Effect of mixed rare earth and Sr on microstructure and brazability of Al-20Cu-5Si-2Ni filler metal

The objective of this study is to investigate the influence of adding tiny amount of mixed rare earth （ La, Ce） and Sr to Al-20Cu-SSi-2Ni filler metal, by analyzing the microstructure, wettability and mechanical properties of brazed joints. The results show that with the addition of mixed rare earth （La, Ce ） into Al-2OCu-SSi-2Ni alloy, the α-Al solid solution as well as CuAl2 （ Ni） intermetallic compound phase significantly reduced, while more Al-Si eutectic phase and AI-Si-Cu ternary eutectic phase were produced. And as mixed rare earth （La, Ce ） added in, the wettability of Al-2OCu-SSi-2Ni filler metal decreased, while the shear strength of the brazed joints increased. The addition of Minor Sr modificated Al-2OCu-SSi-2Ni filler metal, further reduced the CuAl2 （ Ni ） intermetallic compound phase, which was partially replaced Al-Si-Cu ternary eutectic phase. As a result, the tensile strength as well as the wettability of the filler metal was improved.

Microstructure and properties of the joints of Cu/Cu and metallized Cu / kovar brazed with a low-silver vacuum brazing filler metal

In an attempt to develop low-silver brazing filler metals used for hermetic sealing materials in the vacuum interrupter industry,the ternary Ag-50Cu-5Ga low-silver vacuum brazing filler metal was investigated.The melting temperature was measured by differential scanning calorimetry(DSC),and the brazability of Ag-50Cu-5Ga alloy on copper and metallized copper/kovar were ascertained at 850℃under 1×10-4 Pa in this article.The microstructures of the filler metal and the joints have been analyzed by using scanning electron microscopy(SEM),equipped with an energy dispersive spectroscopy.The results show that vacuum brazing was success to join with copper or metallized copper/kovar using Ag-50Cu-5Ga filler and reliable joints were obtained.There were Ag-rich phase,Cu-rich phase and a fine eutectic structure of Ag-based solid solution and Cu-based solid solution in the copper joints and the width of brazing seam is about 60μm.The joints of kovar alloy to copper after surface nickel plating was composed of AgCu eutectic phase,Ag,Cu,Cu2Ga and CuNi2 phase.The tensile strength was 167 MPa and 150 MPa,respectively.The tensile results of joints show that the joint strengths were equivalent to the traditional brazing filler metals.

Joining of activated graphite to 6063 aluminum alloy with Al-Cu-Si-Ni-Mg filler metal

In this work, 6063 aluminum alloy-graphite joint intended for thermal conductive application were realized by applying Al-CuSi-Ni-Mg brazing filler metal and Ag-Cu-Ti pasted on high density graphite substrate to ensure wetting during the brazing process. The interface reactions during brazing and mechanical properties were studied using scanning electron microscopy(SEM) and shear test device.TiC was formed at the graphite/active Ag-Cu-Ti paste interface due to the reaction between Ti and C, and thus the wettability on the graphite was improved.It is shown that joint with a good quality can be produced at a brazing temperature of 550 ℃ for 10 min.The average tensile strength of the joint is 21 MPa. thus the wettability on the graphite was improved.It is shown that joint with a good quality can be produced at a brazing temperature of 550 ℃ for 10 min.

Performance analysis of 5A05 alloy brazed in vacuum with AlCuAg series filler metal

A multi-component alloy grade with liquidus temperature lower than 500℃was obtained by adding Ge and Mg elements on the basis of Al-Cu-Ag alloy,and the melting characteristics,as cast structure,tensile strength and section morphology of the alloy solder were studied.The results show that the solidus-liquidus temperature of the new designed Al-Cu-Ag-Ge-Mg solder is 468-491℃;in the vacuum environment,when heated to 530℃for 5 minutes,the surface of 5A05 aluminum alloy has a good wetting spread phenomenon.Under the same conditions,the tensile strength of the joint obtained by brazing is more than 50 MPa by tensile test at room temperature;combined with the observation and analysis of section morphology.The addition of Ge can effectively reduce the solidus liquidus temperature of solder,and exist in the as cast structure and soldering seam with AlGe and MgGe.The presence of Ge element can inhibit the effect of other elements of the solder and Mg in the base metal,and alleviate the corrosion phenomenon between the solder and the base metal.

Microstructure and mechanical properties of AlSiCu10-10 filler meter brazing 6063 aluminum alloy

AlSiCu_(10-10) flame brazing 6063 aluminum alloy was rearched,and microstructure and mechanical properties of brazed joints were tested in the experiments. The interfacial microstructures and brazing phases of brazed joints were analyzed by scanning electron microscopy( SEM) and X-ray energy dispersive spectroscopy( EDS). The strength of brazed joints was aquired by tensile test. The results show that the AlCu_2 and Mg_2 Si phases were formed in the brazing seam,the former is the brittle phase,the Mg_2 Si phases is considered to be the strengthening phase of the aluminum alloy,which can reduce the brittleness caused by AlCu_2. The average tensile strength of brazed butt joint was 115 MPa,and the average shear strength of brazed joint was 26 MPa. Finally,the fracture form and fracture morphology of the brazed joint were analyzed.

Study on high frequency brazing of brass-red copper

Two kinds of silver based medium temperature brazing filler metals(45AgCuZnSn and 60AgCuSn) were selected to braze and seal brass flange pipe and copper pipe by high frequency heating brazing. In this paper, the quality of the braze was evaluated by immersion ultrasound, and the microstructure of the brazed joint was observed by SEM and EDS. The experimental results show that the high frequency heating brazing can quickly achieve the device sealing;through the ultrasonic flaw detection image calculation, the brazed bonding rate obtained by 60AgCuSn brazing is 87%, and by 45AgCuZnSn brazing is 71%;the cross-sectional area of the brazed joint obtained by two kinds of silver based medium temperature brazing filler metals is observed, the brazed joint obtained by 45AgCuZnSn brazing has defects visual, and a large amount of Zn element gathered in the defects, there is no obvious porosity in the brazed joint by 60AgCuSn brazing,and the bonding layer is dense and coherent. Through the contrast test, the choice of 60AgCuSn alloy brazing can meet the needs of high frequency brazing of brass flange pipe and copper pipe.