The composites prepared by in-situ directional solidification have received considerable attention because of their unique microstructure. In recent decades, a great effort has been directed towards the development of oxide-oxide [1] and metal-metal [2] eutectic composites, and a few carbide-diboride eutectic systems [3]. However, little work has been done on boride-boride eutectics, which usually exhibit high melting points. Recently, the d-and f-transition metal-boride eutectics have been studied by Paderno [4], and unusual thermal and mechanical properties were reported. The LaB 6 -ZrB 2 system was reported to have superb fracture toughness and strength. The electrical conductivity of the boride composites is also high. It suggests that the boride composites are potential materials for structural and functional applications.The ZrB 2 -LaB 6 system has an eutectic temperature of about 2470 o C. Compared with the sintered borides, the toughness and density of eutectic ZrB 2 -LaB 6 are better. The aim of this study was to investigate the microstructure and its stability at elevated temperatures. Mechanical properties such as the hardness and fracture toughness were also determined. Experimental WorkThe LaB 6 and ZrB 2 powders used in the experiment were produced by the Institute Problem of Materials Science in Ukraine. The purity of LaB 6 was >99.4%, with major impurities of 0.3% Fe and 0.1% O, and with minor impurities of Si and Mg. The purity of ZrB 2 was >98.2%, with major impurities of 0.3% Fe, 0.3% Mg and 0.15% O, and minor impurities of 0.03% Ca and 0.04% Al. The impurity concentration was reported by the supplier. The borides with the eutectic composition (20.5 wt% ZrB 2 -79.5 wt%LaB 6 ) were thoroughly mixed, dry-pressed, and melted with an electric arc to form rods of 6 mm in diameter and 80 mm in length. The W.-H. Tuan et al. (eds.), Multiphased Ceramic Materials
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.