Zr-4+xCu+xGe合金在LiOH水溶液中耐腐蚀性能的研究

Corrosion Resistance of Zr-4 + xCu + xGe Alloys in Lithiated Water

对添加少量合金元素Cu和Ge的Zr-4+xCu+xGe(x=0、0.05、0.1、0.2,质量分数,%)合金在360℃/18.6 MPa/0.01 M LiOH水溶液中进行静态高压釜腐蚀试验。利用TEM和SEM研究了合金和氧化膜的显微组织。结果表明:添加适量Cu和Ge可以延缓氧化膜中微裂纹的形成,显著提高Zr-4合金在360℃/18.6 MPa/0.01 M LiOH水溶液中的耐腐蚀性能;在Zr-4+xCu+xGe合金中主要析出密排六方结构的Zr(Fe,Cr)_2和Zr(Fe,Cr,Cu,Ge)_2型第二相,随着Cu和Ge添加量的进一步提高,还会有粗大的四方结构的Zr_2Cu和Zr_3Ge第二相析出,第二相的氧化易导致应力集中并促进微裂纹形成,不利于Zr-4合金耐腐蚀性能的改善。

The corrosion behavior of Zr-4 ＋ xGe ＋ xCu alloys （x =0, 0.05, 0.1, 0.2, mass fraction, % ） and the microstructures of the oxide films formed on the specimens corroded in lithiated water at 360 ℃/18.6 MPa/0.01 M were investigated by autoclave tests. The microstructures of the alloys and oxide films were observed by TEM and SEM. Results showed that Cu and Ge additions could improve the corrosion resistance of the Zr-4 alloy, Zr （ Fe, Cr） 2 and Zr （ Fe, Cr, Cu, Ge ） 2 were the main precipitates in Zr-4 ＋ xGe ＋ xCu alloys. And with further increasing Cu and Ge content, coarse second phase particles （SPPs） such as Zr2 Cu and Zr3 Ge would be precipitated. Stress concentration and micro-cracks in the oxide layers would be easily formed during the oxidation of these SPPs, which was disadvantageous to the corrosion resistance of the alloys.