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Rapid modeling of segregation-driven metal-oxide adhesion in high-entropy alloys using macroscopic atom model

Dennis Boakye, Chuang Deng

Abstract

Accurate prediction of metal-oxide adhesion in high-entropy alloys (HEAs) is challenging because interfacial segregation, atomic environments, and macroscopic thermodynamic quantities are strongly correlated. Relying solely on first-principles approaches is too expensive for exploring composition, solute concentration, and co-segregation effects. To address this, we extend the macroscopic atom model (MAM) for multicomponent alloys using composition-consistent surface fractions and an interfacial pair-probability formalism that captures deviations from random contact statistics. Applied to CoCrFeNi (AlCoCrFeNi) HEA in contact with Cr2O3 (Al2O3), the model predicts segregation energies and work of separation as continuous functions of composition, reproducing the correct segregation hierarchy of Hf, Y, Zr, and S. The stronger segregation tendency at Al2O3 interfaces, and the non-linear dependence of surface energy and adhesion on solute content and co-segregation is also captured. The results are benchmarked with DFT calculations, which shows consistent trends, particularly the strengthening of adhesion by Hf and Zr through strong metal-oxygen bonding and the weakening effect of S. These results demonstrate that the extended MAM provides a physically interpretable, computationally efficient, and quantitatively predictive framework for screening segregation-controlled adhesion beyond the limits of DFT.

Rapid modeling of segregation-driven metal-oxide adhesion in high-entropy alloys using macroscopic atom model

Abstract

Accurate prediction of metal-oxide adhesion in high-entropy alloys (HEAs) is challenging because interfacial segregation, atomic environments, and macroscopic thermodynamic quantities are strongly correlated. Relying solely on first-principles approaches is too expensive for exploring composition, solute concentration, and co-segregation effects. To address this, we extend the macroscopic atom model (MAM) for multicomponent alloys using composition-consistent surface fractions and an interfacial pair-probability formalism that captures deviations from random contact statistics. Applied to CoCrFeNi (AlCoCrFeNi) HEA in contact with Cr2O3 (Al2O3), the model predicts segregation energies and work of separation as continuous functions of composition, reproducing the correct segregation hierarchy of Hf, Y, Zr, and S. The stronger segregation tendency at Al2O3 interfaces, and the non-linear dependence of surface energy and adhesion on solute content and co-segregation is also captured. The results are benchmarked with DFT calculations, which shows consistent trends, particularly the strengthening of adhesion by Hf and Zr through strong metal-oxygen bonding and the weakening effect of S. These results demonstrate that the extended MAM provides a physically interpretable, computationally efficient, and quantitatively predictive framework for screening segregation-controlled adhesion beyond the limits of DFT.
Paper Structure (18 sections, 15 equations, 11 figures)

This paper contains 18 sections, 15 equations, 11 figures.

Table of Contents

  1. Introduction
  2. Theory and calculations
  3. Interfacial adhesion
  4. Interfacial segregation
  5. Geometry and DFT calculations
  6. Results and discussions
  7. Interfacial segregation mechanism
  8. Thermodynamic driving forces for segregation
  9. Chemical origin of RE segregation
  10. MAM-based generalization to HEAs
  11. Surface thermodynamics by segregated solutes (MAM)
  12. Effect of segregated species on interfacial adhesion
  13. Atomistic benchmarks for adhesion (DFT)
  14. Effect of single- and co-segregation on adhesion (MAM)
  15. Effect of chemical ordering on adhesion
  16. ...and 3 more sections

Figures (11)

  • Figure 1: A diagram of the energies involved in interface cleavage, which excludes plastic processes finnis1996theory.
  • Figure 2: Perspective view of relaxed bulk CoCrFeNi HEA, bulk chromia ($\mathrm{Cr_2O_3}$), bulk alumina ($\mathrm{Al_2O_3}$), and side views of chromia-HEA (C-HEA) and alumina-HEA (A-HEA) interfaces.
  • Figure 3: Segregation of trace elements (Hf, Y, and S) in (a) alumina, and (b) chromia interfaces. The segregation tendency (negative) of Y and S is higher at the alumina interface than at the chromia interface. Notice how host Fe sites readily make segregation possible for REs.
  • Figure 4: 2D view of the charge-density difference for (a) and (d) no doping, (b) and (d) Hf-doping, and (c) and (d) Y-doping, of alumina- and chromia interfaces, respectively.
  • Figure 5: Segregation of trace elements (Hf, Y, Zr, and S) in CoCrFeNi and AlCoCrFeNi HEAs. All REs have a higher propensity to occupy interfacial sites and outcompete S.
  • ...and 6 more figures