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) and α-Zr matrix (a₀, c₀) satisfied the relationship of a=9a₀ and c=2c₀, which was called 9a₀-2H structure. When the Zr/O atomic ratio reached 3 and 1, sub-oxides Zr₃O with hcp and ZrO with fcc ordered structures were formed, respectively. When the Zr/O atomic ratio was 0.85, monoclinic ZrO₂ was detected.