DIFFUSION AND RELAXATION PROCESSES OF HYDROGEN IN HETEROGENEOUS MICROCRYSTALLINE FE-ZR ALLOYS

Microcrystalline heterogeneous Fe - Zr alloys with average grain sizes of 200 nm and 1.5 mum were produced by isothermal crystallization tre atments from amorphous Fe90Zr10. The influence of these heterogeneous microstructures on the local relaxation processes of hydrogen (H) was investigated by means of magnetic after-effect (MAE) measurements in a temperature range between 4.2 K and 475 K. The MAE spectra could be d ivided into two diffusion regions: one where the MAE spectra could ass igned to H reorientation processes within the phase and grain boundari es and one where the H diffusion is determined by the crystallized pha ses of the micrometer-sized polycrystalline alloy. The H degassing kin etics measured by a manometric method allows a detailed correlation to the annealing behaviour between the H relaxation spectra and the long -range H diffusion. Considering these results with measurements of H i n homogeneous atomic structures the annealing behaviour of the H-induc ed MAE maxima as well as the long-range H diffusion processes could be described by a potential model taking into account the heterogeneous structures.