Hierarchically organized structures formed during the deposition of a thin film of boron on the surface of high-chromium steel

In the scheme of plasma-assisted RF-sputtering of the cathode from boron powder, a mode is revealed and a film of boron with thickness up to 500 nm in amorphous state is formed on the surface of AISI 310S high-chromium steel. It is shown that deposition of boron film leads to formation of multiphase multilayer hierarchically subordinate nanocrystalline structure in surface layer of steel with thickness up to 700 nm. Hardness of modified layer exceeds hardness of initial steel by 1.2 times, and Young's modulus-by 1.4 times. It has been suggested that the increase in the hardness of the steel surface layer is due, firstly, to the action of the Orovan mechanism (strengthening with nano-sized particles of borides), secondly, to the Hall-Petch mechanism (strengthening with grain boundaries and sub-grains), thirdly, to the substructural strengthening caused by the formation of the dislocation structure, and fourthly, solid-solution hardening associated with the doping of the Ȗ-iron crystal lattice with boron atoms.