中国物理B ›› 2006, Vol. 15 ›› Issue (9): 2092-2101.doi: 10.1088/1009-1963/15/9/032

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Phonon spectrum and related thermodynamic properties of microcrack in bcc-Fe

曹莉霞1, 王崇愚2   

  1. (1)Central Iron and Steel Research Institute, Beijing 100081, China; (2)Central Iron and Steel Research Institute, Beijing 100081, China;International Centre for Materials Physics, Chinese Academy of Sciences,Shenyang 110016, China;Department of Physics, Tsinghua University, Beijing 100084, China
  • 收稿日期:2006-03-22 修回日期:2006-05-16 出版日期:2006-09-20 发布日期:2006-09-20
  • 基金资助:
    Project supported by the State Key Development Program for Basic Research of China (Grant No TG 2000067102) and the National Natural Science Foundation of China (Grant No 90306016).

Phonon spectrum and related thermodynamic properties of microcrack in bcc-Fe

Cao Li-Xia(曹莉霞)a)† and Wang Chong-Yu(王崇愚)a)b)c)   

  1. a Central Iron and Steel Research Institute, Beijing 100081, China; b International Centre for Materials Physics, Chinese Academy of Sciences, Shenyang 110016, Chinac Department of Physics, Tsinghua University, Beijing 100084, China
  • Received:2006-03-22 Revised:2006-05-16 Online:2006-09-20 Published:2006-09-20
  • Supported by:
    Project supported by the State Key Development Program for Basic Research of China (Grant No TG 2000067102) and the National Natural Science Foundation of China (Grant No 90306016).

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摘要： The phonon spectrum and the related thermodynamic properties of microcracks in bcc-Fe are studied with the recursion method by using the Finnis--Sinclair (F--S) N-body potential. The initial configuration of the microcracks is established from an anisotropic linear elastic solution and relaxed to an equilibrium by molecular dynamics method. It is shown that the local vibrational density of states of the atoms near a crack tip is considerably different from the bulk phonon spectrum, which is closely associated with the local stress field around the crack tip; meanwhile, the local vibrational energies of atoms near the crack tip are higher than those of atoms in a perfect crystal. These results imply that the crack tip zone is in a complex stress state and closely related to the structure evolution of cracks. It is also found that the phonon excitation is a kind of local effect induced by microcracks. In addition, the microcrack system has a higher vibrational entropy, which reflects the character of phonon spectrum related to the stress field induced by cracks.

关键词: phonons, microcrack, metals

Abstract: The phonon spectrum and the related thermodynamic properties of microcracks in bcc-Fe are studied with the recursion method by using the Finnis--Sinclair (F--S) N-body potential. The initial configuration of the microcracks is established from an anisotropic linear elastic solution and relaxed to an equilibrium by molecular dynamics method. It is shown that the local vibrational density of states of the atoms near a crack tip is considerably different from the bulk phonon spectrum, which is closely associated with the local stress field around the crack tip; meanwhile, the local vibrational energies of atoms near the crack tip are higher than those of atoms in a perfect crystal. These results imply that the crack tip zone is in a complex stress state and closely related to the structure evolution of cracks. It is also found that the phonon excitation is a kind of local effect induced by microcracks. In addition, the microcrack system has a higher vibrational entropy, which reflects the character of phonon spectrum related to the stress field induced by cracks.

Key words: phonons, microcrack, metals

中图分类号:  (Self-assembly)

  • 81.16.Dn
61.46.Df (Structure of nanocrystals and nanoparticles ("colloidal" quantum dots but not gate-isolated embedded quantum dots)) 81.16.Nd (Micro- and nanolithography) 68.37.Hk (Scanning electron microscopy (SEM) (including EBIC))