| With the development of science and technology,traditional vacuum devices are now gradually substituted by solid-state electron devices.However,due to the high working efficiency,stability and long life,the use of electric vacuum devices is still irreplaceable in the field of high power and high frequency.At present,the brazing temperature of the brazing metal for vacuum devices is mostly above 650?,it is difficult to meet the requirement of brazing temperature below 650?for some vacuum device materials.As a kind of vacuum devices brazing filler brazing metal,Ag-Cu-Sn has a wide range of brazing temperature and can be brazed below 650?.But with the high content of Sn in the filler metal,a lot of brittle phases will be formation.With the increasing the content of brittle phases,the plasticity of the Ag-Cu-Sn alloy will decrease,result in deterioration of its processing performance,it is hard to fabricate by traditional method.In order to solve this problem,the Ag-25.5Cu-27Sn alloy was prepared by magnetic pulse compaction and sinter process.This method can effectively avoid that problem.It is a certain significant to expand the industrial application of Ag-Cu-Sn filler metal and enrich the method of processing technology of filler brazing metal.This paper mainly studies the influences of sintering process on the properties of Ag-25.5Cu-27Sn filler metal.Firstly,taking Ag-25.5Cu-27Sn for research object,a certain density compacts of Ag-25.5Cu-27Sn filler metal were prepared by magnetic pulse compaction.The microstructure and properties of the Ag-25.5Cu-27Sn filler metal after sintering at different temperature and holding time were studied by means of theoretical analysis,performance testing and microscopic analysis.XRD diffraction analysis showed that the phase composition of the compacts changed significantly after sintering at different temperature.The filler metals alloyed completely after holding for 15 min at 400?and was mainly composed of?1-Cu3Sn and?2-Ag3Sn.Relative density indicated that The relative density sintered at 400?was higher than that of the original compact.When the temperature was reached to 500?,the alloy was overburn and out of shape,can not be used normally.Micro-hardness testing showed that the sintering process has great influence on the microhardness of the filler metal.With the increase of sintering temperature and holding time,the microhardness of the filler metal improved.The microhardness of the filler metal was increased 162.6HV after sintering at 400?for 30 minutes.However,long holding time would cause micro-hardness decreased,which may result from the coarse microstructure of the filler metal.The sintering process slightly increased the melting temperature and the melting range of the filler metal.The melting temperature of the filler metal sintered at 400?was about 4?lower than that sintered at 250?.The wettability test results showed that the sintering process have no significant effect on the spread area of the filler metal at the experimental temperature of 580?.The result of tensile strength test showed that the tensile strength of the Cu joints decreased first,and then increased with the increase of sintering temperature of the filler metal.The microstructure observation of brazed joint showed that there are different number of pores defects in the brazed joint,the joint has the most pore which brazed by the filler metal sintering at 250?.Another obvious change is that the microstructural homogeneity of the Cu joints has been improved brazed using the filler metal after sintered.The results of EDS showed that the brazing joint is mainly composed of Ag-based solid solution,Cu-based solid solution and the acicular Cu3Sn dispersed in the Cu-based solid solution. |
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