High-temperature brazing filler metal

High-temperature brazing alloys are filler materials that only become liquid at really high temperatures. They melt and bond with the base material without melting it itself. The structure remains intact, only the surface is wetted. Be careful with cooling: if you cool the part too quickly, you get stresses and the material can crack. Let it cool slowly and evenly, then the joint will hold cleanly. The melting point of the solder must definitely be well above the later service temperature, otherwise the seam will lose its strength.