Formation of short-period multilayer W/B$_4$C compositions

The quantitative characteristics of the interlayer interaction in multilayer W/B$_4$C periodic compositions produced by magnetron sputtering are studied by small-angle X-ray diffraction using Cu-$K_{\alpha}$ radiation and by electron microscopy of transverse cuts. It is found that approximately 0.85 nm of the tungsten layer thickness is consumed for the formation of mixed zones at layer boundaries. The mixed layers have a density of 13.4 $\pm$ 0.7 g/cm$^3$ and contain tungsten in a bound chemical state. The effect of these mixed zones on the X-ray reflectivity of multilayer W/B$_4$C compositions is estimated. A method is proposed to determine the layer thickness at a small number of peaks in an X-ray diffraction pattern.