X-RAY-DIFFRACTION STUDY OF MECHANOCHEMICAL SYNTHESIS AND FORMATION MECHANISMS OF ZIRCONIUM CARBIDE AND ZIRCONIUM SILICIDES

The mechanochemical synthesis and formation mechanisms of zirconium ca rbide (ZrC) and silicides (ZrSi2, ZrSi, Zr5Si3, and Zr2Si) by bail-mil ling were investigated. The spontaneous formation of zirconium carbide during milling occurred by a mechanically induced self-propagating re action (MSR), the mechanism of which is analogous to that of the therm ally ignited self-propagating high-temperature synthesis (SHS). Under the normal milling condition, the Zr/Si powder mixtures (Si=33-66 at.% ) also reacted via the MSR mode to form silicides. The explosive forma tion of zirconium carbide and silicides could be attributed to their r elatively large heats of formation, which made the exothermic reaction s self-sustaining once initiated. (C) 1998 Elsevier Science S.A.