FeNi-based Nanocomposites: Nanocrystallization Reaction Kinetics and Applications in Magnetocaloric Cooling
Michael McHenry, Materials Science & Engineering
Studies of phase formation and chemical partitioning during nanocrystallization of FeNi-based magnetic nanocomposites will be studied. FeCo-based nanocrystalline/amorphous nanocomposites will be produced by melt-spinning and amorphous precursor followed by annealing to form a nanocomposite microstructure. Primary nanocrystallization reactions and kinetics will be studied for selected FeNi-based amorphous precursors with a focus on:- Calorometric and magnetic techniques for measuring nanocrystallization kinetics.
- Structural observations of primary and secondary crystallization products.
- Magnetic and mechanical properties which derive from multi-phase primary nano-crystallization and the role of in-field crystallization on the same.
The synthesis of low Tc Fe-Ni nanocomposites will
also be targeted. Metastable, γ-Fe-Ni monodomain particles have been
synthesized by mechanical milling of melt-spun ribbon for applications
in self-limited RF heating, electromagnetic interference absorption,
magnetic refrigeration and biomedicine. The RF heating response of
these particles demonstrated excellent heating in the room temperature
to 100°C range. These experiments will be used to validate a theory of
self-regulated RF heating. The synthesis of the metastable γ-phase will
be modeled within the constructs of the T0 construction in the Fe-Ni eutectoid phase diagram. The low Tc’s, achievable will be studied in the context of the metastable extension of Tc vs. composition for γ-FeNi.