杂质元素（C，Si）对Zr-4合金板材试样微观结构及腐蚀性能的影响

Effect of Impurity Elements(C, Si) on the Microstructure and Corrosion Resistance of Zircaloy-4 Sheet Samples by TEM, XPS and 3DAP

摘要:

在ASTM范围内，利用板材试样研究了不同杂质元素C、Si含量对Zr-4合金微观结构及耐腐蚀性能的影响。结果显示：降低C含量、提高Si含量，对于Zr-4合金样品400℃均匀腐蚀性能有利。微观检测表明：杂质C易于在基体表面以Zr-C形式富集，其含量高低主要通过影响第二相粒子的析出能力影响腐蚀性能。含量越低，淬火时坯料越易于形成平行板条组织，含量越高越趋向于形成网篮组织，而第二相粒子更易于沿板条组织晶界析出。淬火温度低于1200℃时，Si含量高低对于坯料形成平行板条组织无明显影响。同时，3DAP分析显示，Si易于在第二相粒子周围以SiO2形式偏聚，这对于第二相粒子可起到阻碍或延缓其被氧化的作用，从而改善了锆合金的耐腐蚀性能。

Abstract:

In the range of ASTM, the effect of impurity elements on microstructure and corrosion resistance of Zr-4 alloy were studied by using sheet samples. The results show that reducing carbon content and increasing silicon content are beneficial to uniform corrosion performance of Zr-4 alloy at 400℃ steam. Microscopic analysis shows that carbon is easily enriched in the form of Zr-C on the matrix phase, and its content mainly affects the corrosion resistance by affecting the precipitation of second phase particles. The lower its content is, the easier it is to form the parallel plate (PP) structure during quenching, and the higher its content is, the more likely it is to form basketweave (BW) structure, while the second phase particles are easier to precipitate along the grain boundary of PP structure. When quenching temperature is lower than 1200℃, silicon content has no obvious effect on the formation of PP structure. Meanwhile, three-dimensional atom probe (3DAP) analysis shows that silicon tends to agglomerate in the form of SiO₂ around the second phase particles, delays or weaken the oxidation of second phase particles, thus improving the corrosion resistance of Zr-4 alloy.