Elastic properties of Nb-based alloys by using the density functional theory

• Published in: Chinese physics B 2012, Vol.21 (1), p.357-362
• Main Author: 刘增辉 尚家香
• Format: Article
• Language: English
• Subjects: Alloys; Bonding; Brackets; Chemical bonds; Density; Elastic constants; Hafnium; Niobium base alloys; Tungsten base alloys; 价电子数; 密度泛函方法; 密度泛函理论; 弹性常数; 弹性性能; 溶质原子; 第一原理; 铌基合金
• ISSN: 1674-1056; 2058-3834; 1741-4199
• DOI: 10.1088/1674-1056/21/1/016202

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 cn and c12, the shear modulus CI, and the elastic modulus E（lOO） are found to exhibit similar tendencies, each as a function of valence electron number per atom （EPA）, while c44 seems unclear. Both cu and c12 of Nb15X alloys increase monotonically with the increase of EPA. The C/ and E000） 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.