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The elemental diffusion and corresponding microstructure evolution during oxidation have a direct bearing to excellent oxidation resistance for amorphous silicides. In this work, the oxidation behavior of sputtered amorphous-ZrxSi1−x (0.55 ≤ x ≤ 0.75) films at subcritical water environment (320℃ and 16.4 MPa) was investigated, which can serve as protective coating for nuclear Zr claddings. The oxidation mechanism was determined based on the characterized chemical composition and microstructure of oxide layer. The selective formation of protective Zr–Si–O amorphous oxide scale and Si-rich Zr–Si transition layer was controlled by the changeable atomic Zr/Si ratio and atomic packing density, as proved by AIMD and TEM. EELS and EDS confirm the initial enrichment of Zr in Zr–Si–O, which is conducive to the structural stability. The external diffusion of Zr and the internal diffusion of silicon are suppressed by the gradually formed Si-rich transition layer when x is 0.55. The very low-oxygen permeation in amorphous Zr–Si–O oxide layer and Si-rich transition layer appeared to be beneficial in preventing oxygen permeation to the underlying Zr-4 alloy substrate in 320 ℃ and 16.4 MPa.

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Coordination of Elemental Diffusion and Self-enhanced Oxide Layer on Zr-Si Amorphous Coatings

  • 章节

  • 发表日期：

    2025年

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  • Junhua Hu,
  • Guoqin Cao

摘要

The elemental diffusion and corresponding microstructure evolution during oxidation have a direct bearing to excellent oxidation resistance for amorphous silicides. In this work, the oxidation behavior of sputtered amorphous-ZrxSi1−x (0.55 ≤ x ≤ 0.75) films at subcritical water environment (320℃ and 16.4 MPa) was investigated, which can serve as protective coating for nuclear Zr claddings. The oxidation mechanism was determined based on the characterized chemical composition and microstructure of oxide layer. The selective formation of protective Zr–Si–O amorphous oxide scale and Si-rich Zr–Si transition layer was controlled by the changeable atomic Zr/Si ratio and atomic packing density, as proved by AIMD and TEM. EELS and EDS confirm the initial enrichment of Zr in Zr–Si–O, which is conducive to the structural stability. The external diffusion of Zr and the internal diffusion of silicon are suppressed by the gradually formed Si-rich transition layer when x is 0.55. The very low-oxygen permeation in amorphous Zr–Si–O oxide layer and Si-rich transition layer appeared to be beneficial in preventing oxygen permeation to the underlying Zr-4 alloy substrate in 320 ℃ and 16.4 MPa.