Metallurgy, Microstructure and Properties of Intermetallic TiAl IngotsMetallurgie, Gefüge und Eigenschaften von intermetallischen TiAl Ingots

As a consequence of the progress in processing of intermetallic γ-TiAl based alloys to semifinished and finished products the availability of industrial scale ingots with a defined homogeneous element distribution is strongly required. This paper describes the processing of novel TiAl alloys by means of vacuum arc remelting (VAR). These alloys, so-called TNM alloys, which solidify completely via the β-phase, exhibit fine grained microstructure consisting of lamellar γ/α2-colonies and globular γ and β/B2-grains. The volumetric ratio between the three phases depends mainly on the Al content and the content of the major β-stabilizing alloying elements Mo and Nb. The tensile properties of stress relieved as-cast VAR materials were determined in the temperature range of room temperature to 800 °C and the obtained results are related to the microstructure of the investigated alloys.