Tuning nanostructured Ni-Nb metallic glass thin films by atomic fluence in magnetron sputtering

Abstract

Structure heterogeneity was demonstrated to be the key factor in determining material properties with respect to relatively uniform ones. Here, we reported a deposition power-related nanostructure modulation in magnetron sputtering Ni-Nb metallic glass thin films (MGTFs). With increasing deposition power from 15 W to 120 W, the deposition rate increases from ∼15.3 nm/min to ∼183.6 nm/min. Cauliflower-like morphology gradually changed to randomly distributed nanogranular particles, and the mechanical properties showed remarkable improvement by ∼37 % in nanoindentation hardness, ∼146 % in lateral tensile fracture strength, ∼56 % in micro-pillar compression yielding strength, as well as better wear-resistance and thermal stability. Higher deposition power possesses a larger deposited atom fluence onto the film surface, transferring more kinetic energy per unit time and possibly increasing the substrate temperature. The enhanced adatoms migration facilitated the formation of dense nanocolumn interfaces, resulting in improved mechanical properties. These results uncover the intrinsic relationship between nanostructured morphology and mechanical properties of MGTFs, and can serve as a reference for optimizing the properties of vapor-deposited MGTFs by deposition power.