Effect laws of process parameters on diffusion bonding quality of 5A90 Al-Li alloy
The diffusion bonding process of 5A90 Al-Li alloy was studied by means of metallographic microscope,scanning electron mi-croscope and vacuum hot pressing sintering furnace.The results show that during the diffusion bonding process,with the increase of tem-perature and the extension of holding time,the white strengthening phase in the specimen increases,the voids decreases,and the welding degree increases obviously.The shear strength decreases with the increase of diffusion bonding temperature and the decrease of holding time,and then the bonding strength is reduced.This is mainly due to the effect of diffusion temperature and holding time on the atomic diffusion process.The specimen interface with roughness of 15 μm avoids the excessive thickness of the alumina film and ensures local contact of joint during diffusion bonding,which makes the oxide film rupture,and the best joint quality is obtained.The fracture under typical parameters occurs in the base metal,and the transgranular fracture is the main fracture form,which proves the reliability of the 5A90 Al-Li alloy diffusion bonding joint.Through comparative analysis,the optimum diffusion bonding process parameters are as follows:bonding temperature of 540℃,holding time of 2.5 h,surface roughness of 15 μm.
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