Asymmetric multi-material pairings such as metal-plastic hybrids gain increasing importance across a wide range of different industry sectors. Under the objectives of lightweight construction involving reduced component mass and simultaneous increased component performance, new material combinations are continuously developed. However, substitution of metals by plastics also creates a variety of challenges caused by the combination of dissimilar materials. Innovative joining methods are required to cope with different chemical and physical properties of the used materials. Application of reactive multilayers represents an advanced joining method for flexible and low distortion joining of dissimilar joining partners by short-term and localized input of thermal energy.   
In the context of this publication, the joining process between semi-crystalline polyamide 6 and pre-structured austenitic stainless steel X5CrNi18 10 (EN 1.4301) based on reactive Al/Ni multilayers is investigated. Based on first results in [1], the focus of the investigations is on the influence of the substrate structure upon the reaction behavior of the multilayer and the resulting influence on the overall composite. In addition to evaluating the resulting joint strength, the research is focused in particular on the characterization of the resulting failure behavior at the fracture interface under shear tensile stress and the resulting bonding mechanisms in the joint. From the results obtained, it can be estimated that a direct bond can be generated between plastic and metal despite the presence of a residual reacted foil in the joining area. The structures present in the metal surface have a particularly positive influence on crack initiation and the resulting increased bond strength.