The influence of WS2 layer thickness on microstructures and mechanical behavior of high-entropy (AlCrTiZrNb)N/WS2 nanomultilayered films

Abstract

High-entropy (AlCrTiZrNb)N/WS2 nano-multilayers with different thicknesses of WS2 layers were synthesized by reactive magnetron sputtering. The influence of MoS2 layers on the microstructure of the nano-multilayered films was studied by X-ray diffraction (XRD), scanning electron microscope (SEM), and high-resolution transmission electron microscope (HRTEM). Mechanical properties were examined through nanoindentation, HSR-2M coating friction and wear tester. The results show that when the thickness of the WS2 layer is less than 1.2 nm, the WS2 layer can be transformed into a cubic phase under the action of the (AlCrTiZrNb)N layer template, and a coherent epitaxial interface layer is formed between the two layers, resulting in an increase in hardness. The maximum values of hardness and elastic modulus of the high-entropy (AlCrTiZrNb)N/WS2 film are 22.5 GPa and 300.6 GPa, respectively, when the WS2 layer thickness reaches 1.2 nm. As the thickness of the WS2 layer further increases, the WS2 layer cannot maintain the cubic structure and the epitaxial growth interface is destroyed, resulting in a decrease in the hardness. The friction coefficient of the (AlCrTiZrNb)N/WS2 nano-multilayered film is lower than that of the (AlCrTiZrNb)N monolithic film.