【作者】 马润泽； 张佳楠； 姚美意；

【Author】 MA Runze;ZHANG Jianan;YAO Meiyi;State key laboratory of Materials for Advanced Nuclear Energy,Shanghai University;Institute of Materials,Shanghai University;

【机构】 上海大学核电关键材料全国重点实验室； 上海大学材料研究所；

【摘要】 为探究Zr-0.75Sn-0.35Fc-0.1 5Cr-x Nb（x=0、0.15%、0.30%、0.50%、1.0%,质量分数,下同）合金在模拟失水事故（LOCA）工况下的高温氧化行为,本研究采用同步热分析仪,在800～1 200℃的20%氮气+80%蒸汽混合气氛中对5种合金进行氧化实验,并通过OM、SEM、EPMA等手段分析氧化后样品的显微组织。结果表明:该系列合金的高温抗氧化性能随Nb含量增加未呈现单一变化趋势,其中1#（无Nb）和4#（Nb=0.48%）合金的抗氧化性相对更优;氧化动力学曲线多遵循抛物线-直线或直线规律,在1 000℃和1 200℃会发生氧化转折,800℃和1 200℃下30 min内氧化速率随时间减缓,而1 000℃时氧化膜因基体相变、ZrO₂相转变及ZrN氧化膨胀产生缺陷,失去保护作用,氧化速率加快;氮气在氧化过程中起类似"催化"作用,通过促进ZrN生成及后续反应,导致氧化膜疏松开裂,加速氧化;Nb对氧化性能的影响具有双重性,既可能增大O在α-Zr中的固溶并促进氧化膜开裂,也可降低阴离子空位浓度、阻碍氧扩散,其最终效应取决于含量与温度条件下正负作用的平衡。本研究为新型锆合金的成分优化及严重事故规范制定提供了理论依据与技术指导。更多还原

【Abstract】 To investigate the high-temperature oxidation behavior of Zr-0.75 Sn-0.35 Fe-0.1 5 Cr-xNb（x=0,0.15%,0.30%,0.50%,1.0%,mass fraction） alloys under simulated Loss of Coolant Accident（LOCA） conditions,this study employed a synchronous thermal analyzer to conduct oxidation experiments on the five alloys in a mixed atmosphere of 20% nitrogen+80% steam at800～1 200℃.The microstructures of the oxidized samples were analyzed using techniques such as optical microscopy（OM）,scanning electron microscopy（SEM）,and electron probe microanalysis（EPMA）.The results indicate that the high-temperature oxidation resistance of this series of alloys does not exhibit a single changing trend with the increase of Nb content,among which Alloy 1#（without Nb） and Alloy 4#（Nb=0.48%） show relatively superior oxidation resistance.The oxidation kinetic curves mostly follow the parabola-straight line or straight line law,with oxidation transitions occurring at 1 000℃ and 1 200℃.Within 30 minutes of oxidation at 800℃ and1 200 ℃,the oxidation rate slows down with time;however,at 1 000 ℃,the oxide film loses its protective effect and the oxidation rate accelerates due to defects caused by matrix phase transformation,ZrO₂ phase transformation,and ZrN oxidation-induced expansion.Nitrogen plays a role similar to "catalysis" in the oxidation process:it promotes the formation of ZrN and subsequent reactions,leading to loosening and cracking of the oxide film and thus accelerating oxidation.The effect of Nb on oxidation performance is dualistic:it can not only increase the solid solubility of O inα-Zr and promote the cracking of the oxide film but also reduce the concentration of anion vacancies and hinder oxygen diffusion.The final effect depends on the balance between positive and negative effects under specific content and temperature conditions.This study provides a theoretical basis and technical guidance for the composition optimization of new zirconium alloys and the formulation of severe accident regulations.更多还原