Spray forming and subsequent forging of γ-titanium aluminide alloys

Spray forming experiments with a binary Ti–48.9Al (at.%) alloy and an advanced γ-TiAl alloy with the composition Ti–47Al–4(Nb, Mn, Cr, Si, B) (at.%), designated as γ-TAB, were carried out. Subsequently, the spray formed materials were forged. The sprayed and forged conditions were characterized in terms of microstructure, porosity, and impurity content. Tensile properties were evaluated at room and elevated temperatures. Upon forging the microstructures turned from nearly lamellar to near γ with a grain size of 4.9 μm (Ti–48.9Al) and from duplex to near γ with a grain size of 2.2 μm (γ-TAB) owing to dynamic recrystallization. The porosity of the spray formed materials almost vanished after forging. The room temperature (RT) tensile strength was improved due to the significant microstructural refinement. The sprayed and forged γ-TAB alloy sustains an elongation of 120% at 800 °C indicating the possibility of superplastic forming. The results are discussed in comparison with conventionally P/M-processed and hot isostatically pressed materials of the same composition.