Molecular dynamics simulation of femtosecond ablation and spallation with different interatomic potentials
Molecular dynamics simulation of femtosecond ablation and spallation with different interatomic potentials
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DOI：
10.1016/j.apsusc.2009.04.082
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发表时间：
2009-09-30
影响因子：
6.7
通讯作者：
Nishihara, K.
中科院分区：
文献类型：
--
作者：
Zhakhovskii, V. V.;Inogamov, N. A.;Nishihara, K.
利用脉冲宽度约为40~100ps的飞秒激光脉冲(L)对靶材进行快速加热，形成热机械应力态。Al和Au在50 nm处和100 nm处的亚表层前沿空化是其卸载引起的。在材料内部传播的压缩波以稀疏波的形式射向目标的背面。最后一种可能会产生裂缝和后部剥落。给出了Al和Au金属在fsLP作用下烧蚀和层裂的MD模拟结果。结果表明，所用的EAM电位(Mishin et al.和我们的新模型)预测了不同的烧蚀和层裂阈值对Al吸收通量的影响：烧蚀F-a=60{65}mJ/cm(2)和层裂F-S=120{190}mJ/cm(2)，其中括号中的数字表示相应的Mishin势值。层裂临界点的应变率为4.3×10(9)1/S。模拟得到的Al的层裂强度为7.4{8.7}Gpa，明显低于利用自由后表面速度分布的声学近似得到的10.3{14}Gpa。用新的EAM势对金进行分子动力学模拟，获得了约120mJ/cm(2)的烧蚀阈值Fa和110 nm的凹坑深度。他们很好地赞同实验。(C)2009爱思唯尔B.V.保留所有权利。
Fast heating of target material by femtosecond laser pulse (fsLP) with duration tau(L) similar to 40 similar to 100 fs results in the formation of thermomechanically stressed state. Its unloading may cause frontal cavitation of subsurface layer at a depth of 50 nm for Al and 100 nm for Au. The compression wave propagating deep into material hits the rear- side of the target with the formation of rarefaction wave. The last may produce cracks and rear- side spallation. Results of MD simulations of ablation and spallation of Al and Au metals under action fsLP are presented. It is shown that the used EAM potentials (Mishin et al. and our new one) predict the different ablation and spallation thresholds on absorbed fluence in Al: ablation F-a = 60{65} mJ/cm(2) and spallation F-s = 120{190} mJ/cm(2), where numbers in brackets {} show the corresponding values for Mishin potential. The strain rate in spallation zone was 4.3 X 10(9) 1/s at spallation threshold. Simulated spall strength of Al is 7.4{8.7} GPa, that is noticeably less than 10.3{14} GPa obtained from acoustic approximation with the use of velocity pullback on velocity profile of free rear surface. The ablation threshold Fa approximate to 120 mJ/cm(2) and crater depth of 110 nm are obtained in MD simulations of gold with the new EAM potential. They agree well with experiment. (C) 2009 Elsevier B. V. All rights reserved.