Dependence of coercivity on phase distribution and grain size in nanocomposite Nd2Fe14B/$\alpha$-Fe magnets
Feng Wei-Cun (冯维存)ab, Gao Ru-Wei (高汝伟)b, Li Wei (李卫)a, Han Guang-Bing (韩广兵)b, Sun Yan (孙艳)b
a Division of Functional Materials, Central Iron and Steel Research Institute, Beijing 100081, China; b School of Physics & Microelectronics, Shandong University, Ji'nan 250100, China
Abstract The dependence of coercivity on the grain size in nanocomposite Nd2Fe14B/$\alpha$-Fe magnets with different distributions of magnetically soft and hard phases is investigated by means of statistical mean. The calculations show that when there exists no soft phase, the coercivity of magnets decreases monotonically with hard grain size reducing. For a given volume fraction of hard phase, the coercivity of nanocomposite Nd2Fe14B/$\alpha$-Fe magnets with a random distribution of soft and hard grains shows a peak value as a function of hard grain size. When the hard grain size is larger than an optimum value of soft grain size (15nm), the nanocomposite Nd2Fe14B/$\alpha$-Fe magnets with the multilayer structure of soft and hard grains can possess a higher coercivity than that with the random distribution of soft and hard grains.
Received: 14 January 2005
Revised: 26 April 2005
Accepted manuscript online:
PACS:
75.60.Ej
(Magnetization curves, hysteresis, Barkhausen and related effects)
Fund: Project supported by the National Natural Science Foundation of China (Grant Nos 50371019 and 50371046) and the Doctorate Foundation of the State Education Ministry of China (Grant No 20040422012).
Cite this article:
Feng Wei-Cun (冯维存), Gao Ru-Wei (高汝伟), Li Wei (李卫), Han Guang-Bing (韩广兵), Sun Yan (孙艳) Dependence of coercivity on phase distribution and grain size in nanocomposite Nd2Fe14B/$\alpha$-Fe magnets 2005 Chinese Physics 14 1649
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