超快激光对金属材料烧蚀的超快动力学及超快结晶过程的机理研究

项目名称： 超快激光对金属材料烧蚀的超快动力学及超快结晶过程的机理研究

项目编号： No.11504144

项目类型： 青年科学基金项目

立项/批准年度： 2016

项目学科： 数理科学和化学

项目作者： 任云鹏

作者单位： 江苏大学

项目金额： 20万元

中文摘要： 超快激光具有极高的瞬时功率，可以实现对材料的精密加工。为了减少热影响区，保证加工精度，目前大多数加工过程采用低能激光脉冲，但是低能脉冲加工效率低下。考虑材料对超快激光的多光子吸收效应，对高能超快激光进行调制，可以在光斑中心区域实现多光子吸收，获得小于衍射极限的加工精度，同时提高加工效率。本项目针对上述问题，建立能在室温和高温下描述金属光学性质的Critical Point Model，为了尽量接近实际加工过程，本课题将突破以往普遍采用的一维模型，建立三维连续介质模型，研究超快激光与材料之间的相互作用机理，包括材料对光的非线性吸收、冲击波导致的非热性烧蚀和高能激光脉冲带来的热性烧蚀，弄清楚激光参数与材料去除量之间的关系。同时，本项目还将采用相场模型研究过冷效应带来的超快结晶过程，揭示激光参数对材料表面微观组织的影响，为超快激光在医疗、微电子、航空等行业的应用提供坚实的理论依据。

中文关键词： 超快激光；飞秒激光烧蚀；激光材料处理；超快结晶过程；超快动力学

英文摘要： Ultra-fast laser has extremely high peak power by which it can treat materials with very high precision. Currently, most of the processing is using low energy pulses to guarantee precision by reducing heat affected zone (HAZ). However, the processing speed is pretty low by using low energy pulses. Considering the multi-photon absorption effect, it is possible to realize very high processing precision that even less than diffraction limit by modulating the high energy ultra-fast laser pulses in the center part of the laser spot. Meanwhile, the processing speed can be significantly improved due to much higher pulse energy. But the treatment process is involving complicated optics, mechanism, and thermodynamics. It is critical to get deep understanding of these physics to realize fast precise processing by ultra-fast lasers. This project is intending to build a Critical Point Model which can describe the optical properties of metals such as gold, copper, and aluminum both at room temperature and very high temperature. By incorporating this model into the Two-Temperature Model, the interactions between metals and ultra-fast lasers can be described and the non-thermal ablation induced by low energy pulses and thermal ablation induced by high energy pulses can be studied. Besides, the ultra-fast crystallization process driven by “under-cooling” will be investigated based on phase field model to reveal how the laser parameters influence microstructure of the materials. In order to close to the real processing, a three dimensional continuum model will be set up. Based on this model, how the ablation process and crystallization are influenced by laser parameters will be studied to provide direction of using ultra-fast lasers in more fields.

英文关键词： ultra-fast lasers;femtosecond laser ablation;laser material processing;ultra-fast crystallization;ultra-fast dynamics