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<p>It has been reported that NiCrCo and FeNiCrCo medium-entropy alloys (MEAs), which have a face-centered cubic (FCC) crystal structure, especially NiCrCo, have better mechanical properties than FeNiCrCoMn high-entropy alloy (HEA) with the same crystal structure. In addition, even when MEAs and HEA were charged with hydrogen up to 1400 appm, no hydrogen embrittlement was observed. In the present study, the effects of cold work on the hydrogen embrittlement (HE) resistance of MEAs and HEA were investigated. 20% cold work increased the yield strength and tensile strength, and decreased total elongation of MEAs and HEA, respectively. Adding 1400 appm hydrogen to these alloys increased the yield strength. On the other hand, the tensile stress increased in FeNiCrCo MEA and HEA, but decreased in NiCrCo MEA. Hydrogen significantly reduced the total elongation of MEAs, especially NiCrCo MEA, but had little effect on the total elongation of HEA. According to the calculation results based on the first-principles, hydrogen atom decreases stacking fault energies (SFE) of NiCrCo, FeNiCrCo MEAs, and FeNiCrCoMn HEA. Therefore, in the hydrogen-charged MEAs and HEA, the increase in nano-twin deformation leads to an improvement in the HE resistance of these alloys. In addition, the experimental results indicated that hydrogen promotes the vacancy formation during deformation. The decrease in HE resistance of hydrogen-charged cold-worked MEAs and HEA, especially NiCrCo MEA, is thought to be due to the fact that hydrogen is trapped at the dislocation walls, and the concentration of hydrogen increased near the dislocations, as did the concentration of vacancies due to deformation, as a result, decreases the elongation.</p>

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Effects of cold work on hydrogen embrittlement resistance of medium- and high-entropy alloys in the FeNiCrCoMn system

  • 期刊论文

  • 发表日期：

    2025年11月4日

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  • Q. Xu,
  • X. L. Ren,
  • Z. H. Zhong,
  • K. Sato,
  • T. Zhu

摘要

It has been reported that NiCrCo and FeNiCrCo medium-entropy alloys (MEAs), which have a face-centered cubic (FCC) crystal structure, especially NiCrCo, have better mechanical properties than FeNiCrCoMn high-entropy alloy (HEA) with the same crystal structure. In addition, even when MEAs and HEA were charged with hydrogen up to 1400 appm, no hydrogen embrittlement was observed. In the present study, the effects of cold work on the hydrogen embrittlement (HE) resistance of MEAs and HEA were investigated. 20% cold work increased the yield strength and tensile strength, and decreased total elongation of MEAs and HEA, respectively. Adding 1400 appm hydrogen to these alloys increased the yield strength. On the other hand, the tensile stress increased in FeNiCrCo MEA and HEA, but decreased in NiCrCo MEA. Hydrogen significantly reduced the total elongation of MEAs, especially NiCrCo MEA, but had little effect on the total elongation of HEA. According to the calculation results based on the first-principles, hydrogen atom decreases stacking fault energies (SFE) of NiCrCo, FeNiCrCo MEAs, and FeNiCrCoMn HEA. Therefore, in the hydrogen-charged MEAs and HEA, the increase in nano-twin deformation leads to an improvement in the HE resistance of these alloys. In addition, the experimental results indicated that hydrogen promotes the vacancy formation during deformation. The decrease in HE resistance of hydrogen-charged cold-worked MEAs and HEA, especially NiCrCo MEA, is thought to be due to the fact that hydrogen is trapped at the dislocation walls, and the concentration of hydrogen increased near the dislocations, as did the concentration of vacancies due to deformation, as a result, decreases the elongation.