Fabrication And Structural Evolution Of Micro-Nano Structures Based On Au-Based Metallic Glass

The Au-based micro/nano structures have important applications in catalysis,sense,and optical devices.Therefore,it is of great importance to develop convenient preparation methods of Au-based micro-nano structures.Due to the excellent thermoplastic forming ability as well as the uniform and isotropic structure,metallic glasses（MGs）are very suitable for the synthesis of micro/nano structures by the imprinting and dealloying methods.However,the uniformity of the micro/nano structure prepared by free-imprinting is relatively poor,and dealloying can only obtain single porous structures.Therefore,it is necessary to carry out further investigation on the preparation of Au-based micro-nano structures from MGs.Uniform Au-based nanorod arrays（MNAs）was prepared by die-imprinting technology based on Au₄₉Ag_5.5Pd_2.3Cu_26.9Si_16.3 MG in this paper,which can effectively overcome the non-uniformity and poor-reproducibility in the traditional free-imprinting.The influence of imprinting parameters on the morphology and microstructure of the MNAs was studied.The preparation of the MNAs with tailorable morphologies and structures have been achieved.It is found that the height of the nanorods increases with the extending time and increasing pressure in the constant temperature die-imprinting process.It has an inhibitory effect on crystallization by reducing the imprinting time or increasing the imprinting pressure.The prepared Au-based MNAs was subjected to isothermal oxidation treatment.It is found that the prepared Au-based MNAs exhibit enhanced oxidation resistance with extending die-imprinting time..In this paper,Au-based nanoporous structure was prepared by dealloying the Au₄₉Ag_5.5Pd_2.3Cu_26.9Si_16.3 MG ribbon.The feature size of the pores varies from from ten nanometers to several hundred nanometers.The influence of dealloying parameters on the morphology and composition of Au-based nanoporous structures was studied.The transition from single connected pores to three-dimensional biconnected pores was realized.It is found that with extending dealloying time and increasing the concentration of the corrosive solution,the ligaments in the porous structure gradually become coarser,the pore size gradually becomes larger,and the corrosion depth increases.The prepared Au-based porous structure was subjected to isothermal oxidation treatment.It is found that reducing the concentration of dealloying and shortening the time of dealloying can improve the oxidation resistance of the Au-based nanoporous structureBased on the basis of the above research,the Au-based MNAs prepared by die-imprinting was dealloyed in this paper.Au-based multiple nanocomposites composed of porous gold substrate and Au-based MNAs were prepared.The preliminary morphology control of the multiple nanocomposite structure can be realized by changing the dealloying time and concentration.With extending dealloying time and increasing dealloying solution concentration,the size of the pore and ligament in the porous Au substrate increases,while the diameter of the nanorods decrease.Besides that,sharp protrusions gradually forme on the nanorods,and the Au-based multiple nanocomposites becomes rougher.The prepared Au-based multiple nanocomposites were subjected to isothermal oxidation treatment.Appropriately reducing the concentration of dealloying and shortening the time of dealloying can improve their oxidation resistanceThe obtained results may provide effective solutions for the drawbacks of the Au-based micro/nano structures prepared by imprinting and dealloying of MGs and insights into the preparation of Au-based multiple nanocomposites.