Whether hydrogen diffusion can be accelerated by grain boundaries (GBs) still remains controversial. In this study, the impact of different types of GBs within the directionally solidified polycrystalline nickel specimens on hydrogen diffusion was directly observed at room temperature by combining Electron Back Scattered Diffraction (EBSD) and scanning Kelvin probe force microscopy (SKPFM). The results suggest that the coherent Σ3 twin GB provides a fast path for hydrogen diffusion, while the random GB cannot significantly accelerate the transport of hydrogen atoms. In addition, this study confirms that SKPFM is a reliable technique to allow the detection of the local diffusion and distribution of hydrogen in metals with high lateral resolution down to the GBs.

氢的扩散是否能通过晶界（GBs）加速仍存在争议。在这项研究中，通过结合电子背散射衍射（EBSD）和扫描开尔文探针力显微镜（SKPFM），可以在室温下直接观察到定向凝固的多晶镍试样中不同类型的GBs对氢扩散的影响。结果表明，相干的Σ3孪生GB为氢扩散提供了一条快速路径，而随机GB则不能显着加速氢原子的传输。此外，这项研究证实，SKPFM是一种可靠的技术，可用于检测氢在金属中的局部扩散和分布，并具有直至GBs的高横向分辨率。