Cr和Y对Fe-Cr-Al合金在500℃/10.3 MPa过热蒸汽中长期腐蚀行为的影响  

Effect of Cr and Y on Long-Term Corrosion Behavior of Fe-Cr-Al Alloy in Super-Heated Steam at 500℃/10.3 MPa

作　　者：张杰 戴学峰 林晓冬 张文怀 孙蓉蓉 姚美意[1] ZHANG Jie;DAI Xuefeng;LIN Xiaodong;ZHANG Wenhuai;SUN Rongrong;YAO Meiyi(Institute of Materials,Shanghai University,Shanghai 200072,China)

机构地区：[1]上海大学材料研究所,上海200072

出　　处：《上海金属》2023年第4期30-37,44,共9页Shanghai Metals

基　　金：国家自然科学基金(51871141)。

摘　　要：Fe-Cr-Al合金因具有适中的热中子吸收截面、较好的抗辐照性能和优良的抗高温氧化性能等优点,成为事故容错燃料包壳的候选材料之一。熔炼制备了低Cr(Fe-12Cr-5Al、Fe-12Cr-5Al-0.01Y)和高Cr(Fe-20Cr-5Al、Fe-20Cr-5Al-0.01Y)的Fe-Cr-Al合金,采用静态高压釜研究了4种合金在500℃/10.3 MPa过热蒸汽中长达2000 h的腐蚀行为。采用X射线衍射仪、光学显微镜、扫描电子显微镜分析了合金和氧化膜的显微组织。结果表明:Cr含量的增加使合金晶粒细化,添加微量Y可以细化低Cr合金晶粒。在500℃/10.3 MPa过热蒸汽中腐蚀时,提高Cr含量可以明显降低Fe-Cr-Al合金的腐蚀增重速率;添加质量分数0.01%的Y可适当降低低Cr合金的腐蚀增重速率,但对高Cr合金的腐蚀增重速率影响并不明显。低Cr合金腐蚀形成的氧化膜为3层结构,从外到内依次为Fe_(3)O_(4)、Fe-Cr-Al的尖晶石氧化物、富Fe的内氧化过渡区;高Cr合金的氧化膜为两层结构,由外层Fe_(3)O_(4)和内层Fe-Cr-Al的尖晶石氧化物组成。提高Cr含量可抑制内氧化的发生以及外层Fe_(3)O_(4)的生成,添加微量Y对Fe-12Cr-5Al和Fe-20Cr-5Al合金氧化膜特性的影响不明显。Fe-Cr-Al alloys are one of the candidate materials for accident tolerant fuel cladding due to its moderate thermal neutron absorption cross section,good radiation resistance and high temperature oxidation resistance.Fe-Cr-Al alloys with low Cr content(Fe-12Cr-5Al,Fe-12Cr-5Al-0.01Y)and high Cr content(Fe-20Cr-5Al,Fe-20Cr-5Al-0.01Y)were prepared by smelting,and the corrosion behavior of four alloys exposed to super-heated steam at temperature of 500℃and under pressure of 10.3 MPa for up to 2000 h was studied in a static autoclave.The microstructures of the alloys and oxide films were analyzed by X-ray diffractometer,optical microscope and scanning electron microscope.The results showed that the increase in Cr content could refine the grains of the alloys,and the addition of trace Y could refine the grains in the alloys with low Cr content.When corroded in super-heated steam at temperature of 500℃and under pressure of 10.3 MPa,the corrosion weight gain rate decreased obviously due to the increase in Cr content in Fe-Cr-Al alloys;the addition of 0.01%Y by mass could decrease the corrosion weight gain rate of the alloys with low Cr content,but had a little effect on the corrosion weight gain rate of the alloys with high Cr content.The oxide film formed on the alloys with low Cr content after corrosion had a tri-layered structure,which comprised Fe_(3)O_(4),Fe-Cr-Al spinel oxide and Fe-rich internal oxidation transition layer from the outside to the inside;the oxide film formed on the alloys with high Cr content presented a dual-layered structure consisting of outer Fe_(3)O_(4)layer and inner Fe-Cr-Al spinel oxide layer.Increasing Cr content could inhibit the occurrence of internal oxidation and the formation of outer layer of Fe_(3)O_(4);the effect of adding trace Y on the oxide film characteristic of Fe-12Cr-5Al and Fe-20Cr-5Al alloy was not obvious.

关 键 词：事故容错燃料 FE-CR-AL合金 过热蒸汽 腐蚀行为 显微组织 

分 类 号：TG142.1[一般工业技术—材料科学与工程]