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Artificially produced rare-earth free cosmic magnet.

Makino A, Sharma P, Sato K, Takeuchi A, Zhang Y, Takenaka K - Sci Rep (2015)

Bottom Line: Electron diffraction detects four-fold 110 superlattice reflections and a high chemical order parameter (S  0.8) for the developed L10-FeNi phase.The magnetic field of more than 3.5 kOe is required for the switching of magnetization.Experimental results along with computer simulation suggest that the ordered phase is formed due to three factors related to the amorphous state: high diffusion rates of the constituent elements at lower temperatures when crystallizing, a large driving force for precipitation of the L10 phase, and the possible presence of L10 clusters.

View Article: PubMed Central - PubMed

Affiliation: Tohoku University, Sendai 980-8577, Japan.

ABSTRACT
Chemically ordered hard magnetic L10-FeNi phase of higher grade than cosmic meteorites is produced artificially. Present alloy design shortens the formation time from hundreds of millions of years for natural meteorites to less than 300 hours. Electron diffraction detects four-fold 110 superlattice reflections and a high chemical order parameter (S  0.8) for the developed L10-FeNi phase. The magnetic field of more than 3.5 kOe is required for the switching of magnetization. Experimental results along with computer simulation suggest that the ordered phase is formed due to three factors related to the amorphous state: high diffusion rates of the constituent elements at lower temperatures when crystallizing, a large driving force for precipitation of the L10 phase, and the possible presence of L10 clusters. Present results can resolve mineral exhaustion issues in the development of next-generation hard magnetic materials because the alloys are free from rare-earth elements, and the technique is well suited for mass production.

No MeSH data available.


Related in: MedlinePlus

Observations by electron microscopy.(a) STEM-bright field image and (b) STEM-EDX elemental mapping. (c,d) Nanobeam electron diffraction taken from the area marked with circles in Fig. (a,b). (e) Simulated NBD pattern of the L10 FeNi structure with S = 0.8.
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f2: Observations by electron microscopy.(a) STEM-bright field image and (b) STEM-EDX elemental mapping. (c,d) Nanobeam electron diffraction taken from the area marked with circles in Fig. (a,b). (e) Simulated NBD pattern of the L10 FeNi structure with S = 0.8.

Mentions: Figure 2a shows a bright-field (BF) scanning transmission electron microscope (STEM) image of the Fe42Ni41.3Si8B4P4Cu0.7 alloy after annealing at 400 °C for 288 hours. The microstructure is composed of 30-50 nm sized polycrystalline grains. Elemental mapping by energy dispersive X-ray spectroscopy (EDX) using STEM reveals that these grains include at least three phases: an Fe-rich phase, a Ni-rich phase and a nearly equi-atomic Fe50Ni50 alloy phase (Fig. 2b). It should be mentioned that Si and P were detected in the Ni-rich grains, but not in the Fe-rich or FeNi grains. Detection of Fe3B phase by XRD indicates that B is distributed in Fe-rich phase. Areal fraction of these three phases are 40% (Ni-rich), 37% (Fe-rich), and 23% (Fe-Ni alloy). Thus, partitioning of the solute elements indicates that the Fe-rich grains correspond to the α-Fe and Fe3B phases as detected by the X-ray measurements (Fig. 1). The Ni-rich grains are fcc, and the equi-atomic Fe50Ni50 regions are possibly made from L10 or fcc type of grains.


Artificially produced rare-earth free cosmic magnet.

Makino A, Sharma P, Sato K, Takeuchi A, Zhang Y, Takenaka K - Sci Rep (2015)

Observations by electron microscopy.(a) STEM-bright field image and (b) STEM-EDX elemental mapping. (c,d) Nanobeam electron diffraction taken from the area marked with circles in Fig. (a,b). (e) Simulated NBD pattern of the L10 FeNi structure with S = 0.8.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4644987&req=5

f2: Observations by electron microscopy.(a) STEM-bright field image and (b) STEM-EDX elemental mapping. (c,d) Nanobeam electron diffraction taken from the area marked with circles in Fig. (a,b). (e) Simulated NBD pattern of the L10 FeNi structure with S = 0.8.
Mentions: Figure 2a shows a bright-field (BF) scanning transmission electron microscope (STEM) image of the Fe42Ni41.3Si8B4P4Cu0.7 alloy after annealing at 400 °C for 288 hours. The microstructure is composed of 30-50 nm sized polycrystalline grains. Elemental mapping by energy dispersive X-ray spectroscopy (EDX) using STEM reveals that these grains include at least three phases: an Fe-rich phase, a Ni-rich phase and a nearly equi-atomic Fe50Ni50 alloy phase (Fig. 2b). It should be mentioned that Si and P were detected in the Ni-rich grains, but not in the Fe-rich or FeNi grains. Detection of Fe3B phase by XRD indicates that B is distributed in Fe-rich phase. Areal fraction of these three phases are 40% (Ni-rich), 37% (Fe-rich), and 23% (Fe-Ni alloy). Thus, partitioning of the solute elements indicates that the Fe-rich grains correspond to the α-Fe and Fe3B phases as detected by the X-ray measurements (Fig. 1). The Ni-rich grains are fcc, and the equi-atomic Fe50Ni50 regions are possibly made from L10 or fcc type of grains.

Bottom Line: Electron diffraction detects four-fold 110 superlattice reflections and a high chemical order parameter (S  0.8) for the developed L10-FeNi phase.The magnetic field of more than 3.5 kOe is required for the switching of magnetization.Experimental results along with computer simulation suggest that the ordered phase is formed due to three factors related to the amorphous state: high diffusion rates of the constituent elements at lower temperatures when crystallizing, a large driving force for precipitation of the L10 phase, and the possible presence of L10 clusters.

View Article: PubMed Central - PubMed

Affiliation: Tohoku University, Sendai 980-8577, Japan.

ABSTRACT
Chemically ordered hard magnetic L10-FeNi phase of higher grade than cosmic meteorites is produced artificially. Present alloy design shortens the formation time from hundreds of millions of years for natural meteorites to less than 300 hours. Electron diffraction detects four-fold 110 superlattice reflections and a high chemical order parameter (S  0.8) for the developed L10-FeNi phase. The magnetic field of more than 3.5 kOe is required for the switching of magnetization. Experimental results along with computer simulation suggest that the ordered phase is formed due to three factors related to the amorphous state: high diffusion rates of the constituent elements at lower temperatures when crystallizing, a large driving force for precipitation of the L10 phase, and the possible presence of L10 clusters. Present results can resolve mineral exhaustion issues in the development of next-generation hard magnetic materials because the alloys are free from rare-earth elements, and the technique is well suited for mass production.

No MeSH data available.


Related in: MedlinePlus