Zr-Sn-Nb合金在1000~1250℃蒸汽中氧化后的微观组织  

Microstructure of Zr-Sn-Nb Alloy After 1000~1250℃Steam Oxidation

作　　者：张瑶 应雯清 程赞粼 张锋 王彦峰[2] 王少鹏[2] 张程煜[1] Zhang Yao;Ying Wenqing;Cheng Zantin;Zhang Feng;Wang Yanfeng;Wang Shaopeng;Zhang Chengyu(NPU-SAS Joint Research Center,School of Materials Science and Engineering,Northwestern Polytechnical University,Xi’an 710072,China;Northwest Institute for Nonferrous Metal Research,Xi’an 710016,China)

机构地区：[1]西北工业大学材料学院NPU-SAS联合研究中心,陕西西安710072 [2]西北有色金属研究院,陕西西安710016

出　　处：《稀有金属材料与工程》2022年第11期4173-4179,共7页Rare Metal Materials and Engineering

基　　金：国家自然科学基金(51572224);高等学校学科创新引智计划(BP0820014);国防基础科研计划(WDYX19614260201)。

摘　　要：锆合金包壳管在核反应堆失水事故时发生高温蒸汽氧化而脆化破裂,该过程与锆合金的微观组织变化密切相关,因此,本研究开展了Zr-Sn-Nb包壳管在1000~1250℃蒸汽中的氧化实验,使用光学显微镜、扫描电子显微镜、透射电子显微镜等分析蒸汽氧化后的微观组织,并使用氧氮氢分析仪研究了氢含量的变化规律。结果表明:Zr-Sn-Nb合金在蒸汽氧化后的截面形貌分为ZrO2、α-Zr(O)和Prior-β层。随蒸汽氧化时间增加,ZrO2和α-Zr(O)层厚度增加,同时α-Zr(O)层中的裂纹逐渐增多,Prior-β层中残留的β-Zr逐渐转变为片状α-Zr,且α-Zr晶粒宽度不断增加。在1000℃蒸汽氧化后,形成疏松的ZrO2层,存在大量横向贯穿裂纹,1150~1250℃蒸汽氧化后,ZrO2层较为致密。蒸汽氧化后,Zr-Sn-Nb合金基体的吸氢量随蒸汽氧化时间增加而增加,在1000℃蒸汽氧化后,Zr-Sn-Nb合金的吸氢量远高于其它温度,α-Zr基体与氢化物取向关系为(0002)α-Zr//(202)δ-ZrH1.66,[2110]α-Zr//[011]δ-ZrH1.66;1200℃时,二者的取向关系为(0002)α-Zr//(220)δ-ZrH1.66,[0110]α-Zr//[111]δ-ZrH1.66。During the loss-of-water accident in the nuclear reactor, the high-temperature steam can react with the Zr alloy cladding tube and lead to oxidation of the Zr alloys, which leads to the embrittlement and fracture of the cladding tube. The process is closely related to the microstructural evolution of the Zr alloys. In order to reveal the embrittlement mechanisms of the Zr-Sn-Nb cladding tube, the steam oxidation experiments of ZrSn-Nb alloy at 1000~1250 ℃ were performed. The microstructure was investigated by optical microscope, scanning electron microscope and transmission electron microscope. The hydrogen content was identified by oxygen, nitrogen and hydrogen analyzer. The results show that the ZrSn-Nb alloy can be oxidized into three layers, including ZrO2, α-Zr(O) and Prior-β. The thicknesses of ZrO2layer and α-Zr(O) layer increase with increasing oxidation time, meanwhile, the number of cracks increases in α-Zr(O) layer. The lath β-Zr phase of the Prior-β layer is transformed into sheet-like α-Zr phase and grain width of α-Zr phase becomes larger when the alloy is exposed to longer steam oxidation time. Loose ZrO2layer with a large number of transverse cracks can be formed in 1000 ℃ steam, while dense ZrO2layer can be observed at higher temperatures. H content of the Zr-Sn-Nb alloy matrix increases with the oxidation time. The hydrogen pickup of the Zr-Sn-Nb alloy matrix is much higher at 1000 ℃ steam than those at other temperatures. The orientation relationship between the α-Zr matrix and the hydride is(0002)α-Zr//(2 02)δ-ZrH1.66and [21 1 0]α-Zr//[011]δ-ZrH1.66in 1000 ℃ steam, and(0002)α-Zr//(22 0)δ-ZrH1.66and [011 0]α-Zr//[111]δ-ZrH1.66in 1200 ℃ steam.

关 键 词：Zr-Sn-Nb合金 蒸汽氧化 氧化锆 氢化物 

分 类 号：TG146.4+14[一般工业技术—材料科学与工程]