Ternary Ru/Al-based reactive multilayers

B2金属间化合物RuAl结合了良好的高温性能和高的室温延展性。-62 kJ/mol（原子）的高负生成热使Ru和Al的亚微米复合材料能够自蔓延放热反应形成B2化合物RuAl。这使得系统Ru/Al类似于其它金属间反应系统，如Ni/Al、Pt/Al、Pd/Al和Co/Al。(at室温）和良好的能量密度（与市售Ni/Al箔的能量密度相当）。这使得Ru/Al在反应性键合领域中成为一个有趣的系统，其中局部加热仅限于接合区域。二元反应性多层体系的特征参数是双层厚度，通过该厚度确定体系的基本性质（反应速度、点燃温度、反应产物的微观结构和形态），并且不能独立地改变。本项目的目的是开发一种新的方法来操纵Ru/Al基反应多层膜的性能，从二元到三元Ru/Al/X层（X=Ni，Pt，Hf，Ti）。重点是将Ru/Al多层膜的相对高的点火温度（400-575°C）降低到约300°C的值，与Ni/Al多层膜的点火温度相当，从而改善在存在散热器的情况下的反应（例如，在接合间隙内）。因为有，据申请人所知，没有系统的研究三元金属间反应系统，这个项目的一个重要组成部分是调查的化学组成和堆叠顺序的基本性能的反应多层（反应速度，形态和微观结构）的影响。从而更好地了解潜在的机制。为了能够研究大范围的组成，采用组合溅射。该技术允许通过具有厚度梯度的层的顺序溅射在单个衬底上沉积材料库。的RuAl基B2结构的存在的组成范围进行了研究，通过X射线衍射和高通量的电阻率测量后的热处理的三元多层膜。在这些组成范围内，金属间相的形成作为温度的函数进行了研究，通过原位四点测量的电阻率得出结论的点火温度。基于对组分和堆叠顺序的影响的见解，开发了基于三元Ru/Al的反应多层膜，其结合了Ru/Al的优点和降低的点火温度。

The intermetallic B2 compound RuAl combines good high-temperature properties with high room-temperature ductility. The high negative heat of formation of -62 kJ/mol(atoms) enables sub-µm composites of Ru and Al to self-propagating exothermic reactions forming the B2 compound RuAl. This makes the system Ru/Al similar to other intermetallic reactive systems like Ni/Al, Pt/Al, Pd/Al and Co/Al. However, the system Ru/Al is of particular interest due to the combination of a ductile reaction product, a compositional range of existence of 4.1 % at. (at room temperature) and a good energy density (comparable to that of commercially available Ni/Al foils). This makes Ru/Al an interesting system in the field of reactive bonding with local heating limited to the region of joining. The characteristic parameter of binary reactive multilayer systems is the bilayer thickness by which the basic properties of the system (speed of reaction, ignition temperature, microstructure and morphology of the reaction product) are determined and cannot be varied independently. Aim of this project is to develop a new way to manipulate the properties of Ru/Al-based reactive multilayers by moving from binary to ternary Ru/Al/X layers (X=Ni, Pt, Hf, Ti). The focus is on lowering the relatively high ignition temperature of Ru/Al multilayers (400-575°C) to values of approximately 300°C, comparable to that of Ni/Al multilayers, thus improving the reaction in the presence of a heat sink (e.g. inside a joint gap). Because there are, to the best knowledge of the applicants, no systematic studies on ternary intermetallic reactive systems, an essential part of this project is to investigate the influence of chemical composition and stacking sequence on the basic properties of a reactive multilayer (speed of reaction, morphology and microstructure). Thereby, a better understanding of the underlying mechanisms shall be gained. To enable the investigation of large ranges of composition, combinatorial sputtering is employed. This technique allows deposition of materials libraries on a single substrate by sequential sputtering of layers with thickness gradients. The compositional range of existence of the RuAl-based B2 structure is investigated by X-ray diffraction and high-throughput electrical resistivity measurements after a thermal treatment of the ternary multilayers. Within these compositional ranges, intermetallic phase formation as a function of temperature is investigated by in-situ four point measurements of the electrical resistivity to draw conclusions on the ignition temperature. Based on the insights into the influence of composition and stacking sequence, ternary Ru/Al based reactive multilayers are developed combining the benefits of Ru/Al with a reduced ignition temperature.