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Abstract <p>Guided by the design principles of iron-based oxide-dispersion-strengthened (ODS) steels, this study proposes a preliminary composition framework for Y-X-O nano-oxide-dispersion-strengthened nickel-based alloys tailored for nuclear-reactor applications. Using first-principles density functional theory (DFT), we systematically investigated the nucleation and growth mechanisms of Y-Al-O, Y-Ti-O, and Y-Hf-O nanoclusters (NCs) by atomic-scale energetics. Ti and Hf demonstrate superior nucleation capabilities compared to Al, leading to potential higher-density and finer-size nano-oxide precipitates during the mechanical alloying (MA) of Ni-based ODS alloys. The thermodynamic preference for precipitation evolves in three stages: (1) excess vacancy/solute accumulation in the Ni matrix during MA, (2) (O-Y)-core formation upon sufficient O and Y supply, and (3) preferential Y-Ti/Hf-O NCs nucleation over Y-Al-O NCs under oxygen/yttrium-depleted conditions. Subsequent consolidation and heat treatment promote NC growth into nano-oxides, enhancing the mechanical strength and radiation tolerance of Ni-based ODS alloys. These findings provide critical insights into the energetic driving force of nanocluster phases in Ni-based ODS alloys, enabling optimized dispersion-strengthening strategies for radiation-resistant structural materials.</p> Impact statement <p>The urgency to enhance hydrogen embrittlement resistance in Al alloys used in engineering application makes understanding atomic-level solute-hydrogen interactions essential. Our manuscript contributes novel findings on hydrogen embrittlement mechanisms, specifically in relation to grain boundary chemistry, solute segregation behavior, and the electronic charge distribution affected by hydrogen. This study offers a detailed examination of solute-hydrogen interactions at aluminum grain boundaries using density functional theory calculations, providing essential insights into hydrogen embrittlement mechanisms. We analyzed grain boundary and surface energies relative to hydrogen chemical potential and solute segregation, revealing how solute elements such as Mg and Cu distinctly influence hydrogen embrittlement susceptibility. This work provides a framework to optimize alloy compositions for improved hydrogen embrittlement resistance, particularly relevant for high-strength Al alloys in corrosive or hydrogen-rich environments.</p> Graphical Abstract <p>The superior nucleation tendency of Ti/Hf over Al shall facilitate a higher&#xa0;density and finer&#xa0;size of nanoclusters&#xa0;(NCs) during the mechanical alloying process.</p> <p></p>

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Stability analysis of Y-X-O nanoclusters in Ni-based ODS alloys via DFT-based defect energetics

  • 期刊论文

  • 发表日期：

    2025年12月23日

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  • Yiren Wang,
  • Shuqin Cheng,
  • Fan Jia,
  • Fuhua Cao

摘要

Abstract

Guided by the design principles of iron-based oxide-dispersion-strengthened (ODS) steels, this study proposes a preliminary composition framework for Y-X-O nano-oxide-dispersion-strengthened nickel-based alloys tailored for nuclear-reactor applications. Using first-principles density functional theory (DFT), we systematically investigated the nucleation and growth mechanisms of Y-Al-O, Y-Ti-O, and Y-Hf-O nanoclusters (NCs) by atomic-scale energetics. Ti and Hf demonstrate superior nucleation capabilities compared to Al, leading to potential higher-density and finer-size nano-oxide precipitates during the mechanical alloying (MA) of Ni-based ODS alloys. The thermodynamic preference for precipitation evolves in three stages: (1) excess vacancy/solute accumulation in the Ni matrix during MA, (2) (O-Y)-core formation upon sufficient O and Y supply, and (3) preferential Y-Ti/Hf-O NCs nucleation over Y-Al-O NCs under oxygen/yttrium-depleted conditions. Subsequent consolidation and heat treatment promote NC growth into nano-oxides, enhancing the mechanical strength and radiation tolerance of Ni-based ODS alloys. These findings provide critical insights into the energetic driving force of nanocluster phases in Ni-based ODS alloys, enabling optimized dispersion-strengthening strategies for radiation-resistant structural materials.

Impact statement

The urgency to enhance hydrogen embrittlement resistance in Al alloys used in engineering application makes understanding atomic-level solute-hydrogen interactions essential. Our manuscript contributes novel findings on hydrogen embrittlement mechanisms, specifically in relation to grain boundary chemistry, solute segregation behavior, and the electronic charge distribution affected by hydrogen. This study offers a detailed examination of solute-hydrogen interactions at aluminum grain boundaries using density functional theory calculations, providing essential insights into hydrogen embrittlement mechanisms. We analyzed grain boundary and surface energies relative to hydrogen chemical potential and solute segregation, revealing how solute elements such as Mg and Cu distinctly influence hydrogen embrittlement susceptibility. This work provides a framework to optimize alloy compositions for improved hydrogen embrittlement resistance, particularly relevant for high-strength Al alloys in corrosive or hydrogen-rich environments.

Graphical Abstract

The superior nucleation tendency of Ti/Hf over Al shall facilitate a higher density and finer size of nanoclusters (NCs) during the mechanical alloying process.