Solid-state diffusion joining of Ti6Al4V parts produced by selective laser melting: joint characteristics and bonding mechanism

This work aims to investigate the microstructure and mechanical properties of Ti6Al4V parts produced by selective laser melting (SLM) in the early stage of solid-state diffusion bonding process. A thermomechanical simulator is employed to carry out the experiment. In the experiment, three diffusion temperatures (850°C, 900°C, and 950°C) are adopted, and the pressure is kept constant. It is found that the higher diffusion temperature reduces the voids on the bonding interface and part interior, and thus it improves the mechanical properties of the joint. The diffusion bonding joints consist of criss-cross acicular α′ martensitic structure. The volume fraction of martensitic α′ decreases with the increase of bonding temperature. Finally, the underlying mechanism of morphological evolution on the diffusion plane is analyzed. The results provide insights on the bonding mechanism of SLM-produced Ti6Al4V in solid-state diffusion joining.