Nuclear Science and Techniques

《核技术》(英文版) ISSN 1001-8042 CN 31-1559/TL     2019 Impact factor 1.556

Nuclear Science and Techniques ›› 2017, Vol. 28 ›› Issue (12): 178 doi: 10.1007/s41365-017-0330-8

• NUCLEAR ENERGY SCIENCE AND ENGINEERING • Previous Articles     Next Articles

Effect of thermal exposure time on tellurium-induced embrittlement of Ni–16Mo–7Cr–4Fe alloy

Xiang-Wei Chu 2, Hong-Wei Cheng 3, Cai-Tao Fu 1,2,3, Bin Leng 1, Yan-Yan Jia1,  Fang Liu2, Zhi-Jun Li 1   

  1. 1 Shanghai Institute of Applied Physics, Chinese Academy of Science, Jiading Campus, Shanghai 201800, China
    2 School of Materials Science and Engineering, University of Shanghai for Science and Technology, Shanghai 200093, China
    3 National Center for Electron Microscopy in Beijing, Tsinghua University, Beijing 100084, China
  • Contact: Zhi-Jun Li E-mail:lizhijun@sinap.ac.cn
  • Supported by:

    This work was supported by the National key research and development program of China (No. 2016YFB0700404), the National Natural Science Foundation of China (Nos. 51371188, 51671122, 51671154, 51601213, 51501216), the Strategic Priority Research Program of the Chinese Academy of Sciences (No. XDA02004210), the Shanghai Sailing Program (No. 16YF1414300) and the Talent development fund of Shanghai (No. 201650).

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Xiang-Wei Chu, Hong-Wei Cheng, Cai-Tao Fu, Bin Leng, Yan-Yan Jia, Fang Liu, Zhi-Jun Li. Effect of thermal exposure time on tellurium-induced embrittlement of Ni–16Mo–7Cr–4Fe alloy.Nuclear Science and Techniques, 2017, 28(12): 178     doi: 10.1007/s41365-017-0330-8

Abstract:

The embrittlement of nickel-based structural alloys by fission-produced tellurium (Te) is a major challenge for molten salt reactors (MSR). In this study, the effects of thermal exposure time on tellurium diffusion in a candidate MSR structural alloy (Ni–16Mo–7Cr–4Fe) and the consequent mechanical property degradation of the alloy were investigated through surrogate diffusion experiments at 700 C. The results show that some tellurium reacted with the alloy to form tellurides on the surface, while some tellurium diffused into the alloy along grain boundaries. Ni3Te2 and CrTe were the most stable reaction products at the tested temperature, and the formation of CrTe on the surface induced the Cr depletion at grain boundaries of the alloy. The diffusion depth of Te increased gradually with thermal exposure time, and the diffusion rate kept stable within the test duration of up to 3000 h. The Te diffusion in the alloy caused the embrittlement of grain boundaries, inducing crack formation and strength degradation in tensile test at room temperature.

Key words: Tellurium, Grain boundary, Embrittlement, Intergranular cracking, Nickel-based alloy, Molten salt reactor