Theoretical And Experimental Studies On Femtosecond Laser Micromachining Of Metals

In this dissertation, some theoretical and experimental studies on femtosecond laser micro-machining of metals are presented. The main contents in this dissertation are classified as follows. Double-Temperature Equation (DTE) theory is used to investigate temperature evolution of electron-lattice system. Ablating threshold, surface morphology and component changes are studied in experiment, and then parametric optimization of femtosecond laser micromachining is investigated. The work shows there is bright prospect in the field of femtosecond laser micromachining of metallic materials.(1) The ablating process on nickel by femtosecond laser is simulated by DTE, which is formatted simply. Systematical analysis is done to investigate the relationship between electron-phonon coupling constant, laser duration, laser fluence and the temperature of top surface electron and lattice. The temperature of electron and lattice in depth direction is analyzed at four representative moments from 50fs to 10ps.(2) Ablating threshold of nickel is studied in experiment. Technical condition and parametric optimization of femtosecond laser micromachining of nickel is investigated, which is used to fabricate nickel microcantilever.(3) Femtosecond laser micromachining of amorphous alloy is investigated and some researches are carried out as bellows:1) Research in ablating threshold: the single-pulse ablating threshold is obtained and the incubation and accumulation effect is found in multi-pulse ablation.2) Research in micro-drilling and micro-cutting: Morphology and oxidation of the ablated area is investigated. The result demonstrates that thermal effect may exist in femtosecond laser processing. Oxidation and nano-ripple also appear in the experiment.3) Invariability of noncrystalline structure: Results of TEM and EDD show crystallization doesn't occur in the process of femtosecond laser micromachining of amorphous alloy.