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Effect of Co addition on nanocrystallization and soft magnetic properties of (Fe1−xCox)73.5Cu1Nb3Si13.5B9 alloys
ARTICLE IN PRESS
Journal of Magnetism and Magnetic Materials 272–276 (2004) 1447–1448
Effect of Co addition on nanocrystallization and soft magnetic properties of (Fe1xCox)73.5Cu1Nb3Si13.5B9 alloys Aleksandra Kolano-Buriana,b,*, Tadeusz Kulikb, Gabriel Vlasakc, Jaroslaw Ferencb, Lajos K. Vargad a
b
Institute of Non-Ferrous Metals, ul. Sowinskiego 5, 44-101 Gliwice, Poland Faculty of Materials Science and Engineering, Warsaw University of Technology, ul. Woloska 141, 02-507 Warsaw, Poland c Institute of Physics, Slovak Academy of Science, Dubravska Cesta 9, 842-28 Bratislava, Slovakia d Research Institute for Solid State Physics and Optics, P.O. Box 49, 1525 Budapest, Hungary
Abstract The effect of partial replacement of Fe by Co in ðFe1x Cox Þ73:5 Cu1 Nb3 Si13:5 B9 alloys (x ¼ 020:8) on the nanocrystallization process and on the soft magnetic properties has been investigated. Crystallization process of amorphous alloys was examined by differential scanning calorimetry in order to determine the crystallization temperatures and enthalpies as a function of Co content. The measurements of coercivity, magnetic induction and magnetostriction were carried out at room temperature. It was found that the optimal annealing temperature decreases with the increase of Co content. r 2004 Elsevier B.V. All rights reserved. PACS: 75.50.Kj,75.50.Bb,75.80.+q Keywords: Nanocrystallization; Coercivity; Magnetostriction constant
Recently, much effort was made to investigate a new type of alloy for high-temperature and high-frequency use [1,2]. Partial substitution of Fe by Co in nanocrystalline Finemet-type alloys is a way to extend their outstanding soft magnetic properties to elevated temperatures. The FeCoCuNbSiB nanocrystalline alloys, consisting of nanosized crystals surrounded by residual ferromagnetic amorphous matrix, have slightly worse magnetic properties at room temperature than the FeCuNbSiB alloys, but are more stable at elevated temperatures. The optimal soft magnetic properties of the new alloys are obtained by suitable annealing conditions [3]. The aim of this work was to study an effect of partial substitution of Fe by Co on nanocrystallization process and magnetic properties. *Corresponding author. Institute of Non-Ferrous Metals, ul. Sowinskiego 5, 44-101 Gliwice, Poland. Tel.: +4832-2380-251; fax: +4832-2316-933. E-mail address: [email protected] (A. Kolano-Burian).
The series of (Fe1xCox)73.5Cu1Nb3Si13.5B9 (where x ¼ 0; 0.14, 0.27, 0.40, 0.54, 0.68, 0.80) amorphous ribbons, about 8 mm wide and 20 mm thick, were obtained by melt-spinning technique. Crystallization process of amorphous alloys was examined by differential scanning calorimetry (DSC). Temperatures and enthalpies of both stages of crystallization were determined from DSC upon continuous heating from room temperature to 993 K at a constant heating rate of 20 K/ min. All samples, in forms of toroidal cores and strips, were isothermally annealed within the temperature range of 733–833 K for 1 h in Ar protective atmosphere, and cooled at the rates of 70–80 K/min. After annealing, the AC (50 Hz) magnetic properties (coercivity Hc ; magnetic induction Bm ) were determined using a computerized hysteresis loop tracer. The saturation magnetostriction constant ls was measured at room temperature using a special capacitance device for magnetostriction measurements [4]. Amorphousness of the alloys was checked by X-ray diffractometry.
0304-8853/$ - see front matter r 2004 Elsevier B.V. All rights reserved. doi:10.1016/j.jmmm.2003.12.1349
ARTICLE IN PRESS 1448
A. Kolano-Burian et al. / Journal of Magnetism and Magnetic Materials 272–276 (2004) 1447–1448
Table 1 Dependence of DSC peak temperature and enthalpy of the first (T1 ; H1 ) and second (T2 ) stages of crystallization on Co content x x
T1 (K)
T2 (K)
H1 (J/g)
0 0.14 0.27 0.40 0.54 0.68 0.80
840 830 827 821 809 806 809
988 977 976 977 975 965 961
83.3 73.7 91.1 104.2 106.1 89.8 91.3
Fig. 2. Influence of Co content on the Hc and ls of the alloys annealed at optimal temperature.
Fig. 1. Dependence of Hc of (Fe1xCox)73.5Cu1Nb3Si13.5B9 alloys (x ¼ 020:68) on Ta.
The DSC results obtained for Finemet modified with Co (x ¼ 020:80) alloys in the as-quenched state are presented in Table 1. The primary crystallization of aFe(Co,Si) manifests itself by the first calorimetric peak. The temperature of the first stage of crystallization T1 decreases with the increase of Co content in an alloy. The enthalpy of the first stage of crystallization H1 increases with the increase of Co content, but for the alloy containing 0.68 at% Co the value of enthalpy suddenly decreases. The temperature of the second stage of crystallization T2 is almost constant up to x ¼ 0:68; when suddenly decreases about 10 K. This effect is probably connected with change of the chemical composition of the amorphous matrix. Based on the DSC results, the alloys were annealed at various temperatures within the range between the onset and the peak temperatures of the first stage of crystallization. Fig. 1 illustrates the influence of the annealing temperature Ta on Hc of each alloy. The characteristic minimum of Hc ; observed for all the (Fe1xCox)73.5Cu1Nb3Si13.5B9 alloys studied (x ¼ 020:80), corresponds to optimal temperature Topt of annealing [3]. Up to x ¼ 0:54; of the partial substitution of Fe by Co results in an increase of Hc : For x ¼ 0:68; the noticeable
magnetic softening is observed. This result is a consequence of the magnetic coupling between crystals [5]. Above x ¼ 0:68; the Hc again increases with the increase of Co content in the alloy. Fig. 2 presents the dependence of Hc and ls on Co content for the alloys. It is clearly seen that both dependences are similar to each other. All the alloys studied are surprisingly soft despite of the relatively large value of ls : The Co content dependence of ls for the nanocrystalline samples resembles the Co content dependence of ls for the Fe–Co binary alloy, where we have a minimum for K (magnetic anisotropy constant) and maximum for ls at 50 at% of Co. The Co element is distributed both in crystalline and residual amorphous matrix, so the overall concentration of Co is not necessarily equal to the concentration in Fe–Co crystallites. The residual stress-induced magnetoelastic energy is also random and it is averaging out by exchange interaction, is less effective at large values of ls ; hence a correlated concentration dependence of Hc and ls : This work is supported by the EC GROWTH program, research project Hit-Fcore, contract no. G5RD-CT-2001-03009.
References [1] M. Ohnuma, et al., Proceedings of the 22nd Riso International Symposium on Materials Science, Denmark, 2001, p. 341. [2] J. Zbroszczyk, J. Olszewski, W. Ciurzy!nska, B. Wys"ocki, ! R. Kolano, A. M"ynczyk, M. Łukiewski, A. Kolano, J. ) Lelatko, J. Magn. Magn. Mater 254–255 (2003) 513. [3] A. Kolano-Burian, J. Ferenc, T. Kulik, Mater. Sci. Eng. A, in press. [4] G. Vlasak, J. Magn. Magn. Mater 215–216 (2000) 479. [5] C. Gomez-Polo, P. Marin, L. Pascual, A. Hernando, M. Vazquez, Phys. Rev. B 65 (2002) 024433.
Journal of Magnetism and Magnetic Materials 272–276 (2004) 1447–1448
Effect of Co addition on nanocrystallization and soft magnetic properties of (Fe1xCox)73.5Cu1Nb3Si13.5B9 alloys Aleksandra Kolano-Buriana,b,*, Tadeusz Kulikb, Gabriel Vlasakc, Jaroslaw Ferencb, Lajos K. Vargad a
b
Institute of Non-Ferrous Metals, ul. Sowinskiego 5, 44-101 Gliwice, Poland Faculty of Materials Science and Engineering, Warsaw University of Technology, ul. Woloska 141, 02-507 Warsaw, Poland c Institute of Physics, Slovak Academy of Science, Dubravska Cesta 9, 842-28 Bratislava, Slovakia d Research Institute for Solid State Physics and Optics, P.O. Box 49, 1525 Budapest, Hungary
Abstract The effect of partial replacement of Fe by Co in ðFe1x Cox Þ73:5 Cu1 Nb3 Si13:5 B9 alloys (x ¼ 020:8) on the nanocrystallization process and on the soft magnetic properties has been investigated. Crystallization process of amorphous alloys was examined by differential scanning calorimetry in order to determine the crystallization temperatures and enthalpies as a function of Co content. The measurements of coercivity, magnetic induction and magnetostriction were carried out at room temperature. It was found that the optimal annealing temperature decreases with the increase of Co content. r 2004 Elsevier B.V. All rights reserved. PACS: 75.50.Kj,75.50.Bb,75.80.+q Keywords: Nanocrystallization; Coercivity; Magnetostriction constant
Recently, much effort was made to investigate a new type of alloy for high-temperature and high-frequency use [1,2]. Partial substitution of Fe by Co in nanocrystalline Finemet-type alloys is a way to extend their outstanding soft magnetic properties to elevated temperatures. The FeCoCuNbSiB nanocrystalline alloys, consisting of nanosized crystals surrounded by residual ferromagnetic amorphous matrix, have slightly worse magnetic properties at room temperature than the FeCuNbSiB alloys, but are more stable at elevated temperatures. The optimal soft magnetic properties of the new alloys are obtained by suitable annealing conditions [3]. The aim of this work was to study an effect of partial substitution of Fe by Co on nanocrystallization process and magnetic properties. *Corresponding author. Institute of Non-Ferrous Metals, ul. Sowinskiego 5, 44-101 Gliwice, Poland. Tel.: +4832-2380-251; fax: +4832-2316-933. E-mail address: [email protected] (A. Kolano-Burian).
The series of (Fe1xCox)73.5Cu1Nb3Si13.5B9 (where x ¼ 0; 0.14, 0.27, 0.40, 0.54, 0.68, 0.80) amorphous ribbons, about 8 mm wide and 20 mm thick, were obtained by melt-spinning technique. Crystallization process of amorphous alloys was examined by differential scanning calorimetry (DSC). Temperatures and enthalpies of both stages of crystallization were determined from DSC upon continuous heating from room temperature to 993 K at a constant heating rate of 20 K/ min. All samples, in forms of toroidal cores and strips, were isothermally annealed within the temperature range of 733–833 K for 1 h in Ar protective atmosphere, and cooled at the rates of 70–80 K/min. After annealing, the AC (50 Hz) magnetic properties (coercivity Hc ; magnetic induction Bm ) were determined using a computerized hysteresis loop tracer. The saturation magnetostriction constant ls was measured at room temperature using a special capacitance device for magnetostriction measurements [4]. Amorphousness of the alloys was checked by X-ray diffractometry.
0304-8853/$ - see front matter r 2004 Elsevier B.V. All rights reserved. doi:10.1016/j.jmmm.2003.12.1349
ARTICLE IN PRESS 1448
A. Kolano-Burian et al. / Journal of Magnetism and Magnetic Materials 272–276 (2004) 1447–1448
Table 1 Dependence of DSC peak temperature and enthalpy of the first (T1 ; H1 ) and second (T2 ) stages of crystallization on Co content x x
T1 (K)
T2 (K)
H1 (J/g)
0 0.14 0.27 0.40 0.54 0.68 0.80
840 830 827 821 809 806 809
988 977 976 977 975 965 961
83.3 73.7 91.1 104.2 106.1 89.8 91.3
Fig. 2. Influence of Co content on the Hc and ls of the alloys annealed at optimal temperature.
Fig. 1. Dependence of Hc of (Fe1xCox)73.5Cu1Nb3Si13.5B9 alloys (x ¼ 020:68) on Ta.
The DSC results obtained for Finemet modified with Co (x ¼ 020:80) alloys in the as-quenched state are presented in Table 1. The primary crystallization of aFe(Co,Si) manifests itself by the first calorimetric peak. The temperature of the first stage of crystallization T1 decreases with the increase of Co content in an alloy. The enthalpy of the first stage of crystallization H1 increases with the increase of Co content, but for the alloy containing 0.68 at% Co the value of enthalpy suddenly decreases. The temperature of the second stage of crystallization T2 is almost constant up to x ¼ 0:68; when suddenly decreases about 10 K. This effect is probably connected with change of the chemical composition of the amorphous matrix. Based on the DSC results, the alloys were annealed at various temperatures within the range between the onset and the peak temperatures of the first stage of crystallization. Fig. 1 illustrates the influence of the annealing temperature Ta on Hc of each alloy. The characteristic minimum of Hc ; observed for all the (Fe1xCox)73.5Cu1Nb3Si13.5B9 alloys studied (x ¼ 020:80), corresponds to optimal temperature Topt of annealing [3]. Up to x ¼ 0:54; of the partial substitution of Fe by Co results in an increase of Hc : For x ¼ 0:68; the noticeable
magnetic softening is observed. This result is a consequence of the magnetic coupling between crystals [5]. Above x ¼ 0:68; the Hc again increases with the increase of Co content in the alloy. Fig. 2 presents the dependence of Hc and ls on Co content for the alloys. It is clearly seen that both dependences are similar to each other. All the alloys studied are surprisingly soft despite of the relatively large value of ls : The Co content dependence of ls for the nanocrystalline samples resembles the Co content dependence of ls for the Fe–Co binary alloy, where we have a minimum for K (magnetic anisotropy constant) and maximum for ls at 50 at% of Co. The Co element is distributed both in crystalline and residual amorphous matrix, so the overall concentration of Co is not necessarily equal to the concentration in Fe–Co crystallites. The residual stress-induced magnetoelastic energy is also random and it is averaging out by exchange interaction, is less effective at large values of ls ; hence a correlated concentration dependence of Hc and ls : This work is supported by the EC GROWTH program, research project Hit-Fcore, contract no. G5RD-CT-2001-03009.
References [1] M. Ohnuma, et al., Proceedings of the 22nd Riso International Symposium on Materials Science, Denmark, 2001, p. 341. [2] J. Zbroszczyk, J. Olszewski, W. Ciurzy!nska, B. Wys"ocki, ! R. Kolano, A. M"ynczyk, M. Łukiewski, A. Kolano, J. ) Lelatko, J. Magn. Magn. Mater 254–255 (2003) 513. [3] A. Kolano-Burian, J. Ferenc, T. Kulik, Mater. Sci. Eng. A, in press. [4] G. Vlasak, J. Magn. Magn. Mater 215–216 (2000) 479. [5] C. Gomez-Polo, P. Marin, L. Pascual, A. Hernando, M. Vazquez, Phys. Rev. B 65 (2002) 024433.