Anomalous high-temperature coercivities in hard nanocomposite alloys
- Department of Applied Science, Brookhaven National Laboratory, Upton, New York11973-5000 (United States)
- Magnequench International, Inc., 6435 Scatterfield Road, Anderson, Indiana46013 (United States)
To elucidate the interphase interactions inherent to nanocomposite magnetic alloys, measurements of remanence B{sub r}, and coercivity H{sub ci} were made on a series of four meltspun, remanence-enhanced nanocomposite alloys consisting solely of various amounts of Nd{sub 2}Fe{sub 14}B and {alpha}-Fe. The phase constitution and microstructural scale of the alloys were characterized with synchrotron x-ray diffraction. Magnetic measurements were made using superconducting quantum interference device (SQUID) magnetometry on evacuated and encapsulated samples in the temperature range of 300K{le}T{le}750K, in order to characterize the {alpha}-Fe component independently of the Nd{sub 2}Fe{sub 14}B component. The high-temperature coercivities of the samples increase with the amount of {alpha}-Fe present in the samples, ranging from an average value of approximately 75 Oe for the sample with 14 wt{percent} excess Fe to over 400 Oe at 700 K for the sample with 27 wt{percent} excess Fe. The relatively high coercivities of the samples found at elevated temperatures imply that a tabular morphology of the {alpha}-Fe grains is conferring anisotropy to the phase; this conclusion is supported by transmission electron microscopy. It is concluded that while the significant coercivity of the {alpha}-Fe phase likely reduces the room-temperature remanence enhancement of the alloy below its theoretical ideal, the favorable interphase interface orientation promotes exchange coupling. {copyright} {ital 1998 American Institute of Physics.}
- OSTI ID:
- 627966
- Report Number(s):
- CONF-980102-; ISSN 0021-8979; TRN: 98:006288
- Journal Information:
- Journal of Applied Physics, Vol. 83, Issue 11; Conference: 7. joint MMM-intermag conference, San Francisco, CA (United States), 6-9 Jan 1998; Other Information: PBD: Jun 1998
- Country of Publication:
- United States
- Language:
- English
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