Composition and microstructure dependent spin reorientation in nanocrystalline (

2020-02-14 23:39:00

alloys Co Fe Pr TSR

责任者: Zhongwu Liu;Davies, H.A. 单位: Dept. of Eng. Mater., Univ. of Sheffield, UK 来源出处: IEEE Transactions on Magnetics(IEEE Trans. Magn. (USA)),2004/07/,40(4):2898-900 摘要: The effects of composition, grain size and exchange coupling on the spin-reorientation temperature (TSR) for nanocrystalline (Nd-Pr)-(Fe-Co)-B alloys have been systematically studied. Although TSR is usually considered to be an intrinsic magnetic property, it is nevertheless influenced by the microstructure when the grain size decreases to the nanometer level. The TSR for all single phase nanocrystalline Nd12Fe82B6 alloys were lower than the published value for a single crystal or for an aligned sintered NdFeB magnet. The results consistently demonstrate that the increasing degree of exchange coupling between the RE2Fe14B nano-grains with decreasing grain size leads to a progressive decrease in TSR. As is the case for conventional NdFeB alloys, Pr substitution for Nd decreases TSR linearly and rapidly with increasing Pr concentration but a spin reorientation still occurs at 75% Pr substitution (TSR≈25 K). Co substitution for Fe also decreases TSR, but to a lower degree than Pr for Nd. Introduction of an increasing volume fraction of soft magnetic α-(Fe-Co) phase into the nanocrystalline Nd2Fe14B alloy has no significant influence on the value of TSR in spite of the influence of α-(Fe-Co) on the exchange coupling 关键词: boron alloys;cobalt alloys;ferromagnetic resonance;grain size;iron alloys;nanostructured materials;neodymium alloys;praseodymium alloys;soft magnetic materials;spin dynamics;spin reorientation;nanocrystalline;alloys;grain size;single crystal;magnet sintering;exchange coupling;nano-grains;NdPr-FeCo-B