Chemical and microstructural characterization of a 9 cycle Zircaloy-2 cladding using EPMA and FIB tomography
Chemical and microstructural characterization of a 9 cycle Zircaloy-2 cladding using EPMA and FIB tomography
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DOI：
10.1016/j.jnucmat.2018.01.065
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发表时间：
2018-06-01
影响因子：
3.1
通讯作者：
Abolhassani, S.
中科院分区：
文献类型：
--
作者：
Baris, A.;Restani, R.;Abolhassani, S.
一个高燃耗锆-2包层的特点是，以关联其微观结构和组成的变化的氧化和氢吸收行为在反应堆中长期服务。经过9次循环使用后，熔覆段的化学分析表明，大部分第二相颗粒（SPPs）已溶解到基体中。Fe和Ni均匀分布在金属基体中。含Cr的团簇，原来的Zr（Fe，Cr）（2）型沉淀的残余物，仍然存在。在靠近金属-氧化物界面的金属侧观察到大量氢化物。通过聚焦离子束（FIB）层析成像对氧化物和金属-氧化物界面进行三维（3D）重建，显示了氧化物微结构如何随着循环次数的变化而变化。氧化物和金属的组成和微观结构的变化可以与氧化动力学和H-吸收。据观察，有一个增加的氧化动力学和H-吸收之间的第三和第五个周期，以及在最后两个周期。同时氧化物中裂纹的体积分数显著增加。在最后一次循环中形成的氧化物中存在许多细小的裂纹和孔隙。此外，EPMA结果证实，在最后一个循环中形成的这种氧化物反映了在反应器中长停留时间后金属-氧化物界面处的金属组成。(C)2018 Elsevier B. V.版权所有。
A high burn-up Zircaloy-2 cladding is characterised in order to correlate its microstructure and composition to the change of oxidation and hydrogen uptake behaviour during long term service in the reactor. After 9 cycle of service, the chemical analysis of the cladding segment shows that most secondary phase particles (SPPs) have dissolved into the matrix. Fe and Ni are distributed homogenously in the metal matrix. Cr-containing clusters, remnants of the original Zr(Fe, Cr)(2) type precipitates, are still present. Hydrides are observed abundantly in the metal side close to the metal-oxide interface. These hydrides have lower Fe and Ni concentration than that in the metal matrix.The three-dimensional (3D) reconstruction of the oxide and the metal-oxide interface obtained by Focused Ion Beam (FIB) tomography shows how the oxide microstructure has evolved with the number of cycles. The composition and microstructural changes in the oxide and the metal can be correlated to the oxidation kinetics and the H-uptake. It is observed that there is an increase in the oxidation kinetics and in the H-uptake between the third and the fifth cycles, as well as during the last two cycles. At the same time the volume fraction of cracks in the oxide significantly increased. Many fine cracks and pores exist in the oxide formed in the last cycle. Furthermore, the EPMA results confirm that this oxide formed at the last cycle reflects the composition of the metal at the metal-oxide interface after the long residence time in the reactor. (C) 2018 Elsevier B.V. All rights reserved.