Hf Doping Effect on Hard Magnetism of Nanocrystalline Zr$_{18\hbox{-}{\rm x}}$Hf$_{\rm x}$Co$_{82}$ Ribbons

Al‐Omari, I. A.; Zhang, W. Y.; Yue, Lanping; Skomski, Ralph; Shield, Jeffrey E.; Li, X. Z.; Sellmyer, David J.

doi:10.1109/tmag.2013.2245498

Cited by 13 publications

(7 citation statements)

References 15 publications

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“…The ribbons were made by ejecting molten alloys in a quartz tube onto the surface of a copper wheel with speeds from 5 to 60 ms À1 . The process parameters such as ejection pressure, diameter of the quartz tube hole, melting time and distance between quartz tube and the surface of copper wheel were optimized for obtaining high-quality ribbons [5,6]. The ribbons are about 2 mm wide and 50 lm thick.…”

Section: Methodsmentioning

confidence: 99%

“…The Zr 2 Co 11 intermetallic compound and its magnetic properties have been studied since 1990 [1][2][3][4][5][6][7][8][9][10][11]. Since rare-earth-free permanent-magnets have gained immense focus from the viewpoint of mitigating the critical-material aspects of rare-earth elements, the Zr 2 Co 11 intermetallic compound is considered as one of the promising candidates due to the strong magnetocrystalline anisotropy energy of 1.1 J cm À3 and high Curie temperature of about 500°C [3,4].…”

Section: Introductionmentioning

confidence: 99%

“…Since rare-earth-free permanent-magnets have gained immense focus from the viewpoint of mitigating the critical-material aspects of rare-earth elements, the Zr 2 Co 11 intermetallic compound is considered as one of the promising candidates due to the strong magnetocrystalline anisotropy energy of 1.1 J cm À3 and high Curie temperature of about 500°C [3,4]. Intensive studies were aimed at understanding and improving the magnetic properties of Zr 2 Co 11 and related compounds [5,6 and references cited therein] but only a few studies focused on the crystal structures of the Zr 2 Co 11 compound [7][8][9][10][11]. The crystal structure of the Zr 2 Co 11 intermetallic compound was studied by Demczyk and Cheng [7] using the combination of SAED and convergent-beam electron diffraction (CBED) methods.…”

Section: Introductionmentioning

confidence: 99%

“…In our recent work on the improvement of the magnetic properties of the Zr-Co and related systems [5,6], the structure of the Zr 2 Co 11 compound was revised. In this paper, the crystal lattice of the orthorhombic Zr 2 Co 11 phase has been determined by a tilt series of SAED patterns and the basic structural motif and modulation wave have been revealed in the HREM images.…”

Section: Introductionmentioning

confidence: 99%

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Orthorhombic Zr2Co11 phase revisited

Zhang

Sellmyer

et al. 2014

Journal of Alloys and Compounds

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a b s t r a c tThe structure of the orthorhombic Zr 2 Co 11 phase was revisited in the present work. Selected-area electron diffraction (SAED) and high-resolution electron microscopy (HREM) techniques were used to investigate the structure. They show the orthorhombic Zr 2 Co 11 phase has a 1-D incommensurate modulated structure. The structure can be approximately described as a B-centered orthorhombic lattice. The lattice parameters of the orthorhombic Zr 2 Co 11 phase have been determined by a tilt series of SAED patterns. A hexagonal network with a modulation wave has been observed in the HREM image and the hexagonal motif is considered as the basic structural unit.

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Section: Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Orthorhombic Zr2Co11 phase revisited

Zhang

Sellmyer

et al. 2014

Journal of Alloys and Compounds

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“…The limited resources and supplies of rare earths have led to a renewed interest in rareearth-free magnetic materials [1], and our research [2][3][4] is a part of this trend. Among the considered materials are Zr 2 Co 11 -based rare-earth-free permanent-magnet alloys.…”

Section: Introductionmentioning

confidence: 99%

Magnetic Domain Structure of Nanocrystalline Zr_18-xHf_xCo₈₂ Ribbons: Effect of Hf

et al. 2013

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The effect of Hf on the permanent magnetism of nanocrystalline Zr 18-x Hf x Co 82 ribbons (x = 0, 2, 4, and 6) was investigated by magnetic properties measurement and magnetic force microscopy (MFM). Emphasis is on the local magnetic domain structures in polycrystalline rapidly solidified Zr 18-x Hf x Co 82 ribbons for four different samples with small fractions of Hf dopants (x ≤ 6). The investigation of the magnetic properties of the Zr 18-x Hf x Co 82 ribbons revealed that all the samples under investigation are ferromagnetic at room temperature, and the corresponding MFM images show bright and dark contrast patterns with up-down magnetic domain structures. It is found that the saturation magnetization and the coercivity depend on Hf doping concentration x in the samples. For a sample with Hf concentration x = 4, the maximum energy product (BH) max value is 3.7 MGOe. The short magnetic correlation length of 131 nm and smallest root-mean-square phase shift value of 0.68 0 were observed for x = 4, which suggests the refinement of the magnetic domain structure due to weak intergranular exchange coupling in this sample. The above results indicate that suitable Hf addition is helpful for the magnetic domain structure refinement, the coecivity enhancement, and the energy-product improvement of this class of rare-earth-free nanocrystalline permanent-magnet materials.

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Influence of cooling rate on the magnetic properties of Hf–Co–Fe–B melt-spun alloy

2020

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In the present work, Hf 2 Co 9.5 Fe 1.5 B melt-spun (MS) alloy is synthesized by employing melt spinning at different wheel speeds viz. 16, 20, 24 and 28 m/s to study the effect of quenching on the thermal, structural, microstructural and magnetic properties. The phase purity and the magnetic behaviour of the MS ribbons are highly dependent on the cooling rate that is controlled by altering the tangential wheel speed during melt spinning. Cooling rates are found to increase with increase in wheel speed with a concurrent decrease in the ribbon thickness owing to the increase in the heat transfer coefficient at the thermal contact. The best phase purity and the magnetic properties are found for the ribbons melt-spun at 28 m/s. This could be attributed to the high cooling rate 2.3 × 10 7 K/s causing crystallization of hard magnetic Hf 2 Co 11 B phase leading to refined grain size. A maximum coercivity (H C ) ~ 2.18 kOe, remanence ratio (M r /M s ) ~ 0.61, an appreciable magnetic energy product (BH) max ~ 3 MGOe observed in the MS ribbons at 28 m/s illustrates the critical role of wheel speed in the enhancement of permanent magnetic properties in a single-step without annealing. XRD patterns reveal that the alloy was found to crystallize in orthorhombic Hf 2 Co 11 B in addition to cubic Co and Hf 6 Co 23 phases. FE-SEM analysis is carried out to realize the grain morphology and phase identification. The current work exhibits the efficacy of rapid quenching by melt spinning as an effective technique in the development of high-performance Hf 2 Co 9.5 Fe 1.5 B rare-earth-free permanent magnet alloy for future energy applications in the high-temperature regime.

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Hf Doping Effect on Hard Magnetism of Nanocrystalline Zr$_{18\hbox{-}{\rm x}}$Hf$_{\rm x}$Co$_{82}$ Ribbons

Cited by 13 publications

References 15 publications

Orthorhombic Zr2Co11 phase revisited

Orthorhombic Zr2Co11 phase revisited

Magnetic Domain Structure of Nanocrystalline Zr_18-xHf_xCo₈₂ Ribbons: Effect of Hf

Influence of cooling rate on the magnetic properties of Hf–Co–Fe–B melt-spun alloy

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Hf Doping Effect on Hard Magnetism of Nanocrystalline Zr$_{18\hbox{-}{\rm x}}$Hf$_{\rm x}$Co$_{82}$ Ribbons

Cited by 13 publications

References 15 publications

Orthorhombic Zr2Co11 phase revisited

Orthorhombic Zr2Co11 phase revisited

Magnetic Domain Structure of Nanocrystalline Zr18-xHfxCo82 Ribbons: Effect of Hf

Influence of cooling rate on the magnetic properties of Hf–Co–Fe–B melt-spun alloy

Contact Info

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Magnetic Domain Structure of Nanocrystalline Zr_18-xHf_xCo₈₂ Ribbons: Effect of Hf