The effect of low titanium content on the phase composition, structure, and mechanical properties of magnetron sputtered WB2-TiB2 films

The effect of the low Ti content on the phase composition, structure and mechanical properties of magnetron sputtered WB2 - TiB2 films was studied. Non-equilibrium conditions during the films deposition cause the difference of their phase composition from the composition of the target. Sputtering of a WB2 target (hexagonal crystal lattice) results in formation of the β-WB phase with an orthorhombic crystal lattice and a B/W atoms ratio of about 1.19. It was found that even a very low Ti content (about 0.6 at. %) act as a catalyst for the formation of a diboride phase with hexagonal crystal lattice. A nanocomposite β-(W,Ti)B/(Ti,W)B2 (where (Ti,W)B2 has a hexagonal crystal lattice) is formed in the range of 0.6 < x < 4.6 at. % of Ti. At x = 10.2 at. % a nanocomposite based on the (Ti,W)B2 phase is formed, which results in the highest hardness (33 GPa).