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

反应性金属多层膜形成反应性材料的子类。它们能够进行自蔓延反应，其反应行为基本上由反应物的类型、尺寸、形状和分布决定。在第一个资助阶段，获得了结果的平面，二元Ni/Al和Ru/Al多层膜的自蔓延反应中的独立的样品，以及在基板上的低加热速率的控制热处理的反应行为。建立了一个模拟Ru/Al自蔓延反应过程中及反应后微观结构演变的相场模型，并用实验结果进行了验证。进行热处理实验以阐述双层厚度对Ru/Al中的相序列的影响。基于第一资助阶段的结果，确定了几种新的方法来修改Ni/Al和Ru/Al的结构。为了更深入地了解微尺度上的控制过程，通过高和低加热速率相结合的关键实验，相位场模拟在这里，主要是质量和热量传输过程起主导作用，并遵循两种方法在这个项目中。第一种方法涉及利用激光结构化基板进行层沉积，以通过遮蔽效应在多层内的不同位置处产生孔。这些在反应期间局部抑制质量和热传递。孔的严格定位从而允许与反应后的材料进行前后比较。第二种方法是基于分别在Ru和Al或Ni和Al的单层之间插入B2-RuAl或B2-NiAl的中间层。这降低了储存的能量密度而不改变多层的总体组成，并且将进一步对传质具有抑制作用。后者是相关的自蔓延反应和相变在低加热速率。关于自蔓延反应，重点是独立的样品，以研究没有基板影响的反应的基本原理。这两种方法将进行实验研究，以及通过相场模拟，以确定其效果。为此目的，将扩大第一个供资阶段用于微观结构演变的模型，以纳入放热模拟。

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.