Hydrogen permeability degradation of Pd-coated Nbâ¿¿TiNi alloy caused by its interfacial diffusion

⿢Pd-coated Nb40Ti30Ni30 is a promising material for hydrogen-permeable membrane.⿢The hydrogen permeability decreased exponentially when using above 773 K.⿢Interdiffusion between the Pd coating and alloying elements was a cause.⿢The Ti diffusing outward was concentrated near the topmost surface.⿢The diffused Nb binds to the Pd in the surface, and thus, a Pd3Nb was formed.