Refractory high entropy TiTaZrHfW-N/Si3N4 nano-layered alloy thin film’s oxidation resistance

Refractory high entropy TiTaZrHfW-N/Si 3 -N 4 nano-layered alloy thin films are investigated to study the effect of nano-layered architecture and silicon (Si) mean content on their structural, mechanical, thermal properties and oxidation behavior. The films are deposited using direct current (DC) magnetron sputtering of separate Si and TiTaZrHfW targets. The Si mean content is controlled by tailoring the power discharge applied to the Si target. The deposition process led to a nano-layered architecture where Si 3 N 4 (amorphous) and TiTaZrHfW-N (nano-crystalized NaCl FCC type structure) are alternated. By increasing the thickness of Si 3 N 4 nano-layers, the Si mean content increases. All coatings are found to have good thermal stability after annealing under vacuum at 900 °C. Increasing Si mean content reduces the film’s hardness; however, the annealing treatment at 900 °C improves it. A super-hardness of 41 GPa is found for the post-annealed Si-free film. Si 3 N 4 nano-layers enhance the oxidation resistance at elevated temperatures of 600, 700, and 800 °C. This oxidation resistance is further enhanced by increasing the nano-layer’s period and also by increasing the density of the films. • Refractory high entropy TiTaZrHfW-N/Si 3 -N 4 nanolayered thin films deposited by reactive magnetron sputtering. • Effect of Si alloying on TiTaZrHfW(-N) properties. • Nanolayered architecture structure alternating Si 3 N 4 (amorphous) and TiTaZrHfW-N (nano-crystalized NaCl FCC). • Si 3 N 4 nano-layers enhance oxidation resistance at elevated temperatures (600, 700, and 800 °C). • Oxidation resistance further improves with increased nano-layers period and film density.