飛秒激光燒蝕特種金屬的蝕除深度與機(jī)理研究
發(fā)布時(shí)間：2018-11-14 13:12
【摘要】：飛秒激光具有超快、超高、超強(qiáng)等特點(diǎn),在微納加工領(lǐng)域發(fā)揮出獨(dú)特的優(yōu)勢(shì)。鎳鈦形狀記憶合金和銅鋯非晶合金因其獨(dú)特的性能而應(yīng)用廣泛。飛秒激光與兩特種金屬材料相互作用過程非常復(fù)雜,激光與材料作用機(jī)制也會(huì)因?yàn)榧す鈪?shù)和材料的不同而有所不同。深入研究和探索飛秒激光燒蝕鎳鈦形狀記憶合金和銅鋯非晶合金兩特種金屬材料的蝕除深度以及物理機(jī)制,對(duì)降低材料的燒蝕性損傷,提高激光對(duì)材料的加工能力,完成加工工藝的系統(tǒng)優(yōu)化具有尤為重要的意義。本文采用雙溫模型結(jié)合分子動(dòng)力學(xué)的模擬方法模擬了飛秒激光燒蝕特種金屬的過程。主要做了以下幾個(gè)方面的工作:(1)模擬了典型脈寬飛秒脈沖激光與鎳鈦二元形狀記憶合金相互作用時(shí)能量密度對(duì)靶材燒蝕深度的影響。模擬了脈寬為100 fs,能量密度為0~125 m J/cm2的單脈沖激光照射90 nm厚鎳鈦合金薄膜的過程。模擬結(jié)果表明,飛秒單脈沖激光燒蝕鎳鈦二元形狀記憶合金會(huì)產(chǎn)生兩種不同的燒蝕相。當(dāng)激光能量密度比較低的時(shí)候,靶材的燒蝕深度比較低,并且深度與靶材的光學(xué)穿透深度相關(guān),燒蝕的結(jié)果表現(xiàn)出來為弱燒蝕相;激光的能量密度比較高的時(shí)候,燒蝕深度大幅度增加,燒蝕結(jié)果表現(xiàn)出來為強(qiáng)燒蝕相。(2)采用“拼花法”對(duì)高斯飛秒脈沖激光輻照鎳鈦靶材的形貌進(jìn)行預(yù)測(cè),發(fā)現(xiàn)使用較低能量密度的飛秒激光輻照靶材時(shí),能夠獲得底部較為平坦的燒蝕彈坑。(3)模擬了典型脈寬飛秒脈沖激光與銅鋯非晶合金相互作用時(shí)能量密度對(duì)電聲耦合時(shí)間的影響。發(fā)現(xiàn)能量密度越高電聲耦合時(shí)間越長(zhǎng),同時(shí)達(dá)到平衡時(shí)的溫度越高。(4)模擬了典型脈寬飛秒脈沖激光與銅鋯非晶合金相互作用時(shí)能量密度對(duì)靶材燒蝕深度的影響。發(fā)現(xiàn)銅鋯非晶合金的燒蝕閾值在40 m J/cm2附近;當(dāng)能量密度大于等于80 m J/cm2時(shí)靶材的燒蝕結(jié)果呈現(xiàn)強(qiáng)燒蝕相。另外由于非晶合金初始原子無序化,因此發(fā)生強(qiáng)燒蝕相前無需吸收能量破壞晶體結(jié)構(gòu),從而出現(xiàn)強(qiáng)燒蝕相的閾值較低。
[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.
【學(xué)位授予單位】：南華大學(xué)
【學(xué)位級(jí)別】：碩士
【學(xué)位授予年份】：2016
【分類號(hào)】：TG665
本文編號(hào)：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.
【學(xué)位授予單位】：南華大學(xué)
【學(xué)位級(jí)別】：碩士
【學(xué)位授予年份】：2016
【分類號(hào)】：TG665
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