Cr含量对Ti-Nb-Cr合金抗腐蚀性影响的电子结构计算  

Electronic structure calculation of Cr content effect on corrosion resistance of Ti-Nb-Cr alloy

作　　者：程超 王逊[2] 孙嘉兴[1] 曹超铭 马云莉 刘艳侠[1] Cheng Chao;Wang Xun;Sun Jia-Xing;Cao Chao-Ming;Ma Yun-Li;Liu Yan-Xia(College of Physics,Liaoning University Shenyang 110036,China;College of Science,Shenyang Jianzhu University,Shenyang 110168,China)

机构地区：[1]辽宁大学物理学院,沈阳110036 [2]沈阳建筑大学理学院,沈阳110168

出　　处：《物理学报》2018年第19期228-235,共8页Acta Physica Sinica

基　　金：国家重点研发计划(批准号:2016YFB0701304)资助的课题~~

摘　　要：许多实验报道中表明合金化元素Cr能够提高Ti基合金的抗腐蚀性.为了解Cr元素含量对Ti-Cr-Nb合金的影响,本文计算了不同Cr含量的Ti-Cr-Nb合金的内聚能、形成能、费米能级和态密度等参数.分析了Cr含量对合金的电子结构稳定性以及腐蚀性能的影响.结果表明:随着Cr含量的增加,体系内聚能升高,形成能增加,体系稳定性略有下降,且材料形成条件变得苛刻;费米能级明显降低,体系不易失去电子,抗腐蚀性能增强;体系金属键增强,失电子能力降低,抗腐蚀性能提高;态密度与差分电荷密度研究表明, Cr含量的增加使得体系金属键增强,表明体系抗腐蚀性的提高.从费米能级和态密度图中发现,当Cr含量约为18.75 at.%时,合金的耐腐蚀性最优.Ti-based alloys are widely used in aerospace and medical engineering because of their excellent properties,such as good fracture toughness,high strength,good corrosion resistance,etc.However,the corrosion resistance performance of the alloys is not adequate to meet the requirements in many cases.The Ti-Cr-Nb ternary alloy system exhibits many excellent characteristics,especially the anti-corrosion ability,making it a very promising candidate for the applications in aerospace and medical engineering.The alloying element Cr can improve the corrosion resistance of Ti-based alloys as reported by many experiments.In order to understand and then predict the effect of Cr content on Ti-Nb-Cr alloy,the electronic structures,such as the cohesive energies,the formation energies,the Fermi levels and the densities of states（DOSs）of the Ti-Nb-Cr alloys with different Cr content of the alloys,are calculated by first-principles method.The calculations in this paper are carried out by VASP（Vienna ab-initio simulation package）software package,which is based on the density functional theory.The generalized gradient approximation is selected to deal with the exchange correlation energy of electrons.And the special k-point sample of the Monkhorst-Pack type is used in the Brillouin-zone integration.The effects of Cr content on the electronic stability and corrosion resistance of the alloy are discussed.In this paper,the Ti-25 at.%Nb alloy with the stableβ-phase is a matrix material,and Ti（12）Nb4 supercell model is adopted,in which 1 to 4 Ti atoms are replaced by the Cr atoms,respectively.In energetics,the sequence of the cohesive capacity of the system is as follows：Ti（12）Nb4Ti（11）Nb4Cr1Ti（10）Nb4Cr2Ti9Nb4Cr3Ti8Nb4Cr4,showing that the stability of the structure decreases with Cr content increasing.While the formation energy of the system energy shows a gradual increase trend with the increase of Cr,indicating that the formation of the system becomes gradually difficult when adding more Cr atoms.The Fermi leve

关 键 词：第一原理 电子结构 Ti-Cr-Nb合金 腐蚀机理 

分 类 号：TG178[金属学及工艺—金属表面处理]