Effect of Co or Ge doping on the intergranular magnetic coupling in nanocrystalline Fe89Zr7B3Cu1

Suzuki, Kiyonori; Cochrane, J.W.; Cadogan, J. M.; Xiong, Xiang; Hono, K.

doi:10.1063/1.1447517

Cited by 30 publications

(28 citation statements)

References 6 publications

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“…On the other hand, substitution of Ge for B also decreases the stability of the amorphous alloy, although the partial substitution of Ge for Fe was reported as not affecting the crystallization onset temperature [10]. The measurement of the enthalpy of transformation is strongly affected by the selection of the baseline, especially for wide DSC peaks.…”

Section: Calorimetrymentioning

confidence: 99%

“…% of Co, respectively. However, partial substitution of Ge for B seems to have almost no effect on the Curie temperature (T C slightly decreases from Co5Ge0 alloy to Co5Ge5 alloy), although partial substitution of Ge for Fe was proposed as a promising way for the enhancement of high temperature applications of nanocrystalline alloys [10]. However, it might be noticed that both B and Ge substitution for Fe increase the Curie temperature of amorphous Fe-B alloys [35].…”

Section: High Temperature Phasesmentioning

confidence: 99%

“…Focusing on this problem, Suzuki et al recently proposed a small substitution of Ge for Fe as a more effective way to improve soft magnetic properties at high temperatures than the partial substitution of Co for Fe [10]. However, it must be taken into account that the substitution of Fe by a "non-magnetic" atom will provoke a reduction of the magnetization of the material.…”

Section: Introductionmentioning

confidence: 99%

“…These values, although lower than the nominal concentration of Ge in the as-cast alloy, should indicate a worsening of the preferential partitioning of Ge to the amorphous matrix as the Co content increases in the alloy. The tendency of Ge to enrich in the amorphous matrix was explained in terms of the lower heat of mixing between Ge and Zr (-60 kJ/mol) [32] compared to that between Ge and Fe (-3 kJ/mol) [32], which provokes that Ge will follow the rejected Zr atoms from the crystalline phase to the matrix [10,33]. However, the heat of mixing between Ge and Co (-9 kJ/mol) [32] is slightly more negative than that between Fe and Ge and, consequently, could affect the partitioning behavior of Ge in the nanocrystalline state.…”

Section: Nanocrystalsmentioning

confidence: 99%

“…%, in order to search for a new showed that this parameter is seriously deteriorated for higher Co contents [6][7][8][9]. Although Ge is soluble in -Fe, the benefits of its addition to NANOPERM alloys would be due to its partition to the residual amorphous matrix [10], not producing a deleterious effect on the crystalline phase. In this work, the role of Ge is also studied as the Co content increases in the alloy.…”

Section: Introductionmentioning

confidence: 99%

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Partial substitution of Co and Ge for Fe and B in Fe–Zr–B–Cu alloys: microstructure and soft magnetic applicability at high temperature

et al. 2005

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The partial substitutions of Co for Fe and Ge for B are studied for a Fe 83-x Co x Zr 6 B 10-y Ge y Cu 1 alloy series (x = 0, 5 and 20; y = 0 and 5) as a possible way to enhance the high temperature applicability of NANOPERM alloys. The devitrification process, the nanocrystallization kinetics and the nanocrystalline microstructure are similar for all the studied alloys. Good soft magnetic properties are observed even at a high crystalline volume fraction of bcc -Fe nanocrystals, which are stable up to ~1000 K. The partial substitution of Co for Fe is very effective to increase the Curie temperature of the residual amorphous matrix (T C AM ). Although the substitution of Ge for B is ineffective to increase T C AM , a clear increase of the saturation magnetization with respect to the Ge-free alloy can be observed. These nanocrystalline compositions have a high concentration of Fe and a typical composition: Fe-M-ET-(Cu), where M is a metalloid and ET is an early transition metal. The addition of metalloids, such as B, P, Si, etc., is necessary to enable the production of a precursor amorphous alloy by rapid quenching techniques, from which the nanocrystalline microstructure is obtained after controlled crystallization. It is important to distinguish two different kinds of metalloids: those highly soluble in the -Fe phase (e.g. Si) and those whose solubility in this phase is very restricted (e.g. B). The former elements will be generally dissolved in the crystalline phase, increasing the crystalline volume fraction but deteriorating some magnetic properties like the saturation magnetization and the Curie temperature of the crystalline phase. The latter elements will remain in the amorphous matrix and will diminish the maximum volume fraction of nanocrystals, although preserving the purity of the -Fe phase.The early transition metals (Zr, Nb, Hf, etc.) have a very low solubility in the -Fe phase and, consequently, will remain in the amorphous matrix. However, due to the very slow diffusivity of these elements in the amorphous phase, they pile up at the crystal-matrix interface and constrain the growth of the crystalline phase to the nanocrystalline scale. was proposed mainly because of the strong increase of the Curie temperature of the residual amorphous phase (T C AM ) due to the partial substitution of Co for Fe with respect to the Cofree NANOPERM alloy [7]. In fact, the exchange coupling between nanocrystals is transmitted through the ferromagnetic residual amorphous matrix and thus, at temperatures above the Curie temperature of this residual amorphous matrix, the nanocrystals become exchange uncoupled and, consequently, the outstanding soft magnetic properties of these In this work, the combined effect of partial substitution of Co for Fe and Ge for B on the microstructure and the magnetic properties of nanocrystalline alloys is studied. The maximum Co concentration studied in the alloys is 20 at. %, in order to search for a new showed that this parameter is seriously deteriorated for higher Co con...

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Section: Calorimetrymentioning

confidence: 99%

Section: High Temperature Phasesmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Nanocrystalsmentioning

confidence: 99%