Hydrogen embrittlement in Nb-Mo alloy films prepared by arc-ion plating

In the case of H-2 production via steam reforming of CH4, it is necessary t o prepare a hydrogen-permselective membrane without pin-holes and cracks. T he formation of metal hydride causes cracks in the membrane, resulting in h ydrogen embrittlement. Hydrogen embrittlement was prevented by alloying the membrane with a metal such as Mo which does not form a hydride. Moreover, high Hz permeation is expected by the alloying. In general, a hydrogen perm eable metal has a high melting point. As the alloying of high melting point metals is difficult, there have been few papers on an ahoy membrane of hig h melting point. In this study, a Nb hydrogen-permselective membrane was alloyed with Mo at 1.3 Pa of Ar gas pressure by Physical Vapor Deposition (PVD) method such as are-ion plating (AIP). Two targets of Nb and Mo were used. Vegard's law wa s observed in the Nb-Mo alloys. After the cyclic H-2 absorption/desorption test in 1x10(5) Pa H-2 the forma tion of Nb hydride was confirmed in the Nb membrane, but metal hydride was not observed in the Nb-Mo alloy membrane. It was estimated from the lattice strain that the Nb-10 at%Mo alloy showed the highest H-2 permeation.