Developing thermodynamic stability diagrams for equilibrium-grain-size binary alloys

•We extended bulk computational thermodynamics to poly/nanocrystalline alloys.•We developed a new and more quantitative/realistic thermodynamic model.•We developed a new kind of stability diagram for equilibrium-grain-size alloys.•The first computed diagram for Fe–Zr is verified by multiple prior experiments.•A new, general, materials design tool is developed for equilibrium-grain-size alloys.

Bulk computational thermodynamics are extended to model binary poly/nanocrystalline alloys by incorporating grain boundary energies computed by a multilayer adsorption model. A new kind of stability diagram for equilibrium-grain-size poly/nanocrystalline alloys is developed. Computed results for Zr-doped Fe are validated by prior experiments and provide new physical insights regarding stabilization of nanoalloys and its relation to solid-state amorphization. This work supports a major scientific goal of extending bulk computational thermodynamics methods to interfaces and nanomaterials and developing relevant thermodynamic stability diagrams as extensions to bulk phase diagrams, which can be useful new tools for the “Materials Genome” initiative.