Inﬂuence of the nitrogen content on the structure and properties of MoNbTaVW high entropy alloy thin ﬁlms Ao Xia a, * , Robin Dedoncker b , Oleksandr Glushko a, c , Megan J. Cordill a, c , Diederik Depla b , Robert Franz a a Department of Materials Science, Montanuniversit€ at Leoben, Franz-Josef-Strasse 18, 8700, Leoben, Austria b Department of Solid State Sciences, Ghent University, Krijgslaan 281(S1), 9000, Gent, Belgium c Erich Schmid Institute of Materials Science, Austrian Academy of Sciences, Jahnstrasse 12, 8700, Leoben, Austria article info Article history: Received 3 June 2020 Received in revised form 6 August 2020 Accepted 16 August 2020 Available online 20 August 2020 Keywords: Thin ﬁlm High entropy alloy Refractory metal Arc evaporation Sputter deposition Fragmentation test abstract The inﬂuence of nitrogen incorporation on the chemical composition, structure, mechanical, and elec- trical properties of refractory (MoNbTaVW) 1x N x high entropy alloy thin ﬁlms is investigated. The ﬁlms were synthesized by two different physical vapor deposition methods, cathodic arc deposition and direct current magnetron sputtering, onto silicon and polyimide substrates. Regardless of the deposition method, a change from body centered cubic to face centered cubic structure was observed with increasing nitrogen content in the ﬁlm. This structural change was accompanied by an increase in hardness as measured by nanoindentation but also by a material embrittlement as determined from tensile straining tests. © 2020 Elsevier B.V. All rights reserved. 1. Introduction The strive for thin ﬁlm materials superior to the present ones is inevitable to improve the productivity, efﬁciency and economy for various manufacturing industries. In this context, metallic high entropy alloys (HEAs) [1], also referred to as multi-principle element alloys, multi-component alloys [2,3] or complex concen- trated alloys [4e7], are a new class of materials that were devel- oped and intensively investigated during the last decade. They are characterized by their principal elemental composition, between 5 and 13 constituting elements in near equimolar ratios. It was argued that the high mixing entropy favors the formation of face- centered cubic (fcc) or body-centered cubic (bcc) single solid so- lution phases rather than intermetallic or other complex phases [1]. Even though there have been extensive studies on bulk HEAs in recent years, in comparison, only limited research has been con- ducted on HEA based nitride thin ﬁlms obtained by physical vapor deposition (PVD) [8e12]. The HEA studied in this work, MoN- bTaVW, has been investigated by Lee et al. [13, 14] who focused on the thermal, corrosion, high temperature electrical, and oxidation properties, while in our previous work, the structure, mechanical and electro-mechanical properties have been studied [15, 16]. HEA based nitrides are promising candidates for future appli- cations such as protective coatings for cutting tools [17], effective diffusion barriers in microelectronics [9, 18], or thermal barrier coatings for turbine blades due to their excellent mechanical, wear and friction properties, high strength, ductility, thermal stability, oxidation resistance, and fracture toughness [1 ,3, 18, 19]. Further- more, refractory HEAs and HEA nitrides are potential alloys for ultra-high temperature applications due to the high melting tem- peratures of up to 3500  C and high temperature strengths of the constituting elements [9,20]. Dedoncker and co-workers conducted studies on the inﬂuence of N on the structure and properties of CoCrCuFeNi HEA thin ﬁlms [21]. They observed a transition from the metallic fcc lattice to the nitride B1 (NaCl) structure with increasing N incorporation in the ﬁlm. The ﬁlms were obtained by direct current magnetron sputter deposition (DCMS) in different gas atmospheres with varying N 2 /Ar ratios and by engineering the composition of the constituting elements in the pressed powder targets. Yeh et al. have studied the inﬂuence of N on the structure and mechanical properties of (AlCoCrCuFeNi)N [11], (AlCrTaTiZr)N * Corresponding author. E-mail address: ao.xia@stud.unileoben.ac.at (A. Xia). Contents lists available at ScienceDirect Journal of Alloys and Compounds journal homepage: http://www.elsevier.com/locate/jalcom https://doi.org/10.1016/j.jallcom.2020.156740 0925-8388/© 2020 Elsevier B.V. All rights reserved. Journal of Alloys and Compounds 850 (2021) 156740