Stoichiometry, structure and mechanical properties of co-sputtered Ti 1-x Ta x B 2±Δ coatings

Posted on by Mária Čaplovičová

GRANČIČ, B. – PLEVA, Milan – MIKULA, M. – ČAPLOVIČOVÁ, Mária – SATRAPINSKYY, L – ROCH, Tomáš – TRUCHLÝ, M. – SAHUL, Martin – GREGOR, M. – ŠVEC, Peter, Sr. – ZAHORAN, Miroslav – KÚŠ, Peter

In Surface & Coatings Technology. Vol. 367, June (2019)

https://doi.org/10.1016/j.surfcoat.2019.04.017

Abstract

Magnetron co-sputtering from TiB2 and TaB2 stoichiometric targets is used to prepare AlB2-prototype ternary Ti1-xTaxB2±Δ solid solution, with x in the range from 0 to 1. Using this technique, the boron-to-metal ratio (B/Me) varies with the actual Ti and Ta content. The boron-to‑tantalum ratio can be increased by decreasing the TaB2 target voltage, which has a considerable effect on the coating structure. Coatings with B/Me > 2 reveal highly textured nanocolumnar structure, while the coatings with B/Me < 2 tend to be nanocrystalline (without any preferred crystallite orientation) or amorphous. All the deposited coatings have a hardness higher than 32 GPa. The under-stoichiometric (B/Me < 2) coatings show material pile-up around the cube-corner indent edges, an indication for plastic flow and increased ductility.