Investigation on Effect of Temperature on Mechanical Properties and Microstructure of Dissimilar Ti-5Al-2.5Sn and AA2219 Alloy Joints through Diffusion Bonding Process

The joining of Ti-5Al-2.5Snto AA2219 dissimilar alloys was studied through vacuum diffusion bonding (VDB).Samples were bonded at various temperatures under 15 MPa pressure for 45 minutes.The mechanical properties of the bonded lap joints were evaluated with shear and Vickers micro hardness tests, while scanning electron microscopy (SEM) was utilized to examine their microstructure.Energy-dispersive spectroscopy (EDS) and microstructural analysis revealed that the interfacial oxide layer diminished as the bonding temperature increased.The X-ray diffraction (XRD) analysis showed that TiAl3was the only intermetallic compound formed at the interface.Results indicated that as bonding temperature increased, the interface micro hardness first increased and then decreased at higher temperatures.Furthermore, the shear strength of the bonded joint improved with rising temperature from 525 C to 540 C but decreased at 555 C because of the development of a thick intermetallic layer.