Jiao Benqi, Han Weizhong, Zhang Wen, Hu Zhongwu, Li Jianfeng
Northwest Institute for Nonferrous Metal Research, Xi'an 710016, China.
Center for Advancing Materials Performance from the Nanoscale, State Key Laboratory for Mechanical Behavior of Materials, Xi'an Jiaotong University, Xi'an 710049, China.
Materials (Basel). 2024 Jul 10;17(14):3417. doi: 10.3390/ma17143417.
Refractory metal single crystals have been applied in key high-temperature structural components of advanced nuclear reactor power systems, due to their excellent high-temperature properties and outstanding compatibility with nuclear fuels. Although electron beam floating zone melting and plasma arc melting techniques can prepare large-size oriented refractory metals and their alloy single crystals, both have difficulty producing perfect defect-free single crystals because of the high-temperature gradient. The mechanical properties of refractory metal single crystals under different loads all exhibit strong temperature and crystal orientation dependence. Slip and twinning are the two basic deformation mechanisms of refractory metal single crystals, in which low temperatures or high strain rates are more likely to induce twinning. Recrystallization is always induced by the combined action of deformation and annealing, exhibiting a strong crystal orientation dependence. The irradiation hardening and neutron embrittlement appear after exposure to irradiation damage and degrade the material properties, attributed to vacancies, dislocation loops, precipitates, and other irradiation defects, hindering dislocation motion. This paper reviews the research progress of refractory metal single crystals from three aspects, preparation technology, deformation behavior, and irradiation damage, and highlights key directions for future research. Finally, future research directions are prospected to provide a reference for the design and development of refractory metal single crystals for nuclear applications.
难熔金属单晶因其优异的高温性能以及与核燃料的出色相容性，已被应用于先进核反应堆动力系统的关键高温结构部件中。尽管电子束悬浮区熔和等离子弧熔技术能够制备大尺寸的取向难熔金属及其合金单晶，但由于高温梯度，两者都难以生产出完美无缺陷的单晶。难熔金属单晶在不同载荷下的力学性能均表现出强烈的温度和晶体取向依赖性。滑移和孪生是难熔金属单晶的两种基本变形机制，其中低温或高应变速率更易诱发孪生。再结晶总是由变形和退火的共同作用引起的，表现出强烈的晶体取向依赖性。在受到辐照损伤后会出现辐照硬化和中子脆化现象，这会降低材料性能，其原因是空位、位错环、析出物及其他辐照缺陷阻碍了位错运动。本文从制备技术、变形行为和辐照损伤三个方面综述了难熔金属单晶的研究进展，并突出了未来研究的关键方向。最后，对未来的研究方向进行了展望，为核应用难熔金属单晶的设计与开发提供参考。
