Microstructure and mechanical properties

IWM(RWTH Aachen University)和IEK-2(Forschungszentum Jülich)联合提出了金属陶瓷化合物反应空气钎焊的联合提案，申请第二个为期两年的资助期。在第一个项目阶段，研究了反应空气钎焊金属-陶瓷复合材料的力学行为，钎料与连接部件界面的粘结机制，以及与化学、工艺和热老化有关的损伤机制。在拟议的第二个资助期内，计划对热老化造成的损害进行深入分析，特别侧重于在加工和高温暴露期间在钎焊接头界面形成的强度限制反应层的形成、成分和机械性能。对于这些研究，计划在根据第一项目阶段的结果选择的铜焊接头变种上进行机械测试以及深入的扫描和透射电子显微镜研究。同时，对已有的钎焊接头有限元模型进行了扩展，以模拟界面处的反应区，特别是它们对钎焊接头机械强度的影响。该模型将被用来预测几种金属/陶瓷化合物的力学行为，特别是热膨胀失配较大的化合物。金属-陶瓷化合物在初始状态和等温老化或热循环后的广泛机械特性(即通过弯曲、复合拉伸和铜焊接头的双剪切测试)允许校准和验证有限元模型。此外，根据第一个项目阶段的初步调查，所谓的机械辅助扩散连接被证明是一种很有前途的替代连接工艺，将用于生产成分热膨胀不匹配的化合物。将测量这些化合物的附着力和剪切强度，并计划进行微观研究，特别是界面区域的研究

With their joint proposal Reactive Air Brazing of Metal-Ceramics Compounds,IWM (RWTH Aachen University) and IEK-2 (Forschungszentrum Jülich) apply for a second two-year funding period. During the first project phase, the mechanical behavior of reactive air brazed metal-ceramics compounds, the adhesion mechanisms in the interfaces between braze metal and joined components and the damage mechanisms depending on chemistry, processing and thermal ageing were investigated. During the proposed second funding period, an in-depth analysis of damage induced by thermal ageing is planned with special focus on the formation, composition and mechanical properties of the strength-limiting reaction layers formed at the interfaces of the brazed joint during processing and high temperature exposure. For these investigations, mechanical testing and in-depth scanning and transmission electron microscopy studies are planned at brazed joint variants selected according to the results of the first project phase. At the same time, the existing FEM model of brazed joints will be extended in order to simulate the reaction zones at the interfaces, especially their influence on mechanical strength of the brazed joint. This model will be used to predict the mechanical behavior of several metal/ceramic compounds, especially compounds with large thermal expansion mismatch. Extensive mechanical characterization (i.e. by bending, compound tension and double shear testing of brazed joints) of metal-ceramic compounds in the as-received state and after isothermal ageing or thermal cycling allows calibration and validation of the FEM model. Additionally, so called mechanically assisted diffusion bonding, which proved -according to preliminary investigations during the first project phase- to be a promising alternative joining process will be used to produce compounds with large thermal expansion mismatch of their components. Adhesion and shear strength of these compounds will be measured and microscopic investigation, especially of the interface regions is planned