The addition of Nb to FeCrAl alloy enhanced its mechanical properties owing to the precipitated-phase strengthening effect. However, the additive amount and its effect on hydrogen embrittlement (HE) susceptibility have to be evaluated before implementation, as the hydrogen produced by fission and corrosion in the reactor may affect its mechanical properties. Therefore, hydrogen pre-charged tensile bar specimens were tested, and the HE mechanism was investigated. The results demonstrate that though FeCrAl alloys show low HE susceptibility, the Nb-doped FeCrAl alloys still exhibit a slightly higher HE susceptibility than Nb-free FeCrAl alloys. Their reduced ductility was mainly caused by decohesion and cracking of Fe(Nb, Mo) precipitates and quasi-cleavage cracking induced by AlN inclusions. The underlying HE mechanisms for the Nb-doped FeCrAl alloys are hydrogen-enhanced localized plasticity (HELP) and HELP-mediated hydrogen-enhanced decohesion (HEDE).

中文翻译：

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FeCrAl 合金的氢脆：Laves 相和 AlN 颗粒的重要作用

在FeCrAl合金中添加Nb，由于析出相强化效应，提高了其力学性能。然而，在实施前必须评估添加量及其对氢脆（HE）敏感性的影响，因为反应堆中裂变和腐蚀产生的氢气可能会影响其机械性能。因此，对预充氢拉伸棒样品进行了测试，并研究了 HE 机理。结果表明，尽管 FeCrAl 合金表现出较低的 HE 敏感性，但掺 Nb FeCrAl 合金的 HE 敏感性仍略高于无 Nb FeCrAl 合金。其延展性降低的主要原因是Fe(Nb,Mo)析出物的脱聚和开裂以及AlN夹杂物引起的准解理开裂。Nb 掺杂 FeCrAl 合金的潜在 HE 机制是氢增强局部塑性 (HELP) 和 HELP 介导的氢增强脱聚 (HEDE)。