Abstract
A study of diffusion bonding of Ti-6AI-4V alloy has been made to lower the bonding temperature and pressure.
Al brazing sheet, whihc is consist of 0.6 mm thickness A3003 core material and 0.07 mm thickness Al-10% Si clad metal on both sides, was used as an intrelayer and the bonding parameters, temperature, pressure and time, were changed in different conditions. Al brazing sheet has been also compared with pure Al interlayer in bonding strength in order to make clear the effect of Al-1OSi clad metal in the Ti alloy bonding.
The bonding strength increased with incraesing bonding temperature, pressure and time. The joint bonded at 610°C for 30 min with a pressure of 0.5 kgf/mm2 showed tensile strength of 20 kgf/mm2.
The diffusion bonding of the Ti alloy with an interlayer of Al resulted in the formation of intermetallic compounds at the bond interface, especially the bonding with an interlayer of Al brazing sheet showed the excessive intermetallic formation. However, the bonding strength increased as the thickness of the intermetallic compounds was increased from 2 to 7 μm.
The significant difference between Al brazing sheet and pure Al interlayer was recognized in the strength of joints bonded with the pressure of less than 0.2 kgf/mm2 and for the time of less than 15 min. The bonding strength of the joint with Al brazing sheet interlayer ieacl ed 12.5 kgf/mm2 with no bonding pressure although in the bonding with pure Al interlayer the strength was not achieved.
Improvement of the bonding strength by the use of Al brazing sheet interlayer was attributed io melting of Al-Si clad metal which leads to increase of the contact area and acceleration of diffusional processes at the bond interface.
