The directional crystallization of W-B-C-d-transition metal alloys

摘要

Crystallization from the melt during arc melting and directional solidification during induction zone melting of pseudo-alloys tungsten carbide (WC)-MeB2 (Me-Ti, Zr, Cr) and a number of alloys of the W-B-C system (WB0.12C0.74; WB0.25C0.75; WB0.34C0.32; WB0.49C0.76; WB0.59C0.76; WB0.89C0.75; (WC)(0.9)B-0.1) has been studied. It was shown that the alloys WC-80 mass%-ZrB2-20 mass% and WC-72 mass%-WB-28 mass% are the closest ones to eutectic compositions. Investigation of the microstructure of eutectic alloys in the WC-WB system by thin foil method has revealed that both matrix and reinforcing phases are single crystalline. Hardness tests by indentation of the eutectic structure area (P = 10.3 N) do not result in radial crack formation, which is evidence of the essential plasticity of the obtained composite material. It is established that new ceramic-ceramic eutectic composite materials based on WC with transition metal diborides and with a boride phase of tungsten may be created. Such materials can be successfully applied in contemporary high-temperature techniques. (c) 2006 Elsevier Inc. All rights reserved.