The formation of transient diffusion layer at electrocrystallization in the transition ‘coating—substrate’ layer is considered. Results of the micro-X-ray spectral analysis show that depth of a diffusion layer at nickel electro-deposition on a copper substrate is equal to 1.5—3 $\mu$m at variation of cathodic potential from 0.1 to 0.3 V and is equal to 0.5—2 $\mu$m at zinc electrodeposition on a copper substrate at potential variation from 0.2 to 0.4 V. Within the scope of the model of not coinciding spheres in the elasticity theory, energies, which are necessary for introduction of the adsorbed atoms of nickel and zinc into a crystal lattice of a copper substrate, are calculated. As shown, for systems, which form solid Ni—Cu and Zn—Cu solutions, the energy required for embedding of nickel or zinc into the crystal lattice of the copper substrate is sufficient, but it is not sufficient to embed atoms into the crystal lattice of the tungsten substrate. It is confirmed by results of the micro-X-ray spectral analysis.