Energy density and in-situ heat treatment effect on microstructure of Titanium Aluminide additive manufacturing using Electron Beam Melting Powder Bed Fusion

Titanium Aluminide additive manufacturing using Electron Beam Melting is increasingly of interest as the process can modify the microstructure and resultant mechanical properties. The microstructural uniformity along the build direction has been carried out under different energy input process conditions. We also studied the effect of the in-situ heat treatment and associated discontinuous coarsening of the primary lamellar microstructure in the final layers of the build. The presence of beta phase was also examined to see it’s morphology and effect on the final microstructure. It was found that the energy density and layer thickness created different microstructures in the build direction and better uniformity was found at certain parameters. With in-situ heat treatment in the machine discontinuous coarsening of the primary lamellar structure was completely surpassed by a structure of small colonies and wide lamellae. The results suggest it would be useful to explore further by reducing the colony size to increase the ductility of the material and a finer lamellar thickness for improved creep properties.