Tailoring secondary grains via recrystallization control to restore creep life in high-oxygen PM superalloys

IF 7.9 2区材料科学 Q1 MATERIALS SCIENCE, MULTIDISCIPLINARY

Materials Science and Engineering: A Pub Date : 2026-03-01 Epub Date: 2026-02-02 DOI:10.1016/j.msea.2026.149873

Yuanchen Liang , Yang Liu , Yufeng Liu , Lin Zhang , Peng Zhang , Sha Zhang , Na Liu , Zhou Li , Xuanhui Qu

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引用次数: 0

Abstract

Increasing the proportion of recycled alloy is significant for preparing low-cost powder metallurgy (PM) Ni-based superalloys. However, as this proportion rises, the oxygen content in superalloy powders prepared by gas atomization increases, degrading the mechanical properties of PM superalloys. Therefore, this study investigated the influence of oxygen content on the microstructure, creep performance, and failure mechanism of HIF state FGH96 superalloys. Results reveal that during HIF, the strain induced boundary migration mechanism leads to substantial SGs formation at Prior particle boundaries (PPBs) in the HIP state alloy, with strain gradients driving recrystallization inward from PPBs into powder interior. High-oxygen superalloys exhibit a small grains (SGs) fraction of 52%, compared to 37% in low-oxygen superalloys. During creep, the abundant grain boundaries (GBs) in SGs regions hinder dislocation motion, leading to more severe low angle grain boundaries proliferation than in coarse grains. This results in stress concentration and crack propagation within SGs regions. Consequently, high-oxygen superalloys experience more pronounced stress concentration in SGs, leading to a faster steady-state creep rate of 3.31×10⁻² h⁻¹ with a shorter creep life of 52 h, compared to 85 h for low-oxygen superalloys. First-principles calculations show that pore nucleation preferentially occurs at the high energy MC-γ′ interface, followed by the γ-γ′ phase interface, and lastly at the γ-γ grain boundary. Finite element simulations confirm that the abundant GBs in SGs regions intensify GBs sliding, causing stress accumulation and facilitating crack propagation during high-temperature deformation. Based on these results, by increasing the hot-deformation temperature to suppress recrystallization, the SGs fraction in high-oxygen superalloys was optimized to 38.7% and the creep life is improved to 84 h, which is close to that of low-oxygen superalloys. This study offers technical support for microstructure control and performance optimization of low-cost PM Ni-based superalloys.

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通过再结晶控制调整二次晶粒，恢复高氧PM高温合金的蠕变寿命

提高再生合金的比例对制备低成本粉末冶金镍基高温合金具有重要意义。然而，随着这一比例的增加，气体雾化制备的高温合金粉末中的氧含量增加，降低了PM高温合金的力学性能。因此，本研究研究了氧含量对HIF态FGH96高温合金组织、蠕变性能及失效机制的影响。结果表明：HIF过程中，应变诱导的边界迁移机制导致热态合金在先验颗粒边界（PPBs）处形成大量的SGs，应变梯度驱动PPBs向粉末内部再结晶；高氧高温合金的小晶粒（SGs）分数为52%，而低氧高温合金为37%。蠕变过程中，SGs区域丰富的晶界阻碍了位错运动，导致低角度晶界扩散比粗晶更为严重。这导致应力集中和裂纹扩展在SGs区域。因此，高氧高温合金在SGs中经历了更明显的应力集中，导致稳态蠕变速率更快，为3.31×10−2 h−1，蠕变寿命较短，为52 h，而低氧高温合金为85 h。第一性原理计算表明，孔隙成核优先发生在高能MC-γ′界面，其次是γ-γ′相界面，最后是γ-γ晶界。有限元模拟结果表明，在高温变形过程中，SGs区域中大量的GBs加剧了GBs的滑动，导致应力积累，有利于裂纹扩展。在此基础上，通过提高热变形温度抑制再结晶，使高氧高温合金的SGs分数达到38.7%，蠕变寿命提高到84 h，接近低氧高温合金的蠕变寿命。该研究为低成本PM镍基高温合金的组织控制和性能优化提供了技术支持。

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来源期刊

Materials Science and Engineering: A 工程技术-材料科学：综合

CiteScore

11.50

自引率

15.60%

发文量

1811

审稿时长

31 days

期刊介绍： Materials Science and Engineering A provides an international medium for the publication of theoretical and experimental studies related to the load-bearing capacity of materials as influenced by their basic properties, processing history, microstructure and operating environment. Appropriate submissions to Materials Science and Engineering A should include scientific and/or engineering factors which affect the microstructure - strength relationships of materials and report the changes to mechanical behavior.