中国物理B ›› 2009, Vol. 18 ›› Issue (5): 1923-1930.doi: 10.1088/1674-1056/18/5/033

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Study of theoretical tensile strength of Fe by afirst-principles computational tensile test

刘悦林, 张颖, 洪荣杰, 吕广宏   

  1. Department of Physics, Beijing University of Aeronautics and Astronautics, Beijing 100191, China
  • 收稿日期:2008-06-06 修回日期:2008-10-23 出版日期:2009-05-20 发布日期:2009-05-20
  • 基金资助:
    Project supported by the National Natural Science Foundation of China (Grant No 50771008) and New Century Excellent Talents in University of China.

Study of theoretical tensile strength of Fe by a first-principles computational tensile test

Liu Yue-Lin(刘悦林), Zhang Ying(张颖), Hong Rong-Jie(洪荣杰), and Lu Guang-Hong(吕广宏)†   

  1. Department of Physics, Beijing University of Aeronautics and Astronautics, Beijing 100191, China
  • Received:2008-06-06 Revised:2008-10-23 Online:2009-05-20 Published:2009-05-20
  • Supported by:
    Project supported by the National Natural Science Foundation of China (Grant No 50771008) and New Century Excellent Talents in University of China.

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摘要： This paper employs a first-principles total-energy method to investigate the theoretical tensile strengths of bcc and fcc Fe systemically. It indicates that the theoretical tensile strengths are shown to be 12.4, 32.7, 27.5~GPa for bcc Fe, and 48.1, 34.6, 51.2~GPa for fcc Fe in the [001], [110] and [111] directions, respectively. For bcc Fe, the [001] direction is shown to be the weakest direction due to the occurrence of a phase transition from ferromagnetic bcc Fe to high spin ferromagnetic fcc Fe. For fcc Fe, the [110] direction is the weakest direction due to the formation of an instable saddle-point `bct structure' in the tensile process. Furthermore, it demonstrates that a magnetic instability will occur under a tensile strain of 14%, characterized by the transition of ferromagnetic bcc Fe to paramagnetic fcc Fe. The results provide a good reference to understand the intrinsic mechanical properties of Fe as a potential structural material in the nuclear fusion Tokamak.

关键词: Fe, theoretical tensile strength, phase transition, first-principles computational tensile test

Abstract: This paper employs a first-principles total-energy method to investigate the theoretical tensile strengths of bcc and fcc Fe systemically. It indicates that the theoretical tensile strengths are shown to be 12.4, 32.7, 27.5 GPa for bcc Fe, and 48.1, 34.6, 51.2 GPa for fcc Fe in the [001], [110] and [111] directions, respectively. For bcc Fe, the [001] direction is shown to be the weakest direction due to the occurrence of a phase transition from ferromagnetic bcc Fe to high spin ferromagnetic fcc Fe. For fcc Fe, the [110] direction is the weakest direction due to the formation of an instable saddle-point `bct structure' in the tensile process. Furthermore, it demonstrates that a magnetic instability will occur under a tensile strain of 14%, characterized by the transition of ferromagnetic bcc Fe to paramagnetic fcc Fe. The results provide a good reference to understand the intrinsic mechanical properties of Fe as a potential structural material in the nuclear fusion Tokamak.

Key words: Fe, theoretical tensile strength, phase transition, first-principles computational tensile test

中图分类号:  (Magnetomechanical effects, magnetostriction)

  • 75.80.+q
75.30.Kz (Magnetic phase boundaries (including classical and quantum magnetic transitions, metamagnetism, etc.)) 81.40.Lm (Deformation, plasticity, and creep) 62.20.F- (Deformation and plasticity) 81.70.Bt (Mechanical testing, impact tests, static and dynamic loads)