(TiZrNbHfTa)B2 films deposited by DC magnetron sputtering

DOI: 10.62564/M4-AO1138

Volodymyr Ivashchenko, Alexei Onoprienko, Olena Olifan, Alexei Sinelnichenko, Alexander Marchuk, Andrii Kovalchenko, Dmytro Vedel, Petro Mazur

Frantsevich Institute for Problems of Materials Science National Academy of Science of Ukraine


Recently, a new approach was proposed for alloy design which involves the mixing of several transition metal elements. These alloys were termed as “high-entropy alloys” (HEAs) [1]. Along with bulk materials the researches are carried out with HEA films or coatings doped with non-metal elements. In the present work we investigated the effect of negative substrate bias on the structure and mechanical properties of HEA- boride films. The films were characterized in terms of their microstructure, chemical bonds status, hardness and tribological properties. The (TiZrNbHfTa)B films were prepared by magnetron sputtering of the Ti-Zr-Nb-Hf-Ta-B target manufactured by hot pressing method of TiB2, ZrB2, HfB2, NbB2, and TaB2 powders. The films were deposited with negative bias voltage in the range of 0÷200 V applied to the substrates. The XRD analysis showed that the peaks in XRD patterns of as-deposited films cannot be recognized as the either diboride constituent of sputtered target. This allows suggestion on the formation of single-phase solid solutions of transition metal diborides used. The films are nanocrystalline with grain size calculated by Sherrer formula increased from 9.5 nm to 40 nm when increasing bias voltage from 0 to ‒200 V. The XPS results indicated formation of the following bonds in films: Ti-B, Ti-B-O, Zr-B, Nb-B, Hf-B, Hf-O, Ta-B. The Knoop hardness increased with bias voltage in the range of 0÷ -150 V, and then decreased with further increase of bias voltage. The results obtained clearly show that multi-element films exhibit an essentially higher hardness as compared to the most of bulk binary diborides used for deposition of (TiZrNbHfTa)B films presently studied. The tribological tests showed that the film deposited with Ubias= -200 V exhibited the least value of friction coefficient. This fact agrees with radical decrease in films hardness deposited under this condition.

Keywords
High-entropy film, structure, hardness, tribology

Acknowledgments
Not provided

References
[1] J.-W. Yeh, S.-K. Chen, S.-J. Lin, J.-Y. Gan, T.-S. Chin, T.-T. Shun, C.-H. Tsau, S.-Y. Chang, Nanostructured high-entropy alloys with multiple principal elements: novel alloy design concepts and outcomes, Adv. Eng. Mater., 2004, V. 6, №5, P. 299-303.