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<p>The flow behavior and deformation modes of six [001]-oriented single-crystal (SC) nickel-based superalloys DD4125, CMSX-4, DD6, René N5, DD11 and DESC-1 have been investigated in compression at 750&#xa0;°C and a strain rate of 3.0 × 10<sup>−4</sup>&#xa0;s<sup>−1</sup>. We found that the Protevin-Le Châtelier (PLC) effect occurs in all the experimental alloys during plastic deformation, although differences exist with respect to the critical plastic strain for the initiation of the PLC effect and the strain range where the phenomenon emerges. Microstructural analysis of the deformed specimens discloses that, in contrast to previous findings, initial plastic deformation of the latter five SC superalloys is primarily governed by anti-phase boundary shearing. However, with regard to the superalloy DD4125, apart from the above deformation mechanism, stacking fault shearing and microtwinning have begun to operate just after yielding and before the presence of the PLC effect. Meanwhile, we also found that it is the single <i>a</i>/6 &lt;112&gt; partials that penetrate <i>γ</i>′ precipitates and finally cause the formation of stacking faults and deformation microtwins in the alloys DD4125 and DESC-1, and stacking fault shearing and microtwinning occur frequently with strain in all the experimental alloys, regardless of whether the serrated flow still appears on the stress-strain curves. Our study also demonstrates that manifestation of Type C serrations on the stress-strain curves in nickel-based superalloys is not ascribed to the gradual occurrence of stacking fault shearing and microtwinning during plastic deformation, but rather to the cascade of the two processes on a large scale.</p> Graphical Abstract <p></p>

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The Jerky Flow and Microtwinning in Single-Crystal Nickel-Based Superalloys at 750 °C

  • 期刊论文

  • 发表日期：

    2025年9月10日

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  • Jiao Li,
  • Jiaming Bai,
  • Peng Zhang,
  • Xiufang Gong,
  • Bin Gan,
  • Xiaolong Song,
  • Peng Liu,
  • Yong Yuan

摘要

The flow behavior and deformation modes of six [001]-oriented single-crystal (SC) nickel-based superalloys DD4125, CMSX-4, DD6, René N5, DD11 and DESC-1 have been investigated in compression at 750 °C and a strain rate of 3.0 × 10−4 s−1. We found that the Protevin-Le Châtelier (PLC) effect occurs in all the experimental alloys during plastic deformation, although differences exist with respect to the critical plastic strain for the initiation of the PLC effect and the strain range where the phenomenon emerges. Microstructural analysis of the deformed specimens discloses that, in contrast to previous findings, initial plastic deformation of the latter five SC superalloys is primarily governed by anti-phase boundary shearing. However, with regard to the superalloy DD4125, apart from the above deformation mechanism, stacking fault shearing and microtwinning have begun to operate just after yielding and before the presence of the PLC effect. Meanwhile, we also found that it is the single a/6 <112> partials that penetrate γ′ precipitates and finally cause the formation of stacking faults and deformation microtwins in the alloys DD4125 and DESC-1, and stacking fault shearing and microtwinning occur frequently with strain in all the experimental alloys, regardless of whether the serrated flow still appears on the stress-strain curves. Our study also demonstrates that manifestation of Type C serrations on the stress-strain curves in nickel-based superalloys is not ascribed to the gradual occurrence of stacking fault shearing and microtwinning during plastic deformation, but rather to the cascade of the two processes on a large scale.

Graphical Abstract