Halodová Patricie, Lorinčík Jan, Hojná Anna
Centrum Výzkumu Řež (CVR), 250 68 Husinec-Řež, Czech Republic.
Materials (Basel). 2018 Dec 22;12(1):38. doi: 10.3390/ma12010038.
Liquid lead-bismuth eutectic (LBE) is one of the candidate materials for advanced nuclear systems. The structural materials used in contact with LBE are selected according to the resistance to liquid metal corrosion, irradiation embrittlement, and compatibility with the coolant. However, simultaneous presence of mechanical strain and LBE environment can induce liquid metal embrittlement (LME) in these materials. In this study, a specimen from candidate ferritic-martensitic steel T91 was tested by Constant Extension Rate Tensile (CERT) test exposed to PbBi environment with oxygen concentration 6 × 10 wt % at 300 °C up to rupture. Post-test examination using scanning electron microscopy (SEM) showed a deep crack indicating features of LME in the plastic strained region of the tested specimen. Further investigations focused on characterization of the fracture path and microstructure determination using focused ion beam (FIB) and energy dispersive X-ray spectrometry/electron backscatter diffraction (EDX/EBSD). This observation revealed that the dominant LME failure mode of the observed crack is translath or transgranular and the crack stopped at the high-angle grain boundary. The role of oxides in the crack initiation is discussed.
液态铅铋共晶（LBE）是先进核系统的候选材料之一。与LBE接触使用的结构材料是根据对液态金属腐蚀的抗性、辐照脆化以及与冷却剂的兼容性来选择的。然而，机械应变和LBE环境的同时存在会在这些材料中引发液态金属脆化（LME）。在本研究中，对候选铁素体-马氏体钢T91的一个试样进行了恒应变速率拉伸（CERT）试验，该试样在300℃下暴露于氧浓度为6×10 wt%的PbBi环境中直至断裂。使用扫描电子显微镜（SEM）进行的试验后检查显示，在测试试样的塑性应变区域有一条深裂纹，表明存在LME特征。进一步的研究集中在使用聚焦离子束（FIB）和能量色散X射线光谱/电子背散射衍射（EDX/EBSD）对断裂路径进行表征和微观结构测定。该观察结果表明，观察到的裂纹的主要LME失效模式是穿板条或穿晶的，并且裂纹在大角度晶界处停止。讨论了氧化物在裂纹萌生中的作用。
