Pulsed Metallurgy for 2-Dimensional Structuring of Metallic Thin Films and Surfaces

最大强度和变形能力的结合为未来金属材料的发展提供了指导。然而，实现是非常具有挑战性的，因为强度和延展性/韧性是相互冲突的属性。人们已经广泛认识到，微结构设计是解决这一冲突的关键。Emmy-Noether-Group认为这是动机，并正在开发“脉冲冶金”作为金属薄膜复合材料微观结构设计的工具。目前的项目开发脉冲冶金作为薄膜和表面结构化的工具。Al/Ni多层膜为模型材料。它们被整体加热，而结构化掩模用作散热器。掩模中的结构化腔局部地阻碍通过掩模的热通量，这根据腔几何形状产生温度热点。薄膜中的结构几何形状（温度分布）的准稳态是这种方法的一个优点，使我们能够在更宽的时间范围内利用冶金现象（晶粒生长和相变）的动力学。微观结构可以在更宽的范围内进行调整。由于基板和掩模对相变的潜在影响，不能假设热点中的微结构发展遵循脉冲冶金的当前知识。特别是淬火过程中> 10，000 K/s的高冷却速率在这方面至关重要。因此，目前的建议探讨相变Al/Ni多层膜下的热点的热历史。此外，结构精度是该项目的第二个主题。热点温度随时间变化的测量是非常具有挑战性的。因此，将开发一种方法，使我们能够热分析的热点条件下的相变。详细地，模型构造实验的结果将与模型分析实验的结果相关联。两者都基于在薄膜加热器中样品的结构化或电阻加热期间电阻的时间变化。在两个实验中，相变在电阻导数中产生峰值。加热速率变化将用于调整时间峰值位置，以在两个实验中产生相似的热历史。最后，这种相关性铺平了道路，探索在分析实验中的薄膜相变的热斑的热条件下。支持透射电子显微镜研究被用来调查潜在的影响的相变局部化的微观结构。为了揭示机械感兴趣的结构化条件纳米压痕实验将进行。最后，将热分析、显微组织评价和力学性能测定相结合，为揭示一级组织-性能关系奠定了基础。

The combination of maximal strength and deformability serves as guidance for the development of future metallic materials. However, the realization is very challenging because strength and ductility/toughness are conflicting properties. It has been widely recognized that microstructure design is crucial for solving this conflict. The Emmy-Noether-Group considers this as motivation and is developing “pulsed metallurgy” as a tool for microstructure design of metallic thin film composites. The current project develops pulsed metallurgy as a tool for thin film and surface structuring. Al/Ni multilayers are the model materials. They are globally heated while a structuring mask serves as heat sink. Structuring cavities in the mask locally impede heat flux through the mask which creates temperature hot-spots according to the cavity geometry. The quasi-steady-state of the structure geometry (temperature profile) in the thin film is one advantage of this approach enabling us to utilize the kinetic of the metallurgical phenomena (grain growth and phase transformations) in a wider temporal range. The microstructure could be tuned in a broader spectrum. Due to potential effects of the substrate and the mask on the phase transformations, it cannot be assumed that the microstructure development in the hot spots follows the current knowledge of pulsed metallurgy. In particular, the high cooling rates > 10, 000 K/s during quenching are crucial in this respect. Hence, the current proposal explores phase transformations in Al/Ni multilayers under the hot spot’s thermal history. In addition, structuring precision is a second topic of the project. The measurement of the temporal evolution of the hot spot’s temperature is very challenging. Thus, a method will be developed allowing us to thermally analyze the phase transformations under the conditions of the hot spot. In detail, results of a model structuring experiment will be correlated with those of a model analyzing experiment. Both base on temporal variations in the electrical resistance either during structuring or the resistive heating of the samples in thin film heaters. Phase transformations create peaks in the resistance derivative in both the experiments. Heating rate variations will be used to adjust the temporal peak position to generate similar thermal histories in both the experiments. Eventually, this correlation paves the way to explore phase transformations in thin films in the analyzing experiment under the thermal conditions of the hot spot. Supporting transmission electron microscope studies are used to investigate potential effects of the phase transformations localization in the microstructure. To reveal mechanically interesting structuring conditions nanodindentation experiments will be performed. Finally, the combination of thermal analysis, microstructure evaluation and determination of mechanical properties creates a basis to reveal first microstructure- property-relationships.