Rapidly solidified nanocomposite SmCo7/fcc Co permanent magnets

Shield, Jeffrey E.; Ravindran, V.; Aich, Shampa; Hsiao, Amy; Lewis, L. H.

doi:10.1016/j.scriptamat.2004.08.023

Cited by 34 publications

(21 citation statements)

References 15 publications

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“…Nb tends to reduce the amount of long-range order, 8 while C reduces the scale of the microstructure. 8,17 The x-ray diffraction scan of the as-solidified alloy revealed the presence of only the TbCu 7 -type SmCo 7 phase, and Rietveld analysis using the structural parameters in Ref. 10 fit well.…”

Section: Resultsmentioning

confidence: 88%

Magnetic behavior of Sm-Co-based permanent magnets during order/disorder phase transformations

Aich

Kostogorova

Shield

2005

Journal of Applied Physics

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The structural transformation from the metastable disordered TbCu 7 -type SmCo 7 structure to the equilibrium ordered Th 2 Zn 17 -type Sm 2 Co 17 structure was revealed by x-ray diffraction analysis using Reitveld refinement. The magnetic properties depended strongly on the stage of the transformation, as the coercivity strongly depended on the annealing temperature. The as-solidified alloy in the TbCu 7 -type structure had a coercivity of 4 kOe, which increased to greater than 9 kOe. The coercivity decreased to around 5 kOe as the transformation neared completion upon annealing at higher temperatures. The magnetization processes were also strongly influenced by the structural state. Initially it was totally controlled by nucleation followed by the domain wall pinning-controlled magnetization process.

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Section: Resultsmentioning

confidence: 88%

Magnetic behavior of Sm-Co-based permanent magnets during order/disorder phase transformations

Aich

Kostogorova

Shield

2005

Journal of Applied Physics

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“…2͒. 16 The structure consists of hard magnetic SmCo 7 grains on the order of a few hundred nanometers. Intragranular Co precipitates on the order of 10 nm provide the soft magnetic component, and the fine scale ensures excellent coupling to the surrounding hard magnetic phase.…”

Section: Resultsmentioning

confidence: 99%

“…Samples of stoichiometric Nd 2 Fe 14 B and Nd-Pr-Dy-Fe-Co-B-Ti-C-Zr ͑the "nine component," or 9C, sample͒ are single phase with the 2-14-1 tetragonal structure, 14 two-phase Pr-Fe-B-Zr nanocomposite of ␣-Fe and 2-14-1, 15 and two-phase Sm-Co with fcc Co and the TbCu 7 -type SmCo 7 structure. 16 sample preparation and structural characterization of the various alloys have been presented elsewhere.…”

Section: Methodsmentioning

confidence: 99%

Magnetic reversal in three-dimensional exchange-spring permanent magnets

Shield

Zhou

Aich

et al. 2006

Journal of Applied Physics

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In this paper, we investigate the magnetization reversal in single-phase RE 2 Fe 14 B and two-phase ␣-Fe/ RE 2 Fe 14 B with varying nanoscale grain structures and intergranular exchange interactions produced via controlled segregation during crystallization. We show that the loss of coercivity arises because domain-wall processes dominate the magnetic reversal as the exchange interactions increase. Micromagnetic modeling corroborates a transition to strongly cooperative magnetic reversal as the exchange interactions increase. The magnetic reversal is controlled by the growth of interaction domains via discrete domain-wall motion, and the coercivity is intrinsically limited by the presence of interaction domains. To alleviate this problem, we have built an additional length scale into the structure that is below the interaction domain size but above the limit for intergranular exchange interactions to be significant. These "single-interaction domain" structures retain nucleation-type magnetic reversal and high coercivity. We show experimentally that nanocomposite Sm-Co/Co with this additional length scale has excellent coercivity and nucleation-controlled reversal.

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“…Sm-Co-based magnets have drawn attention since the early 1970s for their highly attractive properties, such as high energy density (15)(16)(17)(18)(19)(20)(21)(22)(23)(24)(25)(26)(27)(28)(29)(30), reliable coercive force, best high-temperature performance and relatively good corrosion and oxidation resistance. These properties have made Sm-Co as the ideal material in dynamic applications such as generators and motors, as well as in demanding environments.…”

Section: Introductionmentioning

confidence: 99%

“…There is strong interest in generating highly coercive materials without the complex heat treatments necessary for magnets produced by classic powder metallurgical approaches [16,17]. In this research, we report the structure and magnetic properties of rapidly solidified SmCo permanent magnets of simple binary alloy systems modified with Nb and C additions.…”

Section: Introductionmentioning

confidence: 99%