Diffusion processes at the interface of titanium/aluminum diffusion welded pair in ambient air atmosphere

摘要

Usually diffusion welding process of titanium (Ti) with aluminum (Al) should be carried out in vacuum or reduced atmosphere. These welding atmosphere conditions were established to avoid the prevented actions of Ti and Al oxide layers on welded metal surfaces from diffusion at the interface. However in this study it is reported that high quality welds could be achieved without the use of vacuum or reducing atmosphere by applying sufficient compression to give high level of plastic deformation of Al layers sandwiched between layers of titanium at 630℃ in laboratory air. During welding the diffusion process at the interface between both components has to be run. The resulting structures and intermetallic phases were characterized using scanning electron microscopy, transmission electron microscopy and microanalyses, which showed that, under above mentioned welding parameters, Ti diffused across the interface into the Al. These diffusion processes were obtainable because of the thermodynamic reaction between Ti- oxide at the Ti surface and uncovered Al surface which has been stripped by the plastic deformation deed. This reaction can cause local thermodynamic conditions of Ti-oxide instability by means of big difference between values of Al and Ti oxides oxygen partial pressures, then, the Ti - diffusion across the interface becomes accessible. Thus the diffusion bonding of studied pair in ambient normal air atmosphere has got real success.