In situ fabrication of ZrC powder obtained by self-propagating high-temperature synthesis from Al-Zr-C elemental powders

The in situ synthesis of ZrC powder utilizing self-propagating high-temperature synthesis (SHS) reaction that occurred in the compact consisting of Al, Zr and C powders was investigated. The result shows when Al contents were 0-40 wt.% SHS reaction proceeded favorably. The as-products display a uniform distribution of ZrC particles with the sizes ranging from 8 μm at Al free to 50 nm at 40 wt.% Al. The temperature curve, coupled with the quenched treatment, indicates that the Al-Zr reaction to form ZrAl₃ initiated and then C reacted with ZrAl₃ to form the more stable ZrC phase. It also proves that the mechanism of reaction-precipitation should be responsible for the formation of ZrC in this system. Al has been playing an important role in determining the formation of ZrC, not only as a diluent to inhibit the ZrC grains from coarsening, but also as an intermediate reactant to participate in the total reaction.