Diffusion brazing of magnesium for automotive applications

Conference · Sat Dec 31 04:00:00 EST 1994

OSTI ID:115518

White, D R; Jones, J E

Use of magnesium in automotive structural application is on the verge of dramatic growth as manufacturers seek to greatly improve mileage standards. As use of magnesium increases, the need for joining processes suitable for high-volume production will also expand. This work examines low-temperature diffusion brazing as a means of joining heat-treatable magnesium alloys, or as an alternative to conventional brazing. In this study, a range of materials were evaluated with the objective of developing robust low cycle time, low-temperature diffusion brazing methods. It was found that fluxless diffusion brazes can readily be made in a nitrogen atmosphere using a zinc interlayer in certain Mg alloys at temperatures of 365--400{degrees}C. Poor results were obtained in ambient atmospheres. However, bond quality is highly sensitive to alloy composition and the presence of porosity in sand and die casting. Bond quality is also very sensitive to interlayer thickness: zinc forms intermetallics with magnesium which result in a brittle bond if excess material is present at the interface. Specimens were leak tested and tensile tests were performed. Experimental methods are reviewed, and results are discussed. Metallographic, microprobe, and tensile data are presented. The effects of surface preparation and activity on bonding, and their relationship to alloying elements are reviewed. The authors conclude that fluxless, inert gas diffusion brazing is a viable means of bonding magnesium components.

• OSTI ID: 115518
• Report Number(s): CONF-9404233--
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
BRAZED JOINTS
BRAZING
MAGNESIUM BASE ALLOYS
MECHANICAL PROPERTIES
MICROSTRUCTURE
POROSITY
SURFACE PROPERTIES