Research On Connection Mechanism Of W-Cu Composite And Stainless Steel By Copper Based Brazing Filler Metals

Because of W-Cu composite has copper and tungsten’s excellent performance.Now it is becoming more and more attention and application in modern life.But in the actual use of the process,tungsten copper composite material has low toughness and oxidation resistance is poor,so in order to improve the oxidation resistance,considered together with stainless steel and tungsten copper compositegood oxidation resistance,this can increase the application range of tungsten copper composite.In the current conditions,the better performance of welding using Ag based solders,Au based solder,brazing joint strength is high,but the cost is too high,it is not suitable for large-scale use.While the use of nickel base solder and brazing metal agreed to appear more brittle,and nickel based joint strength is low.In this paper,on the basis of the study of copper base filler metal for brazing choice of tungsten copper and stainless steel materials.Microstructure of Cu-Mn-Co-Ni3 solder joints is composed of Cu based solid solution and Fe rich phase:Cu（Mn-Fe）and Fe（Co）,to improve the ductility and toughness of the joints.Joint bending strength is up to 590 MPa,the fracture of the joint in the tungsten copper base metal,the emergence of a large number of dimples on the cross section.The addition of Ni can improve the high temperature resistance of joints,Ni and W in the high temperature solid solution to improve the performance of joint.For Cu-Mn-Co-Zr3,Cu-Mn-Co-Zr5 these two kinds of filler,with the activity of Zr,it can improve the element diffusion.The brazing seam is mainly composed of Cu based solid solution and Fe rich phase:Cu（Mn-Fe）and Fe（Co）,through the analysis,we find the Fe₂ Zr,CuZr₂ intermetallic compounds.Two types of filler metals brazing joint strength more than 450 MPa,but with the increase of Zr content leads to the increase of joint of intermetallic compounds,is not conducive to the performance of solder joint,so the performance is not as good as the filler content of 5% content of 3%.For the Cu-Ni-Ti solder,brazing seam is mainly composed of（Cu-Ni）and（Fe-Ni）copper rich or iron rich phase,Cu-Ti and other metal compounds and trace（Ti-W）,（Ni-W）and solid solution.Ti as active element added to the solder,it can promote the tungsten copper in Cu toward the brazing diffusion,Ti can go to W to form limited solid solution,Ni solid solution under the condition of high temperature and W,a positive roleto improve the plasticity and toughness of Cu-Ni-Ti solder joint,solder joints fracturesurface is mainly composed of dimples and cleavage planes.The performance is slightly worse thanthe front solder,the bending strength is 440 Mpa.