As an effective route for near-net-shaping of sheets of poor workability materials, twin-roll casting is applied to production of gamma titanium aluminide sheets. Anexperimental process has beenestablished for shaping of flat 100-mm wide sheets with a uniform thickness in a range of I to 2mm. Changes in parameters controiling the rate of solidification in twin-roll casting provide a fairly wide variety of microstructures in a stoichiometric gamma titanium aiuminide alloy. The microstructures

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... characterized with special attention to their through-the-thickness variations for understanding of the path of solidification and solid state transformation in direct sheet casting. In the subsurface layer of cast sheets a primary alpha phaseforms from liquid and the alpha dendrites grow along the heat flow to form a sharp preferred orientation with the c~direction paralle[ to the sheet normal. Subsequently the alpha grains transform into an extensively refined (Y+ cL2) structure and develop a transformation texture of 11>Y fiber parallel to the sheet normal with an orientation relationship of {OOOI}a // {1 11 }Y' In the intermediate layer gamma single phase increases in relative fraction and evolves a growth texture of [OO1]Y Parallel to the sheet normal. In the dendrite and interdendritic gamma interfaces, gammagrainsaccommodate thermal stresses generated during cooling. Towardthe central zone the growih directions of dendrite deviate from the sheet normal with increasing depth below the surface as a reflection of meniscus profile. [n the central zone shrinkage cavities are formed in the absenceof liquid metal on solidification. Based on these findings metallurgical guides for further improvements in casting procedure and for controlling of cast structure are discussed.