Growth of elastically-stiff, nanostructured, high-entropy alloy nitride, (VNbTaMoW)N/Al2O3(0001) thin film

We demonstrate the growth of 111-oriented, stoichiometric, B1-structured high-entropy alloy nitride (VNbTaMoW)N/Al2O3(0001) thin film via reactive magnetron sputtering and determine its elastic modulus E as 187 +/- 70 GPa using in situ buckling tests. Ab initio density functional theory calculations reveal that B1-MoN and B1-WN are structurally unstable, yet the nitride alloy with nearly equal fractions of parent nitrides is stable in B1 structure with E-111 along [111] around 270 GPa. Interestingly, E-111 values of the nitride alloys are higher than those expected from rule-of-mixture of all as well as the mechanically stable parent binary nitrides (B1-VN, NbN, and TaN). Our results suggest that cocktail effects, expected of high-entropy alloys, help not only stabilize a significant concentration of the unstable B1-WN and B1MoN but also result in an enhanced stiffness of (VNbTaMoW)N. (C) 2021 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

Automated summary

Research has shown that a high-entropy alloy nitride thin film was grown using reactive magnetron sputtering, with its elastic modulus determined through in situ buckling tests. It was found that the alloy was stable and had higher stiffness than the parent binary nitrides due to cocktail effects expected of high-entropy alloys.