飞秒激光烧蚀特种金属的蚀除深度与机理研究
发布时间：2018-11-14 13:12
【摘要】：飞秒激光具有超快、超高、超强等特点,在微纳加工领域发挥出独特的优势。镍钛形状记忆合金和铜锆非晶合金因其独特的性能而应用广泛。飞秒激光与两特种金属材料相互作用过程非常复杂,激光与材料作用机制也会因为激光参数和材料的不同而有所不同。深入研究和探索飞秒激光烧蚀镍钛形状记忆合金和铜锆非晶合金两特种金属材料的蚀除深度以及物理机制,对降低材料的烧蚀性损伤,提高激光对材料的加工能力,完成加工工艺的系统优化具有尤为重要的意义。本文采用双温模型结合分子动力学的模拟方法模拟了飞秒激光烧蚀特种金属的过程。主要做了以下几个方面的工作:(1)模拟了典型脉宽飞秒脉冲激光与镍钛二元形状记忆合金相互作用时能量密度对靶材烧蚀深度的影响。模拟了脉宽为100 fs,能量密度为0~125 m J/cm2的单脉冲激光照射90 nm厚镍钛合金薄膜的过程。模拟结果表明,飞秒单脉冲激光烧蚀镍钛二元形状记忆合金会产生两种不同的烧蚀相。当激光能量密度比较低的时候,靶材的烧蚀深度比较低,并且深度与靶材的光学穿透深度相关,烧蚀的结果表现出来为弱烧蚀相;激光的能量密度比较高的时候,烧蚀深度大幅度增加,烧蚀结果表现出来为强烧蚀相。(2)采用“拼花法”对高斯飞秒脉冲激光辐照镍钛靶材的形貌进行预测,发现使用较低能量密度的飞秒激光辐照靶材时,能够获得底部较为平坦的烧蚀弹坑。(3)模拟了典型脉宽飞秒脉冲激光与铜锆非晶合金相互作用时能量密度对电声耦合时间的影响。发现能量密度越高电声耦合时间越长,同时达到平衡时的温度越高。(4)模拟了典型脉宽飞秒脉冲激光与铜锆非晶合金相互作用时能量密度对靶材烧蚀深度的影响。发现铜锆非晶合金的烧蚀阈值在40 m J/cm2附近;当能量密度大于等于80 m J/cm2时靶材的烧蚀结果呈现强烧蚀相。另外由于非晶合金初始原子无序化,因此发生强烧蚀相前无需吸收能量破坏晶体结构,从而出现强烧蚀相的阈值较低。
[Abstract]:Femtosecond laser has the characteristics of super fast, super high and super strong, and plays a unique advantage in the field of micro-nano processing. Nickel-titanium shape memory alloys and copper-zirconium amorphous alloys are widely used because of their unique properties. The interaction process between femtosecond laser and two special metal materials is very complicated, and the mechanism of laser and material interaction will be different because of the difference of laser parameters and materials. Deeply studying and exploring the etching depth and physical mechanism of femtosecond laser ablation of Ni-Ti shape memory alloy and Cu-Zr amorphous alloy, which can reduce the ablative damage of the material and improve the processing ability of the laser. It is of great significance to complete the system optimization of machining process. In this paper, the process of femtosecond laser ablation of special metals is simulated by double temperature model and molecular dynamics simulation. The main works are as follows: (1) the effects of energy density on the ablation depth of the target are simulated when the typical pulse width femtosecond pulse laser interacts with Ni-Ti binary shape memory alloy. The process of 90 nm thick Ni-Ti alloy films irradiated by single pulse laser with a pulse width of 100 fs, and energy density of 0 ~ 125m J/cm2 was simulated. The simulation results show that there are two different ablative phases in Ni-Ti binary shape memory alloy by femtosecond monopulse laser ablation. When the laser energy density is low, the ablation depth of the target is relatively low, and the depth is related to the optical penetration depth of the target. The ablation results show weak ablation phase. When the laser energy density is relatively high, the ablation depth increases greatly, and the ablation results show strong ablative phase. (2) the morphology of Ni-Ti target irradiated by Gao Si femtosecond pulse laser is predicted by "mosaic method". When the target is irradiated by femtosecond laser with lower energy density, The ablative crater with flat bottom can be obtained. (3) the effect of energy density on the electro-acoustic coupling time of typical pulse width femtosecond pulse laser interacting with Cu-Zr amorphous alloy is simulated. It is found that the higher the energy density the longer the electro-acoustic coupling time and the higher the temperature at the same time. (4) the influence of energy density on the ablation depth of the target is simulated when the typical pulse width femtosecond pulse laser interacts with Cu-Zr amorphous alloy. It is found that the ablation threshold of Cu-Zr amorphous alloy is about 40 m J/cm2, and when the energy density is greater than or equal to 80 m J/cm2, the ablation results of the target show a strong ablation phase. In addition, due to the initial atomic disordering of amorphous alloys, no energy absorption is required to destroy the crystal structure before the strong ablation phase occurs, thus the threshold of strong ablation phase is lower.
【学位授予单位】：南华大学
【学位级别】：硕士
【学位授予年份】：2016
【分类号】：TG665
本文编号：2331249
[Abstract]:Femtosecond laser has the characteristics of super fast, super high and super strong, and plays a unique advantage in the field of micro-nano processing. Nickel-titanium shape memory alloys and copper-zirconium amorphous alloys are widely used because of their unique properties. The interaction process between femtosecond laser and two special metal materials is very complicated, and the mechanism of laser and material interaction will be different because of the difference of laser parameters and materials. Deeply studying and exploring the etching depth and physical mechanism of femtosecond laser ablation of Ni-Ti shape memory alloy and Cu-Zr amorphous alloy, which can reduce the ablative damage of the material and improve the processing ability of the laser. It is of great significance to complete the system optimization of machining process. In this paper, the process of femtosecond laser ablation of special metals is simulated by double temperature model and molecular dynamics simulation. The main works are as follows: (1) the effects of energy density on the ablation depth of the target are simulated when the typical pulse width femtosecond pulse laser interacts with Ni-Ti binary shape memory alloy. The process of 90 nm thick Ni-Ti alloy films irradiated by single pulse laser with a pulse width of 100 fs, and energy density of 0 ~ 125m J/cm2 was simulated. The simulation results show that there are two different ablative phases in Ni-Ti binary shape memory alloy by femtosecond monopulse laser ablation. When the laser energy density is low, the ablation depth of the target is relatively low, and the depth is related to the optical penetration depth of the target. The ablation results show weak ablation phase. When the laser energy density is relatively high, the ablation depth increases greatly, and the ablation results show strong ablative phase. (2) the morphology of Ni-Ti target irradiated by Gao Si femtosecond pulse laser is predicted by "mosaic method". When the target is irradiated by femtosecond laser with lower energy density, The ablative crater with flat bottom can be obtained. (3) the effect of energy density on the electro-acoustic coupling time of typical pulse width femtosecond pulse laser interacting with Cu-Zr amorphous alloy is simulated. It is found that the higher the energy density the longer the electro-acoustic coupling time and the higher the temperature at the same time. (4) the influence of energy density on the ablation depth of the target is simulated when the typical pulse width femtosecond pulse laser interacts with Cu-Zr amorphous alloy. It is found that the ablation threshold of Cu-Zr amorphous alloy is about 40 m J/cm2, and when the energy density is greater than or equal to 80 m J/cm2, the ablation results of the target show a strong ablation phase. In addition, due to the initial atomic disordering of amorphous alloys, no energy absorption is required to destroy the crystal structure before the strong ablation phase occurs, thus the threshold of strong ablation phase is lower.
【学位授予单位】：南华大学
【学位级别】：硕士
【学位授予年份】：2016
【分类号】：TG665
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