Thermodynamic modeling of binaries in Cr-Fe-Mo-Nb-Ni supported by first-principles calculations

TL;DR

This paper develops and refines thermodynamic models for binary systems within the Cr-Fe-Mo-Nb-Ni alloy system, supported by first-principles calculations, enhancing the accuracy of phase predictions for complex alloy design.

Contribution

It introduces improved thermodynamic models for key binary systems using first-principles calculations and experimental data, aiding CALPHAD modeling of multi-component alloys.

Findings

Enhanced accuracy in modeling TCP phases.

Excellent agreement of sigma site occupancies with experiments.

Provides a robust foundation for alloy design.

Abstract

Thermodynamic descriptions of all binaries within the Cr-Fe-Mo-Nb-Ni system have been complied and, where necessary, remodeled. Notably, the Cr-Fe and Fe-Mo systems have been remodeled using comprehensive sublattice models for the topologically close-packed (TCP) phases of Laves_C14, sigma, and mu according to their Wyckoff positions. These refinements are supported by first-principles calculations based on density functional theory (DFT), in conjunction with available experimental data in the literature. The resulting models offer improved accuracy in describing the TCP phases. For instance, the predicted site occupancies of sigma in Cr-Fe show excellent agreement with experimental observations. The present work provides a robust foundation for CALPHAD modeling and the design of complex, multi-component materials, particularly those based on Fe-based and Ni-based alloys.