Crystalline Ni3B samples have been irradiated with GeV heavy ions (from 16O to 238U) at low temperature in order to study the damage induced in this compound by ion electronic energy loss. Electrical resistance measurements were performed in situ during irradiation and during annealing. Subsequent X-ray diffraction data and transmission electron microscopy observations reveal a change of the radiation damage process as a function of the electronic stopping power (dE/dx)e. At low (dE/dx)e isolated defects are created, while at high (dE/dx)e irradiation generates continuous amorphous tracks. Amorphous inclusions (discontinuous tracks) are most likely formed in the intermediate (dE/dx)e range. The amorphous phase induced by swift heavy ion irradiation, different from that formed by quenching techniques, is unstable at room temperature over a period of a few months.