This work provides empirical evidence needed for an in depth phenomenological study of dendrite growth phenomena during brazing of aluminum alloys in form of composite brazing sheets. The main objective of this study was (1) a collection of experimental evidence associated with heat and mass transfer modeling of the Al + Si solid solution dendrite macro morphology evolution inherent to joint formation during brazing, and (2) the dendrite growth kinetics analysis. The isothermal dwell and the quench that follow the clad molten aluminum binary alloy surface-tension-driven flow into the joint at the peak brazing temperature upon melting lead to the solidification of the metal micro layer and joint formation. Before, during and after the isothermal dwell a significant reduction of Si content in the melt is found. So, a subsequent dissolution may affect the interface zone between the molten clad and substrate. α-phase dendrite assemblies imbedded in an irregular eutectic in the joint zone are the main morphological features of the solidification microstructures. The major characteristic of the phenomenon is a sensitivity of the dendrite pattern selection and dendrite population on brazing process parameters, in particular on the temperature during the dwell.
|Number of pages||13|
|Journal||International Journal of Heat and Mass Transfer|
|State||Published - Jun 2005|
Bibliographical noteFunding Information:
The National Science Foundation has provided support through the NSF Grant DMI-9908319, monitored by Dr. Delcie Durham and Dr. Julie Chen. P.K. Galenko acknowledges support from the Alexander von Humboldt Foundation through the research program no. IV RUS 1068584. A portion of this work was supported by Assistant Secretary for Energy, Office of Transportation Technologies, as part of the High Temperature Materials Laboratory user program at ORNL, managed by UT—Battelle, LLC, for the US DOE under contract # DE-AC05-00OR22725 through the project #UA-90-015. One of the co-authors (GF) would like to express his appreciation for the support provided by CRMS, College of Engineering at the UK through a research assistantship. Numerical calculations were performed in part thanks to support from the University of Kentucky Computing Center and the University of Kentucky Center for Computational Sciences (CCS) that operates within the framework of the National Center for Supercomputing Applications (NCSA).
ASJC Scopus subject areas
- Condensed Matter Physics
- Mechanical Engineering
- Fluid Flow and Transfer Processes