Abstract
The magnetic relaxations of hydrogen isotopes in disordered and ordered (L12) Pd3Fe alloys as well as in disordered PdFe alloys were investigated in the temperature range between 4·2 and 500 K by means of magnetic after-effect measurements. In Pd3Fe the relaxation spectrum is composed of three characteristic maxima at 84,130 and 185 K and the relaxation strength is strongly dependent on the degree of order. The disordered PdFe specimens show a spectrum composed of two maxima at 110 and 155 K. Using a statistical configuration model which takes into account the degree of order as well as the stoichiometric composition of f.c.c. alloys, the characteristic relaxation maxima and their activation enthalpies were assigned to local jumps of hydrogen isotopes within different octahedral interstitial sites. A comparison of the activation enthalpies of long-range diffusion and of local jumps, as determined by degassing experiments and magnetic after-effect measurements respectively, shows that long-range diffusion is determined by a few dominating configurations.