Behavior of hydrogen in an Ni3Al compound investigated by means of hydrogen microprint technique

Hydrogen microprint technique, which can visualize microscopic location in the surface where hydrogen atom has been evolved, was applied to an isothermally forged Ni-rich Ni3Al compound to investigate the behavior of hydrogen, and comparison was made with cold-rolled pure nickel. Hydrogen evolution behavior was examined when one side of the specimen was charged with hydrogen gas of 0.2 MPa and/or the specimen was deformed plastically in tension. Hydrogen in nickel aluminide was concluded to be trapped by dislocations and to move with gliding dislocations, as well as the hydrogen in other metals and alloys. It was presumed that molecular hydrogen which exists in the environment decomposes at the surface, invades and permeate the interior in nickel aluminide. Hydrogen in nickel was also found to be transported with gliding dislocations.