TiNb合金磁性起源及掺杂元素对其磁性的影响研究

发布时间：2018-03-14 06:09

本文选题：β钛合金　切入点：第一性原理　出处：《湘潭大学》2017年硕士论文　论文类型：学位论文

【摘要】：β型生物钛合金具有低密度,低的弹性模量及良好的耐腐性和生物相容性,作为生物移植材料具有广阔的应用前景。在钛合金中添加富d轨道电子的过渡金属Nb、Mo、Ta、Zr等元素调控钛合金的价电子浓度,从而影响β相的稳定性和弹性模量。因此,合金化方法是改善钛合金的显微组织和力学性能的有效途径。在这些β型钛合金中,Ti原子与其他过渡金属元素的d轨道电子的自旋耦合作用,有可能使合金产生磁性,而磁性会引起骨细胞定向排列,达到促进新骨的形成的效果,并且可以利用磁性提高植入物的寿命。因此本文采用第一性原理的方法对TiNb合金的磁性进行研究,其主要研究成果如下:(1)运用基于密度泛函理论的第一原理方法,系统性地研究了Nb原子含量对α、α"、β三个相的Ti-Nb合金磁性的影响,发现β-Ti_(0.75)Nb_(0.25)存在较大的磁性,其磁矩大小为6.113μΒ,而其他Nb含量的各相均不存在磁性。分析了β-Ti_(0.75)Nb_(0.25)合金的磁性来源,发现其磁性是由Ti原子的t2g态电子自旋极化产生。对具有不同相结构的TiNb合金的磁性进行试验测试,其结果与计算结果基本保持一致。(2)运用基于密度泛函理论的第一原理方法,研究了Nb含量对β-TiNb磁性的影响,并分析了该合金的磁性的起源。结果表明,在TiNb合金中β相的磁性随Nb含量增大先增大后减小,当Nb含量为0.25时磁矩达到最大值(6.113μΒ)。并且发现磁性起源于Ti原子与Nb原子间d轨道的耦合作用。在此基础上,研究了Nb,Mo,Ta,Zr掺杂原子对β-Ti0.75X0.25(X=Nb,Mo,Ta,Zr)二元合金磁性的影响及其机理,结果表明,β-Ti0.75X0.25二元合金的磁性强弱与掺杂原子X原子半径有关,掺杂原子X的半径减小,β-Ti0.75X0.25的磁性增大。(3)运用基于密度泛函理论的第一原理方法,研究了Mo,Sn,Ta,Zr元素掺杂对β-Ti_(0.75)Nb_(0.25)合金磁性的影响。结果表明,掺杂后四种合金均存在磁矩,但其磁矩均小于β-Ti_(0.75)Nb_(0.25)二元合金,原因在于Mo,Sn,Ta,Zr与Nb原子间产生耦合,使得Ti原子与Nb原子间耦合的电子数减少,其磁性同样来源于Ti原子与Nb原子之间的d轨道的耦合作用.(4)运用基于密度泛函理论的第一原理方法,系统性地研究了Fe掺杂对Ti_(0.75)Nb_(0.25)二元合金的磁性影响。结果表明,Ti0.74Nb0.25Fe0.01合金的α相的没有磁性,而α"相和β相具有磁性,在Ti0.74Nb0.25Fe0.01合金的磁性主要由以Fe原子为中心分布的Ti原子产生,Nb原子不产生磁性。而在Ti0.6875Nb0.25Fe0.0625合金的三中相结构均不存在磁性,试验结果与计算结果基本相符。
[Abstract]:尾-type bio-titanium alloy has low density, low elastic modulus, good corrosion resistance and biocompatibility. As a biological transplant material, it has a broad application prospect. Elements such as NbBX, Mo, Ta-Zr, which are rich in d orbital electrons, are added to titanium alloy to regulate the valence electron concentration of titanium alloy, thus affecting the stability and elastic modulus of 尾 -phase. Alloying is an effective way to improve the microstructure and mechanical properties of titanium alloys. The spin coupling of Ti atoms with the d orbital electrons of other transition metal elements in these 尾 titanium alloys may make the alloys magnetic. Magnetic properties can lead to the directional arrangement of bone cells to promote the formation of new bone, and can be used to improve the lifetime of implants. Therefore, the magnetic properties of TiNb alloys are studied by first-principle method in this paper. The main results are as follows: (1) by using the first principle method based on density functional theory, the effect of NB atom content on the magnetic properties of Ti-Nb alloys with 伪, 伪 "and 尾 phases is systematically studied. The magnetic moment of the alloy is 6.113 渭尾, but the other phases with NB content are not magnetic. The magnetic source of 尾 -Titip 0.75 NbSZ 0.25) alloy is analyzed. It is found that the magnetic properties are produced by the spin polarization of Ti atoms in the t2g state. The magnetic properties of TiNb alloys with different phase structures are tested. The results are in good agreement with the calculated results.) the first principle method based on density functional theory is used. The effect of NB content on the magnetic properties of 尾 -TiNb alloy was studied. The magnetic origin of 尾 -TiNb alloy was analyzed. The results show that the magnetic properties of 尾 phase in TiNb alloy increase first and then decrease with the increase of NB content. When the NB content is 0.25, the magnetic moment reaches a maximum value of 6.113 渭尾 ~ (-1). It is found that the magnetism originates from the coupling of the d orbitals between Ti atoms and NB atoms. On this basis, the effect and mechanism of NB Mota-Zr doped atoms on the magnetic properties of 尾 -Ti0.75X0.25X ~ (0.25) X ~ ((2)) NbLi _ (Mo) Mo _ (Mo) Ta _ (Zr) binary alloy have been studied. The results show that the magnetic strength of 尾 -Ti0.75X0.25 binary alloy is related to the radius of doped atom X, the radius of doped atom X decreases, and the magnetic property of 尾 -Ti0.75X0.25 increases.) the first principle method based on density functional theory is used. The magnetic properties of 尾 -TiS _ (0.75) NbSZ _ (0.25) alloy were studied. The results showed that the magnetic moment of the four alloys was smaller than that of 尾 -Ti-0.75 ~ (0.75) NbStue 0.25) binary alloy, which was due to the coupling between Mo-Ti _ (TaZr) and NB atoms, and the effect of doping on the magnetic properties of 尾 -TiS _ (0.75) / T _ T _ (0.25)) alloy was investigated. The number of electrons coupled between Ti atom and NB atom is reduced, and its magnetism is also derived from the coupling action of d orbital between Ti atom and NB atom.) the first principle method based on density functional theory is used. The effect of Fe doping on the magnetic properties of TiSZ 0.75 Nbs0.25) binary alloy has been systematically studied. The results show that the 伪 phase of Ti0.74Nb0.25Fe0.01 alloy is not magnetic, but the 伪 "phase and 尾 phase are magnetic. The magnetic properties of Ti0.74Nb0.25Fe0.01 alloys are mainly produced by Ti atoms with Fe atoms as the center, but there is no magnetic properties in the three phases of Ti0.6875Nb0.25Fe0.0625 alloys. The experimental results are in good agreement with the calculated results.
【学位授予单位】：湘潭大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TG146.23

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