Structure And Properties Of Ni-based And Au-based Metallic Glass Thin Films

Metallic glass(MG)is also known as amorphous alloy.Due to its long-range disordered structure,there is more outstanding property than crystal for MG,such as high strength,high elastic limit and so on.With the development of microelectronic devices,the requirement of material miniaturization is more and more high,so in order to adapt to the application of micro-devices,unique metallic glass thin film(MGTF)is developed.Because of its small size,MGTFs are more excellent in plastic deformation.They can also be used as coatings for high temperature resistance,wear resistance and oxidation resistance,as well as some functional characteristics,such as high reflectivity.To study the property of the unique MGTFs,control the structure must be necessary.This paper selects the Ni-Nb as the research object,explores the substrate temperature(Tsub)on the structure and property of Ni-Nb MGTF,reveals the mechanism of its structure with Tsub change,and explains the Ni-Nb MGTF property improvement from structure.In addition,Au-Cu-Si is selected as the research object to explore the influence of film thickness on the structure and properties of Au-Cu-Si MGTF,analyze the law of dynamic coarsening during the growth process of Au-Cu-Si MGTF,and study its optical property and deformation mode transformation.The main conclusions are as follows:(1)By controlling Tsub of the magnetron sputtering,Ni-Nb MGTFs were prepared at 293 K to 823 K.The cross-section morphology of Ni-Nb MGTF was columnar structure and the top-surface topography was particle structure.At the same time,it was found that microcrack structures were appeared in the top-surface morphology of the film at a lower Tsub.As Tsub increased,these cracks were gradually eliminated,and the column and particle sizes were gradually decreased.The change was more obvious when Tsub=573 K,and the sizes were increased again at Tsub of 823 K.From the point of density and roughness,there was also a significant change at 573 K for Ni-Nb MGTFs.The change of film structures with Tsub can be attributed to competitive relationship between surface diffusion and shadow effect during film deposition.(2)The optical properties of Ni-Nb MGTFs were tested by ellipsometer and reflection spectrometer,including refractive index,extinction coefficient and reflectivity.The thermal stability and oxidation resistance of Ni-Nb MGTFs were studied by annealing.At the same time,the mechanical properties of Ni-Nb MGTFs were studied by nanoindentation instrument,friction microscope and bending instrument,including hardness,elastic modulus,wear resistance and deformation mode transformation from non-uniform deformation to uniform deformation.After analysis,it was found that there were better optical properties,thermal stability,oxidation resistance and mechanical properties for Ni-Nb MGTFs prepared at higher Tsub,which can be explained by their structural differences.(3)Columnar structures were not shown when the film thickness was thin for Au-Cu-Si MGTFs,while columnar structures with unclear interface were appeared in the thick film.During the growth process,the law of dynamic coarsening of Au-Cu-Si MGTFs were analyzed by atomic force microscopy.The optical properties of Au-Cu-Si MGTFs were studied.Meanwhile,the deformation mode transformation of Au-Cu-Si MGTFs from non-uniform deformation to uniform deformation was studied.Although there was a large T/Tg for Au-Cu-Si MGTF s,the brittleness of the system was increased due to the presence of non-metallic element Si.