Molecular dynamics analyses of the femtosecond laser-induced grain boundary spallation
Molecular dynamics analyses of the femtosecond laser-induced grain boundary spallation
复制标题
飞秒激光诱导晶界散裂的分子动力学分析
DOI：
10.29979/jcsme.200712.0004
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发表时间：
2007
期刊：
影响因子：
--
通讯作者：
Pei
中科院分区：
文献类型：
--
作者：
H. Lai;Pei
以往利用分子动力学(MD)模拟激光诱导烧蚀的研究大多集中在激光与理想单晶物质的相互作用上。因此，由于没有考虑晶界的影响，这一结果可能会低估抛射团簇的烧蚀产额和尺寸分布。本模型首次尝试用标准的Lennard-Jones(L-J)分子动力学模拟来研究飞秒脉冲激光对多晶材料晶界可能产生的层裂效应。用不同的激光入射能量密度和吸收系数表征了晶界的动态行为和结构演化。模拟结果表明，吸收系数是影响晶界结构层裂发生和机理的主要因素之一。计算了界面层裂能。还确定了不同吸收系数的临界层裂阈值。研究结果为激光诱导晶界层裂提供了更好的认识。通过考虑晶界的影响，还可以改进模型以提高激光诱导烧蚀深度和抛射团簇尺寸分布的预测精度。
The previous laser-induced ablation researches by using molecular dynamics (MD) simulation are almost focused on the laser interaction with perfect single-crystal matters. The result can therefore lead to underestimate the ablation yields and size distribution of ejecting clusters due to without including the effect of grain boundary. The present model by using standard Lennard-Jones (L-J) MD simulation is firstly attempted to study the possible spallation effect induced by femtosecond pulse laser at grain boundary for polycrystalline materials. Various laser incident energy densities and absorption coefficient are employed to characterize the dynamic behavior and structural evolution of grain boundary. The simulation results indicate that the absorption coefficient can be one of the dominant factors to influence the occurrence and mechanism of structural spallation at grain interface. The interfacial spallation energy is evaluated. The critical spallation thresholds for various absorption coefficients are also identified. The results provide better understanding for laser-induced spallation of grain interface. The model can be also enhanced to promote the accuracy of the prediction of laser-induced ablation depth and size distribution of ejecting clusters through taking into account the effect of grain boundary.