摘要
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 modi-fied 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.
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 modi-fied 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.
基金
supported by Natural Scientific Research Projects of Education Department of Anhui Province(KJ2013Z046)
Innovation Training Project of Department of Education of Anhui Province(AH201310879077)
Jiangsu Province Natural Science Foundation of China(BK20131261)
General Project of Anhui Science and Technology University(ZRC2013377)
