Effect of strontium and SmO on the microstructure and fracture mode of AlSi-Mg₂Si brazing filler metal

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• 作者：Tuoyu YANG ((杨拓宇))^a ; ^b ; Deku ZHANG ((张德库))^a ; Kehong WANG ((王克鸿))^a ; ^{wkh1602@126.com" class="auth_mail" title="E-mail the corresponding author} ; Jun HUANG ((黄 俊))^a
• 关键词：active filler metal ; brazing interface ; rare earths ; intergranular penetration
• 刊名：Journal of Rare Earths
• 出版年：2016
• 出版时间：February 2016
• 年：2016
• 卷：34
• 期：2
• 页码：187-196
• 全文大小：1895 K

文摘

An AlSi-Mg₂Si self-fluxing brazing filler metal was obtained by activating AlSi brazing filler metal with the Mg₂Si phase and applying a metamorphism treatment of Mg₂Si and Si crystals with Sr and SmO. A good wetting performance between the modified AlSi-Mg₂Si and 3003 Al alloys was achieved in the vacuum brazing without Mg vapour as the activator. The melting point of the brazing filler was measured by STA409Pc differential scanning calorimetry. A scanning electron microscope was used to analyse the microstructure and the component distribution of the brazing filler. The results indicated that the change in morphology of the Mg₂Si phase was remarkable after metamorphism. The analyses of the microstructure indicated that the Mg₂Si and Si phases presented small needle-type and granular morphologies. The follows were found to occur: intergranular penetration of Mg and Si on the base metal, a large amount of granular eutectic structure, and a significant grain boundary effect. The shear fracture of the lap joint presented cleavage fracture; in addition, with the decrease of the Mg₂Si phases, the fracture morphology transformed from a rock candy shape to a steam shape, and cleavage steps appeared. The rock candy-shaped fracture areas enlarged after metamorphism treatment.