Microstructural evolution and thermal stability of magnetron-sputtered TiAlNiVN HEA films deposited on Al2024

Abstract

In this study, TiAlNiVN HEA films were deposited on Al2024 substrates by magnetron sputtering using different Al and V target currents in order to investigate the influence of composition on microstructural evolution and thermal stability. The deposited films, named A1, A2, and A3, were subsequently subjected to thermal treatment at 300, 400, and 500 °C, followed by rapid cooling to room temperature. Structural, chemical, and surface-related changes associated with the thermal treatment were systematically examined using X-ray diffraction (XRD), scanning electron microscopy (SEM), energy-dispersive spectroscopy (EDS), and 3D profilometer. Cross-sectional SEM analyses revealed a gradual increase in film thickness with increasing target currents, confirming the strong dependence of deposition rate on sputtering conditions. As-deposited films exhibited an amorphous or weakly crystalline structure, while thermal treatment up to 400 °C preserved this structural state with only limited surface oxidation. In contrast, thermal treatment at 500 °C led to pronounced phase evolution, including the formation of oxide- and intermetallic-related phases, accompanied by a significant increase in oxygen content. These changes were further reflected in surface morphology, where severe roughening, local blistering, and loss of surface continuity were observed. Indentation-induced crack analyses indicated that the films retained stable crack behavior after 300 and 400 °C treatments, whereas extensive crack initiation and propagation occurred after exposure to 500 °C. Overall, the results demonstrate that TiAlNiVN films maintain structural and surface stability up to 400 °C, while 500 °C represents a critical thermal threshold leading to accelerated degradation.