Impact of Bonding Temperature on Microstructure, Mechanical, and Fracture Behaviors of TLP Bonded Joints of Al2219 with a Cu Interlayer

Abstract

The present study aims at producing transient liquid phase (TLP) bonded Al2219 joints with pure Cu (copper) as an interlayer. The TLP bonding is carried out at the bonding temperatures in the range of 480 to 520 °C while keeping the bonding pressure (2 MPa) and time (30 min.) constant. Reaction layers are formed at the Al-Cu interface with a significant increase in diffusion depth with the increase in the bonding temperature. The microstructural investigations are carried out using scanning electron microscopy and energy-dispersive spectroscopy. X-ray diffraction study confirms the formation of CuAl2, CuAl, and Cu9Al4 intermetallic compounds across the interface of the bonded specimens. An increase in microhardness is observed across the bonding zone with the increase in the bonding temperature, and a maximum hardness value of 723 Hv is obtained on the diffusion zone of the specimen bonded at 520 °C. Furthermore, the fractography study of the bonded specimens is carried out, and a maximum shear strength of 18.75 MPa is observed on the joints produced at 520 °C.