Investigation on microstructure, texture, and magnetic properties of hot deformed Nd-Fe-B ring magnets
Investigation on microstructure, texture, and magnetic properties of hot deformed Nd-Fe-B ring magnets
复制标题
热变形 Nd-Fe-B 环形磁体的显微组织、织构和磁性能研究
DOI：
10.1063/1.3339817
复制
发表时间：
2010-05-01
影响因子：
3.2
通讯作者：
Pan, W.
中科院分区：
文献类型：
--
作者：
Li, A. H.;Li, W.;Pan, W.
采用熔融纺丝粉末反挤压法制备了径向定向钕铁硼环形磁体。研究了挤压环的微观结构、磁性能和晶体排列的位置依赖性。磁性能沿轴向从底部到中间略有增加，在环的上端急剧下降。上端的磁性能和x射线衍射图与各向同性压制前驱体非常接近。结果表明，由于热挤压初期织构难以形成，挤压后的环在上端近似保留了初始组织。在不同的空间位置上发现了典型的微观组织形态：截面内侧为片状晶粒，中部为细长晶粒，外侧为颗粒状晶粒。在环的上端只观察到颗粒状的颗粒。但挤压环形磁体表面磁通密度的周向均匀性优于烧结径向定向环形磁体。讨论了变形和织构的形成过程。熔融纺丝Nd-Fe-B前驱体后挤压磁体的形变和织构形成可能与晶界滑动和晶粒旋转、固溶沉淀过程以及Nd(2)Fe(14)B纳米晶粒沿易生长a轴优先生长有关。(C) 2010年美国物理研究所。(doi: 10.1063/1.3339817)
Radially oriented Nd-Fe-B ring magnets have been prepared by backward extrusion of melt-spun powder. The position dependent of the microstructure, the magnetic properties, and the crystal alignment of the extruded rings have been investigated. The magnetic properties in radial direction increase slightly along the axis from the bottom to the middle then steeply decrease at the upper end of the ring. The magnetic properties and x-ray diffraction patterns of the upper end are very close to that of the isotropic pressed precursor. It suggests that the extruded ring approximately retains the initial structure at its upper end which is because the formation of texture is difficult at the initial stage of hot extrusion. Characteristic microstructure morphologies were found at different spatial positions: flake-shaped grains for the inner, elongated grains for the middle, and particle-shaped grains for the outer region in the cross section. Only particle-shaped grains were observed at the upper end of the ring. But the circumferential homogeneity of the surface magnetic flux densities is better in an extruded ring magnet than in a radially oriented ring prepared by sintering method. The deformation and texture formation processes were discussed. The deformation and texture formation in backward extruded magnets from melt-spun Nd-Fe-B precursors may possibly involve grain boundary sliding and grain rotation, solution-precipitation process, and preferred growth of Nd(2)Fe(14)B nanograins along the easy growth a-axis. (C) 2010 American Institute of Physics. [doi: 10.1063/1.3339817]