Microscopic appraisal and mechanical behavior of hybrid Cu/Al joints fabricated via friction stir spot welding-brazing and modified friction stir clinching-brazing

This paper focuses on the improvement of hybrid Cu/Al weld performance via a combination of self-reacting brazing mechanism (for stable metallurgical transformation) and process modification approach (for the elimination of tool profile-induced stress-raiser). The modified friction stir clinching-br...

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Bibliographic Details
Published inJournal of materials research and technology Vol. 9; no. 6; pp. 13239 - 13249
Main Authors Tong, Lian, Xie, Jianing, Liu, Li, Chang, Gong, Ojo, Olatunji Oladimeji
Format Journal Article
LanguageEnglish
Published Elsevier B.V 01.11.2020
Elsevier
Subjects
Aluminum alloy
Cu alloy
Friction stir spot welding-brazing
Mechanical properties
Microstructure
Modified friction stir clinching-brazing
Friction stir spot welding-brazing
Mechanical properties
Cu alloy
Microstructure
Modified friction stir clinching-brazing
Aluminum alloy
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Summary:This paper focuses on the improvement of hybrid Cu/Al weld performance via a combination of self-reacting brazing mechanism (for stable metallurgical transformation) and process modification approach (for the elimination of tool profile-induced stress-raiser). The modified friction stir clinching-brazing (MFSC-B) and friction stir spot welding-brazing (FSSW-B) of dissimilar AA5083-H321 aluminum and commercially pure Cu alloys are investigated with the use of a thin Zn intermediate layer. The load-bearing capacity, fracture behavior, and microstructure of the respective joints are investigated and compared. The results show that plausible intermetallic phases of Al–Cu (Al2Cu and Al4Cu9) and Cu–Zn are present at the stir zones of all the joints while the brazed zone of the MFSC-B joint is predominated by uniform lamellar eutectic structure due to higher heat input, localized two-fold Zn melting, and frictional-stirring activated eutectic transformation. The increase in the load-bearing area (brazed + stir zones) of the MFSC-B joint improved the fracture resistance of the joint by 59% as the average tensile-shear loads of about 7.0 and 4.4 kN were obtained in the MFSC-B and FSSW-B joints respectively. The use of MFSC-B is thus recommended as a reasonable alternative for improving the weld performance of dissimilar reactive metals.
ISSN:2238-7854
DOI:10.1016/j.jmrt.2020.09.042