The solid solution and microstructural evolution of WC doped Hf-Ta-C powders by induction plasma spheroidization

Abstract

Hf-Ta-C ultra-high temperature ceramics are one of the important candidates for future thermal protective materials due to their high melting point. WC was doped by induction plasma spheroidization (IPS) into Hf-Ta-C to improve the microstructure, thermodynamic properties, and solid solubility. The doped WC is mainly enriched at grain boundaries, which is conducive to the formation of Hf-Ta-W-C solid solution and promotes density of the particle during IPS process. Thus, compared with the undoped WC ceramic, the spheroidization rate, fluidity and apparent density of the WC doped powder are significantly improved. Moreover, based on the melting and the solidification process of the Hf-Ta-W-C solid solution, the microstructure evolution of the particle is explored and summarized. Due to the inhomogeneity of the particle size, the microstructure of IPS-treated powder presents three different spherical particles: loose structure with a rough surface, dense structure with cellular surface and soccer ball surface.