HOT-PRESSING OF TIAL ALLOY POWDER PRODUCED BY PLASMA ROTATING ELECTRODE PROCESS AND THE MECHANICAL-PROPERTIES OF THE HOT-PRESSED COMPACTS

High quality TiAl powder was produced by Plasma Rotating Electrode Process (PREP). Two kinds of powders, the as-PREPed and the Ball Milled (PREP-BM) powders, were consolidated by Vacuum Hot Pressing (VHP). A compact having high relative density (>99%) was obtained from the PREP-BM powder by VHP at 1223 K and 200 MPa. In order to produce such a dense compact from the as-PREPed powder, it was necessary to carry out VHP at 1323 K and 100 MPa. The compact made from the PREP-BM powder showed superior compressive strength and ductility at room temperature to that made from the as-PREPed powder. A positive temperature dependence of 0.2% proof stress was clearly observed in each compact. It was noticeable that the strength of the compacts at elevated temperature such as 973-1 123 K was considerably higher than that of the as-cast specimen of TiAl alloy produced by conventional melting process.