Hydrogen transport and embrittlement for palladium coated vanadium-chromium-titanium alloys

As part of a study of the thermodynamics, kinetics and embrittlement properties of hydrogen in vanadium based alloys, experiments were conducted to determine the rate of hydrogen transport through the vanadium reference alloys, V-7.5Cr-15Ti and V-4Cr-4Ti, and to determine these alloys' hydrogen embrittlement, they were exposed to hydrogen pressures of 3 and 300 kPa (0.03-3 atm) at temperatures between 380 and 475 C. To facilitate hydrogen entry and egress, tubes of these alloys were coated with palladium on the inside and outside faces. Observed permeabilities were 0.015 to 0.065 μmol/(m2 s Pa0.5) for the V-7.5Cr-15Ti alloy and 0.02 to 0.05 μmol/(m2 s Pa0.5) for the V-4Cr-4Ti alloy depending on the quality of the coat and the operating temperature. At 1.7 atm hydrogen, V-7.5Cr-15Ti embrittled at temperatures below 380 C while V-4Cr-4Ti embrittled around 330 C. (orig.)