Wetting behavior of AlAgCu brazing filler on aluminum matrix composites and stainless steel

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• 作者：S. Weis ; M. Elßner ; B. Wielage ; G. Wagner
• 关键词：(IIW Thesaurus)Arc brazing ; Brazing fillers ; Microstructure ; Wettability
• 刊名：Welding in the World
• 出版年：2017
• 出版时间：March 2017
• 年：2017
• 卷：61
• 期：2
• 页码：383-389
• 全文大小：
• 刊物主题：Metallic Materials; Continuum Mechanics and Mechanics of Materials; Theoretical and Applied Mechanics;
• 出版者：Springer Berlin Heidelberg
• ISSN：1878-6669
• 卷排序：61

文摘

Suitable joining technologies are necessary for the application of aluminum matrix composites (AMC). Especially dissimilar joints between AMC and stainless steel are of enhanced interest. In this work, the approach of arc brazing source of this material combination is investigated. Therefore, basic examinations like the wetting behavior of a developed filler on the base metals is realized. The used filler of the system Al-Ag-Cu show a ternary eutectic of the phases Ag₂Al, Al₂Cu, and solid solution of Al. Sessile drop technique is applied for the wetting tests. To generate the arc, a TIG welding unit is used. The results of these wetting tests, like the wetting angles and the microstructure of the interfaces, are described and discussed. The wetting angle measured on cross sections show that the wetting on AMC is good (< 30°) while the wetting on stainless steel (~ 90 °) has to be improved. That demonstrates the excellent wettability of the AMC and the suitability of that approach. The wettability of stainless steel can be improved by pretreating, like preheating and polishing, which results in a wetting angle of approx. 35°. The influence of these pretreatments on the microstructure due to a various diffusion behavior of, for example, Al at the interface of the combined materials are described. Different phases in comparison to the filler can be seen at the interfaces of braze metal and the base metals by using SEM, due to a strong diffusion of Al. Analyze by energy-dispersive x-ray spectroscopy (EDXS) and x-ray diffraction (XRD) at the interface of braze metal to stainless steel indicate intermetallic layers of the system Fe-Al, like AlFe₃, Al₂Fe and Al₁₃Fe₄. In the case of the AMC, a solid solution of Al in shape of a not compact layer occurs and no formation of Al₄C₃ can be detected.