| In this paper, the vacuum brazing process of Al2O3p dispersion-strengthen copper and CuCrZr alloy with Ag-Cu-Ti filler metal was studied. Study the influence of different brazing process on joint microstructure and properties by tensile strength experiment, metallographic analyzer, scanning electron microscope (SEM), and energy disperse spectroscopy (EDS). At the same time, CuCrZr alloy and joints properties by the process of merging vacuum brazing and quenching into one and then aging treatment were discussed.The effects of brazing temperature and holding time on microstructure and properties of the joint are very significant. When the brazing temperature is lower or the holding time is shorter, the effects of diffusion and metallurgy action between filler metal and base metal are not strong and the connection is not tight. With increasing the brazing temperature and holding time, the effects of diffusion and metallurgy action between filler metal and base metal increase, the properties of joints are well. When the brazing temperature is higher or the holding time is longer, the filler will infiltrate into Al2O3p dispersion-strengthen copper seriously, the eutectic structure in the welded seam will disappear, and the Cu solid solution will increase. They will make the width of joints smaller and smaller, and there is not enough filler to fill the weld and this is the reason why get poor tensile strength. The tensile strength of the joint can be over 200MPa under optimized parameters.Brazing at 800℃for 10min, when the thickness of filler metal is less then 0.2mm, the filler metal is relatively little, some of filler will infiltrate into Al2O3p dispersion-strengthen copper, and there are holes in the welded seam, so the properties of joints will be poor. With increasing the thickness of filler metal, the filler metal is adequate, and the microstructure of joints on brazing is dense, so the properties of joints also will be improved.The microstructure of brazing joints under pressure is dense. The influence of different brazing temperature and holding time on strength of brazing under pressure is consistent with brazing without pressure. When the brazing temperature is lower or the holding time is shorter, the microstructure and properties of joints under pressure are similar to the joints without pressure. With increasing the brazing temperature and holding time, the seam width of joints under pressure is smaller, the capillarity of filler in welded seam is serious, and the microstructure of joints is dense. So the properties of joints under pressure are better than the joints without pressure. When the holding time is longer, the filler metal is inadequate, and the strength of joints will be poor. The strength of the joints under pressure is better than the joints without pressure. After aging treatment following brazing, the properties of CuCrZr alloy is superior to the properties after brazing. But compared to the properties of original state, the hardness is lower clearly. But its hardness is still much higher than the copper ( |
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