Development of bulk Nd9.5Fe75.5−xMxB15 (M=Mo, Nb, Ta, Ti, and Zr; x=0–4) magnets by direct casting method

Composition dependence of magnetic properties of directly quenched Nd–Fe–Ti–Zr–B bulk magnets

“…However, as Zr content x increases to 3, the significant decrease of the volume fraction of 2:14:1 phase accompanies the increase of the amount of ␣-Fe phase, leading to the drastic decrease of the magnetic characteristics. This implies that more Zr substitution for Ti may make the 2:14:1 phase more unstable, which is in accordance with the result of our previous study [17]. Besides, from Fig.…”

“…In our previous studies [17,18], magnetic properties of B r = 6.5 kG, i H c = 10.3 kOe, and (BH) max = 8.7 MGOe were obtained for directly quenched Nd 9.5 Fe 72.5 Ti 3 B 15 magnets with a diameter of 0.7 mm and a length of 15 mm. However, increasing the diameter of the magnet to 0.9 mm degraded the magnetic properties to B r = 6.0 kG, i H c = 6.2 kOe, and (BH) max = 5.6 MGOe, because the grain size becomes coarser and the size distribution turns out to be inhomogeneous in the magnet due to its slower cooling rate.…”

“…Alloy ingots with nominal compositions of NdyFe97−y−zTi3−xZrxBz (x = 0-3; y = 7-10; z = [14][15][16][17][18][19] were prepared by arc melting mixtures of pure Nd, Fe, M metal and pure B crystal in an argon atmosphere. 5% excess Nd was adopted to compensate the loss of Nd during processing.…”

“…Additionally, to make sheet specimens with larger area size, Tan et al [15] demonstrated Nd 5 Y 4 Fe 68 Zr 2 B 21 bulk magnets with the size of 0.8 mm × 10 mm × 50 mm, and nevertheless, the ordinary magnetic properties of i H c = 4.8 kOe and (BH) max = 5.4 MGOe were obtained. Meanwhile, in our previous studies [16][17][18], in order to further simplify manufacturing process for making isotropic magnet, by composition modification, directly quenched Pr 9.5 Fe 71. 5 to replace Ti in Nd 9.5 Fe 72.5 Ti 3 B 15 alloy based on Inoue's empirical rules [19] and our previous study [17].…”

“…Meanwhile, in our previous studies [16][17][18], in order to further simplify manufacturing process for making isotropic magnet, by composition modification, directly quenched Pr 9.5 Fe 71. 5 to replace Ti in Nd 9.5 Fe 72.5 Ti 3 B 15 alloy based on Inoue's empirical rules [19] and our previous study [17]. We report on the effects of Zr substitution for Ti and also of Nd and B contents on the magnetic properties, phase evolution, and microstructure of directly quenched Nd y Fe 97−y−z Ti 3−x Zr x B z (x = 0-3; y = 7-10; z = 14-19) magnets with a 0.9 mm in diameter and a length of 15 mm.…”