SYNTHESIS OF INTERMETALLIC ALUMINIDES BY EXPLOSIVE REACTION PRESSING

Shock compression of metal powders can cause good interparticle bondin g and phase transformations. Surface melting of the particles leads to liquid phase sintering. Between dissimilar powders, chemical reaction s can occur as a result of the high energy shock wave passing through the material. In this study shock compression experiments have been pe rformed on stoichiometric mixtures of nickel and aluminium as well as of titanium and aluminium powders, with the aim of synthesising interm etallic materials. The experimental method was direct explosive powder compaction. Completely reacted, intermetallic NiAl, TiAl3 and TiAl we re obtained. It has been found that for each powder mixture, a certain individual threshold pressure has to be exceeded in order to initiate the intermetallic reaction. Microstructural investigations reveal tha t the reacting material melts completely during the exertion of the ex plosive pressure and solidifies rapidly after the passage of the shock wave. Pores caused by gaseous reaction products are observed in the N iAl and TiAl3 compacts. All recovered specimens show strongly increase d hardness and good consolidation.