Jia Yu-Jie, Han Wei-Zhong
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). 2023 Mar 17;16(6):2419. doi: 10.3390/ma16062419.
Zirconium (Zr) hydrides threaten the reliability of fuel assembly and have repeatedly induced failures in cladding tubes and pressure vessels. Thus, they attract a broad range of research interests. For example, delayed hydride cracking induced a severe fracture and failure in a Zircaloy-2 pressure tube in 1983, causing the emergency shutdown of the Pickering nuclear reactor. Hydride has high hardness and very low toughness, and it tends to aggregate toward cooler or tensile regions, which initiates localized hydride precipitation and results in delayed hydride cracking. Notably, hydride reorientation under tensile stress substantially decreases the fracture toughness and increases the ductile-to-brittle transition temperature of Zr alloys, which reduces the safety of the long-term storage of spent nuclear fuel. Therefore, improving our knowledge of Zr hydrides is useful for effectively controlling hydride embrittlement in fuel assembly. The aim of this review is to reorganize the mechanisms of hydride nucleation and growth behaviors, hydride reorientation under external stress, and hydride-induced embrittlement. We revisit important examples of progress of research in this field and emphasize the key future aspects of research on Zr hydrides.
氢化锆（Zr）会威胁燃料组件的可靠性，并多次引发包壳管和压力容器故障。因此，它们引起了广泛的研究兴趣。例如，1983年，延迟氢化物开裂导致一根锆合金-2压力管发生严重断裂和故障，致使皮克灵核反应堆紧急关闭。氢化物硬度高且韧性极低，并且倾向于在温度较低或受拉区域聚集，从而引发局部氢化物沉淀并导致延迟氢化物开裂。值得注意的是，拉伸应力作用下的氢化物再取向会大幅降低Zr合金的断裂韧性，并提高其韧脆转变温度，这会降低乏核燃料长期储存的安全性。因此，增进我们对Zr氢化物的了解有助于有效控制燃料组件中的氢化物脆化。本综述的目的是梳理氢化物形核与生长行为的机制、外部应力作用下的氢化物再取向以及氢化物诱导的脆化。我们回顾了该领域研究进展的重要实例，并强调了Zr氢化物未来研究的关键方向。
