Li Wen

Xiangtan University, Siangtan, Hunan, China

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Publications (7)13.83 Total impact

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    ABSTRACT: The stacking faults of 17 B2-structured magnesium alloys have been studied systematically by means of first-principles calculations. After structure optimization and stability analysis, the generalized stacking fault energy surfaces for two possible slip planes {001} and {110} have been calculated using a super-cell tilling technique, and the main feature of generalized stacking fault energy surfaces was analyzed. Then the most likely slip directions were determined, and the stable and unstable stacking energies were obtained. The dissociation of perfect dislocation was further discussed. The electronic structures were also investigated to reveal the underlying mechanism for stability and stacking faults.
    Computational Materials Science 10/2011; 50(11):3198-3207. DOI:10.1016/j.commatsci.2011.06.001 · 1.88 Impact Factor
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    ABSTRACT: The generalized planner fault energy, twinnability, and ductility of both Al3Sc and Al3Mg are studied by first-principles calculations. The results show that a three-layer thick twin may be described as the smallest twin nucleus for both L12 intermetallic compounds Al3Sc and Al3Mg. Because the unstable stacking fault energy (SFE) γus and unstable twin SFE γut of both materials are relatively high, their twin nucleation is very difficult. Meanwhile, both intermetallic compounds exhibit brittle feature because of the low surface energy and high γus. The electronic structure during slipping demonstrates that the electronic density of states and charge density distribution of both intermetallic compounds vary dramatically at the fault layers, and alters the valence–bonding hybridization, so dislocation nucleation would be difficult owing to such large variation of electronic structure deviated from the initial perfect fcc crystal.
    Solid State Sciences 01/2011; 13(1):120–125. DOI:10.1016/j.solidstatesciences.2010.10.022 · 1.68 Impact Factor
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    ABSTRACT: The structural, electronic and elastic properties of typical hexagonal-close-packed MgZn2 and ScZn2 phases in Mg–Sc–Zn alloy were investigated by means of first-principles calculations within the framework of density functional theory (DFT). The calculated lattice constants were in good agreement with the experimental values. The obtained cohesive energy and formation enthalpy of both phases are negative, showing their structural stability from energetic point of view. The five independent elastic constants were calculated, and then the bulk modulus B, shear modulus G, Young's modulus E and Poisson's ratio ν of polycrystalline aggregates were derived. The ductility and plasticity of the MgZn2 and ScZn2 phases were further discussed. The elastic anisotropy of the two phases was also analyzed. Finally, the electronic density of states (DOS) and charge density distribution were also calculated to reveal the underlying mechanism of structural stability and mechanical properties.
    Journal of Alloys and Compounds 09/2010; 506(1):412-417. DOI:10.1016/j.jallcom.2010.07.018 · 2.73 Impact Factor
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    ABSTRACT: Ab initio density functional theory (DFT) and density function perturbation theory (DFPT) have been used to investigate the thermal properties of the Al–Mg–Sc, Al–Mg–Zr and Al–Mg–Sc–Zr alloys over a wide range of temperature and pressure. Phonon dispersions are obtained at equilibrium and strained configurations by DFPT. Using the quasiharmonic approximation (QHA) for the free energy, several physical quantities of interest such as thermal Grüneisen parameter, heat capacity at constant pressure and at constant volume, thermal expansion coefficient, entropy, adiabatic bulk modulus and isothermal bulk modulus as a function of temperature and pressure are calculated and discussed. The present results show that the thermal expansion coefficient of the Al–Mg–Sc–Zr is far lower than that of Al–Mg–Sc and Al–Mg–Zr, and the variation features in the adiabatic bulk modulus and isothermal bulk modulus for the Al–Mg–Sc–Zr are also very different from that of Al–Mg–Sc and Al–Mg–Zr.Graphical abstract
    Solid State Sciences 05/2010; 12(5):845-850. DOI:10.1016/j.solidstatesciences.2010.02.006 · 1.68 Impact Factor
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    ABSTRACT: We have performed a first-principles calculation within the generalized gradient approximation to investigate the β″ phase in Mg–Gd alloy system. The lattice parameters are determined theoretically by structural optimization of full relaxation and the β″ phase Mg3Gd is found to be energetically favorable from the calculated formation enthalpy. The nine independent elastic constants are calculated, indicating the proposed Mg3Gd structure is mechanically stable. Then the polycrystalline bulk modulus B, shear modulus G, Young's modulus E and Poisson ratio ν are gained by the Voigt–Reuss–Hill (VRH) approximation. The elastic anisotropy is discussed in detail. The electronic density of states and charge density distribution are analyzed, indicating the existence of covalent bonding in Mg3Gd. The Debye temperature is also estimated for the investigation in the future.
    Journal of Alloys and Compounds 03/2010; 492(1-2-492):416-420. DOI:10.1016/j.jallcom.2009.11.127 · 2.73 Impact Factor
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    ABSTRACT: The stacking faults of crystal magnesium have been studied systematically by means of first-principles calculation within the generalized gradient approximation (GGA). The generalized stacking fault (GSF) energy surfaces for four kinds of basal stacking faults as well as other non-basal stacking faults in the prismatic and pyramidal planes have been gained using a supercell approach with the supercell tilling technique. The most likely slip directions for the formation of these stacking faults in the corresponding slip plane were determined, and the generalized stacking fault energy curves along the most likely slip directions were derived, then the stable and unstable stacking energies were obtained and discussed. The present results are helpful for further investigation of dislocations and the correlative mechanical properties.
    Physics of Condensed Matter 12/2009; 72(3):397-403. DOI:10.1140/epjb/e2009-00365-2 · 1.46 Impact Factor
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    ABSTRACT: The β′ phase precipitate in Mg–Gd alloy system has been investigated by means of first-principles calculation within the generalized gradient approximation. The lattice parameters are determined theoretically by structural optimization of full relaxation, and the Mg7Gd is found to be energetically more stable compared with the Mg15Gd from the calculated formation energy. The nine independent elastic constants are calculated, indicating the proposed Mg15Gd structure in literature is mechanically unstable. Then the polycrystalline bulk modulus B, Young's modulus E, shear modulus G, Poisson ratio ν of Mg7Gd are gained by the Voigt–Reuss–Hill (VRH) approximation. The ductility and plasticity, especially elastic anisotropy are discussed in details. Based on the electronic density of states and charge density distribution, the covalent bonding and metallic bonding are exhibited in Mg7Gd compound. Last, the Debye temperature is also calculated for the investigation in the future.
    Solid State Sciences 12/2009; 11(12):2156-2161. DOI:10.1016/j.solidstatesciences.2009.08.011 · 1.68 Impact Factor

Publication Stats

66 Citations
13.83 Total Impact Points

Institutions

  • 2010–2011
    • Xiangtan University
      • Department of Physics
      Siangtan, Hunan, China
  • 2009–2011
    • Guangxi University
      • School of Chemistry and Chemical Engineering
      Yung-ning, Guangxi Zhuangzu Zizhiqu, China