Sm–Co–Cu–Ti high-temperature permanent magnets

A class of promising permanent-magnet materials with an appreciable high-temperature coercivity of 8.6 kOe at 500 °C is reported. The Sm–Co–Cu–Ti magnets are prepared by arc melting and require a suitable heat treatment. Magnetization measurements as a function of temperature and x-ray diffraction patterns indicate that the samples are two-phase mixtures of 2:17 and 1:5 structures. Depending on heat treatment and composition, some of the magnets exhibit a positive temperature coefficient of coercivity. The promising high-temperature behavior of the coercivity is ascribed to the temperature dependence of the domain-wall energy, which affects the curvature of the walls and the pinning behavior.

[1]  FINITE-TEMPERATURE BEHAVIOR OF ANISOTROPIC TWO-SUBLATTICE MAGNETS , 1998 .

[2]  Hisao Yamamoto,et al.  Permanent magnet materials based on the rare earth-iron-boron tetragonal compounds , 1984 .

[3]  Junliang Yang,et al.  Abnormal temperature dependence of intrinsic coercivity in sintered Sm–Co-based permanent magnets , 2000 .

[4]  Ralph Skomski,et al.  Domain-wall curvature and coercivity in pinning type Sm–Co magnets , 1997 .

[5]  J. Coey.  Rare-earth iron permanent magnets , 1996 .

[6]  山元 洋.  Rare-Earth Iron Permanent Magnets Edited by J.M.D.Coey, Clarendon Press, Oxford, 1996年発刊, IBSNO198517920, £75.00 (約1.5万円), 全512頁 , 1997 .

[7]  H. Saito,et al.  Magnetocrystalline anisotropy for Sm2(Co-Mn)17 compound with TbCu7 type disordered structure , 1989 .

[8]  Kaplesh Kumar,et al.  RETM5 and RE2TM17 permanent magnets development , 1988 .

[9]  Michael H. Walmer,et al.  Sm2(Co,Fe,Cu,Zr)17 magnets for use at temperature ⩾400 °C , 1998 .

[10]  D. Dimitrov,et al.  Microstructure and high temperature magnetic properties of Sm(Co, Cu, Fe, Zr)z (z=6.7–9.1) permanent magnets , 1999 .

[11]  G. Hadjipanayis,et al.  New rare-earth permanent magnets with an intrinsic coercivity of 10 kOe at 500 °C , 1999 .

[12]  D. Sellmyer,et al.  Activation entropy, activation energy, and magnetic viscosity , 1999 .

[13]  D. Dimitrov,et al.  Abnormal temperature dependence of intrinsic coercivity in Sm(Co, Fe, Cu, Zr)z powder materials , 1998 .