Cast and PM processing development in gamma aluminides

This paper describes the mechanical properties variability for cast and PM TiAl products. Tensile properties of the 48-2-2 alloy and creep properties of the G4 alloy have been found very sensitive to prior casting defects and to microstructure evolution. Small scatter requirements can be satisfy by obtaining metallurgically sound cast products. The major trend is associated with the increased property scatter by using subsequent heat treatments due to the strong casting history. On the other hand, PM products generate low property variability owing to a good structural homogeneity. Tensile properties appear to be strongly related to the lamellar/γ grain ratio. A more homogeneous deformation is obtained by reducing the powder particle size distribution within the powder compacts and by promoting lamellar microstructures, hence yielding lower scatter in tensile ductility.