Design and microstructural control of new hydrogen permeation alloys fir hydrogen membrane reactor

钯银合金作为一种氢分离纯化合金已在工业上得到广泛应用，但其价格昂贵且资源稀缺。因此，开发低成本、高性能的渗氢合金是迫切需要的。5A金属的氢渗透率φ高于钯银合金，但存在严重的氢脆。也就是说，在单相合金中，高φ值与高抗氢脆是不相容的。本文作者在双相概念的基础上提出了新的渗氢合金。首先，研究了铸态Nb-Ti-Ni合金的组织与φ的关系。由初生bcc-(Nb, Ti)相和共晶{(Nb, Ti)+TiNi}相组成的Nb_<39>Ti_<31>Ni_<30>合金在673 K时φ=1.93 × 10^<-8> [mol H_2 m^<-1> s^<-1> Pa^<-0.5>]最高，高于Pd。此外，在富nb Nb-Ti-Ni合金的共晶点与初相连接的直线上，φ可以测量到。φ随Nb含量和初生相数量的增加而增大。最富铌的Nb_<68>Ti_<17>Ni_<15>合金，由26vol%共晶相和74vol%初生相组成，其φ最高为4.91x10^<-8> (mol H_2 m^<-1>s^<-1>Pa^<-0.5>)。此外，还测量了含有初相ZrNi或bcc （Nb, Zr）的共晶Nb-Zr- ni合金的φ。含初生bcc-(Nb, Zr)相（18 vol %）的Nb_<20>Zr_<40>Ni_<40>合金在673 K时φ为2.73x10^<-8> [mol H_2 m^<-1> s^<-1>Pa^<-0.5>]。这些值高于纯Pd合金和Nb_<39>Ti_<31>Ni_<30>合金。研究结果表明，含有共晶结构的多相合金具有抑制氢脆的作用，是一种很有前途的新型透氢合金膜。

Pd-Ag alloys are commercially used as a hydrogen separation and purification alloy, but they are too expensive and scarce in resources. Then, it is strongly desired the development of low cost and high performance hydrogen permeation alloy. Hydrogen permeability φ of 5A metals are higher than that of Pd-Ag alloys, but they suffer from the severe hydrogen embrittlement. That is, the high φ value is incompatible with high resistance to the hydrogen embrittlement in single-phase alloys. The present authors have proposed new hydrogen permeation alloys on the basis of the concept of duplex phases. Firstly, the relation between microstructures and φ has been investigated in the as-cast Nb-Ti-Ni alloys. The Nb_<39>Ti_<31>Ni_<30> alloy consisting of the primary bcc-(Nb, Ti) phase and the eutectic {(Nb, Ti)+TiNi} one shows the highest φ=1.93x10^<-8> [mol H_2 m^<-1> s^<-1> Pa^<-0.5>] at 673 K, which is higher than that of Pd. Furthermore, φ is measurable in the Nb-rich Nb-Ti-Ni alloys on the straight line connecting the eutectic point and the primary phase. φ increases with increasing Nb content and the amount of the primary phase. The most Nb-rich Nb_<68>Ti_<17>Ni_<15> alloy, consisting of the 26vol% eutectic phase and the 74vol% primary phase, shows the highest φ of 4.91x10^<-8> (mol H_2 m^<-1>s^<-1>Pa^<-0.5>). In addition, φ of the eutectic Nb-Zr-Ni alloys containing the primary phases ZrNi or bcc (Nb, Zr) has been measured. φ of the Nb_<20>Zr_<40>Ni_<40> alloy containing the primary bcc-(Nb, Zr) phase (18 vol %) is 2.73x10^<-8> [mol H_2 m^<-1> s^<-1>Pa^<-0.5>] at 673 K. These values are higher than that of pure Pd and of the Nb_<39>Ti_<31>Ni_<30> alloy. The present works strongly indicates that multiphase alloys containing eutectic structures, which suppress the hydrogen embrittlement, are promising as novel hydrogen permeation alloy membranes.