基于第一性原理计算的Nb含量对hcp Zr-Nb合金力学性质的影响

Effect of Nb Content on Mechanical Properties of hcp Zr-Nb Alloys Based on First-principles Calculations

基于密度泛函理论为基础的第一性原理计算方法,通过虚拟晶体近似建模,以密排六方(hcp)结构的Zr-Nb合金为研究对象,计算其弹性常数、弹性模量、泊松比等力学常数,研究Nb含量对Zr-Nb合金力学性能的影响。结果表明:通过虚拟晶体近似方法计算得到的晶格参数与实验及其的计算值符合良好,晶格常数a、c随Nb含量的增加而减小。当Nb含量大于10%(原子分数,下同)时,hcp Zr-Nb力学失稳,在力学稳定的条件下(Nb含量低于10%),随Nb含量的增加,体积模量B递增,剪切模量G、弹性模量E递减。各韧脆性判据均表明,随着Nb含量的增加,Zr-Nb合金韧性逐步提高。

In order to obtain the effect of Nb content on the mechanical properties of Zr-Nb alloys,the elastic constant,elastic modulus,Poisson’s ratio and other mechanical constants of hcp Zr-Nb alloys have been studied by using first-principles calculation based on density functional theory,and virtual crystal approximation method.The calculation results show that the lattice parameters calculated by the virtual crystal approximation method are in good agreement with experimental and other calculation results,and the lattice constants a and c decrease with the increase of Nb content.When the Nb content is greater than 10%,the hcp Zr-Nb alloy is mechanically unstable.Under mechanically stable conditions such as the Nb content less than 10%,with Nb content increasing,the bulk modulus B increases,while the shear modulus G and the elastic modulus E decrease,and the toughness and brittleness criteria show that with Nb content increasing,the toughness of Zr-Nb alloys become much better.