Microstructural change and hydrogen behaviour in implanted metal

Systematic transmission electron microscope (TEM) observations have been made on the microstructures created in Al implanted with hydrogen as a function of fluence. The fluences were chosen to be above and below a critical fluence where the implanted hydrogen profile, measured with ERD, collapsed. The TEM observations revealed a drastic change of bubble structure in a subsurface layer in ocincidence with the change in the depth profile, producing a tunnel like microstructure beneath the surface. Stereoscopic observations of the bubble structures indicate a correlation between the hydrogen profile and the depth distribution of bubbles. (orig.)