Dependence of the coercivity H/sub cJ/ of high energy Nd-Fe-B magnets on the alignment coefficient

Grain alignment and microstructure of (Nd,Dy)12.8(Fe,M) 80.7B6.5 by strip casting

“…Up to now the studies mainly focus on the HD process, particle size and distribution, additional elements, sintering process and heat treatment, etc. [1][2][3][4][5][6][7][8][9][10]. However, with a fixed composition, the alignment coefficient and the distribution of grain size of the hard magnetic grains in sintered magnets will be influenced by the alignment and microstructure of the strip cast alloy (the master alloy).…”

“…Rodewald et al prepared sintered Nd-Fe-B magnets with maximum energy density 451 kJ/m 3 (56.7 MGOe) in 2002 [3]. The alignment coefficient, the volume fraction, the distribution of grain size of the hard magnetic grains, the overall oxygen and carbon content of the sintered magnets are important factors influencing magnetic properties [5][6][7]. The composition determines the volume fraction of the other constitutions and the microstructure, whereas the processing of Nd-Fe-B-type permanent magnets determine the alignment coefficient, the distribution of the grain size of the hard magnetic grains, the overall oxygen and carbon content of the sintered magnets.…”

Investigation of the domain structure of sintered Nd-Fe-B permanent magnets by Bitter-pattern method

“…Deviations in the domain structure from that of the correct axial plane are due to an imperfect alignment of the c axes of the grains. In this context, it is worth noting that the degree of grain alignment has a considerable effect on the hard magnetic properties of sintered Nd-Fe-B magnets [9]. It should also be noted that deposits of colloidal particles are imaged as dark regions by the optical microscope ( Figs.…”

“…Small additions of A1, Ga, Co, and Cu were introduced to improve the coercivity, temperature coefficients and corrosion stability of the magnets [3]. The specimens were in the shape of cuboid with dimensions 6 × 6 × 5 mm 3 (the alignment axis was parallel to the shortest dimension) and consisted of large grains with typical sizes of about (7)(8)(9)(10)(11)#m. The magnetic properties of the specimens at room temperature were as follows: coercivity jH c ~-1.01 MA/m, remanence Br = 1.47T and maximum energy density (BH)max = 420 kJ/m 3.…”

Studies of the domain structure of anisotropic sintered SmCo5 permanent magnets

“…Some deviations in the domain structure from that of the correct axial plane, due to an imperfect alignment of the c-axis of the grains, are clearly visible in the presented image. In this context, it is interesting to note that the degree of grain alignment has a marked effect on the remanence, coercivity and maximum energy density of sintered magnets [44,45]. In most cases the domain patterns within individual grains were different in the sense that the domain structure of a given grain was not influenced by magnetization distributions of its neighbors.…”