摘要
为了研究Sn对锆合金初期腐蚀行为的影响,将Zr-0.75Sn-0.35Fe-0.15Cr和Zr-1.5Sn-0.35Fe-0.15Cr (质量分数,%) 2种锆合金大晶粒TEM薄样品放入280℃、6.3 MPa、0.01 mol/L LiOH水溶液中短时腐蚀。为了保证在相同的厚度和晶粒取向下观察分析晶体结构演化过程,先采用聚焦离子束(FIB)切出横截面薄区样品,再采用TEM观察腐蚀样品表面和横截面的显微组织,利用离孔周围不同距离处样品厚度差别造成的氧含量差别,研究了Sn对锆合金初期氧化行为、早期氧化膜的形核与长大过程的影响。结果表明,从开始氧化至ZrO2形成前,α-Zr的晶格点阵会随着样品中氧含量增加而不断演变;在取向为[0001]的晶粒上氧化层的演化过程经历了亚氧化物层、晶格畸变层和m-ZrO2层等过程。与Zr-0.75Sn-0.35Fe-0.15Cr合金相比,Zr-1.5Sn-0.35Fe-0.15Cr合金氧化膜横截面薄区中氧化层更厚,晶格条纹畸变层占比更低而m-ZrO2层占比更高,这说明提高Sn含量会促进锆合金的初期腐蚀过程。
Zirconium alloys are widely used as fuel cladding and core structure materials for watercooled nuclear reactors due to its low thermal neutron absorption cross section, good corrosion resistance, moderate mechanical properties and good compatibility with UO2. Corrosion is one of the main factors affecting the service life of zirconium alloy cladding. The influence of initial corrosion behavior of zirconium alloys and the crystal structure of the oxide film formed at the early stage on the microstructural evolution of the oxide film at the later stage has gradually attracted people’s attention. Sn is an important alloying element in zirconium alloys. In order to study the effect of Sn on the initial corrosion behavior ofzirconium alloys, coarse-grain TEM thin samples of Zr-0.75 Sn-0.35 Fe-0.15 Cr and Zr-1.5 Sn-0.35 Fe-0.15 Cr(mass fraction, %) zirconium alloys were corroded in 280 ℃, 6.3 MPa and 0.01 mol/L Li OH aqueous solution for short period. In order to ensure the observation of the crystal structure evolution process under the same thickness and grain orientation, the cross-section thin section samples were cut by focused ion beam(FIB), and then the surface and cross-section microstructures of the corroded samples were observed by TEM. Based on the difference in oxygen content caused by the different thickness of the sample around the hole in TEM sample, the effect of Sn on the initial corrosion behavior of zirconium alloy was investigated, as well as the nucleation and growth process of early oxide film. Results showed that the lattice of α-Zr evolved with the increase of oxygen content in the sample from the beginning of oxidation to the formation of ZrO2. The evolution of the oxide layer on the grain oriented [0001] underwent sub-oxide layer, lattice distortion layer and m-ZrO2 layer. Compared with Zr-0.75 Sn-0.35 Fe-0.15 Cr alloy,Zr-1.5 Sn-0.35 Fe-0.15 Cr alloy had a thicker oxide layer in the thin section, a lower proportion of lattice distortion layer and a higher proportion of the m-ZrO2 layer. T
作者
姚美意
林雨晨
侯可可
梁雪
胡鹏飞
张金龙
周邦新
YAO Meiyi;LIN Yuchen;HOU Keke;LIANG Xue;HU Pengfei;ZHANG Jinlong;ZHOU Bangxin(Institute of Materials,Shanghai University,Shanghai 200072,China;Laboratory for Microstructures,Shanghai University,Shanghai 200444,China)
出处
《金属学报》
SCIE
EI
CAS
CSCD
北大核心
2019年第12期1551-1560,共10页
Acta Metallurgica Sinica
基金
国家自然科学基金项目Nos.51871141和51471102~~
关键词
锆合金
初期腐蚀
晶体结构
zirconium alloy
initial corrosion
crystal structure
