Research On Electron Beam Welding Process And Joint Performance Of Target Of High Purity Aluminum And 5083 Aluminum Alloy

High-purity aluminum refers to pure aluminum products with purity over 99.8%.The base material used in this thesis is high-purity aluminum with 0.5% copper alloy(purity 99.999%)and 5083 aluminum alloy.In this paper,the forming law,mechanical properties,microstructure analysis and composition evolution of welded joints of high purity Al0.5%Cu and 5083 aluminum alloy under different processes were studied.The application of electron beam welding joints in sputtering target materials was studied and the improvement measures were put forward.The welded joints of Al0.5%Cu-5083 are uniform,the weld width is 2mm,and the penetration reaches up to 20 mm.It has large aspect ratio,nail shape of weld section,good bonding and no macroscopic defects.There is an obvious fusion boundary between Al0.5%Cu fusion zone and base metal.The joint without transition zone usually has weak bonding property and fracture is easy to occur in this region.The interface between 5083 and the weld is good.The average hardness of welded joint is 60 HV,and the average hardness of base metal Al0.5%Cu is 33 HV,while that of 5083 aluminum alloy is 83 HV.The hardness of the joint is between Al0.5%Cu and 5083 alloy,which is higher than that of Al0.5%Cu.The hardness of the joint meets the requirement of the target material.The tensile strength of the joint is 70 MPa,70% and 50% of the tensile strength of Al0.5%Cu and 5083 alloy.The fracture location is located in the welded joint next to Al0.5%Cu.The grain size of Al0.5%Cu is 50-60μm,the grain size of 5083 alloy is 75-90μm,and the grain size of the top of weld zone is 40-50μm.The joint grain is refined and obviously smaller than the base metal.As the beam attenuates in the direction of thickness,the microstructure at the center of the weld is different from that at the top and tail of the molten pool.The alloying elements in the base metal are between Al0.5%Cu and 5083 alloy because of melting convection.The convection of Cu is more intense at the top of the molten pool than bottom.The burning of Mg is the most serious at the top of the molten pool.Electron beam welding test was carried out according to the requirements of sputtering target fabrication.It is found that there are spiking defects at the end of the welding process.Defect control by deflecting the tail angle is improved,but it does not meet the requirements of target fabrication.While the welding joint can meet the requirement of target fabrication by deflecting the ending position.