REACTION SYNTHESIS OF REFRACTORY DISILICIDES BY MECHANICAL ALLOYING AND SHOCK REACTIVE SYNTHESIS TECHNIQUES

The reaction synthesis of disilicides of Group IVA-VIA transition meta ls by mechanical alloying and shock reactive synthesis techniques has been investigated. All nine disilicide compounds were directly produce d from their elemental powder mixtures by mechanical alloying. Moreove r, the formation of some disilicides, such as MoSi2 and NbSi2, proceed ed by mechanically induced self-propagating reactions, the mechanism o f which is analogous to that of the self-propagating high-temperature synthesis (SHS). Shock reactive synthesis of MoSi2, NbSi2, and TiSi2 w as conducted with a one-stage gun. Powder samples used for the shock s tudy were prepared from metal-silicon powder mixtures that had been su bjected to high-energy ball milling. The explosive driven flyer plate struck the sample-containing capsule at a velocity of 1 km s(-1). In m ost cases, shock-induced reactions went to completion. The effect of t hermochemical driving force on the reactive formation of the disilicid e compounds is discussed. (C) 1997 Elsevier Science S.A.