- Email: [email protected]
Minor-metalloid substitution for Fe on glass formation and soft magnetic properties of Fe–Co–Si–B–P–Cu alloys
Journal of Non-Crystalline Solids 533 (2020) 119937
Contents lists available at ScienceDirect
Journal of Non-Crystalline Solids journal homepage: www.elsevier.com/locate/jnoncrysol
Minor-metalloid substitution for Fe on glass formation and soft magnetic properties of Fe–Co–Si–B–P–Cu alloys
T
Wen Lia, , C.X. Xiea, , H.Y. Liua, K.W. Wanga, Z.L. Liaoa, Y.Z. Yangb ⁎
a b
⁎
School of Mechanical Engineering, Dongguan University of Technology, Dongguan, 523808, China Faculty of Materials and Energy, Guangdong University of Technology, Guangzhou, 510006, China
ARTICLE INFO
ABSTRACT
Keywords: Minor metalloids Fe-based amorphous alloy Amorphous formation Soft magnetic properties
Fe78.8Co6Si4B8P2.5Cu0.7, Fe78.3Co6Si4B8P3Cu0.7, Fe78.3Co6Si4B8.5P2.5Cu0.7, and Fe78.3Co6Si4.5B8P2.5Cu0.7 alloys were fabricated through the melt-spun technique, and their glass formation and magnetic properties were investigated. Results showed that a fully amorphous structure could be formed by substituting Fe with 0.5 at.% metalloids (B, P, Si) in the Fe78.8Co6Si4B8P2.5Cu0.7 alloy. The substitution of minor metalloids delayed the precipitation of the α-Fe phase, but had minimal effect on the precipitation of Fe-(B, P) compounds. Among the three amorphous alloys, Fe78.3Co6Si4B8.5P2.5Cu0.7 presented the best magnetic properties in both as-cast and annealed states (833 K). In the as-cast condition, Ms and Hc of the Fe78.3Co6Si4B8.5P2.5Cu0.7 alloy were 171 Am2/ kg and 5.1 A/m respectively. After annealing at 833 K for 10 min, the magnetic properties were obviously optimized, Ms was 208 Am2/kg, and Hc was 3.5 A/m.
1. Introduction Fe-based amorphous/nanocrystalline alloy is a new kind of soft magnetic material that has been widely used for several years. This alloy is mainly composed of ferromagnetic metals (e.g., Fe, Co, and Ni), metalloid elements (e.g., B, Si, and P), transition metal elements (e.g., Zr, Nb, and Hf) and nanocrystalline forming elements (e.g., Cu, and Ag). However, the amorphous/nanocrystalline alloy without transition metal elements has considerable advantages, the most obvious of which are its excellent soft magnetic properties and low cost. Three kinds of common commercial soft magnetic alloys, namely, Finemet (FeSiBNbCu) [1], Nanoperm (FeZrBCu) [2], and Hitperm (FeCoZrBCu) [3], contain more or less transition metal elements, such as Nb and Zr, which greatly increases the alloys’ cost. Since 2009, the FeSiBPCu series alloy without transition metal elements has been greatly developed. Named Nanomet, the alloy is the fourth kind of nanocrystalline soft magnetic alloy [4–6]. Nanomet has become a potential soft magnetic material of the future because of its high saturation magnetic flux density (Bs > 1.8 T), low coercive force (Hc < 10 A/m), and low cost. Among metalloid elements, B, as an amorphous forming element, plays an important role in Fe-metalloid amorphous alloys. Si can effectively expand the optimum annealing temperature range and reduce the annealing temperature sensitivity of soft magnetic properties. The addition of P can improve the ability of amorphous formation and
⁎
effectively suppress the bcc-Fe grain growth in Fe-based nanocrystalline alloys because of its small diffusibility [7,8]. Compared with B, P is cheaper, which can reduce the cost. During preparation, P can reduce the energy loss in the alloy melting because of its low melting point. However, excessive P-containing alloys are likely to oxidize during melting and narrow the annealing temperature range, resulting in high requirements for vacuum and temperature uniformity during annealing [9,10]. Previous research [11] shows the influence of different Co content on the glass formation and soft magnetic properties of FeSiBPCu alloy. When the Co content is in the 0 − 10 at.% range, the alloy displays a completely amorphous structure, and its saturation magnetization (Ms) and coercive force (Hc) can reach 181–194 Am2/kg and 10.2–12.3 A/m, respectively, in the as-quenched state. In the present study, the minormetalloid substitution for Fe on the glass formation and magnetic properties of Fe–Co–Si–B–P–Cu alloy are investigated on the basis of the previous Co-containing alloy. 2. Experimental procedure Multicomponent alloy ingots with nominal compositions of Fe78.8 Co6Si4B8P2.5Cu0.7, Fe78.3Co6Si4B8P3Cu0.7, Fe78.3Co6Si4B8.5P2.5Cu0.7, and Fe78.3Co6Si4.5B8P2.5Cu0.7 were cast using high-purity Fe, Co, Si, Cu and pre-alloy of Fe-17.9%B and Fe-25%P under argon atmosphere. The
Corresponding authors. E-mail addresses: [email protected] (W. Li), [email protected] (C.X. Xie).
https://doi.org/10.1016/j.jnoncrysol.2020.119937 Received 6 November 2019; Received in revised form 8 January 2020; Accepted 15 January 2020 0022-3093/ © 2020 Elsevier B.V. All rights reserved.
Journal of Non-Crystalline Solids 533 (2020) 119937
W. Li, et al.
Fig. 2. SEM EDX spectra of Fe, Co, Si, B, P, and Cu elements for the as-quenched (b) Fe78.3Co6Si4B8.5P2.5Cu0.7, (c) (a) Fe78.3Co6Si4B8P3Cu0.7, Fe78.3Co6Si4.5B8P2.5Cu0.7 amorphous alloys. Fig. 1. XRD patterns of the different FeCoSiBPCu melt-spun ribbons.
ribbons of 1.0−1.5 mm in width and 0.025−0.03 mm in thickness were rapidly solidified on a single rotating copper wheel. In order to reduce the oxidation, all the annealing was carried out under vacuum (~10 Pa) in a quartz tube applying a heating rate of 10 K/s. Phase identification was carried out using X-ray diffraction (XRD, D/Max-IIA) with Cu Kα radiation. The detailed distribution of elements in melt-spun amorphous samples was studied by scanning electron microscope-energy dispersive X-ray spectroscopy (SEM-EDX). Thermal properties associated with crystallization events were analyzed by differential scanning calorimeter (DSC, SDT Q600). Ms under an applied field of 1000 kA/m was measured using vibrating sample magnetometer (VSM, WK-II) at room temperature. Hc under a maximum applied field of 800 A/m was evaluated by soft magnetic DC B − H loop analyzer.
Fig. 3. DSC curves of FeCoSiBPCu melt-spun ribbons.
3. Results and discussion
alloys exhibit minimal change, while the first exothermic peak moves to the high temperature region as a whole. The results show that a 0.5 at. % increase of metalloid content mainly affects the precipitation of α−(Fe, Co) phase but has no significant effect on the precipitation of the Fe−(B, P) phase. Notably, the first exothermic peak temperature of FS alloy increases by approximately 49 K to the high temperature zone when 0.5 at.% Si is added, and the offset temperature is the most obvious. The temperature interval (∆T = Tx2−Tx1) between the characteristic temperature Tx1 and Tx2 is wide, reaching 121−179 K. During annealing, the large ∆T can effectively control the precipitation of α−Fe in the amorphous precursor, allowing the easy formation of single α−(Fe, Co) nanocrystalline structure and optimizing the soft magnetic properties [14,15]. The variation of Tx1, Tx2, and ∆T value with alloy composition is plotted in Fig. 4. Compared with the FF alloy, the change of Tx1 is obvious with the composition of the 0.5 at.% metalloids, whereas Tx2 shows slight changes. Fig. 5 presents the magnetic hysteresis loop (M–H) curves of the FeCoSiBPCu alloys. Nonlinear changes can be observed, and all hysteresis loops show typical soft magnetic behavior. The variation in Ms value clearly depends on the type of metalloid substitution. Fig. 6 shows the dependences of Ms and Hc on 0.5 at.% metalloid content for the FP, FB, and FS melt-spun ribbons. Among the three amorphous alloys, the Ms of FP alloy is the highest, reaching 184 Am2/kg, followed by the Ms of FB alloy, which reaches 171 Am2/kg. Finally, FS alloy and Ms are equal to 161 Am2/kg. This result shows that the change of 0.5% metalloid content has a great influence on Ms. By contrast, the addition of 0.5% metalloid to P and B is advantageous for Ms. For Hc, FB alloy has
Fig. 1 depicts XRD patterns for Fe78.8Co6Si4B8P2.5Cu0.7, Fe78.3Co6Si4 B8P3Cu0.7, Fe78.3Co6Si4B8.5P2.5Cu0.7, and Fe78.3Co6Si4.5B8P2.5Cu0.7 (hereafter denoted as FF, FP, FB, and FS, respectively) alloys in the asquenched state with varying metalloid content. Notably, sharp diffraction peaks corresponding to the α–(Fe, Co) phase appear in the XRD spectra. Partial crystallization clearly occurs during preparation. When 0.5 at.% Fe is substituted by P, B or Si metalloids, typical broad amorphous halos appear near 2θ = 44.8° on the XRD spectra of FP, FB, and FS alloys, demonstrating their fully amorphous structures. The XRD results reveal that the minor substitution of metalloids (i.e., B, P, Si) with Fe improves the glass-forming ability of the present Fe–Co–Si–B–P–Cu alloy system. To check the homogeneous mixing of all elements during preparation and eliminate the influence of defects, such as segregation of components and element enrichment on the magnetic properties, the three fully amorphous samples are measured by SEMEDX spectra. The SEM-EDX spectra in Fig. 2 show that the chemical compositions of the FP, FB, and FS alloys are almost homogeneous. Fig. 3 displays the DSC curves of FF, FP, FB, and FS melt-spun ribbons. Two exothermic peaks occur for all the samples during heating, indicating the existence of two-stage crystallization that corresponds to the precipitation of the α–(Fe, Co) phase and Fe−(B, P) compounds [12,13]. Through the following annealing experiments, we find that the α–(Fe, Co) and Fe3(B, P) phases precipitate in the first and second exothermic peaks of the three amorphous alloys. The thermal characteristic temperatures of the FeCoSiBPCu alloys, such as the first and second crystallization onset and peak temperatures, are labeled as Tx1, Tx2, Tp1, and Tp2. Tx2 and Tp2 of these four 2
Journal of Non-Crystalline Solids 533 (2020) 119937
W. Li, et al.
Fig. 4. Variation of Tx1, Tx2, and ∆T values with alloy composition.
Fig. 5. M–H curves of the fully amorphous Fe−Si−B−P−Cu ribbons in the asquenched state.
Fig. 7. XRD patterns of amorphous alloys annealed at 613−833 K for 10 min: (a) Fe78.3Co6Si4B8P3Cu0.7, (b) Fe78.3Co6Si4B8.5P2.5Cu0.7, (c) Fe78.3Co6Si4.5B8P2.5 Cu0.7 (AQ represents as-quenched state).
properties in the as-quenched state, with an Ms and Hc of 171 Am2/kg and 5.1 A/m, respectively. Fig. 7 depicts the XRD patterns for the FP, FB, and FS ribbons annealed at 613−833 K for 10 min. After annealing at 613 K and before, the FP and FB alloys maintain amorphous structure, and structural relaxation may occur in its interior. For FS alloys, the annealing temperature can last up to 673 K. Once the annealing temperature reaches near Tx1, a single α–(Fe, Co) phase begins to precipitate and grow gradually. When the annealing temperature increases to 753−793 K, new crystallization peaks begin to appear, and a small amount of Fe−(B, P) compounds begin to precipitate. When the annealing temperature continues to rise, the multiphase precipitates and grows up. To explain well the crystallization of the annealed ribbons in this study, the corresponding microstructure schematics are illustrated in Fig. 8. The difference of characteristic temperature between the FP and FB alloys is small, and the crystallization of the two alloys is similar.
Fig. 6. Dependences of Ms and Hc on the component for Fe−Si−B−P−Cu melt-spun ribbons.
the lowest value, reaching 5.1 A/m. FP alloy displays the highest value of 12.5 A/m. Although the increase of 0.5 at.% P obtained a high Ms, it also deteriorated Hc. In conclusion, FB alloy has the best soft magnetic 3
Journal of Non-Crystalline Solids 533 (2020) 119937
W. Li, et al.
precipitation of the hard magnetic phase Fe−(B, P) compounds and the obvious exchange coupling between the soft-magnetic phase α−(Fe, Co) grain and the hard-magnetic phase Fe3(B, P) grain, thereby reducing the effective anisotropy and Hc. The characteristic temperature of FS alloy is different from those of FP and FB alloys, Thus, to observe the magnetic properties of the three amorphous components after annealing near the characteristic temperature point, the Ms and Hc of the three alloys after annealing near Tx1 and Tx2, respectively, are compared, as shown in Figs 10(a) and (b). As shown in Fig. 10(a), the Ms of FP alloy keeps the highest value at the three annealing temperatures of Tx1, Tx2- (i.e., is the temperature point slightly lower than Tx1), and Tx2+ (i.e., the temperature point slightly higher than Tx2). Moreover, the Ms of all three alloys has the highest value when annealed at Tx2+. However, as shown in Fig. 10(b), the difference of Hc among the three alloys is obvious. When Ta = Tx1, the Hc of FS alloy is the lowest at 35.2 A/m; when Ta = Tx2-, the Hc of FP alloy is the lowest at 9.3 A/m; and when Ta = Tx2+, the Hc of FB alloy is the lowest at 3.5 A/m. For different annealing temperatures in the range of 613−833 K, the Hc of the three alloys is always the lowest value at Ta = Tx2+ (833 K). Here, the Hc of FP, FB and FS are 8.4, 3.5, and 5.9 A/m, respectively. In general, the soft magnetic properties of the three alloys are the best when annealed at Ta = Tx2+ (833 K), while the FB alloy has the best soft magnetic properties, with Ms and Hc at 208 Am2/kg and 3.5 A/m, respectively.
Fig. 8. Crystallization and the corresponding microstructure schematics of the FP, FB, and FS ribbons at different annealing temperatures.
The crystallization of FS alloy lags behind that of the first two alloys. This condition indicates that the amorphous precursors of these alloys have good thermal stability, ensuring that the pre-existing α–(Fe, Co) nuclei is stable and does not precipitate at the annealing temperature before Tx1. Fig. 9 reveals the annealing temperature-dependent behavior of Ms and Hc in the FP, FB, and FS amorphous ribbons. With the increase in annealing temperature from as-quenched state to 833 K, the Ms of FP and FB alloys improves significantly from the 184 and 171 Am2/kg to 215 and 208 Am2/kg, respectively. In FS alloy, the Ms is 161 Am2/kg in the as-quenched state. After a downward trend at the annealing temperature of 673−753 K, the Ms rapidly rises to 192 Am2/kg at 833 K. The continuous growth of Ms may be due to the precipitation of the α–(Fe, Co) phase throughout the annealing process. However, in the annealing temperature range of 613−833 K, Hc of the three alloys generally increases, and when the annealing temperature approaches Tx2, Hc begins to decrease rapidly. This result is due to the gradual
4. Conclusion We investigated the minor-metalloid substitution for Fe on glass formation and magnetic properties of Fe–Co–Si–B–P–Cu alloys. From the results, the following conclusions were drawn: 1) The 0.5 at.% metalloid (B, P, Si) substitution for Fe can form a fully amorphous state in the Fe78.8Co6Si4B8P2.5Cu0.7 alloy. 2) Fe78.3Co6Si4B8P3Cu0.7, Fe78.3Co6Si4B8.5P2.5Cu0.7, and Fe78.3Co6 Si4.5B8P2.5Cu0.7 show a wide temperature interval ∆T of 121−179 K. The minor-metalloid substitution for Fe delays the precipitation of the α-Fe phase and improves the thermal stability of the alloy.
Fig. 9. Dependences of Ms and Hc on the annealing temperature of the ribbons annealed for 10 min.
4
Journal of Non-Crystalline Solids 533 (2020) 119937
W. Li, et al.
Fig. 10. Ms and Hc of the three alloys after annealing near Tx1 and Tx2. (Note: Ta is the annealing temperature).
3) The 0.5 at.% B substitution for Fe is the most beneficial to the improvement of soft magnetic properties. The as-cast Ms and Hc of the Fe78.3Co6Si4B8.5P2.5Cu0.7 alloy are 171 Am2/kg and 5.1 A/m respectively. After annealing at 833 K for 10 min, Ms and Hc of the alloy can reach 208 Am2/kg and 3.5 A/m, respectively.
References [1] Y. Yoshizawa, S. Oguma, K. Yamauchi, New Fe-based soft magnetic alloys composed of ultrafine grain structure, J. Appl. Phys. 64 (1988) 6044–6046. [2] K. Suzuki, N. Kataoka, A. Inoue, et al., High saturation magnetization and soft magnetic properties of bcc Fe–Zr–B alloys with ultrafine grain structure, Mater. Trans. JIM 31 (1990) 743–746. [3] M.A. Willard, D.E. Laughlin, M.E. McHenry, et al., Structure and magnetic properties of (Fe0.5Co0.5)88Zr7B4Cu1 nanocrystalline alloys, J. Appl. Phys. 84 (1998) 6773–6777. [4] A. Makino, H. Men, T. Kubota, et al., New excellent soft magnetic FeSiBPCu nanocrystallized alloys with high Bs of 1.9 T from nanohetero-amorphous phase, IEEE T. Magn. 45 (2009) 4302–4305. [5] A.D. Setyawan, K. Takenaka, P. Sharma, et al., Magnetic properties of 120-mm wide ribbons of high Bs and low core-loss NANOMET® alloy, J. Appl. Phys. 117 (2015) 17B715. [6] X. Fan, T. Zhang, M. Jiang, et al., Synthesis of novel FeSiBPCCu alloys with high amorphous forming ability and good soft magnetic properties, J. Non-Cryst. Solids 503 (2019) 36–43. [7] Y. Wang, Y. Zhang, A. Takeuchi, et al., Investigation on the crystallization mechanism difference between FINEMET® and NANOMET® type Fe-based soft magnetic amorphous alloys, J. Appl. Phys. 120 (2016) 145102. [8] L. Jiang, Y. Zhang, X. Tong, et al., Unique influence of heating rate on the magnetic softness of Fe81.5Si0.5B4.5P11Cu0.5C2 nanocrystalline alloy, J. Magn. Magn. Mater. 471 (2019) 148–152. [9] Z. Zhang, P. Sharma, A. Makino, Role of Si in high Bs and low core-loss Fe85.2B10−xP4Cu0.8Six nano-crystalline alloys, J. Appl. Phys. 112 (2012) 103902. [10] F.G. Chen, Y.G. Wang, Investigation of glass forming ability, thermal stability and soft magnetic properties of melt-spun Fe83P16−xSixCu1 (x= 0, 1, 2, 3, 4, 5) alloy ribbons, J. Alloys Compd. 584 (2014) 377–380. [11] W. Li, C.X. Xie, C.L. Yao, et al., Amorphous formation and magnetic properties of Co-containing FeSiBPCu nanocrystalline alloys, J. Non-Cryst. Solids 505 (2019) 87–91. [12] A. Urata, M. Yamaki, K. Satake, et al., Magnetic properties and structure of Fe83.3–85.8B7.0–4.5P9Cu0.7 nanocrystalline alloys, J. Appl. Phys. 113 (2013) 17A311. [13] X.B. Zhai, Y.G. Wang, L. Zhu, et al., Effect of heating rate on atom migration, phase structure and magnetic properties of the Fe82Si2B11P4Cu1 alloy, J. Non-Cryst. Solids 499 (2018) 337–343. [14] K. Hono, D.H. Ping, M. Ohnuma, et al., Cu clustering and Si partitioning in the early crystallization stage of an Fe73.5Si13.5B9Nb3Cu1 amorphous alloy, Acta Mater. 47 (1999) 997–1006. [15] L.H. Kong, R.R. Chen, T.T. Song, et al., Magnetic characterization of dual phase FeZrB soft magnetic alloy, J. Magn. Magn. Mater. 323 (2011) 3285–3289.
CRediT authorship contribution statement Wen Li: Conceptualization, Methodology, Software, Investigation, Writing - original draft. C.X. Xie: Validation, Formal analysis, Data curation. H.Y. Liu: Resources, Formal analysis. K.W. Wang: Resources, Writing - review & editing. Z.L. Liao: Resources, Software. Y.Z. Yang: Writing - review & editing, Supervision. Declaration of Competing Interest We declare that we have no financial and personal relationships with other people or organizations that can inappropriately influence our work, there is no professional or other personal interest of any nature or kind in any product, service and/or company that could be construed as influencing the position presented in, or the review of, the manuscript entitled “Minor-metalloid substitution for Fe on glass formation and soft magnetic properties of Fe–Co–Si–B–P–Cu alloys”. Acknowledgments This work was supported by National Natural Science Foundation of China (no. 51801025), Research start-up funds of DGUT(no. GC300502-49, GC300502-48), Research and Reform Project of Higher Education in Guangdong Province(no. E1201601) and Scientific Research Foundation of Advanced Talents (Innovation Team)(DGUT, No. KCYCXPT2016004).
5
Contents lists available at ScienceDirect
Journal of Non-Crystalline Solids journal homepage: www.elsevier.com/locate/jnoncrysol
Minor-metalloid substitution for Fe on glass formation and soft magnetic properties of Fe–Co–Si–B–P–Cu alloys
T
Wen Lia, , C.X. Xiea, , H.Y. Liua, K.W. Wanga, Z.L. Liaoa, Y.Z. Yangb ⁎
a b
⁎
School of Mechanical Engineering, Dongguan University of Technology, Dongguan, 523808, China Faculty of Materials and Energy, Guangdong University of Technology, Guangzhou, 510006, China
ARTICLE INFO
ABSTRACT
Keywords: Minor metalloids Fe-based amorphous alloy Amorphous formation Soft magnetic properties
Fe78.8Co6Si4B8P2.5Cu0.7, Fe78.3Co6Si4B8P3Cu0.7, Fe78.3Co6Si4B8.5P2.5Cu0.7, and Fe78.3Co6Si4.5B8P2.5Cu0.7 alloys were fabricated through the melt-spun technique, and their glass formation and magnetic properties were investigated. Results showed that a fully amorphous structure could be formed by substituting Fe with 0.5 at.% metalloids (B, P, Si) in the Fe78.8Co6Si4B8P2.5Cu0.7 alloy. The substitution of minor metalloids delayed the precipitation of the α-Fe phase, but had minimal effect on the precipitation of Fe-(B, P) compounds. Among the three amorphous alloys, Fe78.3Co6Si4B8.5P2.5Cu0.7 presented the best magnetic properties in both as-cast and annealed states (833 K). In the as-cast condition, Ms and Hc of the Fe78.3Co6Si4B8.5P2.5Cu0.7 alloy were 171 Am2/ kg and 5.1 A/m respectively. After annealing at 833 K for 10 min, the magnetic properties were obviously optimized, Ms was 208 Am2/kg, and Hc was 3.5 A/m.
1. Introduction Fe-based amorphous/nanocrystalline alloy is a new kind of soft magnetic material that has been widely used for several years. This alloy is mainly composed of ferromagnetic metals (e.g., Fe, Co, and Ni), metalloid elements (e.g., B, Si, and P), transition metal elements (e.g., Zr, Nb, and Hf) and nanocrystalline forming elements (e.g., Cu, and Ag). However, the amorphous/nanocrystalline alloy without transition metal elements has considerable advantages, the most obvious of which are its excellent soft magnetic properties and low cost. Three kinds of common commercial soft magnetic alloys, namely, Finemet (FeSiBNbCu) [1], Nanoperm (FeZrBCu) [2], and Hitperm (FeCoZrBCu) [3], contain more or less transition metal elements, such as Nb and Zr, which greatly increases the alloys’ cost. Since 2009, the FeSiBPCu series alloy without transition metal elements has been greatly developed. Named Nanomet, the alloy is the fourth kind of nanocrystalline soft magnetic alloy [4–6]. Nanomet has become a potential soft magnetic material of the future because of its high saturation magnetic flux density (Bs > 1.8 T), low coercive force (Hc < 10 A/m), and low cost. Among metalloid elements, B, as an amorphous forming element, plays an important role in Fe-metalloid amorphous alloys. Si can effectively expand the optimum annealing temperature range and reduce the annealing temperature sensitivity of soft magnetic properties. The addition of P can improve the ability of amorphous formation and
⁎
effectively suppress the bcc-Fe grain growth in Fe-based nanocrystalline alloys because of its small diffusibility [7,8]. Compared with B, P is cheaper, which can reduce the cost. During preparation, P can reduce the energy loss in the alloy melting because of its low melting point. However, excessive P-containing alloys are likely to oxidize during melting and narrow the annealing temperature range, resulting in high requirements for vacuum and temperature uniformity during annealing [9,10]. Previous research [11] shows the influence of different Co content on the glass formation and soft magnetic properties of FeSiBPCu alloy. When the Co content is in the 0 − 10 at.% range, the alloy displays a completely amorphous structure, and its saturation magnetization (Ms) and coercive force (Hc) can reach 181–194 Am2/kg and 10.2–12.3 A/m, respectively, in the as-quenched state. In the present study, the minormetalloid substitution for Fe on the glass formation and magnetic properties of Fe–Co–Si–B–P–Cu alloy are investigated on the basis of the previous Co-containing alloy. 2. Experimental procedure Multicomponent alloy ingots with nominal compositions of Fe78.8 Co6Si4B8P2.5Cu0.7, Fe78.3Co6Si4B8P3Cu0.7, Fe78.3Co6Si4B8.5P2.5Cu0.7, and Fe78.3Co6Si4.5B8P2.5Cu0.7 were cast using high-purity Fe, Co, Si, Cu and pre-alloy of Fe-17.9%B and Fe-25%P under argon atmosphere. The
Corresponding authors. E-mail addresses: [email protected] (W. Li), [email protected] (C.X. Xie).
https://doi.org/10.1016/j.jnoncrysol.2020.119937 Received 6 November 2019; Received in revised form 8 January 2020; Accepted 15 January 2020 0022-3093/ © 2020 Elsevier B.V. All rights reserved.
Journal of Non-Crystalline Solids 533 (2020) 119937
W. Li, et al.
Fig. 2. SEM EDX spectra of Fe, Co, Si, B, P, and Cu elements for the as-quenched (b) Fe78.3Co6Si4B8.5P2.5Cu0.7, (c) (a) Fe78.3Co6Si4B8P3Cu0.7, Fe78.3Co6Si4.5B8P2.5Cu0.7 amorphous alloys. Fig. 1. XRD patterns of the different FeCoSiBPCu melt-spun ribbons.
ribbons of 1.0−1.5 mm in width and 0.025−0.03 mm in thickness were rapidly solidified on a single rotating copper wheel. In order to reduce the oxidation, all the annealing was carried out under vacuum (~10 Pa) in a quartz tube applying a heating rate of 10 K/s. Phase identification was carried out using X-ray diffraction (XRD, D/Max-IIA) with Cu Kα radiation. The detailed distribution of elements in melt-spun amorphous samples was studied by scanning electron microscope-energy dispersive X-ray spectroscopy (SEM-EDX). Thermal properties associated with crystallization events were analyzed by differential scanning calorimeter (DSC, SDT Q600). Ms under an applied field of 1000 kA/m was measured using vibrating sample magnetometer (VSM, WK-II) at room temperature. Hc under a maximum applied field of 800 A/m was evaluated by soft magnetic DC B − H loop analyzer.
Fig. 3. DSC curves of FeCoSiBPCu melt-spun ribbons.
3. Results and discussion
alloys exhibit minimal change, while the first exothermic peak moves to the high temperature region as a whole. The results show that a 0.5 at. % increase of metalloid content mainly affects the precipitation of α−(Fe, Co) phase but has no significant effect on the precipitation of the Fe−(B, P) phase. Notably, the first exothermic peak temperature of FS alloy increases by approximately 49 K to the high temperature zone when 0.5 at.% Si is added, and the offset temperature is the most obvious. The temperature interval (∆T = Tx2−Tx1) between the characteristic temperature Tx1 and Tx2 is wide, reaching 121−179 K. During annealing, the large ∆T can effectively control the precipitation of α−Fe in the amorphous precursor, allowing the easy formation of single α−(Fe, Co) nanocrystalline structure and optimizing the soft magnetic properties [14,15]. The variation of Tx1, Tx2, and ∆T value with alloy composition is plotted in Fig. 4. Compared with the FF alloy, the change of Tx1 is obvious with the composition of the 0.5 at.% metalloids, whereas Tx2 shows slight changes. Fig. 5 presents the magnetic hysteresis loop (M–H) curves of the FeCoSiBPCu alloys. Nonlinear changes can be observed, and all hysteresis loops show typical soft magnetic behavior. The variation in Ms value clearly depends on the type of metalloid substitution. Fig. 6 shows the dependences of Ms and Hc on 0.5 at.% metalloid content for the FP, FB, and FS melt-spun ribbons. Among the three amorphous alloys, the Ms of FP alloy is the highest, reaching 184 Am2/kg, followed by the Ms of FB alloy, which reaches 171 Am2/kg. Finally, FS alloy and Ms are equal to 161 Am2/kg. This result shows that the change of 0.5% metalloid content has a great influence on Ms. By contrast, the addition of 0.5% metalloid to P and B is advantageous for Ms. For Hc, FB alloy has
Fig. 1 depicts XRD patterns for Fe78.8Co6Si4B8P2.5Cu0.7, Fe78.3Co6Si4 B8P3Cu0.7, Fe78.3Co6Si4B8.5P2.5Cu0.7, and Fe78.3Co6Si4.5B8P2.5Cu0.7 (hereafter denoted as FF, FP, FB, and FS, respectively) alloys in the asquenched state with varying metalloid content. Notably, sharp diffraction peaks corresponding to the α–(Fe, Co) phase appear in the XRD spectra. Partial crystallization clearly occurs during preparation. When 0.5 at.% Fe is substituted by P, B or Si metalloids, typical broad amorphous halos appear near 2θ = 44.8° on the XRD spectra of FP, FB, and FS alloys, demonstrating their fully amorphous structures. The XRD results reveal that the minor substitution of metalloids (i.e., B, P, Si) with Fe improves the glass-forming ability of the present Fe–Co–Si–B–P–Cu alloy system. To check the homogeneous mixing of all elements during preparation and eliminate the influence of defects, such as segregation of components and element enrichment on the magnetic properties, the three fully amorphous samples are measured by SEMEDX spectra. The SEM-EDX spectra in Fig. 2 show that the chemical compositions of the FP, FB, and FS alloys are almost homogeneous. Fig. 3 displays the DSC curves of FF, FP, FB, and FS melt-spun ribbons. Two exothermic peaks occur for all the samples during heating, indicating the existence of two-stage crystallization that corresponds to the precipitation of the α–(Fe, Co) phase and Fe−(B, P) compounds [12,13]. Through the following annealing experiments, we find that the α–(Fe, Co) and Fe3(B, P) phases precipitate in the first and second exothermic peaks of the three amorphous alloys. The thermal characteristic temperatures of the FeCoSiBPCu alloys, such as the first and second crystallization onset and peak temperatures, are labeled as Tx1, Tx2, Tp1, and Tp2. Tx2 and Tp2 of these four 2
Journal of Non-Crystalline Solids 533 (2020) 119937
W. Li, et al.
Fig. 4. Variation of Tx1, Tx2, and ∆T values with alloy composition.
Fig. 5. M–H curves of the fully amorphous Fe−Si−B−P−Cu ribbons in the asquenched state.
Fig. 7. XRD patterns of amorphous alloys annealed at 613−833 K for 10 min: (a) Fe78.3Co6Si4B8P3Cu0.7, (b) Fe78.3Co6Si4B8.5P2.5Cu0.7, (c) Fe78.3Co6Si4.5B8P2.5 Cu0.7 (AQ represents as-quenched state).
properties in the as-quenched state, with an Ms and Hc of 171 Am2/kg and 5.1 A/m, respectively. Fig. 7 depicts the XRD patterns for the FP, FB, and FS ribbons annealed at 613−833 K for 10 min. After annealing at 613 K and before, the FP and FB alloys maintain amorphous structure, and structural relaxation may occur in its interior. For FS alloys, the annealing temperature can last up to 673 K. Once the annealing temperature reaches near Tx1, a single α–(Fe, Co) phase begins to precipitate and grow gradually. When the annealing temperature increases to 753−793 K, new crystallization peaks begin to appear, and a small amount of Fe−(B, P) compounds begin to precipitate. When the annealing temperature continues to rise, the multiphase precipitates and grows up. To explain well the crystallization of the annealed ribbons in this study, the corresponding microstructure schematics are illustrated in Fig. 8. The difference of characteristic temperature between the FP and FB alloys is small, and the crystallization of the two alloys is similar.
Fig. 6. Dependences of Ms and Hc on the component for Fe−Si−B−P−Cu melt-spun ribbons.
the lowest value, reaching 5.1 A/m. FP alloy displays the highest value of 12.5 A/m. Although the increase of 0.5 at.% P obtained a high Ms, it also deteriorated Hc. In conclusion, FB alloy has the best soft magnetic 3
Journal of Non-Crystalline Solids 533 (2020) 119937
W. Li, et al.
precipitation of the hard magnetic phase Fe−(B, P) compounds and the obvious exchange coupling between the soft-magnetic phase α−(Fe, Co) grain and the hard-magnetic phase Fe3(B, P) grain, thereby reducing the effective anisotropy and Hc. The characteristic temperature of FS alloy is different from those of FP and FB alloys, Thus, to observe the magnetic properties of the three amorphous components after annealing near the characteristic temperature point, the Ms and Hc of the three alloys after annealing near Tx1 and Tx2, respectively, are compared, as shown in Figs 10(a) and (b). As shown in Fig. 10(a), the Ms of FP alloy keeps the highest value at the three annealing temperatures of Tx1, Tx2- (i.e., is the temperature point slightly lower than Tx1), and Tx2+ (i.e., the temperature point slightly higher than Tx2). Moreover, the Ms of all three alloys has the highest value when annealed at Tx2+. However, as shown in Fig. 10(b), the difference of Hc among the three alloys is obvious. When Ta = Tx1, the Hc of FS alloy is the lowest at 35.2 A/m; when Ta = Tx2-, the Hc of FP alloy is the lowest at 9.3 A/m; and when Ta = Tx2+, the Hc of FB alloy is the lowest at 3.5 A/m. For different annealing temperatures in the range of 613−833 K, the Hc of the three alloys is always the lowest value at Ta = Tx2+ (833 K). Here, the Hc of FP, FB and FS are 8.4, 3.5, and 5.9 A/m, respectively. In general, the soft magnetic properties of the three alloys are the best when annealed at Ta = Tx2+ (833 K), while the FB alloy has the best soft magnetic properties, with Ms and Hc at 208 Am2/kg and 3.5 A/m, respectively.
Fig. 8. Crystallization and the corresponding microstructure schematics of the FP, FB, and FS ribbons at different annealing temperatures.
The crystallization of FS alloy lags behind that of the first two alloys. This condition indicates that the amorphous precursors of these alloys have good thermal stability, ensuring that the pre-existing α–(Fe, Co) nuclei is stable and does not precipitate at the annealing temperature before Tx1. Fig. 9 reveals the annealing temperature-dependent behavior of Ms and Hc in the FP, FB, and FS amorphous ribbons. With the increase in annealing temperature from as-quenched state to 833 K, the Ms of FP and FB alloys improves significantly from the 184 and 171 Am2/kg to 215 and 208 Am2/kg, respectively. In FS alloy, the Ms is 161 Am2/kg in the as-quenched state. After a downward trend at the annealing temperature of 673−753 K, the Ms rapidly rises to 192 Am2/kg at 833 K. The continuous growth of Ms may be due to the precipitation of the α–(Fe, Co) phase throughout the annealing process. However, in the annealing temperature range of 613−833 K, Hc of the three alloys generally increases, and when the annealing temperature approaches Tx2, Hc begins to decrease rapidly. This result is due to the gradual
4. Conclusion We investigated the minor-metalloid substitution for Fe on glass formation and magnetic properties of Fe–Co–Si–B–P–Cu alloys. From the results, the following conclusions were drawn: 1) The 0.5 at.% metalloid (B, P, Si) substitution for Fe can form a fully amorphous state in the Fe78.8Co6Si4B8P2.5Cu0.7 alloy. 2) Fe78.3Co6Si4B8P3Cu0.7, Fe78.3Co6Si4B8.5P2.5Cu0.7, and Fe78.3Co6 Si4.5B8P2.5Cu0.7 show a wide temperature interval ∆T of 121−179 K. The minor-metalloid substitution for Fe delays the precipitation of the α-Fe phase and improves the thermal stability of the alloy.
Fig. 9. Dependences of Ms and Hc on the annealing temperature of the ribbons annealed for 10 min.
4
Journal of Non-Crystalline Solids 533 (2020) 119937
W. Li, et al.
Fig. 10. Ms and Hc of the three alloys after annealing near Tx1 and Tx2. (Note: Ta is the annealing temperature).
3) The 0.5 at.% B substitution for Fe is the most beneficial to the improvement of soft magnetic properties. The as-cast Ms and Hc of the Fe78.3Co6Si4B8.5P2.5Cu0.7 alloy are 171 Am2/kg and 5.1 A/m respectively. After annealing at 833 K for 10 min, Ms and Hc of the alloy can reach 208 Am2/kg and 3.5 A/m, respectively.
References [1] Y. Yoshizawa, S. Oguma, K. Yamauchi, New Fe-based soft magnetic alloys composed of ultrafine grain structure, J. Appl. Phys. 64 (1988) 6044–6046. [2] K. Suzuki, N. Kataoka, A. Inoue, et al., High saturation magnetization and soft magnetic properties of bcc Fe–Zr–B alloys with ultrafine grain structure, Mater. Trans. JIM 31 (1990) 743–746. [3] M.A. Willard, D.E. Laughlin, M.E. McHenry, et al., Structure and magnetic properties of (Fe0.5Co0.5)88Zr7B4Cu1 nanocrystalline alloys, J. Appl. Phys. 84 (1998) 6773–6777. [4] A. Makino, H. Men, T. Kubota, et al., New excellent soft magnetic FeSiBPCu nanocrystallized alloys with high Bs of 1.9 T from nanohetero-amorphous phase, IEEE T. Magn. 45 (2009) 4302–4305. [5] A.D. Setyawan, K. Takenaka, P. Sharma, et al., Magnetic properties of 120-mm wide ribbons of high Bs and low core-loss NANOMET® alloy, J. Appl. Phys. 117 (2015) 17B715. [6] X. Fan, T. Zhang, M. Jiang, et al., Synthesis of novel FeSiBPCCu alloys with high amorphous forming ability and good soft magnetic properties, J. Non-Cryst. Solids 503 (2019) 36–43. [7] Y. Wang, Y. Zhang, A. Takeuchi, et al., Investigation on the crystallization mechanism difference between FINEMET® and NANOMET® type Fe-based soft magnetic amorphous alloys, J. Appl. Phys. 120 (2016) 145102. [8] L. Jiang, Y. Zhang, X. Tong, et al., Unique influence of heating rate on the magnetic softness of Fe81.5Si0.5B4.5P11Cu0.5C2 nanocrystalline alloy, J. Magn. Magn. Mater. 471 (2019) 148–152. [9] Z. Zhang, P. Sharma, A. Makino, Role of Si in high Bs and low core-loss Fe85.2B10−xP4Cu0.8Six nano-crystalline alloys, J. Appl. Phys. 112 (2012) 103902. [10] F.G. Chen, Y.G. Wang, Investigation of glass forming ability, thermal stability and soft magnetic properties of melt-spun Fe83P16−xSixCu1 (x= 0, 1, 2, 3, 4, 5) alloy ribbons, J. Alloys Compd. 584 (2014) 377–380. [11] W. Li, C.X. Xie, C.L. Yao, et al., Amorphous formation and magnetic properties of Co-containing FeSiBPCu nanocrystalline alloys, J. Non-Cryst. Solids 505 (2019) 87–91. [12] A. Urata, M. Yamaki, K. Satake, et al., Magnetic properties and structure of Fe83.3–85.8B7.0–4.5P9Cu0.7 nanocrystalline alloys, J. Appl. Phys. 113 (2013) 17A311. [13] X.B. Zhai, Y.G. Wang, L. Zhu, et al., Effect of heating rate on atom migration, phase structure and magnetic properties of the Fe82Si2B11P4Cu1 alloy, J. Non-Cryst. Solids 499 (2018) 337–343. [14] K. Hono, D.H. Ping, M. Ohnuma, et al., Cu clustering and Si partitioning in the early crystallization stage of an Fe73.5Si13.5B9Nb3Cu1 amorphous alloy, Acta Mater. 47 (1999) 997–1006. [15] L.H. Kong, R.R. Chen, T.T. Song, et al., Magnetic characterization of dual phase FeZrB soft magnetic alloy, J. Magn. Magn. Mater. 323 (2011) 3285–3289.
CRediT authorship contribution statement Wen Li: Conceptualization, Methodology, Software, Investigation, Writing - original draft. C.X. Xie: Validation, Formal analysis, Data curation. H.Y. Liu: Resources, Formal analysis. K.W. Wang: Resources, Writing - review & editing. Z.L. Liao: Resources, Software. Y.Z. Yang: Writing - review & editing, Supervision. Declaration of Competing Interest We declare that we have no financial and personal relationships with other people or organizations that can inappropriately influence our work, there is no professional or other personal interest of any nature or kind in any product, service and/or company that could be construed as influencing the position presented in, or the review of, the manuscript entitled “Minor-metalloid substitution for Fe on glass formation and soft magnetic properties of Fe–Co–Si–B–P–Cu alloys”. Acknowledgments This work was supported by National Natural Science Foundation of China (no. 51801025), Research start-up funds of DGUT(no. GC300502-49, GC300502-48), Research and Reform Project of Higher Education in Guangdong Province(no. E1201601) and Scientific Research Foundation of Advanced Talents (Innovation Team)(DGUT, No. KCYCXPT2016004).
5