Features of Zirconium Boride–Chromium Interaction

Abstract

The interaction of zirconium boride with chromium in the temperature range 1300–1900°C in vacuum is studied. In case of solid-phase interaction, reaction diffusion takes place at the interface to form Cr2B and CrB at the metal boundary. The process is controlled by the diffusion of boron atoms from the zirconium diboride lattice into the metal. In the high-temperature range, the interaction proceeds through the contact melting mechanism, being typical of eutectic systems. The eutectic temperature is about 1780°C. The resultant liquid phase wets the boride surface at a contact angle of 40°, interacts with the boride, and disappears since higher-temperature reaction products are formed. Their phase composition depends on the ratio of alloy components, changes with increasing ZrB2/Cr ratio, and represents binary and ternary compounds based on the zirconium boride and chromium lattices. Given the eutectic nature of interaction in the quasibinary ZrB2–Cr phase diagram, a small contact angle that the eutectic forms on zirconium boride, and the potential for homogeneous chromium distribution through the vapor phase, chromium is a promising addition that can activate sintering.