Simulation and experimental investigation of the reaction behavior of morphologically modified reactive multilayers

反应性金属多层膜是反应性材料的一个子类。它们具有自蔓延反应的能力，其反应行为本质上由反应物的类型、大小、形状和分布决定。在第一个资助阶段，研究了平面、二元Ni/Al和Ru/Al多层膜在独立样品中的自蔓延反应以及在衬底上低升温速率下的受控热处理的反应行为。建立了模拟Ru/Al自蔓延反应过程中及反应后微观组织演变的相场模型，并与实验结果进行了验证。通过热处理实验，研究了双层膜厚度对Ru/Al相序列的影响。根据第一个资助阶段的结果，确定了几种新的方法来以受控方式改变Ni/Al和Ru/Al多层膜的结构，以便通过在高和低升温速率下的关键实验结合相场模拟来更深入地理解微观尺度上的控制过程。在这里，主要是质量和热量传输过程占主导地位，在这个项目中遵循两种方法。第一种方法涉及利用激光结构的衬底进行层沉积，以通过阴影效应在多层内的不同位置产生气孔。这些物质在局部抑制了反应过程中的质量和热量传输。因此，孔的严格定位允许与反应材料进行前后比较。第二种方法是在Ru和Al或Ni和Al的单层之间分别插入B2-Ru1或B2-NiAl中间层。这在不改变多层膜的总体组成的情况下降低了存储的能量密度，并且将进一步对传质具有抑制作用。后者与低升温速率下的自蔓延反应和相变有关。关于自蔓延反应，重点放在独立样品上，以研究反应的基本原理，而不受底物的影响。这两种方法都将通过实验和相场模拟来研究，以确定它们的影响。为此，将扩展第一个资助阶段用于微观结构演变的模型，以纳入热释放的模拟。

Reactive metallic multilayers form a subclass of reactive materials. They are capable of self-propagating reactions and their reaction behavior is essentially determined by the type, size, shape and distribution of the reactants. In the first funding phase, results were obtained on the reaction behavior of planar, binary Ni/Al and Ru/Al multilayers in self-propagating reactions in free-standing samples as well as in controlled heat treatments at low heating rates on substrates. A phase field model for simulating the microstructure evolution in Ru/Al during and after self-propagating reaction was established and validated with experimental results. Heat treatment experiments were conducted to elaborate the effect of the bilayer thickness on the phase sequence in Ru/Al. Based on the results of the first funding phase, several new approaches were identified to modify the architecture of Ni/Al and Ru/Al multilayers in a controlled manner in order to gain a deeper understanding of the governing processes on the microscale through key experiments at high and low heating rates in combination with phase field simulations. Here, mainly mass and heat transport processes play a dominant role, and two approaches are followed in this project. The first approach involves utilizing laser-structured substrates for layer deposition to generate pores through shadowing effects at distinct locations within the multilayer. These locally inhibit mass and heat transport during the reaction. The strict localization of the pores thereby allows the before-after comparison with the reacted material. The second approach is based on the insertion of intermediate layers of B2-RuAl or B2-NiAl between the single layers of Ru and Al or Ni and Al, respectively. This reduces the stored energy density without changing the overall composition of the multilayer and will further have an inhibitory effect on mass transfer. The latter is relevant for both the self-propagating reaction and the phase transformation at low heating rates. With respect to self-propagating reactions, the focus is on free-standing samples to investigate fundamentals of the reaction without substrate influence. Both approaches will be investigated experimentally as well as by phase field simulations to determine their effects. For this purpose, the model used for microstructure evolution during the first funding phase will be extended to incorporate the simulation of heat release.