Magnetic properties, phase evolution, and microstructure of melt spun SmCo7−xHfxCy (x=0–0.5; y=0–0.14) ribbons

Abstract

Articles you may be interested inMagnetic properties and crystal structure of melt-spun Sm(Co, M)7 (M=Al and Si) ribbons J. Appl. Phys. 111, 07E306 (2012); 10.1063/1.3671429 Effect of Ge on the magnetic properties and crystal structure of melt spun SmCo7-xGex ribbons J. Appl. Phys. 109, 07A730 (2011); 10.1063/1.3562451 Magnetic properties, phase evolution, and microstructure of melt spun Sm ( Co , M ) x C y ( M = Hf and Zr; x = 5 -9 ; y = 0 -0.15 ) ribbons J. Appl. Phys. 107, 09A710 (2010); 10.1063/1.3337575 Crystal structure and magnetic properties of melt spun Sm ( Co , V ) 7 ribbonsMagnetic properties, phase evolution, and microstructure of melt spun SmCo 7−x Hf x C y ͑x = 0 -0.5; y = 0 -0.14͒ ribbons via direct quenching have been investigated. For SmCo 7−x Hf x series ribbons, proper volume fraction of Hf is effective to stabilize and increase the magnetocrystalline anisotropy field of the TbCu 7 -type structure. Accordingly, the optimal magnetic properties of B r = 6.4 kG, i H c = 7.3 kOe, and ͑BH͒ max = 8.7 MG Oe could be obtained for x = 0.1. Furthermore, a slight C addition to above alloys is helpful in refining the grain size of the ribbons from 100-400 nm for C-free to 10-80 nm for C-containing samples. As a result, the magnetic properties are further improved to B r = 6.9 kG, i H c = 11.8 kOe, and ͑BH͒ max = 10.6 MG Oe for SmCo 6.8 Hf 0.2 C 0.12 nanocomposite ribbons.

Effects of Hf and CNTs on structure and magnetic properties of TbCu7-type Sm–Co magnets

“…The elements with larger electronegativity difference prefer to combine together, thus the affinities to form ionic bond, from big to small, are Sm-C(1.43), Hf-C(1.27), HfCo(0.47) and Hf-Sm(0.16). However, no Sm-C compounds are found in SmCo 6.9 Hf 0.1 (CNTs) 0.05 , which is different from the results reported by Chang [11], that is, Sm 2 C 3 is formed in Sm-Co-Hf-C mixtures. The reason may be that CNTs are adopted in this paper, while in Chang's work, it is C to add into the alloy.…”

“…Nevertheless, even if there exists, the content must be very low. The CNTs mentioned here are probably C elements, but if they are graphite, the morphology is quite different from that reported in [11,20,21]. So here we still interpret it as CNTs, whereas its accurate status demands further investigations.…”

“…Zhang et al [10] prepared bulk nanocrystalline SmCo 6.6 Nb 0.4 sintered magnet with TbCu 7 -type structure by spark plasma sintering (SPS) technique, the magnet exhibited good thermal stability with a coercivity of 0.48 T at 500 C and coercivity temperature coefficient b of -0.169 %/K. Chang et al [11] prepared SmCo 7Àx Hf x C y ribbons with TbCu 7 -type structure from the ingots under a wheel speed of 40 m/s. They found a slight C addition was helpful in refining the grain size of the ribbons, and the maximum coercivity of 11.8 kOe was obtained.…”

Effect of additives on the magnetic properties and microstructure of melt spun SmCo6.9Hf0.1M0.1 (M=B, C, Nb, Si, Ti) ribbons

“…In our previous studies [11], we also confirmed that the appropriate Hf substitution is beneficial for the formation of 1:7 phase to improve the permanent magnetic properties of melt spun SmCo 7 ribbons, from i H c = 1.9 kOe and (BH) max = 3.8 MGOe for SmCo 7 ribbons to i H c = 7.3 kOe and (BH) max = 8.7 MGOe for SmCo 6.9 Hf 0.1 ribbons, even though the grain size (100-400 nm) of the ribbons is unchanged with a slight Hf substitution.…”

“…All samples were magnetized by a 50 kOe peak pulse field prior to the VSM measurement. [11], and besides, the magnetic properties of SmCo 6.9 Hf 0.1 ribbons are modified by various additives, as listed in Table 1. For ternary SmCo 6.9 Hf 0.1 ribbon, magnetic properties of σ 12 kOe = 61.5 emu/g, σ r = 58.2 emu/g, and i H c = 7.3 kOe are obtained.…”