Incorporating first-principles energetics in computational thermodynamics approaches

Computational thermodynamic approaches have become a valuable tool in the calculation of complex, multicomponent phase equilibria often found in industrial alloys. These methods rely on databases of free energies, obtained from an optimization process involving experimental thermodynamic and phase diagram data. However, many phases of practical interest (e.g., metastable precipitate phases) are absent from computational thermodynamics databases, due to insufficient information to perform the optimization process. We demonstrate that first-principles, density functional calculations provide a means to obtain thermodynamic functions of phases absent from current databases. Two examples illustrate this hybrid first-principles/computational-thermodynamics approach: (1) the famous metastable Cu-containing precipitate phase, Al2Cu-θ′, often found in age-hardened aluminum alloys, and (2) a new assessment of thermodynamic data in the Al–Sr system. We show how first-principles input may be used in both binary and multicomponent industrial systems.