Concurrent solid state diffusion bonding and superplastic forming

Conference · Sun Dec 31 04:00:00 EST 1995

OSTI ID:194206

Sunwoo, A; Lum, R; Vandervoort, R ^[1]

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1. Lawrence Livermore National Lab., CA (United States)

Earlier studies on diffusion bonding (DB) of Al alloys have focused mostly on extrinsically changing the surface condition through the use of interlayers, surface etching, or vacuum environment. The problem with focusing on the extrinsic conditions only is that the benefits of the DB process are not fully utilized. The approach the authors have taken to study solid state diffusion bondability of Al alloy 7475 is to utilize the intrinsic deformation behavior of superplastic material to break-up the surface oxide film. Beginning with this preprocessed superplastic Al alloy 7475, they used a unique apparatus that applied simultaneous a tensile pull on the specimen and a bonding pressure on the bonding surface to simulate diffusion bonding concurrently with superplastic forming of a multiple sheet forming and bonding application. The authors were able to produce ductile, oxide-free bonds at significantly lower pressures and temperature in an argon atmosphere, while maintaining the superplastic microstructure of the alloy. The results clearly indicate that there is a narrow bonding pressure range where the superplastic deformation can be applied to enhance solid-state diffusion bonding. They also suggest that after the alloy reaches yielding, a continuous application of large bonding pressure is not necessary. The peel strength-values show the advantage of applying a greater bonding pressure during initial forming.

• DOE Contract Number: W-7405-ENG-48
• OSTI ID: 194206
• Report Number(s): CONF-950201--; ISBN 0-87339-300-7
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
ALUMINIUM BASE ALLOYS
BONDING
CHROMIUM ADDITIONS
COPPER ALLOYS
DIFFUSION
GRAIN BOUNDARIES
HOT WORKING
INTERFACES
KINETICS
MAGNESIUM ALLOYS
MICROSTRUCTURE
OPTICAL MICROSCOPY
PLASTICITY
PRESSURE DEPENDENCE
SCANNING ELECTRON MICROSCOPY
ZINC ALLOYS