Coatings of the composition of 310S heat-resisting steel dopped Al and Ir additions, deposited on a substrate of the same steel by the magnetron sputtering method, were examined. The measurements were made in the classical Bragg-Brentano geometry and by the GXRD method. With the fixed and different position of the coated sample by rotating the sample by angles ψ. The coating as deposited and after being soaked at 400°C for 15 minutes was subjected to examinations. The examination carried out have shown that coatings may have a unique, subtle structure which is metastable and undergoes irreversible changes in the temperatures up to 400°C. It has been found that in the outermost coating zones and zones closer to the substrate, areas occur in the coating structure, which have the different lattice parameter compared to the basic phase. Additionaly, the local period of the structure equal 5.9 nm was found.