[en] Rutherford backscattering and Auger-electron spectroscopy have been employed to study the processes of the surface doping of iron samples by elements Nb, W, Ni, Al and Cu, using ion mixing technique. The conclusion is made that in the system Fe-Ni mixing proceeds by linear cascades, in the systems Fe-Nb and Fe-W by thermal peaks, and in the systems Fe-Cu and Fe-Al the determinant role is played by the processes of radiation-stimulated diffusion. Based on this, it has been established that at high mobility of radiation defects the process of the elements propagation is determined by magnitude and sign of the mixing heat. At small mobility of defects the mixing effectiveness is independent of the mixing heat, and is determined by cascade density