Femtosecond Laser Ablation Of Metallic Materials And Fabrication Of Micro-components

Using the femtosecond (fs) laser micromachining system, the experimental investigations of fs laser ablating and micromachining the new type of metallic material—amorphous alloy were performed. Combined with the theoretical simulation, the parameter optimization of fs laser micromachining stainless steel and nickel was conducted for fabrication and application of metallic microcomponents. The main contents, research conclusions and contributions to innovation are summarized as following:(1) The general physical processes and mechanisms of fs laser ablating metallic materials in the previous works were systematically analyzed and summarized. With the method of molecular dynamic simulation combined with the two-temperature model, the physical process of fs laser ablating nickels was theoretically simulated. The results show two regimes of fs laser ablation nickel under high and low fluences.(2) The architecture and working principle of the fs laser micromachining system, especially, the optics propagation and processing device, were described detailedly. Checking and analyzing of the fs laser parameters and their changes, such as pulse duration, spot size and spatial distribution of intensity were performed while the laser beam propagated through the system.(3) Femtosecond laser ablating and micromachining of a Zr-based amorphous alloy in air were investigated in detail for the first time. Laser-induced ablation and related effects were examined by means of scanning electron microscopy (SEM),energy dispersive X-ray analysis (EDX), transmission electron microscopy (TEM) and electron diffraction diagram (EDD). The ablation threshold of fs laser ablating the Zr-based amorphous alloy was determined. The results show that the surface morphology of single-pulse ablation region seems like a circular crater with edge upheaved; in the multi-pulse ablation region surface, periodic ripples and firn-like morphology appeared; slight oxidation occurred at high laser fluences, and the thickness of the oxidation layer is determined to be nano-scale. With selected parameters, micron-size scale holes and trenches machined without crystallization around the ablated region were achieved for the first time. The results show that femtosecond laser ablation with selected parameters is a promising method for non-crystalline micromachining of amorphous alloys. (4) Femtosecond laser direct fabrication of stainlesssteel and Ni microcantilever was investigated, and the laser processing parameters were optimized. The metallic microcantilevers of good quality with structure and dimensions according commendably with that of the designed cantilever were obtained. Using the fs laser fabricated metallic microcantilever, the cyclic fatigue test under corrosion was investigated for the first time. The testing results are very important for the design and application of metallic MEMS devices. Femtosecond laser direct fabricating various stainless steel micro-patterns, microstructures and components were also conducted to investigate the flexibility of fs laser micromachining technology. A microhole electrode mask was successfully fabricated for pulse laser deposition (PLD) experiments.