I made the analysis phase AZ31 magnesium alloy samples with 1.5 micrometer layer of Cr and 1.6 micrometer CrAlN layer. Samples were examined using the technique of grazing incidence diffraction angles for fixed beam radius: 3, 5, 7.5, 10, 12.5 and 15 degrees to the sample surface. In addition, for comparison, were examined in a model of magnesium aluminum and zinc - AZ31. Method of measuring grazing incidence diffraction is a technique that allows the examination of very thin films and coatings that cover some of the interest eg for corrosion protection and improve the quality of the surface.