First-Principles Phase-Field Prediction of the Ni-Al Alloy Microstructures at Room Temperature

Accurate prediction of microstructure evolution in alloys is essential for understanding their functional properties and thermodynamic stability. This task is challenging due to the exponential complexity of compositional and processing phase spaces, as well as the limited predictive power of empirically parameterized phase-field models, which require extensive experimental characterization. Here, we employ the First-Principles Phase Field (FPPF) method, a robust multiscale framework that systematically bridges nanoscale first-principles calculations with macroscale phase-field simulations. The approach utilizes cluster expansion theory to construct the compositional free-energy function and incorporates temperature effects through vibrational contribution to the free energies obtained from first-principles phonon calculations. This comprehensive free-energy formulation enables direct solution of the Cahn-Hilliard equation to simulate microstructure evolution. The predictive capability of the FPPF method is demonstrated for the Ni-Al alloy system at room temperature (∼300 K), successfully reproducing key microstructural features including cuboidal precipitates at ∼80 at.% Ni and mosaic-type patterns at 50 at.% Ni. The close correspondence between predicted and experimental microstructures confirms the reliability of FPPF for the Ni-Al alloy microstructure prediction.