摘要
本工作采用基于密度泛函理论的第一性原理方法从原子尺度对不同成分W-Re二元合金的弹性性能和热力学性能进行了研究。根据特殊准随机模型构建不同成分合金的无序固溶体模型,并对其晶格结构进行了优化。计算结果表明,随着固溶体中Re原子浓度的增加,生成焓和结合能的数值变大,固溶体越难生成,固溶体的稳定性越差。通过电子态密度对固溶体稳定性进行了解释。采用应力-应变法对优化后结构的独立弹性常数进行计算,结果表明,本工作构建的所有固溶体均满足力学稳定性判据。根据V-R-H(Voigt-Reuss-Hill)近似对固溶体各项力学常数进行计算,结果表明,随着固溶体中Re原子浓度的增大,其体模量不断增大,剪切模量和杨氏模量不断减小。由各脆韧性判据可知,各固溶体均呈韧性,且提高Re原子的浓度会提升固溶体的韧性。最后在准谐近似的基础上计算不同成分合金的声子谱和相应的声子态密度,W 12 Re 4声子谱中存在大量虚频,表明该结构不能稳定存在。本工作可为W-Re合金的相关实验研究和实际生产提供一定的参考。
In this work,the first-principles method based on density functional theory was used to study the elastic and thermodynamic properties of W-Re binary alloys with different compositions.According to the special quasi-random model,the disordered solid solution model of solid solution alloys was constructed and its lattice structure was optimized.The results showed that,the value of enthalpy and binding energy was increasing,and the solid solution was more difficult to form,the stability of solid solution was worse as the concentration of Re atoms in the solid solution increasing.The electronic level density was used to explain its stability.Then,the stress-strain method was used to calculate the independent elastic constant of the optimized structure.It was verified that the solid solutions constructed satisfy the mechanical stability criterion in this work.The mechanical constants of the solid solution were calculated according to the V-R-H(Voigt-Reuss-Hill)approximation,and the results showed that the bulk modulus of the solid solution increased,and the shear modulus and Young s modulus decreased with the increase of the concentration of Re.Each solid solution showed toughness,according to the brittleness and toughness criterion,the toughness of the solid solution was increased by increasing the concentration of Re atoms.Finally,based on the quasi-harmonic approximation,the phonon spectra and the corresponding phonon densities of states of alloys with different composition were calculated.There was a large number of virtual frequencies in the W 12 Re 4 phonon spectrum,which indicates that the structure is unstable.The calculation and research in this work can provide some references for the relevant experimental research and practical production of W-Re alloys.
作者
宋政骢
米国发
王有超
刘晨
历长云
SONG Zhengcong;MI Guofa;WANG Youchao;LIU Chen;LI Changyun(School of Materials Science and Engineering,Henan Polytechnic University,Jiaozuo 454100)
出处
《材料导报》
EI
CAS
CSCD
北大核心
2019年第16期2785-2792,共8页
Materials Reports
基金
河南省自然科学基金(182300410266)~~
