摘要
为研究锆合金从开始氧化至生成ZrO2的相组成及其晶体结构变化,采用锆合金大晶粒TEM薄样品在250℃、3 MPa去离子水中短时腐蚀的方法,利用距离TEM薄样品穿孔周围不同距离处样品厚度差别造成的O含量差别,采用HRTEM研究了Zr-0.75Sn-0.35Fe-0.15Cr合金的初期腐蚀行为以及早期形成的氧化膜晶体结构演化过程。结果表明:从开始氧化至ZrO2形成前,α-Zr的晶格点阵随着样品中O含量增加而不断演变;在Zr/O原子比为5~7时,基体晶格中原本无序的O原子有序地固溶在α-Zr中,形成有公度的长周期超点阵,其晶格常数(a、c)与基本晶格α-Zr的晶格常数(a0、c0)之间的关系为a=9a0,c=2c0,称其为9a0-2H结构;当Zr/O原子比为3时,形成具有hcp超结构的Zr3O亚氧化物;当Zr/O原子比为1时,转变为具有fcc超结构的ZrO亚氧化物;Zr/O原子比为0.85时,形成单斜结构ZrO2。
Zirconium alloys are important structural materials in pressurized water reactors.During actual operation,the corrosion resistance of water side is the most important factor affecting its service life.The oxide film of zirconium alloys formed during the corrosion process will reduce the heat transfer performance,mechanical properties and service life of the cladding material,thus becoming a factor restricting the development of nuclear power.The initial phase composition and the defect state in the crystal affect the microstructural evolution of the oxide film during the corrosion process,which in turn determines the late growth of the oxide film.In order to study the phase composition and crystal structure evolution of zirconium alloys from the initial oxidation to the formation of ZrO2,the initial corrosion behavior of Zr-0.75Sn-0.35Fe-0.15Cr alloy was studied by using TEM thin foil specimens with coarse grains.The oxygen content varied due to the change of sample thickness at different distances along the perforation of TEM thin foil specimens with coarse grains,which could be investigated the crystal structure evolution of oxide film with the variation of oxygen content.Corrosion tests of these TEM specimens were conducted in an autoclave at 250℃and 3 MPa in deionized water for short time exposure.The results showed a variation of the crystal structure along with the increase of oxygen contents at the initial oxidation stage.When the Zr/O atomic ratio reached 5~7,a commensurable long period super-lattice structure was formed.The lattice constants of the super-lattice(a,c)andα-Zr matrix(a0,c0)satisfied the relationship of a=9 a0 and c=2 c0,which was called 9 a0-2H structure.When the Zr/O atomic ratio reached 3 and 1,suboxides Zr3O with hcp and Zr O with fcc ordered structures were formed,respectively.When the Zr/O atomic ratio was 0.85,monoclinic ZrO2 was detected.
作者
姚美意
张兴旺
侯可可
张金龙
胡鹏飞
彭剑超
周邦新
YAO Meiyi;ZHANG Xingwang;HOU Keke;ZHANG Jinlong;HU Pengfei;PENG Jianchao;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
2020年第2期221-230,共10页
Acta Metallurgica Sinica
基金
国家自然科学基金项目Nos.51471102和51871141.
关键词
锆合金
晶体结构转变
初期腐蚀
亚氧化物
zirconium alloy
crystal structural evolution
initial oxidation
sub-oxide
作者简介
通讯作者:姚美意,女,1973年生,研究员,博士,yaomeiyi@shu.edu.cn,主要从事核电用锆合金研究
