Development, Structural Characterization, And Laser Beam Powder Bed Fusion Of Ti/Nb/Ta Alloy Powders

The development of spherical Ti/Nb/Ta alloy powders with compositions Ti-xNb-6Ta (x = 20, 27, 35 wt%) by electrode induction melting gas atomization (EIGA) and their processing by laser beam powder bed fusion (PBF-LB/M) are reported. Microstructure investigations by X-ray diffraction and scanning electron microscopy including energy dispersive X-ray spectroscopy and electron backscatter diffraction reveal a significant impact of the composition on the structural properties, i.e., phase evolution and texture, and the possibility for a direct microstructure design. Ti-rich alloys preferably solidify in the orthorhombic α’’-phase, whereas in Nb/Ta-rich alloys the body-centered cubic (bcc) β-phase is observed. The alloys possess a very broad processing window and can be printed to full density over a wide range of printing parameters. Additively manufactured Ti-27Nb-6Ta shows a unique behavior, since strength and elongation at failure strongly depend on the printing parameters applied. The underlying microstructural mechanisms, i.e., the influence of the laser energy on texture effects and phase formation, are discussed.