工艺参数对5A90铝锂合金扩散连接质量的影响规律

Effect laws of process parameters on diffusion bonding quality of 5A90 Al-Li alloy

采用金相显微镜、扫描电镜和真空热压烧结炉等设备探究了5A90铝锂合金的扩散连接工艺。结果表明,在扩散连接过程中,随着温度的升高和保温时间的延长,试样中白色强化相增多,空洞减少,焊合度明显提高。剪切强度随扩散连接温度的提高而降低,随保温时间的减少而降低,进而使连接强度降低;这主要是由于扩散温度及保温时间对原子扩散过程产生影响。试样界面15μm的粗糙度避免了氧化铝薄膜的过厚,并保证了扩散连接时接头处的局部接触,使氧化膜破裂,得到最佳接头质量。典型参数下的断裂发生在母材中,以穿晶断裂为主要断裂形式,证明了5A90铝锂合金扩散连接接头的可靠性。通过对比分析,得到扩散连接最佳工艺参数为:连接温度540℃、保温2.5 h、表面粗糙度15μm。

The diffusion bonding process of 5A90 Al-Li alloy was studied by means of metallographic microscope,scanning electron microscope and vacuum hot pressing sintering furnace.The results show that during the diffusion bonding process,with the increase of temperature 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 15μm 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 15μm.