Abstract
Cathodic polarization of a 50.9at%Ni-Ti alloy in aqueous solutions picked up large amounts of hydrogen, forming hydrides making up the majority of hydrogen in specimens. Hydrogen was not observed to be released from the specimen at room temperature. In polarization in a sodium hydroxide solution, the concentration of hydrogen was proportional to the cathodic current density. In polarization in a sulfuric acid solution containing trace amounts of arsenic trioxide, the concentration of hydrogen was proportional to the square root of the current density. Thus the evolution reactions of hydrogen gas differ in these solutions. The concentration of hydrogen in tetragonal hydride changed with 0.03∼0.5H/metal. The lattice parameters of the hydride changed with a=0.609∼0.625nm and c=1.14∼1.26nm. The diffusion coefficient of hydrogen was 5×10-14m2/s at 298K.
