Electroplated cobalt-boron alloys: Formation and structure features

Co-B alloys containing 3–22 at % boron were produced by electroplating from a cobalting bath containing sodium decahydro-closo-decaborate as a source of boron. Alloys containing 3–8 at % boron are found to be mixed substitutional-interstitial solid solutions with an α-Co crystal lattice. At a boron content of 15 at % or higher, amorphous coatings are formed. The microstructure of amorphous alloys is characterized by the existence of regions with different substance density. With an increase in the boron content from 16 to 20 at %, the regions of the increased and decreased substance density become larger and more pronounced. The existence of chemical bonds between cobalt and boron atoms was discovered with the use of X-ray photoelectron spectroscopy.