Legal regulations for efficiency and emissions are an important factor for design and development in the automotive industry. Brazing sheets consisting of an AlMn core alloy, cladded with a near eutectic Al-Si layer are state of the art for the production of automotive heat exchangers. These conventional material combinations reach their property limits, for special applications with high mechanical and temperature loads (e.g. charged air coolers). The goal of the project is the substitution of the AlMn core by a high-strength age-hardenable AlZnMg alloy, which exhibits significantly higher tensile strength. This also leads to higher mechanical properties of the finished product. If the core material is in direct contact with the molten cladding, at brazing temperature, severe liquid dissolution at grain boundaries is occurring. Therefore an intermediate diffusion barrier is necessary to retain the possibility of brazing. Another problem is the decreased service life of the product, due to the higher corrosion susceptibility of the core. The first part of the thesis is concerned with the corrosion resistance of the new brazing sheet compound. Laboratory scale sheets with different interlayers (pure aluminium, AlZn2.7, AlMn1) were produced. Additionally a variation of main alloying elements (Zn, Mn, Fe, Mg) and homogenization treatment of the AlZn2.7 and AlMn1 materials was conducted. “Sea Water Acetic Acidified Testing” (SWAAT) was used for the characterization of the corrosion attack. In depth measurements also include polarization experiments with subsequent damage evaluation by scanning electron microscopy (SEM). The experiments clearly show that the attack of the AlZn2.7 compound is strongly influenced by element additions. A wide variety of morphologies (pitting, exfoliation, intercrystalline corrosion) was observed. After penetration of the interlayer the interface between core and barrier layer is preferentially dissolved and delamination occurs, which significantly decreases the service time. By using an AlMn1 interlayer this process can be avoided. The second part focuses of the occurring diffusion phenomenon’s during brazing and the estimation of the necessary minimal interlayer thickness to avoid negative consequences (dissolution at grain boundaries, improper brazing joints). For this experimental run, compounds with AlMn1 interlayer were produced on an industrial scale. Two different sheet thicknesses (0.6 mm and 1.6 mm) were compared. The sheets were subjected to a simulated brazing cycle in a circulating air furnace. Afterwards the chemical composition of the surface and the diffusion profiles across the different interfaces were measured. The simulated brazing cycle encompasses the process range (maximum temperature: 595 to 610 °C, holding interval: 12 to 90 minutes) of the most commonly used methods (controlled atmosphere brazing, vacuum brazing). The sheet with a thickness of 1.6 mm is in general braze-able, but strong interdiffusion is occurring at the most extreme parameter combinations (610 °C for 90 min). In comparison, the 0.6 mm sheet exhibits a significant enrichment of Zn and Mg at the surface. This already arises at brazing temperatures of 595 °C. An in depth analysis allows the evaluation of the diffusion constants and diffusion length of the different elements. An additional heat treatment was conducted on selected samples to simulate the influence of the service conditions and over-aging of the core material. For the characterization of the damage evolution at the microstructural level and the interfaces between the materials, “Kelvin Probe Force Microscopy” (KPFM) was applied. Although all the samples with delamination corrosion show a potential minimum near the core-interlayer interface, no definitive microstructural cause was detected. A higher resolution method like transmission electron microscopy (TEM) should provide n