Experimental Characterization and Sequential Multi-Scale Modeling of Reactive Wetting

技术：高温系统(例如金属衬底上的液态金属)中的润湿、相变和反应是复杂的现象，人们对此还知之甚少。这些现象是连接过程(焊接和铜焊)、薄膜加工和烧结等过程中的关键。反应性润湿的特点是化学和物理过程跨越了广泛的空间和时间尺度。有效地研究反应润湿需要多学科的努力，涉及化学热力学、相变、毛细行为和多尺度传输方面的专业知识。PIS将为几个重要的合金系统进行一项全面的研究，涉及在受控环境中在金属衬底上扩散的液态金属固着液滴的实验特征。为了更好地从根本上理解实验结果，并更充分地解释实验结果，将使用三个级别的计算模拟。建模将在不同的长度和时间尺度上模拟相关的物理过程。序贯多尺度模式的框架为未来更充分耦合的多尺度模式的发展提供了必要的基础。本研究的建模和模拟包括液滴尺度的准一维扩散模型、宏观和细观尺度的流体动力输运耦合相场模型以及高温金属-金属体系润湿和溶解的分子动力学模拟。桑迪亚国家实验室的一个研究小组将利用他们现有的能力来模拟反应性润湿，从而进行原子模拟。独特的实验表征能力与多尺度模型量化输运和接触线动力学的能力相结合，在理解与反应润湿相关的复杂现象方面取得了显着进步。非技术性：创新研究将涉及一支经验丰富的调查团队(工程师、材料科学家)和工程专业学生(包括研究生和本科生)。与桑迪亚国家实验室的合作将使学生能够与执行原子建模的研究小组进行互动。研究人员相信，这种合作的实验/计算研究工作将为参与计算建模的学生提供宝贵的经验，指导他们如何将从实验表征研究中获得的知识融入到连续统和第一原理模型中。连续体水平模型将使用开源软件开发，学生可以使用该软件研究相关的润湿和流体动力学现象，并可扩展到一系列应用程序。

TECHNICAL: Wetting, phase change and reaction in high temperature systems (e.g., a liquid metal on a metal substrate) are complex phenomena that are only partially understood. These phenomena are key to joining processes (soldering and brazing), thin film processing and sintering among others. Reactive wetting is characterized by chemical and physical processes that span a broad range of spatial and temporal scales. Effective study of reactive wetting requires a multi-disciplinary effort involving expertise in chemical thermodynamics, phase transformations, capillary behavior and multi-scale transport. PIs will undertake a comprehensive study involving experimental characterization of liquid metal sessile drops spreading on metallic substrates in a controlled environment for several important alloy systems. To gain better fundamental understanding and to more fully interpret the experimental results, three levels of computational modeling will be used. The modeling will simulate the relevant physical processes on different length and time scales. A framework of sequential multi-scale models provides a necessary foundation for the future development of more fully-coupled multi-scale models. The modeling and simulation in this study incorporate a quasi-one-dimensional diffusion model at the drop scale, a phase-field model coupled to hydrodynamic transport at the macro- and meso-scopic scales and molecular dynamics modeling of wetting and dissolution of high temperature metal-metal systems. A research group at Sandia National Laboratories will conduct atomistic simulations by applying their existing capability to model reactive wetting. The unique experimental characterization capabilities combined with the ability of the multi-scale models to quantify transport and contact line dynamics yields a significant advancement in the ability understand the complex phenomena associated with reactive wetting. NON-TECHNICAL: The innovative research will involve an experienced team of investigators (engineers, material scientists) and engineering students (both at the graduate and undergraduate level). The collaboration with Sandia National Laboratory will enable the students to interact with the research group performing the atomistic modeling. The investigators believe that this collaborative experimental/computational research effort will provide the students involved in the computational modeling valuable experience on how to incorporate knowledge gained from experimental characterization studies into continuum and first-principles models. The continuum level models will be developed using open-source software which will be available to students for use in studying related wetting and hydrodynamic phenomena and that can be extended to a range of applications.