Abstract The susceptibility of Fe–26Al–0.5Cr (at.%) intermetallic alloy to hydrogen assisted cracking was evaluated by micromechanical fracture mechanics specimens. The notched micro-beams were loaded in situ in an environmental scanning electron microscope under two conditions: one with low pressure to avoid any hydrogen effect and the other with water vapour to promote hydrogen uptake and hydrogen assisted cracking. Fractographic and electron backscatter diffraction analysis carried out on the fracture surfaces of the ruptured beams revealed the mechanisms of the crack propagation. Under both conditions, the failure was cleavage-like, accommodated with plastic deformation. The results show the influence of hydrogen-induced embrittlement on the initiation of the fracture and the plasticity of the crack tip during the propagation of the crack, where the latter becomes localised and uniform over the fracture surface. From the observations, a three stage crack propagation process is proposed. Also, the fracture toughness of the samples was evaluated by linear elastic fracture mechanics and the validity of the results are discussed.

中文翻译：

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环境扫描电子显微镜中的原位微机械测试：氢辅助裂解的新见解

摘要 Fe-26Al-0.5Cr (at.%) 金属间合金对氢辅助开裂的敏感性通过微观机械断裂力学试样进行评估。缺口微束在两种条件下在环境扫描电子显微镜中原位加载：一种是低压以避免任何氢效应，另一种是水蒸气以促进氢吸收和氢辅助裂解。对断裂梁的断裂表面进行的断口和电子背散射衍射分析揭示了裂纹扩展的机制。在这两种情况下，破坏都是像解理一样的，伴随着塑性变形。结果表明，在裂纹扩展过程中，氢致脆化对裂纹萌生和裂纹尖端塑性的影响，其中后者在断裂表面上变得局部和均匀。根据观察结果，提出了一个三阶段裂纹扩展过程。此外，还通过线弹性断裂力学评估了样品的断裂韧性，并讨论了结果的有效性。