Bonding pressure effects on characteristics of microstructure, mechanical properties, and mass diffusivity of Ti-6Al-4V and TiAlNb diffusion-bonded joints
J Kundu and A Chakraborty and S Kundu, WELDING IN THE WORLD, 64, 2129-2143 (2020).
This research highlights the influence of bonding pressure on the features of diffusion-bonded joints (DBJs) between Ti6Al4V alloy and TiAlNb alloy investigated at 900 degrees C for 120 minutes in vacuum with variable pressures of 0.5, 1, 2, 3, and 4 MPa. Characterization of the bonded interfaces was conducted using optical microscopy and scanning electron microscopy in backscattered mode. A molecular dynamics (MD) model was developed with the commercial Large-scale Atomic/Molecular Massively Parallel Simulator (LAMMPS) package utilizing second nearest neighbor modified embedded atom method (2NN MEAM) potentials to predict the diffusion mechanism with variable compressive pressures along the TiAlNb|Ti6Al4V joint interface. Microstructural characterization with light microscopy and scanning electron microscopy in back-scattered mode (SEM-BSE) along the TiAlNb|Ti6Al4V DBJs revealed no interfacial intermetallic phase nucleation. Energy dispersive spectroscopy (EDS) maps and line profiles helped to understand composition variation across the interface. The maximum joint tensile strength of similar to 875 MPa, similar to 13.1% elongation, and mass diffusivity on both sides were obtained at 4 MPa processing pressures with a significant tendency of diffusivity improvement in the TiAlNb side.
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