飞秒激光烧蚀金属镍热影响区的数值模拟

为了定量分析飞秒激光金属加工中的热影响,基于一个二维的双温模型,采用有限差分法计算了飞秒激光烧蚀金属镍的径向热影响区.提出一种飞秒激光烧蚀热影响区定义,把热影响区定义为两部分,一部分是熔化再凝固区(晶格温度介于相爆炸温度和熔化温度之间的区域),另一部分是热激活区(晶格温度介于熔化温度和热激活温度之间的区域).通过研究表层晶格不同时刻的径向温度分布,得到飞秒激光烧蚀500nm厚金属镍的径向热影响区是160nm.结果表明,飞秒激光加工的热影响区非常小,可以实现对金属材料的超精密加工.并分析了电子热导率和电子比热容对径向热影响区的影响.

Numerical Simulation of the heat affected zone of Nickel ablated with femtosecond laser

In order to quantify the heat affected zone(HAZ) of femtosecond machining.Based on a two-dimensional model of the two temperature model(TTM),the radial heat affected zone of femtosecond laser ablation on nickel was simulated numerically with finite-difference method.The radial HAZ was defined as two parts,one was the melting and resolidification zone(between melting temperature and phase explosion temperature) and the other was thermal activation zone(between thermal activation temperature and melting temperature).The evolution of the temperature as a function of time was studied,leading to a radial HAZ width of 160nm for 500nm thick Ni samples,which showed that the heat affected zone of femtosecond machining is very small.Besides,the effects of the thermal conductivity and the specific heat of the electron on the radial HAZ were analyzed.