Open Ceramics (Dec 2022)
Effect of W and C addition on the microstructure and phase composition of W–ZrC composites prepared by using Zr2Cu alloy and variant reactant compositions
Abstract
W–ZrC composites were successfully fabricated by reacting amounts of Zr2Cu alloy with powder mixtures of varying composition including stoichiometric WC, WC with additional/W (WC/W), and WC with additional/C (WC/C). The use of WC/C powders to reactively form W–ZrC composites with increased ZrC phase content is a new approach that shows potential for ultra-high temperature applications where higher ZrC content, relative to W, is preferred such as land and aeroengines, aerospace thermal protection, and nuclear. The focus of this work was to stabilize diffusion between W and ZrC during formation, limit interfacial phases, and increase the ZrC content. This was done by varying reactant powder compositions while understanding the final phase composition and microstructure. The composites were prepared by heating the powder mixtures to 1400 °C for 8 h in a furnace with 96% Ar - 4% H2 gas atmosphere. The W–ZrC sample prepared using WC/C powders gave the W–ZrC composite with the highest ZrC phase compared to W and showed promise for phase stabilization. Additionally, there was no W2C, or residual WC identified in the final composite indicating complete conversion from WC to ZrC when adding additional carbon to the WC powder. WC/C sample had the highest hardness due to the increased ZrC phase content. This research addresses the critical comparison of carbon addition on the W–ZrC composites and produced composite with high ZrC content, limited interfacial phases and interlocking microstructure.
