中国物理B ›› 2012, Vol. 21 ›› Issue (1): 16202-016202.doi: 10.1088/1674-1056/21/1/016202
• CONDENSED MATTER: STRUCTURAL, MECHANICAL, AND THERMAL PROPERTIES • 上一篇 下一篇
刘增辉, 尚家香
Liu Zeng-Hui(刘增辉) and Shang Jia-Xiang (尚家香)†
摘要: A first-principles density functional approach is used to study the electronic and the elastic properties of Nb15X(X = Ti, Zr, Hf, V, Ta, Cr, Mo, and W) alloys. The elastic constants c11 and c12, the shear modulus C', and the elastic modulus E〈100〉 are found to exhibit similar tendencies, each as a function of valence electron number per atom (EPA), while c44 seems unclear. Both c11 and c12 of Nb15X alloys increase monotonically with the increase of EPA. The C' and E〈100〉 also show similar tendencies. The elastic constants (except c44) increase slightly when alloying with neighbours of a higher d-transition series. Our results are supported by the bonding density distribution. When solute atoms change from Ti(Zr, Hf) to V(Ta) then to Cr(Mo, W), the bonding electron density between the central solute atom and its first neighbouring Nb atoms is increased and becomes more anisotropic, which indicates the strong interaction and thus enhances the elastic properties of Nb-Cr(Mo, W) alloys. Under uniaxial 〈100〉 tensile loading, alloyed elements with less (more) valence electrons decrease (increase) the ideal tensile strength.
中图分类号: (Other elastic constants)