We successfully achieved atomic scale visualization of hydrogen atoms at trapping sites associated with the nano-sized precipitates of titanium carbide and vanadium carbide in ferritic steels using a modified three-dimensional atom probe with a deuterium charge cell. We proposed that the hydrogen trapping sites of fine carbide precipitates were at the (001) broad interface between the precipitate and the ferrite matrix. In this study, the precipitate size dependence in the trapping site and its energy was systematically investigated in vanadium carbide precipitation strengthening steels with various aging times. Hydrogen thermal desorption spectrometry analysis showed that the hydrogen trapping energy in the peak- and over-aged steels was larger than that in the under-aged steel. Atom probe tomography analysis showed the {001} platelets of vanadium carbide were covered by charged deuterium atoms in the peak-aging steel with large trapping energy, whereas no deuterium atoms around the {001} platelets were observed in the under-aged steel with small trapping energy. High-resolution transmission electron microscopy observation showed that misfit dislocations hardly appeared on the (001) surface of the precipitates in the two steels with large and small trapping energies. In contrast, the vanadium–carbon atomic ratios of vanadium carbide precipitates were definitely different between the two steels with large and small trapping energies. The precipitates in the under-aged steel with small trapping energy showed a chemical composition similar to VC, whereas the precipitates in the peak- and over-added steels with large trapping energy showed a chemical composition similar to V₄C₃. These results suggested that the origin of the hydrogen trapping site with large trapping energy is not the misfit dislocation core but the carbon vacancy on the (001) broad surface of V₄C₃ precipitates.

我们使用带氘电荷电池的改进型三维原子探针，成功实现了铁素体钢中与碳化钛和碳化钒的纳米级沉淀物相关的俘获位点处氢原子的原子级可视化。我们提出，细小的碳化物沉淀物的氢捕获位点在沉淀物和铁素体基体之间的（001）宽界面处。在这项研究中，系统地研究了具有不同时效时间的碳化钒沉淀强化钢中俘获位点的沉淀物尺寸依赖性及其能量。氢热脱附光谱分析表明，峰值时效和过时效钢中的氢捕获能大于未时效钢中的氢俘获能。原子探针层析成像分析显示，在具有高捕集能的峰值时效钢中，碳化钒的{001}血小板被带电荷的氘原子覆盖，而在具有较小捕集能的时效钢中，未观察到{001}血小板附近的氘原子。捕获能量。高分辨率透射电子显微镜观察表明，在具有大和小的俘获能的两种钢中，析出物的（001）表面几乎没有出现失配位错。相反，在具有大和小的俘获能的两种钢之间，碳化钒沉淀物的钒碳原子比肯定不同。捕集能小的未时效钢中的析出物显示出类似于VC的化学成分，₄ C ₃。这些结果表明，具有较大捕获能量的氢捕获位点的起源不是错配位错核，而是V ₄ C ₃的（001）宽表面上的碳空位沉淀。