Deng Yun, Hajilou Tarlan, Barnoush Afrooz
Department of Mechanical and Industrial Engineering, Norges teknisk-naturvitenskapelige universitet, Trondheim, Norway
Department of Mechanical and Industrial Engineering, Norges teknisk-naturvitenskapelige universitet, Trondheim, Norway.
Philos Trans A Math Phys Eng Sci. 2017 Jul 28;375(2098). doi: 10.1098/rsta.2017.0106.
To evaluate the hydrogen (H)-induced embrittlement in iron aluminium intermetallics, especially the one with stoichiometric composition of 50 at.% Al, a novel micro-cantilever bending test was applied within an environmental scanning electron microscope (ESEM), which provides both a full process monitoring and a clean, H-charging condition. Two sets of cantilevers were analysed in this work: one set of un-notched cantilevers, and the other set with focused ion beam-milled notch laying on two crystallographic planes: (010) and (110). The cantilevers were tested under two environmental conditions: vacuum (approximately 5 × 10 Pa) and ESEM (450 Pa water vapour). Crack initiation at stress-concentrated locations and propagation to cause catastrophic failure were observed when cantilevers were tested in the presence of H; while no cracking occurred when tested in vacuum. Both the bending strength for un-notched beams and the fracture toughness for notched beams were reduced under H exposure. The hydrogen embrittlement (HE) susceptibility was found to be orientation dependent: the (010) crystallographic plane was more fragile to HE than the (110) plane.This article is part of the themed issue 'The challenges of hydrogen and metals'.
为评估铁铝金属间化合物中氢（H）致脆化情况，尤其是化学计量比组成为50原子百分比铝的化合物，在环境扫描电子显微镜（ESEM）内进行了一种新型微悬臂梁弯曲试验，该试验既能对全过程进行监测，又能提供清洁的充氢条件。本研究分析了两组悬臂梁：一组是无缺口悬臂梁，另一组是在两个晶面上有聚焦离子束铣削缺口的悬臂梁，这两个晶面分别为（010）和（110）。悬臂梁在两种环境条件下进行测试：真空（约5×10 帕）和ESEM（450帕水蒸气）。当悬臂梁在有氢的情况下进行测试时，观察到应力集中位置会引发裂纹，并扩展导致灾难性失效；而在真空中测试时则未出现裂纹。在氢暴露条件下，无缺口梁的弯曲强度和有缺口梁的断裂韧性均降低。发现氢脆（HE）敏感性与取向有关：（010）晶面比（110）晶面对氢脆更敏感。本文是主题为“氢与金属的挑战”的特刊的一部分。
