【作者】 刘学；

【导师】 姚可夫；

【作者基本信息】 清华大学 ， 材料科学与工程， 2015， 博士

【摘要】 金属微纳结构在催化、传感、检测和光学器件等领域具有广阔的应用前景。非晶合金因具有优异的热塑性成型能力和结构均匀特性,非常适宜于作为制备金属微纳结构的前驱材料。但现有的成型技术难以获得均匀的、大面积非晶合金微纳米结构。因此研究新的非晶合金微纳米结构成型方法,研究新型成型性能优异的非晶合金和扩展非晶合金微纳结构的应用领域具有重要意义。本文在实验研究的基础上提出了非晶合金模压热塑性成型方法,开发出非晶合金模压热塑性成型技术工艺。ANSYS定性模拟仿真结果和实验研究结果均表明,非晶合金模压热塑性成型技术能够消除传统自由压印热塑性成型中存在的压印热塑性成型后微结构不均匀的缺陷,制备出面积大、均匀性好的非晶合金微纳结构。与此同时,在前人的基础上得到了模压热塑性成型过程中的动力学充型公式,该公式预测结果与实验结果相吻合。采用开发的模压热塑性成型工艺,制备出了面积大、尺寸均匀的Pd40.5Ni40.5P19非晶态及晶态纳米线阵列,阵列中纳米线直径约为55 nm,长度可调。揭示了模压热塑性成型参数对纳米线阵列形貌和结构的影响规律以及纳米线晶化机制,实现了纳米线形貌和结构的可控制备。发现提高成型温度、成型压力和增加成型时间可增加纳米线长度。将制备的聚集型Pd40.5Ni40.5P19非晶合金纳米线阵列具有强的表面拉曼增强效应,同时获得了较大的增强因子和很好的空间重复性,为制备高空间重复性的表面拉曼增强基底提供了新的思路。研发出成本低、非晶形成能力大、热塑性成型能力优异和综合力学性能好的Ni62Pd19Si2P17非晶合金,其临界尺寸达11 mm以上。模压热塑性成型制备的Ni62Pd19Si2P17复杂微米结构具有成型精度高的特征,并可作为模具热压印成型制备有机玻璃等塑料和冷压印成型制备纯铜、纯铝和不锈钢等金属的复杂微米结构。Ni62Pd19Si2P17非晶合金可通过电化学脱合金获得表面纳米多孔结构,Zr48Cu36Ag8Al8非晶合金薄带和Zr-Cu-Ag-Al-O非晶态/晶态复合材料薄带可通过化学脱合金方法制备得到多种形态和结构的纳米多孔结构。通过将模压热塑性成型技术和脱合金方法相结合,制备出了基于Ni62Pd19Si2P17和Zr48Cu36Ag8Al8非晶合金的微纳米复合结构。更多还原

【Abstract】 Metallic micro/nano structures have wide potential applications in catalysis, sense, detection and optical devices. 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, it’s very hard to obtain large-area and uniform micro/nano MG structures by the existing technologies. Therefore, it’s meaningful to develop new MGs with excellent forming ability as well as new preparation method for micro/nano MG structures, and extend the application fields of micro/nano MG structures.The thermoplastic forming based die imprinting technique was proposed and developed on the basis of experimental study in present work. The experimental and ANSYS simulated results indicate that the die imprinting technique can effectively overcome the drawback of nonuniform structures in the free imprinting, and large-area as well as uniform micro/nano structures were successfully prepared by this technique. Meanwhile, a kinetic equation, which can describe the filling kinetics of viscous MG supercooled liquid during the die imprinting process, was obtained based on the previous research. The predictions based on the obtained kinetic equation are consistent with the experimental results.By employing the die imprinting technique, large-area and uniform Pd40.5Ni40.5P19 amorphous/crystalline metallic nanowire arrays(MNWAs) with nanowire diameters of about 55 nm and tailorable length have been prepared. The influence of the die imprinting parameters on the MNWAs’ morphologies and structures as well as the crystallization mechanism of the MNWAs have been investigated. The preparation of the MNWAs with tailorable morphologies and structures have been achieved. It has been found that increasing the processing temperature, pressure and time during the die imprinting can increase the length of the nanowires. The aggregated-type Pd40.5Ni40.5P19 MNWA exhibits strong surface enhanced Raman scattering(SERS) activity, and high SERS activity as well as excellent reproducibility were obtained, which provides important insights into the employment of MG materials for highly sensitive and reproducible SERS applications.Ni62Pd19Si2P17 MG with low cost, high glass-forming ability, excellent thermoplastic formability and good comprehensive mechanical properties was developed. The critical size of the Ni62Pd19Si2P17 MG is larger than 11 mm. The die imprinted Ni62Pd19Si2P17 complex micro/nano structures possess high forming precision, and is capable capable of serving as mould inserts for the hot embossing of polymers and the cold imprinting of metals.By employing the electrochemical dealloying, nanoporous structures were obtained on the surfaces of the Ni62Pd19Si2P17 MG samples. By employing the chemical dealloying, Cu-Ag bimetallic porous nanomembrane and Cu skeleton supported core-shell nanoporous Ag-Cu alloy were prepared based on the Zr48Cu36Ag8Al8 MG and the Zr-Cu-Ag-Al-O amorphous/crystalline composite ribbon samples, respectively. By combining the die imprinting technique with the dealloying method, micro and nano hierarchical structures based on Ni62Pd19Si2P17 and Zr48Cu36Ag8Al8 MGs were prepared.更多还原