Brazing of dispersion-strengthened aluminum
- Norwegian Inst. of Technology, Trondheim (Norway). Dept. of Metallurgy
- SINTEF Materials Technology, Oslo (Norway)
- Raufoss Technology (Norway)
In recent years, the use of rapid solidification powder metallurgy has made it possible to develop a new family of aluminum alloys exhibiting unique properties. One of these materials, dispersion-strengthened (DS) aluminum, is currently being produced for commercial purposes at Raufoss Technology AS, Norway. Dispersion-strengthened aluminum derives its high strength from nanoscale AlN particles embedded in an aluminum matrix. DS Al is expected to be well suited as construction material for high-temperature applications where weight reductions are of particular concern. The present investigation has focused on the wetting behavior of DS aluminum under conditions applicable to brazing. The results from the Sessile drop experiments show that a eutectic Al-Si brazing alloy will completely wet the base metal both under high-vacuum conditions and in controlled argon atmospheres, provided that the partial pressure of oxygen is sufficiently low. The main problem appears to be the stability of the matrix grain structure. In general, the process of grain erosion and coarsening can be controlled by restricting the supply of the brazing alloy so that only a small metal volume is exposed to erosion. In addition, there is a great potential for reducing the thermodynamic driving force of the erosion reaction by proper adjustments of the brazing alloy composition and/or the brazing temperature. Sill, grain boundary liquidation may be a problem which, in turn, may require additions of surface active elements to the filler metal to control the wetting behavior.
- OSTI ID:
- 218527
- Journal Information:
- Welding Journal, Vol. 75, Issue 3; Other Information: PBD: Mar 1996
- Country of Publication:
- United States
- Language:
- English
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