Simulation-aided material design of iron-based amorphous brazing foils

• Applicants: Professorin Dr.-Ing. Kirsten Bobzin; Dr.-Ing. Ulrike Hecht
• Subject Area: Thermodynamics and Kinetics as well as Properties of Phases and Microstructure of Materials
• Term: since 2020
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 448510847

The research project presented here is a elongation of the previous project of the same name. The aim is to develop a new amorphous Fe-based alloy and make it suitable for use in the brazing process. In the previous project, a thermodynamic database was developed in the quinary multi-component system Fe-Ni-Cr-Si-B, which successfully predicted the amorphous microstructure of Fe-based alloys so that they could be produced in the melt-spin process. With the help of this database, an amorphous Fe-based alloy with an increased Fe-content and reduced Ni-content optimized for the brazing process is now to be produced. This amorphous Fe-based alloy will then be used in the vacuum furnace process for brazing joints. In order to investigate which process conditions are ideally suited to this, the microstructure that forms in the brazed joint and the resulting mechanical properties are to be investigated and the brazing process adapted accordingly. Preliminary work has already shown that it is possible to produce a joint with one of the newly developed amorphous Fe-based alloys. The optimization of the brazing process and research into the joint gap microstructure and mechanical properties represent open questions, the answers to which will bring decisive advantages for future users. Amorphous foils are flexible due to their glass-like microstructure and can therefore be easily adapted to a wide variety of component geometries. Although numerous amorphous Fe-based alloys have already been researched, they are not suitable for brazing due to their chemical composition and liquidus temperature. Therefore, despite the rising price of Ni as a raw material, amorphous Ni-based foils are used in the brazing of highly stressed components. In order to create a more cost-effective alternative and to establish the CALPHAD-method in brazing alloy development, the optimal brazing process route for brazing joints with a newly defined amorphous Fe-based alloy is to be researched.

• DFG Programme: Research Grants