Modelling of Phase Equlibria in the Hf-V System\nBelow Room Temperature

0480868 - ÚFM 2018 RIV RS eng J - Journal Article
Vřešťál, Jan - Pavlů, Jana - Wdowik, U. D. - Šob, Mojmír
Modelling of Phase Equlibria in the Hf-V System
Below Room Temperature.
Journal of Mining and Metallurgy Section B-Metallurgy. Roč. 53, č. 3 (2017), s. 239-247. ISSN 1450-5339. E-ISSN 2217-7175
R&D Projects: GA ČR GA14-15576S; GA MŠMT(CZ) LQ1601
Institutional support: RVO:68081723
Keywords : Laves phases * Hf-V system * Ab initio calculations * Phase diagram * Zero Kelvin * CALPHAD method
OECD category: Condensed matter physics (including formerly solid state physics, supercond.)
Impact factor: 1.400, year: 2017

Phase transformation from orthorhombic HfV2 structure to cubic C15 Laves phase structure, which occurs during heating
at about 114 K, is well known. In this contribution, a thermodynamic description of this phenomenon is provided supported
by ab initio calculations. We utilize the third generation of thermodynamic database extending the Scientific Group
Thermodata Europe (SGTE) unary data to zero Kelvin and demonstrate that it may be also applied to intermetallic phases.
The data from a recent thermodynamic assessment of the Hf-V system (valid for temperatures above 298.15 K) were used
and extended to zero Kelvin by the same method as it was used for unary data. Under the assumption of validity of harmonic
approximation and electronic contribution to the heat capacity, the thermodynamics of C15 and orthorhombic phase were
described. With the help of ab initio approach, we demonstrate that the HfV2 orthorhombic phase and C15 Laves phase are
mechanically stable at 0 K and thanks to entropy stabilization they are in equilibrium with pure element phases in the
temperature region of structural change.
Permanent Link: http://hdl.handle.net/11104/0276544