Control of the microstructure of thin multilayer systems by ultrashort pulsed laser irradiation - process understanding by complementary in situ and ex situ characterizations and multiscale simulations

通过超短脉冲激光照射控制薄多层系统的微观结构 - 通过互补的原位和异位表征以及多尺度模拟来理解过程

• 批准号: 469106482
• 负责人: Professor Dr. Alexander Horn
• 金额: --
• 依托单位: Institut für Werkstoffwissenschaft
• 依托单位国家: 德国
• 项目类别: Research Grants
• 资助国家: 德国
• 项目状态: 未结题
• 来源: https://gepris.dfg.de/gepris/projekt/469106482?language=en
• 关键词: Control; microstructure; thin; multilayer; systems

Laser-assisted techniques belong to state of the art in the materials processing, and are widely used for laser ablation and structuring of materials in many fields of applications. The processes accompanying the laser ablation are typically simulated using hydrodynamic approaches in combination with molecular dynamics. On the nanometer scale, however, the application of high-intensity laser radiation leads additionally to the modifications of the materials microstructure, which are related to local melting, solidification, interdiffusion of involved species, formation of microstructure defects and recrystallization. These processes could be used for a targeted manipulation of the materials microstructure, but because the microstructure changes that are induced by the laser irradiation also affect the interaction between the laser beam and the material, the adjustment of a desired microstructure on the nanoscale is a very complex task. As a holistic model describing the effect of the microstructure on the interaction between the laser beam and the material is still missing, the adjustment of the parameters of the laser process is currently carried out using a trial-and-error approach in many cases.The aim of this project is to contribute to the understanding of laser-induced changes in the microstructure of thin metallic films and to the description of the effect of microstructure on the materials characteristics, which are relevant for the laser processes, e.g., absorption of the laser beam, electron-phonon coupling, heat transfer, etc. This aim should be achieved by combining in situ (ultrafast ellipsometry and reflectometry during the laser irradiation) and ex situ experiments (scanning and transmission electron microscopy, X-ray and electron spectroscopy) with simulations using mesoscopic (hydrodynamics) and microscopic (molecular dynamics) approaches. The evaluation of the electron micrographs will be supported by a multimodal analysis based on deep learning. The information obtained from the molecular dynamic simulations will complement the ex situ microstructure studies by providing, e.g., the atomic positions for the in situ microstructure analyses during the laser irradiation.The materials proposed for this study are single layers (Cr, Mo, Ti, Fe) and bilayers (Au/Cr, Mo/Ti, Au/Fe) consisting of unary metallic phases with different melting points, different sequences of high-temperature and high-pressure phases, and with different mutual solubilities and diffusivities in the respective binary system. Experimentally observed phase transitions and concentration profiles will be used as “sensors” for the temperatures and pressures induced by the laser irradiation. The effect of the microstructure on the laser process will be studied in samples having different grain size and preferred orientation of crystallites in the original state.

激光辅助材料加工技术是材料加工领域的一种新技术，在许多应用领域中被广泛用于材料的激光烧蚀和结构化。伴随激光烧蚀的过程通常使用流体动力学方法与分子动力学相结合来模拟。然而，在纳米尺度上，高强度激光辐射的应用另外导致材料微观结构的改变，这与局部熔化、固化、所涉及的物种的相互扩散、微观结构缺陷的形成和再结晶有关。这些过程可以用于材料微观结构的目标操纵，但是由于由激光照射引起的微观结构变化也影响激光束和材料之间的相互作用，因此在纳米尺度上调整所需的微观结构是一项非常复杂的任务。由于描述微结构对激光束和材料之间相互作用的影响的整体模型仍然缺失，目前，在许多情况下，激光工艺参数的调整都是采用试错法进行的。本项目的目的是促进对激光工艺的理解，在薄金属膜的微观结构中引起的变化，以及微观结构对材料特性的影响的描述，这与激光处理有关，例如，这一目标应通过将原位实验（激光照射期间的超快椭圆偏振法和反射法）和非原位实验（扫描和透射电子显微镜、X射线和电子能谱）与使用介观（流体动力学）和微观（分子动力学）方法的模拟相结合来实现。电子显微照片的评估将得到基于深度学习的多模态分析的支持。从分子动力学模拟中获得的信息将补充非原位微观结构研究，例如，本研究提出的材料是单层（Cr，Mo，Ti，Fe）和双层（Au/Cr，Mo/Ti，Au/Fe），它们由具有不同熔点的一元金属相组成，具有不同的高温和高压相序列，在各自的二元体系中具有不同的互溶度和扩散系数。实验观察到的相变和浓度分布将被用作激光照射引起的温度和压力的“传感器”。将在原始状态下具有不同晶粒尺寸和晶粒择优取向的样品中研究微观结构对激光加工的影响。