Formation and Structure of Thin–Film Fe–Ni and Fe–Co Coatings for Electromagnetic Radiation Screens

Abstract

The elemental composition and structure of coatings made of Fe–Ni and Fe–Co alloys, formed by electron beam evaporation, were investigated. The azeotropic composition of the Fe–Co alloy was calculated. It was shown that the alloy containing 54 wt.% (∼55 at.%) Fe and 46 wt.% (∼45 at.%) Co evaporates congruently. It was found that at a deposition rate of coatings made of the above alloys on substrates made of polymer materials of 5 nm/s or more, the surface layer of these substrates is heated to a temperature above 100 °C. This leads to the destruction of the surface layer of the polymer with the release of volatile components and the formation of a relief coating surface. At coating deposition rates from 0.5 to 1.0 nm/s, the substrate temperature does not exceed 50 °C, while the surface roughness of the coating decreases and its reflectivity increases. It was shown that 150 nm thick coatings of Fe₅₆Ni₄₄ and Fe₅₅Co₄₅ alloys with azeotropic compositions obtained at a deposition rate of 1.0 nm/s have an X-ray amorphous (Fe–Ni system alloy) or predominantly amorphous (Fe–Co system alloy) structure. The elemental composition of the coatings was studied, and it was found that in the Fe–Ni alloy, the deviation towards a decrease in the iron content in the coating relative to the azeotropic one was less than 5 %, while in the Fe–Co alloy, the deviation towards an increase was 18 %.