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<p>Face-centered cubic (FCC) high-entropy alloys (HEAs), especially medium-entropy alloys (MEAs), are known to exhibit outstanding mechanical properties. Moreover, even with the introduction of 1400&#xa0;appm hydrogen, no degradation in mechanical properties due to hydrogen was observed. In contrast, a significant difference was observed in the same alloys when dislocations were introduced by 20% cold working. In particular, the elongation of the CrNiCo MEA decreased markedly when 1400&#xa0;appm hydrogen was introduced. To clarify this mechanism, the microstructures of all fractured tensile specimens were characterized using electron backscatter diffraction (EBSD). In the alloys without pre-introduced dislocations, the hydrogen-charged specimens exhibited fewer intragranular dislocations. This is considered to result from a decrease in stacking fault energy caused by hydrogen, which promotes deformation twinning. On the other hand, in alloys with introduced dislocations, the elongation of the CrNiCo MEA decreased significantly due to hydrogen-induced intragranular crack initiation. In the CrFeNiCo MEA and CrFeMnNiCo HEA, intragranular dislocations slightly increased due to enhanced dislocation generation induced by hydrogen. The state of hydrogen in the alloys strongly affects their elongation. Trapped hydrogen promotes crack initiation, whereas mobile hydrogen promotes deformation twining, resulting in a smaller reduction in elongation.</p>

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Study of hydrogen effects on the tensile behavior of CrFeMnNiCo-based ternary, quaternary, and quinary alloys using EBSD

  • 期刊论文

  • 发表日期：

    2026年7月31日

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  • Q. Xu,
  • K. Sato,
  • H. Q. Guan,
  • Z. H. Zhong,
  • S. S. Huang,
  • T. Zhu

摘要

Face-centered cubic (FCC) high-entropy alloys (HEAs), especially medium-entropy alloys (MEAs), are known to exhibit outstanding mechanical properties. Moreover, even with the introduction of 1400 appm hydrogen, no degradation in mechanical properties due to hydrogen was observed. In contrast, a significant difference was observed in the same alloys when dislocations were introduced by 20% cold working. In particular, the elongation of the CrNiCo MEA decreased markedly when 1400 appm hydrogen was introduced. To clarify this mechanism, the microstructures of all fractured tensile specimens were characterized using electron backscatter diffraction (EBSD). In the alloys without pre-introduced dislocations, the hydrogen-charged specimens exhibited fewer intragranular dislocations. This is considered to result from a decrease in stacking fault energy caused by hydrogen, which promotes deformation twinning. On the other hand, in alloys with introduced dislocations, the elongation of the CrNiCo MEA decreased significantly due to hydrogen-induced intragranular crack initiation. In the CrFeNiCo MEA and CrFeMnNiCo HEA, intragranular dislocations slightly increased due to enhanced dislocation generation induced by hydrogen. The state of hydrogen in the alloys strongly affects their elongation. Trapped hydrogen promotes crack initiation, whereas mobile hydrogen promotes deformation twining, resulting in a smaller reduction in elongation.