Intermetallic γ-TiAl based alloys are innovative lightweight structural high-temperature materials used in aerospace and automotive applications due to already established industrial-scale processing routes, like casting and hot-working, i.e., forging. A promising alternative method of production, regarding manufacturing of near net-shape components, goes over the powder metallurgy route, more precisely by densification of TiAl powder via spark plasma sintering. In this study, gas atomized powder from the 4th generation TNM alloy, Ti-43.5Al-4Nb-1Mo-0.1B (in at.%), was densified and the microstructure was investigated by means of electron microscopy and X-ray diffraction. The sintered microstructure exhibits lamellar α₂-Ti₃Al /γ-TiAl colonies surrounded by globular γ- and ordered β_o-TiAl phase. The coarse lamellar spacing stems from the low cooling rate after densification at sintering temperature. Against this background, subsequent heat treatments were designed to decrease the lamellar widths by a factor of ten. Accompanying, tensile tests and creep experiments at different temperatures revealed that the modified almost fully lamellar microstructure is enhanced in strength and creep resistance, where a small volume fraction of globular γ-phase provides ductility at ambient temperatures.

“Top-quality powder is a precondition for additive manufacturing of quality components.” This paper covers the powder characterization of high-melting and highly reactive intermetallic γ-TiAl powders by combining technological and metallographic examinations. Measurements of tap density, bulk density, flow behaviour, particle size distribution and sphericity of the powder will reveal characteristic parameters which have an effect on process stability. The subsequent analysis of the powder microstructure will show possible gas inclusions or defects which may negatively affect the mechanical properties of the manufactured component. Each of these factors presents a quality criterion, which is also applicable – irrespective of the alloy system – to other materials systems.