Thermo-mechanical grain refinement in gamma (γ) based TiAl intermetallics

The purpose of this study was to refine the grain structure of cast and powder material (PM) Ti–48Al–2Cr–2Nb, and improve the room temperature properties of this α2+γ alloy. Thermo-mechanical grain refinement was investigated at 950 and 1050 °C for 50% deformation in cast material and at 50 and 75% deformation in the PM material. The grain size of the cast structure was reduced to 7–10 μm, whereas the grain size of the PM material decreased to submicron size. Room temperature compression tests revealed that the yield strength and the fracture stress of the alloys increase without an associated fracture energy loss. Submicron PM alloys showed intergranular fracture while as-received cast material exhibited cleavage fracture in room temperature tensile tests.