A Study on the Synthesis and Consolidation of Ti3Al by Electro-Discharge

Direct syntheses of bulk Ti3Al via electro-discharge-sintering (EDS) of a stoichiometric elemental powder mixture were investigated. A capacitor bank of 450 mu F was charged with three input energies, 0.5, 1.0, and 1.5 kJ. The charged capacitor bank was then instantaneously discharged through 0.3 g of a Ti-25.0 at.%Al powder mixture for consolidation. Complete phase transformation occurred in less than 200 mu sec by the discharge and a bulk Ti3Al compact was obtained. Compared with consolidated samples fabricated by conventional methods such as high vacuum sintering and casting, the electro-discharge-sintered Ti3Al compact shows a very fine microstructure with a hardness value of 425 Hv. Electro-discharge-sintering under a N-2 atmosphere successfully modified the surface Ti oxide of the Ti3Al compact into Ti nitride, which concurred with the synthesis and consolidation of Ti3Al. Complete conversion Yielding a single phase Ti3Al is primarily dominated by the fast solid state diffusion reaction.