Gas Atomized γ‐Titanium Aluminide Alloys

HIP temperature and properties of a gas-atomized γ-titanium aluminide alloy

“…The tensile properties in the as-HIP conditions are in good agreement with the literature in that higher HIP-temperatures lead to higher ductilities and lower yield stresses [7][8][9]. The fine grain size, high Al-content, and near-g microstructure of PM Ti-46Al-2Cr-2Nb HIP-ed at 1200 C result in extremely high strength and very low ductility as can be expected for this microstructure and composition [4,19]. Higher HIP-temperatures increase the content of lamellar colonies at the expense of equiaxed g-grains and coarsen of the microstructures, which, consistent with basic microstructural observations, reduce yield stress [20].…”

“…The inherently high cooling rate of gas atomization suppresses segregation and results in uniform composition. Small compositional variations can have a significant effect on strength and ductility of g-TiAl based alloys, making the uniform composition obtained by PM (powder metallurgy) processing of prealloyed powders particularly attractive [3,4]. Consistent process scale increases and yield improvements have resulted in substantial manufacturing cost reductions making PM titanium aluminides a realistic alternative high temperature material [5].…”

Identification of microstructural mechanisms during densification of a TiAl alloy by spark plasma sintering

“…Moreover, we have not systematically distinguished between the low-temperature ordered ˛2 and B2 phases, and hightemperature disordered ˛ and ˇ phases, and we will most of the time call them (maybe abusively) ˛ and ˇ. In powders, due to the fast quenching rate of the liquid particles during atomization, the powder particles contain a large fraction of out of equilibrium p hase [7,12,13]. In our case, estimates of volume fractions from X-ray measurements gave: 27% of , 65% of ˛ and 8% of ˇ.…”