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<p>The mechanical degradation of Ni-based superalloys induced by uncontrolled γ′ phase evolution during brazing directly threatens the structural integrity and service reliability of components. To address the critical issue, simulated brazing thermal processes with five typical cooling regimes and subsequent two-step aging were applied on Waspaloy samples. Microstructural characterizations reveal that the post-brazing cooling rate dictates the size and distribution of <i>γ</i>′ precipitates rather than the total volume fraction (~ 26%). Mechanistic calculations reveal that the precipitation strengthening mechanism transits from weakly coupled dislocation cutting to strongly coupled dislocations cutting and Orowan looping upon exceeding the critical size of ~ 19&#xa0;nm and ~ 66&#xa0;nm, respectively. In engineering practice, the maximum feasible post-brazing cooling regime, i.e., rapid cooling in the argon atmosphere, is recommended for Waspaloy to optimize <i>γ</i>′ precipitate behavior and enhance the mechanical properties. This study establishes a precise regulatory map of the simulated brazing thermal process, <i>γ</i>′ phase size evolution, hardness, and tensile properties, providing a scientific basis for optimizing the brazing process and tailoring the mechanical properties of Waspaloy superalloy components for high-temperature service applications.</p> Graphical abstract <p></p>

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γ′ phase precipitation and mechanical properties of Waspaloy superalloy during simulated brazing thermal processes: regulatory role of cooling rate

  • 期刊论文

  • 发表日期：

    2026年6月28日

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  • Guowei Wang,
  • Kun Liu,
  • Hongliang Liu,
  • Boning Zhang,
  • Lan Liu,
  • Chao Shen,
  • Haoze Zhou,
  • Lei Zheng

摘要

The mechanical degradation of Ni-based superalloys induced by uncontrolled γ′ phase evolution during brazing directly threatens the structural integrity and service reliability of components. To address the critical issue, simulated brazing thermal processes with five typical cooling regimes and subsequent two-step aging were applied on Waspaloy samples. Microstructural characterizations reveal that the post-brazing cooling rate dictates the size and distribution of γ′ precipitates rather than the total volume fraction (~ 26%). Mechanistic calculations reveal that the precipitation strengthening mechanism transits from weakly coupled dislocation cutting to strongly coupled dislocations cutting and Orowan looping upon exceeding the critical size of ~ 19 nm and ~ 66 nm, respectively. In engineering practice, the maximum feasible post-brazing cooling regime, i.e., rapid cooling in the argon atmosphere, is recommended for Waspaloy to optimize γ′ precipitate behavior and enhance the mechanical properties. This study establishes a precise regulatory map of the simulated brazing thermal process, γ′ phase size evolution, hardness, and tensile properties, providing a scientific basis for optimizing the brazing process and tailoring the mechanical properties of Waspaloy superalloy components for high-temperature service applications.

Graphical abstract