Nb涂层N36锆合金原位加热过程中的缺陷演化行为

Defect Evolution Behavior of Nb-Coated N36 Alloy During In-situ Heating

福岛核事故之后,为锆合金表面涂覆涂层是一种提高核燃料包壳事故容错能力的重要方式。含Nb涂层N36合金辐照后的透射电镜样品利用聚焦离子束进行制备,并通过原位透射电子显微镜研究了氪(Kr)离子注入后,Nb涂层在原位加热过程中的气泡生长行为。原位加热结果表明,界面对气泡的生长存在影响,界面在加热过程中通过对周围气泡的捕获与输送,导致界面附近气泡的生长速度低于远离界面的气泡生长速度。原位加热后的元素分析表明,辐照与加热均会导致涂层-基体元素扩散距离的增加,其中辐照过程中的元素扩散由热峰混合机制主导。元素的扩散有助于提高涂层的结合性能,并为N36合金提供一定的抗腐蚀能力。

Coating the surface of zirconium alloy is an important way to improve the accident tolerance capability for nuclear fuel cladding after the Fukushima nuclear power plant accident.Transmission electron microscope(TEM)samples of the irradiated N36 alloy with Nb coating were prepared by focusing ion beam(FIB).Bubble evolution during in-situ heating of the irradiated Nb-coated N36 alloy samples was investigated by in-situ TEM.The results show that the interface has a strong effect on bubble growth during the in-situ heating process.The bubbles near the interface are captured and transported by the interface,which leads to the fact that the growth rate of the bubbles near the interface is lower than that away from the interface.The analysis of elements after in-situ heating indicates that both irradiation and heating can increase the diffusion distance of the elements between coating and matrix,and the diffusion during irradiation is mainly caused by the thermal spike diffusion.The diffusion of elements is beneficial to improve the bonding properties of the coating,which provides certain corrosion resistance for N36 alloy.