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 ...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.展开更多
The contact-reactive brazing of Al_(0.3)CoCrFeNi high-entropy alloys with a Nb interlayer was researched.The effects of Nb thickness and brazing temperature on the interfacial microstructure and mechanical properties ...The contact-reactive brazing of Al_(0.3)CoCrFeNi high-entropy alloys with a Nb interlayer was researched.The effects of Nb thickness and brazing temperature on the interfacial microstructure and mechanical properties of Al_(0.3)CoCrFeNi joints were investigated.The results show that with Nb thickness increasing from 10 to 100μm,the average width of Al_(0.3)CoCrFeNi joints is increased from 127 to 492μm and the erosion volume of Al_(0.3)CoCrFeNi base metals(BMs)by face-centered cubic-Nb eutectic liquid is enlarged accordingly.With increasing brazing temperature from 1280 to 1360℃,the intergranular penetration of eutectic liquid into Al_(0.3)CoCrFeNi BMs becomes more severe and lamellar Laves phase is broken-up and spherized.The shear strength of joint is increased gradually from 374 to 486 MPa and then decreased to 475 MPa.The maximum shear strength value of 486 MPa is obtained when brazing at 1340℃ for 10 min,reaching about 78% of the shear strength of Al_(0.3)CoCrFeNi BMs.Besides,the brazing mechanism was analyzed in details.展开更多
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)+1 种基金Jiangsu Province Natural Science Foundation of China(BK20131261)General Project of Anhui Science and Technology University(ZRC2013377)
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 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the Outstanding Youth Innovation Team in Universities of Shandong Province(2023KJ114)National Natural Science Foundation of China(Grant No.52305344)Natural Science Foundation of Shandong Province,China(Grant No.ZR2022QE073).
文摘The contact-reactive brazing of Al_(0.3)CoCrFeNi high-entropy alloys with a Nb interlayer was researched.The effects of Nb thickness and brazing temperature on the interfacial microstructure and mechanical properties of Al_(0.3)CoCrFeNi joints were investigated.The results show that with Nb thickness increasing from 10 to 100μm,the average width of Al_(0.3)CoCrFeNi joints is increased from 127 to 492μm and the erosion volume of Al_(0.3)CoCrFeNi base metals(BMs)by face-centered cubic-Nb eutectic liquid is enlarged accordingly.With increasing brazing temperature from 1280 to 1360℃,the intergranular penetration of eutectic liquid into Al_(0.3)CoCrFeNi BMs becomes more severe and lamellar Laves phase is broken-up and spherized.The shear strength of joint is increased gradually from 374 to 486 MPa and then decreased to 475 MPa.The maximum shear strength value of 486 MPa is obtained when brazing at 1340℃ for 10 min,reaching about 78% of the shear strength of Al_(0.3)CoCrFeNi BMs.Besides,the brazing mechanism was analyzed in details.
