[en] The aim of this work is to investigate the radiation stability of pure nickel and iron– nickel Fe_0.56Ni_0.44 alloy nanowires fabricated by matrix synthesis using polymer track membranes and Ar⁺ and Xe⁺ ( E = 20 keV, j = 300 μA/cm²) beam irradiation. The dependence of the stability of nanowires on their diameter, fluence, and type of implanted ions is investigated. The assumption that the thermalized regions of dense cascades of atomic displacements (thermal spikes) play an important role in the nanowire structure change is made. These regions are nanosized zones of explosive energy release and heated to several thousands of degrees. (paper)