Constitution, physical properties and thermodynamic modeling of the Hf-Mn system

0579738 - ÚFM 2025 RIV CH eng J - Článek v odborném periodiku
Brož, P. - Yan, X. - Romaka, V. - Fabrichnaya, O. - Kriegel, M. J. - Buršíková, V. - Buršík, Jiří - Vřešťál, J. - Rogl, G. - Michor, H. - Bauer, E. - Eiberger, M. - Grytsiv, A. - Giester, G. - Rogl, P.F.
Constitution, physical properties and thermodynamic modeling of the Hf-Mn system.
Journal of Alloys and Compounds. Roč. 976, March (2024), č. článku 173060. ISSN 0925-8388. E-ISSN 1873-4669
Institucionální podpora: RVO:68081723
Klíčová slova: Intermetallics * Crystal structure * Laves phase * Phase diagrams * Physical properties * DFT
Obor OECD: Condensed matter physics (including formerly solid state physics, supercond.)
Impakt faktor: 6.2, rok: 2022
Způsob publikování: Omezený přístup
https://www.sciencedirect.com/science/article/pii/S0925838823043633?via%3Dihub

The Hf-Mn system is of a long-time interest due to the intermetallic Laves phase HfMn2, a hydrogen storage material. Although this system has been experimentally investigated by several authors and critical reviews and thermodynamic modelling have been performed, there is still a lack of reliable information, particularly as the phase HfMn (sometimes labelled as Hf3Mn2 or Hf2Mn) is suspected to be oxygen stabilized. This work includes a thorough investigation of the Hf-Mn phase equilibria employing diffusion zones, thermal analysis, powder and single crystal X-ray analyses, analytical electron microscopy as well as physical property studies of the Laves phase (magnetic susceptibility, specific heat, electrical resistivity and mechanical properties). The phase near HfMn was shown (TEM, WDX electron microprobe data, X-ray single crystal analysis) to be an oxygen stabilized phase with the formula Hf3+xMn3−xO1−y (defect η-W3Fe3C type). Properties such as magnetic susceptibility/magnetization, 2–300 K, specific heat (2–1100 K), electrical resistivity (2–300 K) classify HfMn2 as a metallic spin-fluctuation system with itinerant paramagnetism, originating from 3d states at Mn-sites and local moment paramagnetism of antisite Mn-atoms at Hf-sites. Mechanical properties (elastic moduli from density functional theory (DFT) and nanoindentation as well as hardness) group the Laves phase among rather hard and brittle intermetallics. DFT modeling revealed that Hf3+xMn3−x is thermodynamically unstable, but significant gains in enthalpy of formation arise from the inclusion of oxygen atoms, stabilizing the η phase. All phase diagram and DFT data together with the former literature information were used for the thermodynamic CALPHAD-type modelling of the Hf-Mn system.
Trvalý link: https://hdl.handle.net/11104/0350125