Multiple phase alloys and membranes thereof for hydrogen separation-purification and their method of preparation.

An Ni-Ti-Nb based multiple phase alloy consists of a combined phase which comprises a phase for the hydrogen permeability and a phase for the resistance to hydrogen embrittlement. The alloy has a composition satisfying the formula: NixTiyNb(100-x-y) in which x = 25 &tilde& 45 mol % and y = 25 &tilde& 55 mol %. A metal membrane for hydrogen separation-purification is prepared using the alloy material. The alloy material is prepared by blending Ni, Ti and Nb and melting the blend. The metal membrane permits the hydrogen separation-purification and thus the resulting purified hydrogen gas can be used as a fuel and can be applied to fields of production of semiconductors.