NOVELTY - A crystalline dual-phase hydrogen-permeation alloy of dual-phase cobalt-titanium-niobium type consists of a compound phase and is alloy composition consisting of primary and eutectic phases. The crystalline dual-phase hydrogen-permeation alloy is in the region containing line segment PQ which connected point P (complex oxides of cobalt, titanium and niobium) and point Q (complex oxides of cobalt, titanium and niobium), in a cobalt-titanium-niobium ternary state figure.    USE - For hydrogen permeation alloy film (claimed).    ADVANTAGE - The crystalline dual-phase hydrogen permeation alloy provides film with favorable hydrogen permeability and water resistance.    DETAILED DESCRIPTION - A crystalline dual-phase hydrogen-permeation alloy of dual-phase cobalt-titanium-niobium type consists of a compound phase and is alloy composition consisting of primary and eutectic phases. The compound phase has a structure surrounding the titanium-niobium phase that the eutectics (cobalt-titanium and titanium-niobium) of cobalt-titanium phase in which niobium formed a solid solution and the titanium-niobium phase in which coabalt formed a solid solution, produce as a primary. The crystalline dual-phase hydrogen-permeation alloy of dual-phase cobalt-titanium-niobium type is alloy composition in the area surrounded by point A (Co20Ti30Nb50), point B (Co20Ti10Nb70), point C (Co10Ti10Nb80) and point D (Co10Ti30Nb60) (all alloy compositions are atomic%), in a cobalt-titanium-niobium ternary state figure, and is in region containing line segment PQ which connected point P (Co35Ti35Nb30) and point Q (Co5Ti8Nb87) (all alloy compositions are atomic%), in a cobalt-titanium-niobium ternary state figure. An INDEPENDENT CLAIM is included for hydrogen permeation alloy film obtained by mixing each of constituent element of crystalline hydrogen permeation alloy. The thickness of dual-phase alloy is 0.01-3 mm.    DESCRIPTION OF DRAWING(S) - The graph shows the cobalt-titanium-niobium ternary state figure. (Drawing includes non-English language text)