Synthesis and characterization of the ceramic refractory metal high entropy nitride thin films from Cr-Hf-Mo-Ta-W system

High entropy alloy and nitride coatings from the Cr-Hf-Mo-Ta-W system were deposited by reactive magnetron sputtering from elemental segmented targets. The study aimed to investigate the effects of deposition parameters on the microstructure and mechanical properties of this novel multicomponent material. Samples without ni-trogen flow and under different nitrogen flows were prepared in two series of samples prepared at ambient temperature and at 750 degrees C. The proportion of metallic elements varied with increasing nitrogen flow. The ni-trogen content revealed saturation below 50 % under high flow. The thin films showed a different microstructure depending on the deposition conditions, from a single nanocrystalline bcc phase (a = 3.174 angstrom) in the metallic sample prepared at 750 degrees C without nitrogen flow, through an amorphous structure under low nitrogen flow to a major nanocrystalline NaCl-type fcc nitride phase (a = 4.186-4.268 angstrom, in agreement with the ab-initio predicted values) in samples deposited under high nitrogen flow. The cross-section morphology of the amorphous sample was very homogeneous, while the samples with a major fcc nitride phase showed a typical columnar morphology. Overall, the films revealed hardness and Young's modulus up to 20.3 GPa and 471 GPa, respec-tively, for the fcc nitride coating. The experimental values of Young's modulus were in good agreement with the values of directional [100] Young's modulus obtained by ab-initio calculations. The results of our research showed that coatings consisting of bcc and fcc phases could be produced by magnetron sputtering with inter-esting mechanical properties such as high Young's modulus. Moreover, the results contribute to the under-standing of the influence of the nitrogen flow on the microstructural features such as crystallite size, vacancies in the lattice, and lattice parameter change.

Automated summary

High entropy alloy and nitride coatings from the Cr-Hf-Mo-Ta-W system were deposited by reactive magnetron sputtering. The effects of deposition parameters on the microstructure and mechanical properties of the coatings were investigated. The results showed that the deposition conditions influenced the microstructure of the coatings, with high nitrogen flow leading to the formation of a major fcc nitride phase with higher hardness and Young's modulus. The study provides insights into the influence of nitrogen flow on the microstructural features of the coatings.