High performance isotropic Sm–(Co,Fe)–C and Sm–(Co,Fe,Mn)–C magnets by melt spinning (original) (raw)
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Journal of Magnetism and Magnetic Materials, 2013
The structural, magnetic, magnetocaloric and magnetotransport properties of Ni 46 Co 4 Mn 38 Sb 12 melt spun ribbons have been systematically investigated. The partially ordered B2 phase of the as-spun ribbon transforms to fully ordered L2 1 phase upon annealing, which signifies a considerable change of the atomic ordering in the system. The presence of atomic disorder in the as-spun ribbon gives rise to a higher martensitic transition temperature and a lower magnetization as compared to the bulk sample. However, annealing the ribbons helps in regaining the bulk properties to a large extent. Significant changes in magnetocaloric effect, exchange bias and magnetoresistance have been observed between the as-spun and the annealed ribbons, indicating the role of atomic ordering on the functional as well as fundamental properties in the Heusler system. Importantly, the study shows that one can reduce the hysteresis loss by preparing melt spun alloys and subjecting them to appropriate annealing conditions, which enable them to become practical magnetic refrigerants.
Journal of Applied Physics, 2014
We have investigated effects of metal substitutions on the magnetic properties and microstructure of melt-spun Sm-Co-Cu-Fe-M (M ¼ Zr, V, Nb, Mo, Ta) magnets. We prepared melt-spun ribbons with compositions of Sm(Co 1Àx Cu x) 5 Fe 0.54Ày M y (x ¼ 0.1-0.5, y ¼ 0-0.43, M ¼ Zr, V, Nb, Mo, Ta). For compositions of Sm(Co 1Àx Cu x) 5 Fe 0.54 (x ¼ 0.1-0.5), coercivity increased with increasing of annealing temperature, and a high coercivity of 17.6 kOe was obtained at a Cu content of x ¼ 0.3. The coercivity was found to increase with increasing melting point of the substitution element. A high coercivity of 24.5 kOe was obtained for a composition of Sm(Co 0.7 Cu 0.3) 5 Fe 0.34 Ta 0.2. V
Structure and magnetic properties of Sm(Co0.74Fe0.1Cu0.12Zr0.04)8 melt-spun nanostructured alloys
Materials Science and Engineering: B, 2008
Phase stability and magnetic-field-induced martensitic transformation in Mn-rich NiMnSn alloys AIP Advances 2, 042181 Field-induced lattice deformation contribution to the magnetic anisotropy J. Appl. Phys. 112, 103920 (2012) Effects of DyHx and Dy2O3 powder addition on magnetic and microstructural properties of Nd-Fe-B sintered magnets J. Appl. Phys. 112, 093912 (2012) Observation of rotatable stripe domain in permalloy films with oblique sputtering
Intermetallics, 2011
a b s t r a c t SmCo 6.8Àx Sn x Zr 0.2 (x ¼ 0, 0.1 and 0.3) melt-spun ribbons have been produced from bulk as-cast samples by varying wheel speeds from 8 to 32 m/s. The microstructure, phase evolution and magnetic properties of as-spun ribbon samples were investigated using X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and vibrating sample magnetometer (VSM), respectively. The XRD results show that the addition of Sn to SmCo 6.8 Zr 0.2 alloy has significant role to shift the TbCu 7structure into Sm 2 Co 17 (H) and Sm 2 Co 17 (R) -phases for the Sn content of 0.1 and 0.3, respectively. The SEM analysis reveals that the grain size of the as-spun ribbon samples is gradually refined from several microns to 600À800 nm with the increase of wheel speed from 8 to 32 m/s. A wheel speed of 24 m/s has been found to be optimal in achieving reasonably good combination of coercivity (H c ) and magnetization (M s ) values in the as-spun SmCo 6.8-x Sn x Zr 0.2 (x ¼ 0, 0.1 and 0.3) ribbons. Maximum values of H c of 5.1 kOe and M s of 76.9 emu/g were achieved for the SmCo 6.5 Sn 0.3 Zr 0.2 ribbons spun at 24 m/s; upon annealing at 550 C, the H c values of these ribbons were significantly improved (10.4 kOe) with not much destruction in the M s value.
Journal of Applied Physics, 2002
In this work we examine the effect of small boron substitution (xϭ0, 0.005, 0.010, 0.015) on the structural and magnetic properties of Sm(Co 0.86Ϫx Fe 0.1 Zr 0.04 B x ) 7.5 and Sm͑Co 0.74Ϫx Fe 0.1 Cu 0.12 Zr 0.04 B x ) 7.5 melt-spun samples, as a function of wheel speed and annealing conditions. Boron substituted as-spun ribbons are found to have increased coercivity, HcϾ5 kOe, and small grain size of 60-100 nm. For copper containing samples, the highest coercivity (Hc ϭ16.3 kOe) was obtained in as-spun ribbons with xϭ0.015. In samples without copper the coercivity increased after short annealing ͑Hcϭ12 kOe for xϭ0.015͒. The large coercivities are attributed to a fine microstructure consisting mainly of hexagonal TbCu 7 -type phase and a small amount of soft-phase grains.
Nanostructured melt-spun Sm(Co-Fe-Zr-B)/sub 7.5/ alloys for high temperature magnets
Digest of INTERMAG 2003. International Magnetics Conference (Cat. No.03CH37401), 2003
High coercivity, the highest for Cu-free 2 : 17 Sm-Co ribbons, has been obtained in as-spun ( = 21 1 kOe) and short time annealed ( = 23 2 kOe) samples of Sm(Co bal Fe Zr B ) 7 5 alloys, with varying B, Zr, and Fe content ( = 0-0 06, = 0-0 16, = 0 08-0 3) and wheel speed. In as-spun samples, the TbCu 7 type structure and in annealed samples the Th 2 Zn 17 and CaCu 5 type structures is observed, plus fcc Co as minority phase is observed. Reduced remanence ( ) is higher than 0.7. High-temperature magnetic measurements show very good stability above 300 C with coercive field as high as 5.2 kOe at 330 C. For annealed Sm(Co bal Fe 0 3 Zr 0 02 B 0 04 ) 7 5 , very good loop squareness and high maximum energy product of 10.7 MGOe have been obtained. Increasing Zr content results in less uniform microstructure of annealed ribbons.
Mn\(_{55-x}\)Co\(_x\)Bi\(_{45}\) Melt Spun Ribbons: Microstructures and Magnetic Properties
Communications in Physics, 2022
In this paper, we present the effect of Cobalt (Co) addition on the crystallization, microstructures and magnetic properties of Mn55-xCoxBi45 (x = 0, 5, 10, 20) melt – spun ribbons. The ribbons were prepared by the melt-spinning techique and subsequent anneal at 280 oC for 5 h. The investigations by using X-ray diffraction (XRD), Differential Scanning Calorimetry (DSC) traces as well the Vibration Sample Magnetometer (VSM) measurements result in the optimal content of Co added to the MnBi system is arounf 5 %at. The larger Co content causes the eutectic Mn-Co formation which restricts the reaction between Mn and Bi to form MnBi ferromagnetic phase responsible for ribbons’ performance the saturation magnetization Ms. The maximum saturation magnetization Ms of 65emu/g and the coercivity iHc of 4.7 kOe was achived for the ribbon of Mn50Co5Bi45. The effect of Co content on the microstructures and magnetic properties of Mn55-xCoxBi45 melt – spun ribbons will be discussed in detail.
Sm(Co, Fe, Cu, Zr, C)8.2 ribbons for high-temperature magnets
Journal of Magnetism and Magnetic Materials, 2004
The effect of carbon substitution for cobalt on the structure and magnetic properties at room and high temperature of melt spun ribbons with composition Sm(Co 0.86Àx Fe 0.1 Zr 0.04 C x ) 8.2 and Sm(Co 0.74Àx Fe 0.1 Cu 0.12 Zr 0.04 C x ) 8.2 (x ¼ 0 À 0:015) has been studied. Arc-melted bulk samples have Th 2 Ni 17 -type structure while ribbons have TbCu 7type structure. Average grain size for Cu-free sample with x ¼ 0:005 is 23 nm while for Cu-doped samples it varies from 53 to 22 nm when x varies from 0.005 to 0.015, respectively. Coercive as-spun samples have H c B2:227:8 kOe and reduced remanence m r ¼ M r =M s up to 0.74. Ribbons of the Cu-free composition with x ¼ 0 and 0.005 and annealed at 750 C for 1 h have TbCu 7 -type structure with coercivity values 4.9 and 3.0 kOe respectively, while for x ¼ 0:01 and 0.015, FCC-Co is the dominant phase. Cu-doped ribbons with x ¼ 0:005; after annealing at 750 C for 2 h, are characterized at room temperature by square hysteresis loop with H c ¼ 8:3 kOe, reduced remanence m r ¼ 0:75 and (BH) max =6.3 MGOe. Loops at higher temperatures are also square with high m r ; for x ¼ 0:01 the magnetization is 89 emu/g and the coercive field is 1.8 kOe at 400 C. r 2004 Elsevier B.V. All rights reserved.
Microstructure and magnetic properties of melt spinning Ni–Mn–Ga
Intermetallics, 2013
The amorphous formation ability, crystallization behavior, microstructure and magnetic properties of melt-spun and heat treated Sm Fe Cr C magnets have been systematically studied using XRD, DSC, TEM and magnetic measurements. It has been found that the as-spun ribbons are comprised of a mixture of -Fe, a small amount of 2 : 17 phase and an amorphous phase when the wheel speed is 17 m/s and become pure amorphous when the wheel speed is increased up to 61 m/s. The coercivity is dramatically increased by subsequent annealing. A higher annealing temperature combined with a shorter annealing time leads to a higher coercivity and annealing at 900°C for 1 min was found to give the highest coercivity of 12.1 kOe. XRD and TEM studies reveal that the microstructure of the annealed ribbon is composed of 2 : 17 carbide as the majority phase and a small amount of -Fe as the minority phase. The average grain size at the optimum annealing was found to be about 35 nm for the 2 : 17 and 60 nm for -Fe. It is further found that a small amount of Co substitution for Fe not only increases the Curie temperature of the 2 : 17 carbides, but also significantly reduces the grain size of -Fe to about 20 nm, leading to a much smoother hysteresis loop and a better temperature dependence of coercivity.