Giant magnetostrains in MnFe(P,Si,B)/epoxy composites at intermediate magnetic fields
B. Huhe (Inner Mongolia Normal University China)
H. Yibole (Inner Mongolia Normal University China)
F. Guillou (Normandie University, Inner Mongolia Normal University China)
N. H. van Dijk (TU Delft - RST/Fundamental Aspects of Materials and Energy)
E. Brück (TU Delft - RST/Fundamental Aspects of Materials and Energy)
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Abstract
Magnetostrictive materials are widely used in actuators, sensors, and energy-harvesting systems, but many high-performance compounds rely on heavy rare-earth elements or require high magnetic fields to develop giant magnetostrains. Here, we present Fe2P/epoxy composites, exploiting an anisotropic first-order ferromagnetic transition (FOMT) to generate giant magnetostrains. A parametric model based on structural discontinuities and thermodynamic considerations is proposed to guide composition selection. Textured MnFe0.95P0.55Si0.40B0.05/epoxy composites were prepared by magnetic field alignment and characterized by strain-gauge dilatometry measurements as a function of temperature and magnetic field. Near the FOMT, despite matrix dilution effects, linear magnetostrains up to 0.22% at 2 T (0.37% at 7 T) are achieved. In particular, at intermediate fields, the magnetostrain shows a nearly linear increase with the field of about 0.1%/T (1000 ppm/T) with limited hysteresis. These results demonstrate that Fe2P-type compounds, previously developed for magnetocaloric applications, can be adapted into scalable, low-cost magnetostrictive composites with tunable transition temperatures that rely only on abundant elements.
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