ABSTRACT
This chapter describes the use of a modified rheocasting process with high rotation speeds to manufacture intermetallic TiAl alloys and composites. Basically, the apparatus comprises an isothermal furnace in a vacuum or an inert gas atmosphere which holds the TiAl or composite sample, and a stirrer. The microstructures of intermetallic TiAl alloys prepared by rheocasting at high stirrer speeds were observed by scanning electron microscopy. For the purpose of comparison, reference intermetallic TiAl alloys were prepared by allowing the molten charge to solidify spontaneously in the isothermal furnace without using the stirrer. The distributions of titanium and aluminium were measured in rheocast and unstirred intermetallic TiAl alloys and composites and microanalysis in the scanning electron microscope on transverse sections from the top, middle and bottom of ingots. Tensile testing at room and elevated temperature was carried out on the rheocast and unstirred intermetallic TiAl alloys and composites.
