with the inherent approximations of the CALPHAD method. This is the main problem being addressed in MAPPA project. Advanced materials are involved in everyday life of the general public and the applications of computational strategies involving artificial intelligence are of interest to the general public. The activities carried out in MAPPA project will promote and create awareness among the widest possible audience of the the application of computational strategy, especially the virtually discovery of new alloys. The objective of the MAPAA project was to develop a novel methodology to determine the precipitate structure resulting from high temperature aging and the resulting precipitate strength of the alloys from first principles calculations. The strategy was applied to Al alloys (with particular emphasis in the Al-Cu system) and it was based in two main pillars. The first one is the determination of the phase diagram by means the construction of effective cluster expansion Hamiltonians that can extrapolate first-principles calculations in combination with statistical mechanics approaches based on Monte Carlo simulations to include the entropic contributions, enabling parameter-free predictions of the phase diagram. The second one was the combination of this information with phase field modeling to predict the homogeneous and heterogeneous nucleation and growth of precipitates during high temperature aging and the application of molecular dynamics and dislocation dynamics simulations to predict the strengthening provided by the precipitates.

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