Experimental Study of the Cr-Hf-Nb System: Liquidus Projection and 1200 °C Isothermal Section

• Published in: Journal of phase equilibria and diffusion Vol. 41; no. 5; pp. 702 - 721
• Main Authors: Gigolotti, João Carlos Jânio, da Silva, Antonio Augusto Araújo Pinto, Coelho, Gilberto Carvalho, Nunes, Carlos Angelo, Joubert, Jean-Marc
• Format: Journal Article
• Language: English
• Published: New York Springer US 01-10-2020; Springer Nature B.V; Springer Verlag
• Subjects: Ceramics; Chemical Sciences; Composites; Crystallography and Scattering Methods; Electron probe microanalysis; Engineering Thermodynamics; Eutectic reactions; Glass; Hafnium; Heat and Mass Transfer; Heat treatment; Jet engines; Laves phase; Liquidus; Material chemistry; Metallic Materials; Natural Materials; Niobium; Physics; Physics and Astronomy; Projection; Silicides; Ternary systems; Thermodynamics; Zirconium; Cr-hf-nb system; intermetallics; phase diagram; microstructure; phase stability; Intermetallics; Cr-Hf-Nb system
• ISSN: 1547-7037; 1863-7345; 1934-7243; 5555-1515
• DOI: 10.1007/s11669-020-00838-w

Phase equilibria data from ternary Cr-Nb-X (X = Hf, Ta, Ti, Zr) systems are relevant to the development of Niobium-silicide based composites for use in jet engines. Such systems present at several temperatures a pseudo-binary of Cr
2
Nb-Cr
2
X Laves phases. This work presents the experimentally determined liquidus projection and the 1200 °C isothermal section for the Cr-Hf-Nb system based on microstructural characterization of as-cast and heat-treated alloys. The microstructural characterization using x-ray diffractometry, scanning electron microscopy and electron probe microanalysis showed four eutectic-type monovariant reactions and two class II invariant reactions in the liquidus projection. The 1200 °C isothermal section showed complete solubility between Nb and Hf in (
C
15) phase and one three phase equilibria field.