Abstrakt
In the present work, positron annihilation spectroscopy was employed for investigation of hydrogen-induced defects in Pd. Well annealed Pd samples were electrochemically charged with hydrogen and development of defects during hydrogen loading was investigated.
At low concentrations (a-phase, xH < 0.017 H/Pd) hydrogen loading introduced vacancies. When the hydrogen concentration exceeds 0.017 H/Pd, particles of hydrogen rich a'-phase are formed.
This generates dislocations in the sample in order to accommodate the volume mismatch between the a and the a'-phase. Moreover, additional vacancies are introduced into the sample by crossing dislocations.
Vickers hardness testing revealed that absorbed hydrogen causes hardening of the sample. In the a-phase region the hardness increases due to solid solution hardening caused by dissolved hydrogen.
At higher hydrogen concentrations when dislocations were created hardness increases due to strain hardening caused by dislocations.