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

最大强度与变形能力的结合对未来金属材料的发展具有指导意义。然而，实现是非常具有挑战性的，因为强度和延展性/韧性是相互冲突的性能。人们普遍认识到微观结构设计是解决这一矛盾的关键。Emmy-Noether-Group认为这是一个动力，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。目前的项目发展脉冲冶金作为薄膜和表面结构的工具。Al/Ni多层材料是模型材料。它们被全球加热，而一个结构面罩充当散热器。掩模中的结构腔局部阻碍通过掩模的热通量，从而根据腔的几何形状产生温度热点。薄膜中结构几何（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。微观结构可以在更广的范围内调整。由于衬底和掩膜对相变的潜在影响，不能假设热点处的微观组织发展遵循当前脉冲冶金的知识。特别是，在淬火过程中的高冷却速率bbb10 000 K/s在这方面是至关重要的。因此，目前的建议是在热点的热历史下探索Al/Ni多层膜的相变。此外，结构精度是该项目的第二个主题。测量热点温度的时间演变是一项极具挑战性的工作。因此，将开发一种方法，使我们能够热分析在热点条件下的相变。具体来说，模型构造实验的结果将与模型分析实验的结果相关联。两者都基于在结构或薄膜加热器中样品的电阻加热过程中电阻的时间变化。在这两个实验中，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。最终，这种相关性为在热点热条件下的分析实验中探索薄膜的相变铺平了道路。采用辅助透射电子显微镜研究了相变局部化在微观结构中的潜在影响。为了揭示机械上有趣的结构条件，将进行纳米压痕实验。最后，结合热分析、显微组织评价和力学性能测定，为揭示第一个显微组织-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.