Magnetic and metallurgical properties of directionally solidified eutectic Bi/MnBi composites: The effects of annealing
作者:
Ron G. Pirich,
D. J. Larson,
期刊:
Journal of Applied Physics
(AIP Available online 1979)
卷期:
Volume 50,
issue B3
页码: 2425-2427
ISSN:0021-8979
年代: 1979
DOI:10.1063/1.326974
出版商: AIP
数据来源: AIP
摘要:
Eutectic Bi/MnBi (97.8 a/o Bi) samples have been plane‐front directionally solidified. The resultant microstructures consist of elongated, aligned particles of MnBi dispersed in a Bi‐matrix. Magnetization as a function of temperature (4.2 to 300 K) and applied field (up to 220 kG) has been used to evaluate solidification parameters and magnetic properties. At room temperature, in addition to the diamagnetic contribution of Bi, one finds a superposition of the ferromagnetic, low temperature (LTP) MnBi phase and paramagnetic phases. At cryogenic temperatures, one of the room temperature paramagnetic phases is ferromagnetic with an intrinsic coercivity of 120 kOe while the other remains paramagnetic for low fields and orders ferromagnetically at high fields in a complicated way. Annealing of as‐grown samples was found to produce significant changes in magnetic properties. The origins of the paramagnetic phases and their relation to the mechanisms which control the coercive field of the hard magnetic LTP MnBi phase are discussed.
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