He~+离子辐照后Hastelloy N合金的耐腐蚀性研究
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摘要
高温、辐照以及强腐蚀所引起的Hastelloy N合金的失效问题是影响熔盐堆(Molten Salt Reactor,MSR)结构材料使用寿命中的关键问题。在常温下用4.5 MeV的He+离子辐照Hastelloy N合金,吸收剂量分别为:1×1015 He+·cm-2、5×1015He+·cm-2、1×1016 He+·cm-2,采用浸入法在700°C熔融氟化盐(FLiNaK)中进行300 h腐蚀试验,研究辐照剂量对合金耐腐蚀性的影响。利用扫描电子显微(Scanning Electron microscope,SEM)、同步辐射微束X射线荧光分析(Microbeam X-ray fluorescence,μ-XRF)对腐蚀后的样品进行分析测试。结果表明,随着辐照剂量的增大,合金的耐腐蚀性逐渐减弱。μ-XRF结果表明:Hastelloy N合金在熔融氟化盐中的腐蚀主要表现为合金中Cr元素的流失。
Background: The invalidation problems of irradiated Hastelloy N alloy caused by high temperature, intense irradiation and severe corrosion are the key factors to the service life of structural materials of molten salt reactor(MSR). Purpose: The aim is to investigate the effect of absorbed dose on the corrosion resistance of Hastelloy N alloy. Methods: Hastelloy N alloy was irradiated by 4.5-MeV He+ ions, and the absorbed doses were 0 He+·cm-2, 1×1015 He+·cm-2, 5×1015 He+·cm-2 and 1×1016 He+·cm-2 respectively. The virgin and irradiated specimens were immersed into molten fluoride salts at 700 oC for 300 h. Then the corroded specimens were imaged by scanning electron microscopy and analyzed by synchrotron radiation microbeam X-ray fluorescence(μ-XRF). Results: The weight-loss results showed that the corrosion generally correlated with the absorbed dose of the alloy. The μ-XRF results indicated that the corrosion was mainly due to the dealloying of alloying element Cr in the matrix. Conclusion: The density of dislocations of Hastelloy N alloy increased with the absorbed dose, which acted as quick paths for Cr element diffusion, and the diffusion of element Cr out of matrix became easier. Finally became weak of the corrosion resistance of Hatelloy N alloy.
Background: The invalidation problems of irradiated Hastelloy N alloy caused by high temperature, intense irradiation and severe corrosion are the key factors to the service life of structural materials of molten salt reactor(MSR). Purpose: The aim is to investigate the effect of absorbed dose on the corrosion resistance of Hastelloy N alloy. Methods: Hastelloy N alloy was irradiated by 4.5-MeV He+ ions, and the absorbed doses were 0 He+·cm-2, 1×1015 He+·cm-2, 5×1015 He+·cm-2 and 1×1016 He+·cm-2 respectively. The virgin and irradiated specimens were immersed into molten fluoride salts at 700 oC for 300 h. Then the corroded specimens were imaged by scanning electron microscopy and analyzed by synchrotron radiation microbeam X-ray fluorescence(μ-XRF). Results: The weight-loss results showed that the corrosion generally correlated with the absorbed dose of the alloy. The μ-XRF results indicated that the corrosion was mainly due to the dealloying of alloying element Cr in the matrix. Conclusion: The density of dislocations of Hastelloy N alloy increased with the absorbed dose, which acted as quick paths for Cr element diffusion, and the diffusion of element Cr out of matrix became easier. Finally became weak of the corrosion resistance of Hatelloy N alloy.
引文
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2 Rosenthal M W,Haubenreich P N,Briggs R B.The development status of molten-salt breeder reactors[R].ORNL-4812,1972:195-218
3 McCoy H E.Status of materials development for molten salt reactors[R].ORNL-TM-5920,1978:1-30
4 Vacik J,Naramoto H,Cervena J,et al.Absorption of molten fluoride salts in glassy carbon,pyrographite and Hastelloy B[J].Journal of Nuclear Materials,2001,289(3):308-314
5 Keiser J R.Compatibility studies of potential molten-salt breeder reactor materials in molten fluoride salts[M].Oak Ridge National Laboratory,May,1977
6 Volkov S,Omel’chuk A,Azhazha V,et al.Corrosion stability of irradiated Hastelloy-type alloys in molten NaF-ZrF4 mixture[J].Journal of New Materials for Electrochemical Systems,2006,9:305-311
7 Lucas G E.The evolution of mechanical property change in irradiated austenitic stainless steels[J].Journal of Nuclear Materials,1993,206(2-3):287-305
8 Angeliu T M,Ward J T,Witter J K.Assessing the effects of radiation damage on Ni-base alloys for the prometheus space reactor system[J].Journal of Nuclear Materials,2007,366(1-2):223-237
9 李红梅,杨武.核电用奥氏体不锈钢的辐照模拟研究[J].腐蚀与防护,2001,22(5):196-201LI Hongmei,YANG Wu.Irradiation simulating research austenitic stainless steels in nuclear power plant[J].Corrosion and Protection,2001,22(5):196-201
10 Kai J J,Huang W I,Chou H Y.The microstructural evolution of zircaloy-4 subjected to proton radiation[J].Journal of Nuclear Materials,1990,170:193-209
11 Cann C D,So C B,Styles R C,et al.Precipitation in Zr-2.5Nb enhanced by proton radiation[J].Journal of Nuclear Materials,1990,205:267-272
12 Olson L C,Ambrosek J W,Sridharan K,et al.Materials corrosion in molten LiF-NaF-KF salt[J].Journal of Fluorine Chemistry,2009,130:67-73
13 Degueldre C,Kuri G,Borca C N,et al.X-ray micro-fluorescence,diffraction and absorption spectroscopy for local structure investigation of a radioactive zinc ferrite deposit[J].Corrosion Science,2009,51:1690-1695
14 Orlov A V,Restani R,Kuri G,et al.Investigation on a corrosion product deposit layer on a boiling water reactor fuel cladding[J].Nuclear Instruments and Methods in Physical Research Section B,2010,238:297-305
15 Liu M,Lu Y L,Zhou X T,et al.Investigation on corrosion behavior of Ni-based alloys in molten fluoride salt using synchrotron radiation techniques[J].Journal of Nuclear Materials,2013,440:124-128
16 Ziegler J F,Biersack J P.Stopping power and range of ions in matter[OL].SRIM-2008,2008
17 刘敏,陆燕玲,周兴泰.高温He离子辐照引起的Hastelloy N合金微结构变化研究[J].核技术,2013,36 (5):46-52LIU Min,LU Yanling,ZHOU Xingtai.Investigation on microstructure of Hastelloy N after irradiation by 30 keV He ions[J].Nuclear Techniques,2013,36(5):46-52