Effect of deposition rate on the structure and properties of NiNb metallic glass thin films

By investigating the formation mechanism of thin films prepared via physical vapor deposition at different deposition rates, the structure and properties of metallic glass thin films (MGTFs) can be tuned. Here, we report the structure and properties of Ni 60 Nb 40 MGTFs by controlling deposition rate in a wide range. In addition to the deposition rate, the structure and performance of MGTFs are also affected by the temperature of the deposited atoms, i.e. the film temperature. The correlation between film temperature T and deposition rate q is as: T = T b + A exp ( − h ρ C p q ) . The dominate structural formation mechanism for MGTFs prepared at different deposition rates is based on the competition among surface relaxation, shadowing effect, and atomic diffusion. It indicates that when the deposition rate is below the subcritical deposition rate q c , the film structure is mainly affected by surface relaxation. When the deposition rate falls between the subcritical deposition rate q c and the upper critical deposition rate q m , the film structure is predominantly determined by shadowing effect. When the deposition rate exceeds the upper critical rate q c , the film structure is mainly affected by atomic diffusion. This transition in the structural formation mechanism directly leads to a non-monotonic “first decrease then increase” behavior in the modulus, hardness, and resistance to plastic deformation, which is highly consistent with the microstructural evolution. This study not only identifies a clear processing window for fabricating high-performance Ni 60 Nb 40 MGTFs but also deepens the fundamental understanding of the processing-structure-property relationship in physical vapor deposition.