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<p>The first-principles method was used to model the grain boundary (GB) segregation and strengthening effects considering the chemical and elastic contributions of the segregated solutes. In this study, the segregation behavior of typical alloying elements (hydrogen (H), boron (B), carbon (C), oxygen (O), chromium (Cr), zirconium (Zr)) at typically symmetrical tilt GB (Σ3[110] (111), Σ3[110](112), Σ5[001](210)) was studied. The correlations of GB segregation and strengthening effects, GB structure, group number atomic radius, and electronegativity were revealed. The results demonstrate distinct and interconnected roles of alloying elements in influencing GB mechanical properties and stability. Notably, B exhibits strong spontaneous segregation across all three GBs (e.g., with a segregation energy (<i>E</i><sub>seg</sub>) of − 1.698&#xa0;eV at the Σ5&#xa0;GB), effectively reducing GB energy (down to 0.269&#xa0;J/m<sup>2</sup>) and increasing the energy of separation (up to 3.509&#xa0;J/m<sup>2</sup>), thereby synergistically enhancing both GB strength and thermal stability. In contrast, H induces GB embrittlement by weakening atomic bonding, as evidenced by a reduced energy of separation (2.866&#xa0;J/m<sup>2</sup>), thereby deteriorating both strengthening and stabilization effects. O enhances fracture resistance at Σ3(112) and Σ5(210) boundaries through strong covalent bonding, though its thermodynamic preference for free surfaces results in positive strengthening energy values. Zr, with an <i>E</i><sub>seg</sub> of − 0.416&#xa0;eV at the Σ5 GB, improves stability via lattice expansion, whereas Cr shows negligible segregation tendency (<i>E</i><sub>seg</sub> &gt; 0.2&#xa0;eV) and minimal impact on GB properties. Further electronic structure analyses, including charge density, electron localization function, differential charge density, and density of states, reveal that the covalent interactions of B, C, and O play a dominant role in the strengthening mechanism and are crucial for stabilization. Meanwhile, Zr contributes to both strengthening and stabilization mainly through lattice expansion caused by excessive atomic radius.</p>

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First-principles calculation of the correlation between stabilization and strengthening effects induced by grain boundary segregation in nickel-based superalloy

  • 期刊论文

  • 发表日期：

    2026年3月28日

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  • Liang Wang,
  • Xinyue Chen,
  • Sifang Yue,
  • Peishan Zhou,
  • Bin Wang,
  • Hualin Zheng

摘要

The first-principles method was used to model the grain boundary (GB) segregation and strengthening effects considering the chemical and elastic contributions of the segregated solutes. In this study, the segregation behavior of typical alloying elements (hydrogen (H), boron (B), carbon (C), oxygen (O), chromium (Cr), zirconium (Zr)) at typically symmetrical tilt GB (Σ3[110] (111), Σ3[110](112), Σ5[001](210)) was studied. The correlations of GB segregation and strengthening effects, GB structure, group number atomic radius, and electronegativity were revealed. The results demonstrate distinct and interconnected roles of alloying elements in influencing GB mechanical properties and stability. Notably, B exhibits strong spontaneous segregation across all three GBs (e.g., with a segregation energy (Eseg) of − 1.698 eV at the Σ5 GB), effectively reducing GB energy (down to 0.269 J/m2) and increasing the energy of separation (up to 3.509 J/m2), thereby synergistically enhancing both GB strength and thermal stability. In contrast, H induces GB embrittlement by weakening atomic bonding, as evidenced by a reduced energy of separation (2.866 J/m2), thereby deteriorating both strengthening and stabilization effects. O enhances fracture resistance at Σ3(112) and Σ5(210) boundaries through strong covalent bonding, though its thermodynamic preference for free surfaces results in positive strengthening energy values. Zr, with an Eseg of − 0.416 eV at the Σ5 GB, improves stability via lattice expansion, whereas Cr shows negligible segregation tendency (Eseg > 0.2 eV) and minimal impact on GB properties. Further electronic structure analyses, including charge density, electron localization function, differential charge density, and density of states, reveal that the covalent interactions of B, C, and O play a dominant role in the strengthening mechanism and are crucial for stabilization. Meanwhile, Zr contributes to both strengthening and stabilization mainly through lattice expansion caused by excessive atomic radius.