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Phase transformation in nanocrystalline Sm 2 Co 17 permanent magnet material
Author(s) -
Song Xiaoyan,
Lu Nianduan,
Xu Wenwu,
Zhang Zhexu,
Zhang Jiuxing
Publication year - 2009
Publication title -
journal of applied crystallography
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.429
H-Index - 162
ISSN - 1600-5767
DOI - 10.1107/s0021889809020081
Subject(s) - nanocrystalline material , materials science , crystallite , crystal structure , magnetization , magnet , annealing (glass) , alloy , nanocrystal , phase (matter) , crystallography , metallurgy , nanotechnology , chemistry , magnetic field , physics , organic chemistry , quantum mechanics
Single‐phase ultrafine nanocrystalline Sm 2 Co 17 , a candidate material for permanent magnets, was prepared by a novel simple route based on a home‐built `oxygen‐free' in situ fabrication system. The as‐prepared nanocrystalline Sm 2 Co 17 has the stable hexagonal Th 2 Ni 17 ‐type (2:17 H) crystal structure at room temperature, which is distinctly different from the conventional polycrystalline Sm 2 Co 17 having the rhombohedral Th 2 Zn 17 ‐type (2:17 R) crystal structure at room temperature. Phase transformations in the nanocrystalline Sm 2 Co 17 alloy were investigated systematically by a series of annealing experiments. It was found that, along with the nanograin growth in the heat‐treatment process, the crystal structure of the room‐temperature phase transforms from 2:17 H to 2:17 R. The magnetization behavior of Sm 2 Co 17 alloys in different structural states was characterized. The relationship between the magnetic performance and the structure characteristics was analyzed. Understanding the phase transformation of Sm 2 Co 17 nanocrystals facilitates the development of nanocrystalline Sm 2 Co 17 ‐type magnets for high‐temperature applications.