HYDROGEN EMBRITTLEMENT OF MFR CANDIDATE VANADIUM ALLOYS

Pure vanadium, V-3Ti-1Si and V-15Cr-5Ti alloys were charged with 0.3 at% H, and tested in tension between 77 and 520 K. The fracture surfaces of specimens were examined by SEM. Both non-hydrogenated alloys were appreciably solution-strengthened, but had good ductility even at 77 K. The specimen hydrogenated with 0.3 at% H exhibited a precipitous ductility loss at 150 K for V-3Ti-1Si, at 200 K for pure V and at 300 K for V-15Cr-5Ti. The V-3Ti-1Si alloy has a greater resistance to hydrogen embrittlement than pure vanadium. On the other hand, the V-15Cr-5Ti alloy was most severely deteriorated by hydrogen and always fractured in a brittle mode at temperatures lower than 300 K. Hydrogen embrittlement in both alloys was discussed in terms of the inhomogeneity of deformation on yielding and the solute effect on the diffusion coefficient and solubility of hydrogen.