Fabrication of ZrC particles and its formation mechanism by self-propagating high-temperature synthesis from Fe-Zr-C elemental powders

ZrC particles were prepared via self-propagating high-temperature synthesis (SHS) reaction from 0 to 30 wt.% Fe-Zr-C elemental powder mixtures. The ZrC particles of the SHS products greatly decreased from about 10 mu m with an irregular shape in free Fe addition to nano-meter order with a nearly spherical shape in 30 wt.% Fe addition. The reaction mechanism of ZrC during the SHS processing was explored through the microstructural observation and phase constituents analysis on the combustion-wave quenched sample in combination with differential thermal analysis (DTA). For the low Fe contents, the solid-state reaction between C and Zr powders should be responsible for the formation of ZrC. While for the high Fe contents, the formation mechanism of ZrC could be ascribed to the dissolution of C into the Fe-Zr melt and the precipitation of ZrC. The addition of Fe to Zr-C reactants not only inhibits the growth of ZrC particles but also promotes the occurrence of ZrC-forming reaction. (C) 2011 Elsevier B.V. All rights reserved.