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Physico-chemical Modeling of Phase Separation in Fe-21.4 Cr Steel with 1.14 Mo Using the Provisions of Non-equilibrium Thermodynamics

Received: 18 May 2021    Accepted: 8 June 2021    Published: 21 June 2021
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Abstract

The use of ferritic-martensitic steels, for example, Fe-Cr and Fe-Cr-Al alloys as structural material for fast neutron reactors has been advocated due to their relatively low rate of swelling at elevated temperatures. Because of the high Cr-content, the Fe-Cr alloys are not suitable for use at temperatures around 500°С due to the miscibility gap in the Fe-Cr system. Phase separation in such alloys can also be prevented by doping with elements that impede the segregation of chromium. In solid state physics for calculating phase separation in similar metal systems are used physicochemical and phase-field modeling. The aim of the work is the physicochemical modeling of diffusion phase transformation and determination of the long-term microstructural stability of the Fe-21.4 Cr-1.16 Mo. A conventional Fe-21.4 Cr alloy is used as a reference material. The article proposes an integral approach to modeling phase separation in chromium alloys, combining the determination of diffusion coefficients and fluxes of elements, taking into account their dependences on the concentration and an assessment of the mutual diffusion of elements, using the provisions of nonequilibrium thermodynamics. The calculated values of diffusion fluxes are used to calculate the current concentrations of carbon and chromium in the alloy and the size of chromium formations. They show that the thermal stability of the Fe - 21.4% Cr alloy with 1.16% Mo is much higher than without molybdenum. In alloy Fe – 21,4% Cr – 1,16% Mo at a temperature of 973°K, the chromium concentration during the same operation time decreases three times slower with the formation of inclusions of the σ-phase about 6 microns in size.

Published in American Journal of Mechanical and Materials Engineering (Volume 5, Issue 2)
DOI 10.11648/j.ajmme.20210502.11
Page(s) 23-28
Creative Commons

This is an Open Access article, distributed under the terms of the Creative Commons Attribution 4.0 International License (http://creativecommons.org/licenses/by/4.0/), which permits unrestricted use, distribution and reproduction in any medium or format, provided the original work is properly cited.

Copyright

Copyright © The Author(s), 2021. Published by Science Publishing Group

Keywords

Physicochemical Modeling, Phase Transformation, Fluxes, Chromium Alloys, Nonequilibrium, Thermodynamics, Diffusion Coefficients

References
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    Serhii V. Bobyr, Dmitro V. Loshkarev. (2021). Physico-chemical Modeling of Phase Separation in Fe-21.4 Cr Steel with 1.14 Mo Using the Provisions of Non-equilibrium Thermodynamics. American Journal of Mechanical and Materials Engineering, 5(2), 23-28. https://doi.org/10.11648/j.ajmme.20210502.11

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    ACS Style

    Serhii V. Bobyr; Dmitro V. Loshkarev. Physico-chemical Modeling of Phase Separation in Fe-21.4 Cr Steel with 1.14 Mo Using the Provisions of Non-equilibrium Thermodynamics. Am. J. Mech. Mater. Eng. 2021, 5(2), 23-28. doi: 10.11648/j.ajmme.20210502.11

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    AMA Style

    Serhii V. Bobyr, Dmitro V. Loshkarev. Physico-chemical Modeling of Phase Separation in Fe-21.4 Cr Steel with 1.14 Mo Using the Provisions of Non-equilibrium Thermodynamics. Am J Mech Mater Eng. 2021;5(2):23-28. doi: 10.11648/j.ajmme.20210502.11

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  • @article{10.11648/j.ajmme.20210502.11,
      author = {Serhii V. Bobyr and Dmitro V. Loshkarev},
      title = {Physico-chemical Modeling of Phase Separation in Fe-21.4 Cr Steel with 1.14 Mo Using the Provisions of Non-equilibrium Thermodynamics},
      journal = {American Journal of Mechanical and Materials Engineering},
      volume = {5},
      number = {2},
      pages = {23-28},
      doi = {10.11648/j.ajmme.20210502.11},
      url = {https://doi.org/10.11648/j.ajmme.20210502.11},
      eprint = {https://article.sciencepublishinggroup.com/pdf/10.11648.j.ajmme.20210502.11},
      abstract = {The use of ferritic-martensitic steels, for example, Fe-Cr and Fe-Cr-Al alloys as structural material for fast neutron reactors has been advocated due to their relatively low rate of swelling at elevated temperatures. Because of the high Cr-content, the Fe-Cr alloys are not suitable for use at temperatures around 500°С due to the miscibility gap in the Fe-Cr system. Phase separation in such alloys can also be prevented by doping with elements that impede the segregation of chromium. In solid state physics for calculating phase separation in similar metal systems are used physicochemical and phase-field modeling. The aim of the work is the physicochemical modeling of diffusion phase transformation and determination of the long-term microstructural stability of the Fe-21.4 Cr-1.16 Mo. A conventional Fe-21.4 Cr alloy is used as a reference material. The article proposes an integral approach to modeling phase separation in chromium alloys, combining the determination of diffusion coefficients and fluxes of elements, taking into account their dependences on the concentration and an assessment of the mutual diffusion of elements, using the provisions of nonequilibrium thermodynamics. The calculated values of diffusion fluxes are used to calculate the current concentrations of carbon and chromium in the alloy and the size of chromium formations. They show that the thermal stability of the Fe - 21.4% Cr alloy with 1.16% Mo is much higher than without molybdenum. In alloy Fe – 21,4% Cr – 1,16% Mo at a temperature of 973°K, the chromium concentration during the same operation time decreases three times slower with the formation of inclusions of the σ-phase about 6 microns in size.},
     year = {2021}
    }
    

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  • TY  - JOUR
    T1  - Physico-chemical Modeling of Phase Separation in Fe-21.4 Cr Steel with 1.14 Mo Using the Provisions of Non-equilibrium Thermodynamics
    AU  - Serhii V. Bobyr
    AU  - Dmitro V. Loshkarev
    Y1  - 2021/06/21
    PY  - 2021
    N1  - https://doi.org/10.11648/j.ajmme.20210502.11
    DO  - 10.11648/j.ajmme.20210502.11
    T2  - American Journal of Mechanical and Materials Engineering
    JF  - American Journal of Mechanical and Materials Engineering
    JO  - American Journal of Mechanical and Materials Engineering
    SP  - 23
    EP  - 28
    PB  - Science Publishing Group
    SN  - 2639-9652
    UR  - https://doi.org/10.11648/j.ajmme.20210502.11
    AB  - The use of ferritic-martensitic steels, for example, Fe-Cr and Fe-Cr-Al alloys as structural material for fast neutron reactors has been advocated due to their relatively low rate of swelling at elevated temperatures. Because of the high Cr-content, the Fe-Cr alloys are not suitable for use at temperatures around 500°С due to the miscibility gap in the Fe-Cr system. Phase separation in such alloys can also be prevented by doping with elements that impede the segregation of chromium. In solid state physics for calculating phase separation in similar metal systems are used physicochemical and phase-field modeling. The aim of the work is the physicochemical modeling of diffusion phase transformation and determination of the long-term microstructural stability of the Fe-21.4 Cr-1.16 Mo. A conventional Fe-21.4 Cr alloy is used as a reference material. The article proposes an integral approach to modeling phase separation in chromium alloys, combining the determination of diffusion coefficients and fluxes of elements, taking into account their dependences on the concentration and an assessment of the mutual diffusion of elements, using the provisions of nonequilibrium thermodynamics. The calculated values of diffusion fluxes are used to calculate the current concentrations of carbon and chromium in the alloy and the size of chromium formations. They show that the thermal stability of the Fe - 21.4% Cr alloy with 1.16% Mo is much higher than without molybdenum. In alloy Fe – 21,4% Cr – 1,16% Mo at a temperature of 973°K, the chromium concentration during the same operation time decreases three times slower with the formation of inclusions of the σ-phase about 6 microns in size.
    VL  - 5
    IS  - 2
    ER  - 

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Author Information
  • Iron and Steel Institute of Z. I. Nekrasov NANU, Academic Starodubova Square, Dnipro, Ukraine

  • Iron and Steel Institute of Z. I. Nekrasov NANU, Academic Starodubova Square, Dnipro, Ukraine

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