Research On Vacuum Diffusion Welding Of Dissimilar Metals Aluminum, Copper And Tungsten

The vacuum diffusion welding connection is mainly studied in this thesis with thedissimilar metals copper, aluminum, and tungsten. Connection structure of dissimilarmetallic materials in many fields has been widely used. It is able to connect differentproperties of metal material, so that the excellent performance of different materialsintegrate together to play their respective advantages. Copper and aluminum connectorswhich connect the dissimilar metals play an important role, because copper and aluminumuse in our daily life behind steel. If it can be easier and convenient realization of copperaluminum connections, can reduce production cost and improve the performance.Therefore, based on the diffusion of copper aluminum welding connection, devised a newvacuum diffusion welding process, to solve the dissimilar metals, especially theperformance of different metal materials.This entire research ideas can be divided into three parts. Firstly, the processingparameters for vacuum diffusion welding of copper and aluminum was investigated toobtain copper and aluminum welding specimen; Secondly, with the vacuum diffusionwelding experiment results and data by copper and aluminum, further studied to achievealuminum and tungsten connection which greater difference in performance; Finally,fruitful combination of the former two parts the realization of copper, aluminum andconnect three metals. The vacuum diffusion welding process could apply to moredissimilar metal materials.In the experiments, the welding base materials which include copper-aluminum,aluminum-tungsten and copper-aluminum-tungsten, are loaded in a mould. Withoutexternally applied pressures, the welded materials were contacted each other by the forcesprovided by nuts during tightening. By doing so, diffusion welding between the weldedmaterials can be realized under vacuum and desired temperatures. Using universal testingmachine and scanning electron microscopy (SEM) on the mechanical properties ofwelding, surface morphology by SEM and EDS composition analysis, got the suitablevacuum diffusion welding process parameters eventually: For the copper and aluminum welding at450℃temperature for3hours can obtain a tensile strength of about17MPa welded joint, aluminum and tungsten at500℃temperature for3hours cangain a tensile strength of about60MPa welded joint, meanwhile, copper aluminum andtungsten at450℃temperature for3hours can also gain a tensile strength ofabout17MPa welded joint. The welding joints surface morphology observed in theSEM, the welds are straight continuous, with no obvious problems such as welding defects.By component analysis identified the base metal atoms are fully spread.