Processing of ZrC–Mo Cermets for High-Temperature Applications, Part I: Chemical Interactions in the ZrC–Mo System |
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| Authors: | Sean E Landwehr Gregory E Hilmas William G Fahrenholtz Inna G Talmy |
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| Affiliation: | Materials Science and Engineering Department, University of Missouri-Rolla, Rolla, Missouri 65409; Ceramic Science Group, Naval Surface Warfare Center Carderock Division, West Bethesda, Maryland 20817 |
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| Abstract: | The chemical compatibility of ZrC and Mo was investigated in carburizing and carbon-free environments at temperatures from 1700° to 2200°C. Heating in the carburizing atmosphere resulted in the complete reaction of Mo with C, while the carbon-free atmosphere resulted in retained metallic phase with a maximum of 13.8 mol% Mo2C formed. The presence of Mo2C was not detected at 2100°C in the carbon-free atmosphere, confirming the existing phase equilibria in the Zr–Mo–C system. Heat treatments in the carbon-free atmosphere also showed liquid formation at 2200°C, as evident from microstructure analysis. Liquid formation was consistent with the interaction between Mo and Mo2C. The liquid was found to comprise at least 7 vol% of the total component, based on a phase diagram for the Mo–C system. The formation of a liquid should allow for the processing of ZrC–Mo cermets by liquid-phase pressureless sintering. |
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