Structural and microstructural evolution of amorphous Zr-Cu-Ag thin-film alloys under thermal constraint: An in situ approach

摘要

The thermal stability of magnetron-sputtered Zr-Cu-Ag thin films, presenting key-antibacterial properties against E. coli and S. aureus, is studied by using an in situ multiscale approach. This study is carried out to better understand the general evolution of these amorphous films under thermal constraint, and to determine their limit of use in aggressive conditions. The general crystallization behavior and structural stability are investigated by in situ X-ray diffraction (XRD) in heating mode, and completed at micro- and nano-scale by complementary electron microscopy characterizations. The global crystallization temperature of films, determined by XRD, is found between 200 degrees C and 400 degrees C depending on the composition. The in situ HT-ESEM (High Temperature - Environmental Scanning Electron Microscope) observations show that, for the composition with the lowest Zr/(Cu + Ag) ratio (Zr33Cu35Ag32), the crystallization process is followed by a total dewetting of the thin film. The Zr73Cu16Ag11 film is a thin film metallic glass (TFMG), and was also investigated at the nanoscale. In situ HT-TEM (High Temperature - Transmission Electron Microscope) allows observing the progressive crystallization of the TFMG, describing the different steps of transformation from the amorphous as-deposited structure, the individual formation of intermetallics and to the whole crystalline state. (C) 2020 Elsevier B.V. All rights reserved.