Exploring the negative thermal expansion and magnetocaloric effect in Fe2(Hf,Ti) Laves phase materials

Journal article (2023)

Authors

Q. Shen RST/Fundamental Aspects of Materials and Energy - AS
I. Batashev Radboud Universiteit Nijmegen, RST/Fundamental Aspects of Materials and Energy - AS
F. Zhang RST/Fundamental Aspects of Materials and Energy - AS
Hamutu Ojiyed External organisation
A.I. Dugulan RST/Fundamental Aspects of Materials and Energy - AS , RID/TS/Instrumenten groep
A. Iulian Dugulan RST/Fundamental Aspects of Materials and Energy - AS , RID/TS/Instrumenten groep
N.H. van Dijk RST/Fundamental Aspects of Materials and Energy - AS
E.H. Brück RST/Fundamental Aspects of Materials and Energy - AS
Research Group
RST/Fundamental Aspects of Materials and Energy (AS) (TU Delft)
Copyright: © 2023 Q. Shen, I. Batashev, F. Zhang, Hamutu Ojiyed, A.I. Dugulan, N.H. van Dijk, E.H. Brück
DOI: https://doi.org/10.1016/j.actamat.2023.119149
More Info
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Published Date

2023

Language

English

Faculty

Applied Sciences

Department

RST/Radiation, Science and Technology

Research Group

RST/Fundamental Aspects of Materials and Energy

Abstract

The transition-metal based Laves phase materials represent an extended family of alloys with rich and fascinating physical properties. In this work, we have investigated the negative thermal expansion and magnetocaloric effect in arc-melted and melt-spun Fe2Hf1-xTix (x = 0.15, 0.27, 0.30, 0.33, 0.36, 0.40) alloys. For x = 0.30–0.40, two hexagonal phases with different compositions share the same P63/mmc lattice symmetry, but have slightly different lattice parameters. The saturation magnetization and Curie temperature both follow a decreasing trend with the average unit-cell volume. For Fe2Hf0.6Ti0.4 melt spinning improves the saturation magnetization from 48.7 to 59.6 Am2/kg and the magnetic entropy change from 0.46 to 0.54 J/kgK at a magnetic field change of 2 T. These enhanced values are attributed to an improved homogeneity caused by a suppression of phase segregation during rapid solidification. We have utilized neutron powder diffraction and Mössbauer spectroscopy to illustrate the correlation between the magnetic order and the negative thermal expansion in single-phase Fe2Hf0.85Ti0.15. The magnetic moments of Fe align below 400 K in the a-b plane and a moment change for the Fe atoms is responsible for the large volumetric coefficient of thermal expansion of −25 × 10−6 K−1 over a wide temperature range of 300–400 K.