Study On Vacuum Diffusion Welding Process Of 6061Al/TC4 And 6063Al/CE11

Aluminum alloy is widely used in the field of lightweight research due to its low density,high strength and good machinability.High silicon aluminum alloy is an aluminum matrix composite material prepared by adding silicon particles to aluminum alloy.It has excellent thermal conductivity and adjustable thermal expansion coefficient,and has great potential in the field of electronic packaging.Titanium alloy has high specific strength,low density,high price and high cost.In this paper,the forming law of TC4/6061Al joint and the welding feasibility of 6063Al/CE11（Al Si50）are studied by vacuum diffusion welding.The following conclusions are obtained:In the experiment of different diffusion bonding pressures of TC4/6061 Al,it was found that with the increase of welding pressure,the strength of the joint increased first and then decreased.When the welding pressure reached 30 MPa,the tensile strength of the joint reaches the maximum value of 208.13 MPa.When the welding pressure continued to increase,the appearance size of the material deformed,the deformation of the welding surface is blocked,and more pits appeared on the side of the Al matrix when the joint breaks.A diffusion layer composed of Ti Al₃intermetallic compound and Al solid solution with a thickness of less than 1μm were observed at the interface of welded joints obtained by different welding pressures.According to the plastic deformation theory,the Derby model is established.Therefore,the contribution of welding pressure to the improvement of joint strength is mainly to promote the micro plastic deformation of materials,increase the connection area of welding surface and reduce the size of holes.In the experiment of TC4/6061 Al with different holding time,it was found that with the increase of holding time,the tensile strength of the joint increased first and then decreased.When the holding time was 150 min,the joint strength reached the maximum value of 217.9 MPa.The gradually thickened diffusion layer was observed at the interface.The diffusion layer was mainly composed of Ti Al₃,Al（ss）,Ti（ss）and a small amount of Ti Al.The atomic diffusion distance is positively correlated with the square root of the holding time,and the extension of the holding time will not lead to a rapid increase in the atomic diffusion distance.In the experiment of different welding temperatures of TC4/6061Al,it was found that the thickness of Ti Al₃ intermetallic compound layer increased gradually with the increase of welding temperature.When the welding temperature was 520°C,the tensile strength of the joint reached the maximum value of 233.4 MPa,and the fracture position occurred at the Ti Al₃ intermetallic compound layer and 6061Al base metal.Increasing the welding temperature helped to increase the diffusion rate of atoms and promote the closure of interface pores.In the experiment of 6063Al/CE11 vacuum diffusion welding weldability verification,the tensile strength of the joint increased first and then decreased with the increase of welding pressure.When the pressure was small,the hole of the welding surface was difficult to close,and when the pressure was large,it was easy to cause the CE11 base metal to break.The diffusion welded joint with high strength can be obtained by welding temperature of 530°C,holding time of 180 min and welding pressure of 20MPa.