EFFECTS OF ELECTRONIC-ENERGY LOSS IN CRYSTALLINE AND AMORPHOUS NI3B IRRADIATED WITH HIGH-ENERGY HEAVY-IONS

Crystalline Ni-B (c-Ni-B) and amorphous Ni-B (a-Ni-B) ribbons have been irradiated at 80 K with 3 GeV Xe ions in order to study the influence of the alloy structure on the disordering process induced by heavy-ion electronic energy loss. The relative electrical resistance variation of the samples measured in situ during irradiation reveals that the effect is much larger in the amorphous than in the crystalline system. The behaviour of a-Ni75B25 is basically that of a-Fe85B15: an increase in the alloy resistivity at the beginning of the irradiation, certainly due to disorder production, followed by a large growth of the sample dimensions. Both effects are attributed to electronic energy loss. On the contrary, c-Ni3B does not present any measurable growth; high-resolution electron microscopy experiments on single crystals indicate that, in the electronic stopping power range studied, the resistivity increase is essentially due to elastic collision events. A model has been derived to account for the experimental results obtained.