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采用第一性原理的方法计算了Zr, Nb, V固溶于 α-Fe(C)后形成晶胞的体积变化率、晶胞总能、结合能、态密度、电荷布居数及力学性能, 并由此研究了Zr, Nb, V与 α-Fe(C)的微观作用机理. 结果表明, V优先置换 α-Fe(C)晶胞中顶角位置的Fe原子, 而Zr, Nb优先置换 α-Fe(C)晶胞中体心位置的Fe原子. Zr, Nb降低了铁素体的稳定性, Zr比Nb更难固溶于 α-Fe(C). V固溶后增加了晶胞结合能, 对晶胞主要起到提高韧性的作用. Zr, Nb, V固溶于铁素体后, Zr, Nb仅与Fe原子形成金属键, 而V与铁素体晶胞中的Fe原子形成了金属键和Fe—V离子键, 其离子键的作用均强于Zr, Nb原子与铁素体晶胞中的键合作用, 是晶胞结合能增加的主要因素. Zr, Nb主要是通过弥散强化的方式改善钢铁材料的力学性能, V固溶能在一定程度上提高铁素体的韧性, 是提高力学性能的主要原因.The volume change rate, total energy, binding characteristics, state density, charge distribution number and mechanical properties of cells formed by solid solution of Zr, Nb and V in α-Fe(C) are calculated by using the first-principles method. Thus, the effect of Zr, Nb, V on α-Fe(C) are studied in this paper. The results show that V displaces Fe atoms which is at the apex angle of α-Fe (C) cells preferentially, while Zr and Nb displace Fe atoms at the body center of α-Fe(C) cells. Zr and Nb reduce the stability of ferrite, but Zr is more difficult to solidly solubilize in α-Fe(C) than Nb. Solid solution of V increases the binding energy of crystal cells, meanwhile the toughness of crystal cell is mainly improved. After solid is solubilized in ferrite, Zr and Nb atoms only form metal bonds with Fe atoms while V and Fe atoms form the metal bonds and Fe—V ionic bonds. The ionic bonds of Fe—V are stronger than metal bonds of Zr and Nb atoms with Fe atoms, which is the main factor of the cell increasing. Zr and Nb mainly improve the mechanical properties of steel material by means of dispersion strengthening. To some extent, V solid solution can improve the toughness of ferrite, which is the main reason for improving the mechanical properties.
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Keywords:
- first principle study/
- α-Fe(C)/
- Zr/
- Nb/
- V/
- bonding characteristics
[1] [2] [3] [4] [5] [6] [7] [8] [9] [10] [11] [12] [13] [14] [15] [16] [17] [18] [19] [20] [21] [22] [23] [24] [25] [26] [27] [28] [29] [30] [31] [32] -
V/Å3 体积变化率ε/% 晶胞总能Etot/eV α-Fe(C) 54.88 –3769.31 α-Fe(C)-Zr (体心) 63.49 15.68% –4185.81 α-Fe(C)-Zr (顶角) 69.16 26.01% –4185.27 α-Fe(C)-Nb (体心) 61.11 11.34% –4456.27 α-Fe(C)-Nb (顶角) 64.53 17.59% –4456.25 α-Fe(C)-V (体心) 57.93 5.56% –4881.30 α-Fe(C)-V (顶角) 57.19 4.21% –4881.78 
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晶胞 结合能E0/eV·atom–1 α-Fe(C) 4.51 α-Fe(C)-Zr (体心) 4.37 α-Fe(C)-Nb (体心) 4.44 α-Fe(C)-V (顶角) 4.64 下载:
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原子 s p d 总电荷 得/失电荷 α-Fe(C)-Zr Fe1 0.38 0.68 6.75 7.8 0.20 Fe2 0.27 0.56 6.77 7.61 0.39 Fe3 0.28 0.56 6.77 7.61 0.39 C1 1.49 3.16 0 4.66 –0.66 C2 1.49 3.16 0 4.66 –0.66 Zr 2.19 6.53 2.95 11.67 0.33 α-Fe(C)-Nb Fe1 0.39 0.72 6.74 7.85 0.15 Fe2 0.27 0.53 6.77 7.58 0.42 Fe3 0.27 0.53 6.77 7.58 0.42 C1 1.48 3.17 0 4.65 –0.65 C2 1.48 3.17 0 4.65 –0.66 Nb 2.30 6.38 3.99 12.68 0.32 α-Fe(C)-V Fe1 0.33 0.72 6.75 7.81 0.19 Fe2 0.33 0.72 6.75 7.81 0.19 Fe3 0.28 0.59 6.76 7.63 0.37 C1 1.47 3.21 0 4.68 –0.68 C2 1.50 3.17 0 4.67 –0.67 V 2.26 6.38 3.77 12.41 0.59 注: 电荷为正表示失电子, 为负表示得电子. 下载:
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α-Fe(C)-Zr α-Fe(C)-Nb α-Fe(C)-V 键 聚居数 个数 键 聚居数 个数 键 聚居数 个数 C—Fe 0.16 2 C—Fe 0.20 1 C—Fe 0.26 1 1.61 2 0.21 1 0.25 1 C—Zr 0.06 1 1.53 2 0.13 1 0.05 1 C—Nb 0.11 1 0.12 1 0.10 1 1.42 1 C—V 1.41 1 Fe—Fe 0.11 2 V—Fe 0.0 2 成键 3.65 3.68 3.81 反键 0 0 0 下载:
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C11 C12 C13 C33 C44 C66 B G E σ B/G α-Fe(C) 407.59 232.72 125.38 758.58 86.89 207.24 282.30 148.90 379.89 0.28 1.89 α-Fe(C)-Zr 348.44 331.21 101.14 680.12 89.50 231.44 271.55 138.32 354.73 0.28 1.96 α-Fe(C)-Nb 436.45 242.81 139.25 661.79 74.68 148.99 286.37 127.23 332.45 0.30 2.25 α-Fe(C)-V 391.84 342.96 167.67 645.00 55.02 74.18 309.48 86.87 238.32 0.37 3.56 下载:
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[1] [2] [3] [4] [5] [6] [7] [8] [9] [10] [11] [12] [13] [14] [15] [16] [17] [18] [19] [20] [21] [22] [23] [24] [25] [26] [27] [28] [29] [30] [31] [32]
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