X-ray diffraction study of mechanochemical synthesis and formation mechanisms of zirconium carbide and zirconium silicides

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The mechanochemical synthesis and formation mechanisms of zirconium carbide (ZrC) and silicides (ZrSi 2, ZrSi, Zr 5Si 3, and Zr 2Si) by ball-milling were investigated. The spontaneous formation of zirconium carbide during milling occurred by a mechanically induced self-propagating reaction (MSR), the mechanism of which is analogous to that of the thermally 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 formation of zirconium carbide and silicides could be attributed to their relatively large heats of formation, which made the exothermic reactions self-sustaining once initiated.