In order to investigate the swift heavy-ion-induced mixing of nitride coatings we have irradiated Ni3N films on SiO2-, Si 3N4-, SiC- and Si-substrates with Ar, Kr, Xe and Au ions of energies ranging from 90 to 350 MeV, for which electronic energy loss dominates. The Ni-concentration profiles at the interfaces before and after irradiation were determined by means of Rutherford backscattering spectrometry with 900 keV He2+ ions. In all the cases, strong mixing occurred as soon as a material-dependent threshold Sec in the electronic stopping power Se was exceeded. The mixing rate exhibits a squared scaling k = Δσ2/Φ = η2 (Se - Sec)2 and estimation of the effective diffusion constant indicates interdiffusion in molten ion tracks. The threshold value Sec depends on the substrate material and seems to be determined by its melting point and specific heat. © 2003 Published by Elsevier Ltd.