[Back]

V. Moraes, C. Fuger, R Hahn, T. Wojcik, M. Arndt, P. Polcik, P.H. Mayrhofer, H. Riedl:
"Ternary diboride based thin films from scratch: Is WB2-z a proper base system for future concepts?";
Talk: 65. Metallkunde-Kolloquium, Lech; 2019-04-24 - 2019-04-26.

Future tasks in many different fields of academia and industry are directed towards environmental sustainability, and hence the application of ultra-stable materials featuring novel properties. Especially, transition metal borides (TMBs) exhibit a tremendous potential to be applied in various applications ranging from wear and corrosion resistant coatings, to superconductive thin films, or as superhard and extremely stable protective layers in diverse fields of engineering. In contrast to classic diborides - such TiB2, ZrB2, WB2, or ReB2, which has been theoretically predicted to be the most incompressible material exceeding the properties of diamond - are ternary or even multinary diborides (e.g. W1-xMxB2) relatively unexplored. Based on Density Functional Theory studies is the stabilization of ternary diborides dominated by two hexagonal competing structure types - α AlB2-prototype vs. ω-W2B5-x-prototype - as well as structural defects (especially vacancies). Within this study, we want to address the challenges in depositing ternary diborides in a prototype based on α-W1-xMxB2 solid solutions, applying non-reactive sputtering processes, whereas M represents different transition metals such as Ta or Ti. Due to the strong tendency of WB2 to be stabilized through structural defects in the AlB2 structure type - exhibiting distinct advantages concerning the relatively low ductility of TMBs in general - it can be an excellent base system for studying various alloying concepts utilizing physical vapour deposition (PVD) techniques. To gain an in-depth insight on the specific effects of selected transition metals on α structured W1-xMxB2 coatings, we correlated the synthesis parameter with structure property relationships applying a set of high-resolution characterization techniques as well as micro-mechanical testing methods.

Project Head Helmut Riedl:
CDL-SEC