Investigation of structure and mechanical properties of TiZrHfNiCuCo high entropy alloy thin films synthesized by magnetron sputtering

Abstract

Nano-composite-structured thin films reinforced by two phases, such as a nanocrystallite TiN phase distributed in an amorphous Si3N4 matrix, have received increasing attention due to their extraordinary mechanical properties. In the present study, a novel TiZrHfNiCuCo high entropy alloy (HEA), which contains two different body-centered-cubic phases in bulk form, was utilized with the aim of developing nano-composite-structured HEA thin films via a reactive direct current magnetron sputtering. The HEA films were prepared by controlling various sputtering parameters, such as sputtering power/time and amount of N2 gas flow. The microstructure and mechanical properties of the TiZrHfNiCuCo HEA metallic and nitride films were investigated using scanning-electron microscopy (SEM), X-ray diffraction (XRD), transmission-electron microscopy (TEM), and nanoindentation. It was observed that the TiZrHfNiCuCo HEA thin films are composed of a single phase (amorphous or face-centered-cubic phase) under the current process parameters, and the mechanical properties are inferior to other HEA thin films. Based on these results, the effect of the microstructure on the mechanical properties and possible strategy to achieve the nano-composite-structured thin films are discussed.