Nb-Mo-Ti-Ni铸态合金组织及氢传输性能

发布时间：2018-01-15 17:39

  本文关键词：Nb-Mo-Ti-Ni铸态合金组织及氢传输性能　出处：《哈尔滨工业大学》2016年硕士论文　论文类型：学位论文

  更多相关文章： Nb-Mo-Ti-Ni合金 铸态组织 氢传输性能 氢脆

【摘要】：本文主要研究Mo的加入对Nb-Ti-Ni系合金铸态组织和氢传输性能的影响。采用真空非自耗电弧熔炼制备了四组合金:a组:亚共晶Nb15-xMoxTi42.5Ni42.5(x=0,5,10)、b组:近共晶Nb20-xMoxTi40Ni40(x=0,5,10)、c组:过共晶Nb30-xMoxTi35Ni35(x=0,5,10)、d组:过共晶Nb40-xMoxTi30Ni30(x=0,5,10)。利用扫描电子显微镜和X射线衍射分析仪对四组合金的相和微观组织进行了分析,获得了Mo的加入对合金凝固路径的影响规律。根据微观组织演化规律,选取d组合金进行氢溶解、扩散和渗透等传输性能测试,建立了Nb-Mo-Ti-Ni合金成分、组织和氢传输性能之间的关系。XRD、SEM等结果表明,Mo的加入会导致合金凝固相组成向富Nb区域靠近。随着Mo含量逐渐增加,a组和b组合金相组成由初生TiNi加二元共晶[bccNb+TiNi]变为初生bcc-Nb加TiNi,在Nb15Mo5Ti40Ni40合金中出现了三元共晶相{[bcc-Nb+TiNi]+Ti2Ni},在Nb5Mo10Ti42.5Ni42.5合金和Nb10Mo10Ti40Ni40合金中出现了Ti2Ni相;c组和d组合金在Mo含量为5%时保持了初生bcc-Nb加二元共晶相[bcc-Nb+TiNi]的相组成,满足“多相构成、功能分担”的氢分离合金设计原则,Mo含量为10%时,出现了少量三元共晶相。选择渗氢性能最好的d组合金进行吸氢和渗氢测试,结果表明,随着Mo的加入,合金的氢溶解性能明显下降,氢扩散性能和氢渗透性能先上升,后下降。其中,Nb35Mo5Ti30Ni30合金具有最高的氢渗透性能,在673K下达到3.15×10-8 molH2·m-1·s-1·Pa-0.5,约为纯Pd同条件下的1.98倍。通过恒压缓冷测试表明,Nb30Mo10Ti30Ni30合金抗氢脆性能最好,Mo的加入可以提高合金的抗氢脆性能。氢在合金中的渗透主要遵循溶解-扩散方式,该行为主要发生在初生bcc-Nb内,Mo的加入会减小bcc-Nb晶格间隙尺寸,降低氢溶解度,提高抗氢脆性能,同时减小了氢跳跃间隙距离导致合金的渗透和扩散性能出现增加,但随着Mo含量的进一步增加,合金中的低能间隙过多,高能间隙的减少导致氢原子在膜内扩散速度大幅降低。另外,Nb30Mo10Ti30Ni30合金上下游间氢浓度梯度较低,氢原子扩散动力不足也是导致其氢扩散性能和渗透性能发生下降的原因。
[Abstract]:In this paper, the effect of Mo addition on the as-cast microstructure and hydrogen transport properties of Nb-Ti-Ni alloys was studied. Four groups of alloys were prepared by vacuum non-consumable arc melting. Hypoeutectic Nb15-xMoxTi42.5Ni42.5(. X0. (5) Nb20-xMoxTi40Ni40Ni40Ni40Ni40Ni40Ni40Ni40Ni40Ni40Nb20-xMoxTi40Ni40Ni40Ni40Nb30-xMoxTi35Ni35Ni35Ni35Ni35Nb30-xMoxTi35Ni35Ni35Nb30-xMoxTi35Ni35Ni35 and subeutectic Nb30-@@. Hb40-xMoxTi30Ni30Ni30Nb40-xTi30Ni30Ni30Nb40-xTi30Ni30Ni30Nb40-xTi30Ni30Ni30Nb40-xTi30Ni@@. The phase and microstructure of four groups of alloys were analyzed by scanning electron microscope (SEM) and X-ray diffraction analyzer (XRD). The effect of Mo addition on the solidification path of the alloy was obtained. According to the law of microstructure evolution d group of alloys were selected to test the hydrogen solubility diffusion and permeability. The relationship between the composition, microstructure and hydrogen transport properties of Nb-Mo-Ti-Ni alloy was established. With the addition of Mo, the solidification phase composition of the alloy will be closer to the NB rich region. With the increase of Mo content, the composition of a group and a combination of b are composed of primary TiNi and binary eutectic. [BccNb TiNi was transformed into primary bcc-Nb and TiNi. ternary eutectic phase {in Nb15Mo5Ti40Ni40 alloy was found. [Bcc-Nb TiNi] Ti2Ni}. Ti2Ni phase appeared in Nb5Mo10Ti42.5Ni42.5 alloy and Nb10Mo10Ti40Ni40 alloy. C and d alloys kept primary bcc-Nb and binary eutectic phase when Mo content was 5. [The phase composition of bcc-Nb TiNi meets the requirement of "multiphase composition, function sharing". The design principle of hydrogen separation alloy is that the Mo content is 10%. A small amount of ternary eutectic phase appeared. The hydrogen absorption and hydrogen permeation test of group d alloy with the best hydrogen permeation performance was carried out. The results showed that the hydrogen solubility of the alloy decreased obviously with the addition of Mo. The hydrogen diffusivity and hydrogen permeability increased firstly and then decreased, among which Nb35Mo5Ti30Ni30 alloy had the highest hydrogen permeability. At 673K, 3.15 脳 10 ~ (-8) molH2 路m ~ (-1) 路s ~ (-1) 路s ~ (-1) 路Pa-0.5, about 1.98 times of pure PD. The hydrogen embrittlement resistance of Nb30Mo10Ti30Ni30 alloy is the best. The hydrogen embrittlement resistance of Nb30Mo10Ti30Ni30 alloy can be improved with the addition of Mo. Hydrogen permeation in the alloy mainly follows the dissolution-diffusion mode. The behavior mainly occurs in the addition of Mo in the primary bcc-Nb, which reduces the lattice gap size of bcc-Nb, reduces the hydrogen solubility and improves the hydrogen embrittlement resistance. At the same time, the hydrogen jump gap distance is reduced, the permeability and diffusion properties of the alloy increase, but with the further increase of Mo content, the low energy gap in the alloy is excessive. The decrease of high energy gap leads to a significant decrease in the diffusion rate of hydrogen atoms in the film. In addition, the hydrogen concentration gradient between upstream and downstream of Nb30Mo10Ti30Ni30 alloy is lower than that of Nb30Mo10Ti30Ni30 alloy. The lack of hydrogen diffusion power also leads to the decrease of hydrogen diffusion and permeability.
【学位授予单位】：哈尔滨工业大学
【学位级别】：硕士
【学位授予年份】：2016
【分类号】：TG146.416
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本文编号：1429396