Microsegregation, macrosegregation and related phase transformations in TiAl alloys

In the first part of the paper the influences of microsegregation on the microstructure establishment in Ti–Al based alloys are described. Examples are taken concerning the primary solidification phase, the grain refinement through boron addition, the occurrence of B2 phase in as-cast parts and the link between microsegregation and creep properties. In the second part, a numerical model of macrosegregation devoted to centrifugal casting of TiAl alloys is presented and the influences of the parameters of the model are discussed.