Ultra-hard AlMgB$_{14}$ coatings fabricated by RF magnetron sputtering from a stoichiometric target

For the first time hard aluminium magnesium boride films were fabricated by RF magnetron sputtering from a single stoichiometric ceramic AlMgB$_{14}$ target. Optimized processing conditions (substrate temperature, target sputtering power and target-to-substrate distance) enable fabrication of stoichiometric in-depth compositionally homogeneous films with the peak values of nanohardness $88$ GPa and Young's modulus $517$ GPa at the penetration depth of $26$ nm and, respectively, $35$ and $275$ GPa at $200$ nm depth in $2$ $\mu$m thick film.