Development of Low-Melting Al-Fillers for High-Strength Aluminium Alloys

Aluminium alloys are widely used in technical areas due to the good availability, good machinability, the excellent weight-strength ratio and the advantageous physical and chemical properties. However, there are restrictions for many high-strength alloys regarding heat damage during the joining process.
The standard AlSi fillers are only suitable for joining of non- and low-alloyed aluminium materials (1xxx and 3xxx series) due to the high brazing temperatures. ZnAl fillers are be an alternative, but they can’t be used in vacuum processes. Also the corrosive behaviour and the optical properties are comparatively poor. When using high-strength aluminium alloys as lightweight structural components, the strength of the joints, their corrosion resistance but also its visual appearance is important. Therefore the development of suitable fillers is a major challenge. It will be presented results on the development of low-melting Al-based alloys in the system Al-Ag-Cu able to soldering in vacuum and appropriate for high-strength aluminium alloys.