Effect of geometry measurements on characteristics of femtosecond laser ablation of HR4 nickel alloy
Effect of geometry measurements on characteristics of femtosecond laser ablation of HR4 nickel alloy
复制标题
DOI：
10.1016/j.optlaseng.2014.07.011
复制
发表时间：
2015
影响因子：
4.6
通讯作者：
T. See;Zhu Liu;Hong Liu;Lin Li;J. Chippendale;Simon Cheetham;Steve Dilworth
中科院分区：
文献类型：
--
作者：
T. See;Zhu Liu;Hong Liu;Lin Li;J. Chippendale;Simon Cheetham;Steve Dilworth
采用脉冲宽度100 fs、波长800 nm、重复频率1 kHz的钛宝石飞秒激光对HR 4镍基铸造合金进行了烧蚀实验研究。基于点烧蚀和线烧蚀两种烧蚀方法的烧蚀几何形状，估算了激光与材料相互作用的烧蚀特性参数，即烧蚀阈值、光穿透深度和孕育因子。研究表明，单脉冲烧蚀阈值与激光能量密度和脉冲数有关。烧蚀阈值随着NOP的增加而减小，在NOP处，由于孵化效应，烧蚀阈值达到渐近值。通过改变激光能量密度，确定了两种烧蚀机制，即低能量密度烧蚀机制和高能量密度烧蚀机制。前者由光学穿透深度决定，后者由能量穿透深度决定。同时还观察到，基于线烧蚀直径得到的激光材料相互作用参数与点烧蚀得到的参数一致，而与基于线烧蚀深度得到的参数不一致。结果表明，基于烧蚀直径的激光材料相互作用参数的评价比基于烧蚀深度的激光材料相互作用参数的评价更可靠。HR 4镍合金的烧蚀阈值（低注量烧蚀区域）估计为F th 1= 0。39 J/cm 2，孵育因子λ = 0.8，光学穿透深度为47.3nm。
This paper presents an investigation on ablation characteristics of HR4 nickel cast alloy with a Ti: Sapphire femtosecond laser (100 fs pulse width, 800 nm wavelength and 1 kHz repetition rate). The ablation characteristics including laser material interaction parameters, ie ablation threshold, optical penetration depth and incubation factor are estimated based on ablated geometries from two ablation methods, ie spot ablation and line ablation. The work shows that the single pulse ablation threshold is dependent on the laser fluence and the number of pulses (NOP). The ablation threshold decreases with the NOP, where it reaches an asymptotical value due to incubation effect. By varying the laser fluence, two ablation regimes are identified which are the low fluence ablation regime and the high fluence ablation regime. The former is governed by optical penetration depth; and the latter is governed by the energy penetration depth. It is also observed that the laser material interaction parameters obtained based on ablation diameters through the line ablation agree with the values obtained through the spot ablation but not with those obtained based on ablated depth through the line ablation. It is found that the evaluation of the laser material interaction parameters based on ablated diameters is more reliable compared to those based on ablated depth. The ablation threshold (low fluence ablation region) for the HR4 nickel alloy is estimated to be F th 1= 0. 39 J/cm 2 with the incubation factor, ξ= 0.8 and optical penetration depth of 47.3 nm.