MECHANOCHEMICAL SYNTHESIS OF NONSTOICHIOMETRIC TANTALUM DISILICIDE

Tantalum disilicide synthesis was developed by means of mechanochemica l activation under intensive mechanical treatment. The concentration i nterval from Ta75Si25 to Ta18Si82 (at. %) was under investigation. Act ivator-mills of planetary type were used for mechanical treatment with balls accelerated under 600 ms(-2). The increase of elementary cell p arameter takes place during the initial period of mechanical activatio n up to 12 min. The intensity of Ta lines diminishes, and reflexes of the TaSi2 phase appears during treatment. The metastable structures on the base of TaSi2 were produced containing up to 15 at. % of silicon and 5 at. % of tantalum excess. The homogeneity region of the TaSi2 ph ase can be extended from Ta38.3Si61.7 to Ta18.3Si81.7. Tantalum disili cide materials with tantalum excess have better oxidation resistance. (C) 1998 Published by Elsevier Science S.A.