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Improving soft magnetic properties in FINEMET-like alloys with Ga addition
Journal of Magnetism and Magnetic Materials 487 (2019) 165297
Contents lists available at ScienceDirect
Journal of Magnetism and Magnetic Materials journal homepage: www.elsevier.com/locate/jmmm
Research articles
Improving soft magnetic properties in FINEMET-like alloys with Ga addition a
a
b
a
a
c
Qianke Zhu , Zhe Chen , Shuling Zhang , Qiushu Li , Yong Jiang , Peixuan Wu , Kewei Zhang a b c
a,⁎
T
School of Materials Science and Engineering, Taiyuan University of Science and Technology, Taiyuan, China School of Material of Science and Engineering, North Minzu University, Yinchuan, China Guangdong Provincial Key Laboratory of Micro-nano Manufacturing Technology and Equipment, Guangdong University of Technology, Guangzhou, China
A R T I C LE I N FO
A B S T R A C T
Keywords: Annealing Coercivity Nanocrystalline Ga Nucleation sites Amorphous
The effect of partial substitution of Si by Ga on the microstructure and soft magnetic properties of FINEMET-like Fe73.5Si13.5−xNb3B9Cu1Gax (x = 0, 3, 6, 9, 12 at.%) alloys has been investigated. It was found that the primary crystallization of ribbons was gradually changed from α-Fe (Si) into α-Fe (Ga, Si) phase with the increase of Ga content. Besides, the Fe-Ga clusters were detected in the amorphous ribbon with x = 6, which could provide nucleation sites for the α-Fe (Ga, Si) phase. In such case, the crystallization temperature of the ribbons with Ga addition was lower than that of ribbon without Ga addition. For the ribbon with x = 6, the precipitation of Ga element was priority to that of Si, which leads to the ‘increase-decrease’ tendency for the changes of lattice parameter with the increase of annealing temperature. Meanwhile, compared to the α-Fe (Si) phase with enrichment of Si for x = 0 ribbon, the α-Fe (Ga, Si) phase with high Ga and low Si concentration for the x = 6 ribbon was obtained, together with fine grain size (11 nm) of α-Fe (Ga, Si) phase, resulting to the same low coercivity (0.24 A/m), higher saturation magnetization (1.37 T) and maximum permeability after annealed at 455 °C for 1 min.
1. Introduction FINEMET alloys, with excellent soft magnetic properties such as high maximum permeability μm and very low coercivity Hc [1,2], are one of the most promising substitute materials for silicon steel sheet to reduce loss in the field of transformers. The power electronic components and every area relating to industry also call for such nanocrystalline alloys to conserve energy. Unfortunately, the application of FINEMET alloys is restricted due to the relatively low saturation magnetization Bs (1.2 T) which leads to size increase of magnetic devices [3]. According to Hc ∝ D6 and Es = 3/2λsσ (where D is grain size, Es the stress anisotropy energy, λs the saturation magnetostrictive coefficient, σ the inner stress) [4,5], the magnetic softness of the alloy is related to vanishing magnetocrystalline anisotropy K1 due to nanocrystalline α-Fe (Si) grains and low effective λs that result from the balance between negative contribution of the crystallites (λcr) and positive contribution of residual amorphous matrix (λam) [6,7]. Low value of D can be obtained by facilitating the nucleation sites and restraining the grain growth. To achieve negative value of λcr, Si is enriched in the α-Fe phase [8], which, however, can significantly reduce the Fe atomic magnetic dipole moment [9] and thus the Bs. Considering the deterioration of Bs due to the existing of much α-Fe (Si) phase, exploring
new types of α-Fe (M) (where M is the additive element) phase is a future development trend. Many researches have been done to find new FINEMET-like alloys with high μm, Bs and low Hc, such as, alloying elements like Ge, Al, P and Co [10–13], adjusting atom percentage of Si, B and Cu [14–16]. But it was hard to obtain negative λcr value that could offset positive λam, which increases the Hc [17], or some elements addition decreased the Bs of alloys after annealed [18], such as Fe85Si2B8P4Cu1 alloy [14] with high Bs of 1.85 T but high λs of 2.3 × 10−6 and Hc of 5.8 A/m, (Fe,B,Cu,Nb)84.5Si9.5Ge6 alloy [19] with low Hc of 0.41 A/m but low Bs of 0.92 T, and so on. Thus, it is necessary to find a new way of vanishing λs and increasing the magnetic contribution of α-Fe (M) phase. Our former researches [20] have found that α-Fe (Ga) phase was formed in the Fe-Ga-B-Nb-Cu alloys and its grain size was refined by Ga addition which raised the nucleation rate. Meanwhile, it has been reported that Ga addition could enhance the magnetic moment of Fe [21,22] compared to Si addition [9,23]. Consequently, by means of partial substitution of Si by Ga, it is possible to obtain a new type of FINEMET-like alloy with high Bs and low Hc. In this work, Fe73.5Si13.5-xNb3B9Cu1Gax (x = 0, 3, 6, 9, 12 at.%) alloys have been fabricated and the influence of partial substitution of Si by Ga on the microstructure and soft magnetic properties of the new FINEMET-like alloys has been investigated.
⁎ Corresponding author at: School of Materials Science and Engineering, The Key Laboratory of Magnetic and Electric Functional Materials and Their Applications of Shanxi Province, Taiyuan University of Science and Technology, 030024 Taiyuan, China. E-mail address: [email protected] (K. Zhang).
https://doi.org/10.1016/j.jmmm.2019.165297 Received 21 March 2019; Received in revised form 24 April 2019; Accepted 11 May 2019 Available online 13 May 2019 0304-8853/ © 2019 Elsevier B.V. All rights reserved.
Journal of Magnetism and Magnetic Materials 487 (2019) 165297
Q. Zhu, et al.
2. Experimental procedure Fe73.5Si13.5-xNb3B9Cu1Gax (x = 0, 3, 6, 9, 12 at.%) ribbons were fabricated using the melt spinning technique with the wheel speed of 29.9 m/s. To achieve optimal soft magnetic properties, the samples were annealed at different temperatures (from 355 to 605 °C) for 1, 2 and 3 min under vacuum at a heating rate of 100 K/min. The structural evolution of the samples were inspected by X-ray diffraction (XRD) (MiniFlex 600) using Cu Kα radiation (λ = 1.5418 Å). The mean diameters, lattice parameter of crystal phase and the crystallized fraction of the annealed samples were estimated by XRD analysis. The thermal stability was followed by differential scanning calorimetry (DSC) using a Netzsch STA 449 F3 Jupiter® calorimeter at the heating rate of 35 ℃/min under N2 protection. Magnetic properties were measured with a dc B-H loop tracer (MATS-2010SD-K50), and the samples were straight ribbons with a dimension of 50 mm × 2 mm × 30 μm. The microstructure of the selected annealed ribbon was examined by transmission electronic microscopy (TEM, JEM 2100F).
Fig. 2. DSC curves of as-spun Fe73.5Si13.5−xNb3B9Cu1Gax (x = 0, 3, 6, 9, 12 at. %) ribbons.
with x = 0, 3, 6 and 9 ribbons, which correspond to the crystallization processes. For the ribbon with x = 0, the first exothermic peak Tp1 at 555 °C is identified as the crystallization process of α-Fe (Si) phase and followed by the crystallization (Tp2) of the residual amorphous phase, as is well known for the FINEMET alloy. With the Ga content increasing to 3 at.%, an extra exothermic peak Tp1′ appears at 455 °C, which will be identified later by XRD. It is interesting that Tp1 disappears and the peak for Tp1′ turns to be broader and more asymmetric when the Ga content increases to 6 and 9 at.%. Meanwhile, the value of Tp2 decreases with the increase of Ga content. Thus, the evolution of exothermic peaks with the gradual substitution of Si by Ga can be concluded as follows:
3. Results Fig. 1 shows the XRD patterns of as-spun Fe73.5Si13.5-xNb3B9Cu1Gax (x = 0, 3, 6, 9, 12 at.%) ribbons. It can be seen from Fig. 1a that the ribbons with x = 0 and 6 consist only of a series of broad band feature without any detectable sharp peaks, meaning the fully amorphous structure of the alloys. The ribbons with x = 3, 9, and 12 exhibit obvious diffraction peaks overlapping in the amorphous phase, indicating the crystallization of the as-spun ribbons. To figure out the type of α-Fe phase, the XRD patterns of as-spun ribbons with x = 3, 9 and the annealed Fe81Nb3B15Cu1 ribbon [20] are shown in Fig. 1b. Comparing to the α-Fe phase in Fe81Nb3B15Cu1 ribbon, the diffraction peak position of x = 3 ribbon lies in higher value of 2θ, demonstrating the solubility of Si which diminishes the lattice parameter of α-Fe phase. With the gradual substitution of Si by Ga, the peak position of α-Fe phase shifts to lower value of 2θ, meaning the expanding of lattice parameter due to the increase of Ga concentration in α-Fe phase and the decrease of Si. Consequently, the crystal peaks in the ribbons with Ga addition turn out to be α-Fe (Ga, Si) phase, and the variation concentration of Si and Ga in the α-Fe (Ga, Si) phase corresponds to their content in ribbons. In Fig. 1c, the broad band for the as-spun ribbon with x = 6 slightly shifts to lower value of 2θ comparing to the x = 0 ribbon, indicating that the same Fe-Ga clusters are formed in the amorphous matrix, as in our previous report [20]. Fig. 2 displays the DSC curves acquired from as-spun Fe73.5Si13.5−xNb3B9Cu1Gax (x = 0, 3, 6, 9, 12 at.%) ribbons at the heating rate of 35 °C/min. There are exothermic peaks in the ribbons
Tp1 + Tp2 (x = 0) → Tp′ 1 + Tp1 + Tp2 (x = 3) → Tp′ 1 + Tp2 (x = 6 and 9) The endothermic peaks correspond to the melting of ribbons. With the increase of Ga content, the melting point and the liquidus temperature TL of ribbons increase, indicating that the substitution of Si by Ga diminishes the glass forming ability of the ribbons due to the decrease of reduced glass transition temperature Trg (Trg = Tg/TL) (where Tg is glass transition temperature). Thus, the as-spun ribbons with x = 9 and 12 is almost crystallized. It can be seen that the ribbon with x = 3 has a complicated broad melting process, which could diminish the glass forming ability due to the wide solid-liquid coexistence zone. That is why the microstructure of x = 3 ribbon is not complete amorphous. To seek the optimal annealing condition, the amorphous ribbons with x = 0 and 6 were annealed at different temperatures for 1, 2 and 3 min. The XRD patterns of annealed ribbons for 2 min are shown in Fig. 3, together with the mean diameters D (Fig. 3c1 and d1), crystallized fraction vcr (Fig. 3c2 and d2) and the lattice parameter a (Fig. 3c3
Fig. 1. XRD patterns of (a) as-spun Fe73.5Si13.5−xNb3B9Cu1Gax (x = 0, 3, 6, 9, 12 at.%) ribbons, (b) x = 3, 9 ribbons and Fe81Nb3B15Cu1 ribbon, (c) x = 0 and 6 ribbons. 2
Journal of Magnetism and Magnetic Materials 487 (2019) 165297
Q. Zhu, et al.
Fig. 3. XRD patterns of (a) x = 0 and (b) x = 6 ribbons that annealed for 2 min, and (c1, d1) mean diameters D, (c2, d2) crystallized fraction vcr and (c3, d3) the lattice parameter a of the annealed samples.
in x = 6 ribbon), D firstly increases at 2 min and then decreases at 3 min, and the vcr keeps increasing over annealing time, meaning that new crystal nucleus is formed with annealing time increasing from 2 to 3 min, which leads to the heterogeneity of grain size. As shown in Fig. 3d3, a of the annealed ribbon with x = 6 firstly increases and then decreases, indicating that the precipitation of Ga was priority to that of Si, since Ga has stronger driving force to partition into the α-Fe phase than Si. When the Ga element is exhausted, the precipitation of Si occurs and reduces a of α-Fe (Ga, Si) phase. In other words, the substitution of Si by Ga can suppress the partition of Si into α-Fe phase, which results in the α-Fe (Ga, Si) phase with high Ga and low Si concentration. Eventually, the exothermic peak Tp1′ appearing at the DSC curves of as-spun ribbons with Ga addition is identified as the precipitation of α-Fe (Ga, Si) phase, and its broad and asymmetric feature can be explained as the long-range atomic rearrangements of Ga and Si elements which can inhibit the initial grain growth and thus further refine the nanocrystalline. Consequently, the evolution of crystallization processes with the gradual substitution of Si by Ga can be concluded as follows:
and d3) of the precipitated nanocrystallites in the ribbons. It can be seen that the ribbon with x = 0 is still amorphous after annealed at 455 ℃ for 2 min. With the increase of annealing temperature, the ribbon starts to crystallize, and the D and vcr increase, except for D of ribbon annealed for 2 min which shows a ‘V’ curve tendency. Meanwhile, a decreases at 505 °C and then keeps almost constant, by which the nanocrystalline is identified as α-Fe (Si) and Fe3Si. Clearly, massive Si precipitates from the amorphous matrix and dissolves into the α-Fe phase once the crystallization occurs. The ribbon with x = 6 crystallizes at 355 °C, and vcr increases with rising annealing temperature. D of annealed x = 6 ribbon firstly decreases and then increases with rising annealing temperature, except for that of ribbon annealed for 3 min which presents a variation tendency of ‘increase-decrease-increase’. The minimum D of x = 6 ribbon is obtained while D of x = 0 ribbon keeps increasing. This could be attributed to the formation of Fe-Ga clusters which provide adequate nucleation sites for the precipitation of α-Fe (Ga, Si) phase, which refines the nanocrystalline [20]. It is noteworthy that, when the annealing temperature is relatively low (505 °C in x = 0 ribbon and 355 ℃ 3
Journal of Magnetism and Magnetic Materials 487 (2019) 165297
Q. Zhu, et al.
Fig. 4. Soft magnetic properties of annealed ribbons with x = 0 and 6, including (a1,b1) Hc, (a2, b2) Bs and (a3, b3) μm. (c) Hysteresis loop of as-spun and annealed ribbons with optimal soft magnetic properties.
α − Fe (Si) + Fe3 Si + Fe − B compounds (x = 0)
induce the internal stress between crystallites and residual amorphous matrix, which hinders the motion of magnetic domain walls, leading to the decrease of μm. That is why the trend of the change of the μm is opposite to that of Hc, since Hc is also relates to the λs. For the ribbon with x = 6, the trends of Hc versus annealing temperature is the same as x = 0 ribbon. The Bs firstly increases due to the crystallization and the partition of Ga into α-Fe phase then decreases owning to the precipitation of Si and Fe-B compounds. It can be seen that the Bs of the ribbon with x = 6 is higher than that of x = 0 ribbon at same vcr, indicating that Ga certainly improves the magnetic contribution of α-Fe (Ga, Si) phase. Finally, the change of μm present a complicated tendency, which is result from the variation of λs on the one hand, on the other hand, the positive effect of Bs on the μm can be confirmed since they have almost same varying tendency. Relatively low values of Hc of annealed ribbons, together with the Bs, μm, D, vcr and a, are listed in Table 1. For the x = 0 ribbon, after annealed at 505 °C for 1 and 2 min, low value of Hc is obtained due to the fine grains, but relatively low values of vcr and a lead to poor Bs,
→ α − Fe (Ga, Si) + α − Fe (Si) + Fe − B compounds (x = 3) → α − Fe (Ga, Si) + Fe − B compounds (x = 6 and 9) Fig. 4 displays the magnetic properties including Hc, Bs and μm. With the increase of annealing temperature, Hc of the ribbons with x = 0 firstly decrease due to the release of internal stress and the grain refining combining with optimal vcr, then increase as the result of the grain growth and the precipitation of Fe3Si and Fe-B compounds, except for that of ribbon annealed for 3 min, which increases at 455 °C owing to the heterogeneity of grain size as discussed above. The Bs of x = 0 ribbon firstly decreases due to the structure relaxation and the formation of α-Fe (Si), then increases as the result of high value of vcr, and finally decreases owing to the precipitation of Fe3Si and Fe-B compounds. The changes of μm present a tendency of ‘decrease-increasedecrease’ which reflects the balance between negative λcr value and positive λam value to a certain extent. Because high value of λs will 4
Journal of Magnetism and Magnetic Materials 487 (2019) 165297
Q. Zhu, et al.
Table 1 Soft magnetic and microstructure properties of annealed ribbons with low value of Hc. The published data in literatures is also listed for comparison. Alloys
Hc (A/m)
Bs (T)
μm (×103)
D (nm)
vcr (%)
a (nm)
x = 0 an. 505 °C, 1 min x = 0 an. 505 °C, 2 min x = 0 an. 555 °C, 2 min x = 6 an. 405 °C, 2 min x = 6 an. 455 °C, 1 min Fe85Si2B8P4Cu1 [14] Fe81.3Si4B13Cu1.7 [16] Fe76Al4P12B4Si4 [24] FINEMET [2] (Fe,B,Cu,Nb)84.5Si9.5Ge6 [19]
0.22 0.23 0.25 0.22 0.24 5.8 7.1 2.6 0.53 0.41
1.16 1.20 1.23 1.35 1.37 1.85 1.77 1.24 1.24 0.92
18.1 12.3 16.9 22.8 25.3
11 12 12 10 11 < 25 14
39 46 67 54 67
0.28384 0.28391 0.28355 0.28750 0.28707
10
70–80
also be achieved by the new balance between λcr and λam. Meanwhile, the α-Fe (Ga, Si) phase with Ga enrichment can improve the Bs, and the Ga addition can facilitate the nucleation of α-Fe (Ga, Si) phase. Consequently, the annealed x = 6 ribbon with low Hc and higher Bs is obtained.
since Si significantly reduces the Fe atomic magnetic dipole moment [9,23]. Thus, optimal soft magnetic properties of x = 0 ribbon are achieved after annealed at 555 °C for 2 min, which is 0.25 A/m of Hc, 1.23 T of Bs and 16.9 × 103 of μm. For the ribbon with x = 6, the optimal Hc, Bs and μm are 0.24 A/m, 1.37 T and 25.3 × 103, respectively, which belongs to the ribbon annealed at 455 °C for 1 min. The ribbon annealed at 405 °C for 2 min also has excellent soft magnetic properties. In summary, the Bs of x = 6 ribbon is higher than that of x = 0 ribbon while the Hc stays nearly the same value. Moreover, the Ga addition significantly improves the μm. The improvements are shown in Fig. 4c by hysteresis loops. Table 1 also shows the published date in literatures for comparison. It can be seen that, to achieve low value of Hc, Fe usually is substituted by metalloid elements like Si and Ge for vanishing λs, which diminishes the Bs of FINEMET [2] and (Fe,B,Cu,Nb)84.5Si9.5Ge6 [19] alloys. However, for the x = 6 ribbon in this work, the substitution of 6 at.% Si by Ga can increase the Bs by 11.4% while the Hc stays the extremely low value compared to the FINEMET alloy. Thus, a new way of improving soft magnetic properties of FINEMET-like alloys can be obtained by Ga addition. In Fig. 5(a), the results of selected area diffraction pattern show that nanocrystals with size of 11 nm is confirmed in the x = 6 ribbon that annealed at 455 °C for 1 min. Moreover, one of the interplanar spacing d of (1 1 0) in α-Fe (Ga, Si) grain is detected, which is higher than that of pure α-Fe (0.2027 nm) due to Ga enrichment, as shown in Fig. 5(b). To explain the reason why the annealed ribbon with x = 6 exhibits such soft magnetic properties, the discussion about its λs is given as follows. In FINEMET alloys, the low value of λs is due to the balance between negative λcr and positive λam, as shown in Fig. 6. To obtain negative λcr, the concentration of Si in the α-Fe phase is higher than that in the remaining amorphous matrix, which decreases the Bs to a certain extent. In this work, for the FINEMET-like alloy with partial substation of Si by Ga, the precipitation of Ga can suppress the partition of Si into α-Fe phase. Thus, it is believed that the α-Fe (Ga, Si) phase with Ga enrichment has positive λcr [25,26], and the remaining amorphous matrix with high ratio of Si/Fe has negative λam, which is opposite to that in FINEMET alloy. That is to say, low value of λs can
4. Conclusion The effect of partial substitution of Si by Ga on the microstructure and soft magnetic properties of FINEMET-like alloys has been studied. Several points are concluded as follows: During the primary crystallization, the precipitated phase changed from α-Fe (Si) into α-Fe (Ga, Si) with the gradual substitution of Si by Ga. Meanwhile, the Fe-Ga clusters were detected in the amorphous ribbon with x = 6, which could provide nucleation sites for the α-Fe (Ga, Si) phase. For the annealed ribbon with x = 6, the addition of Ga could suppress the partition of Si into α-Fe phase, and thus the α-Fe (Ga, Si) phase with high Ga and low Si concentration could be obtained at the optimal annealing condition. Compared to the FINEMET alloy, the substitution of 6 at.% Si by Ga can increase the Bs by 11.4 percent while the Hc stays nearly the same value. The optimal magnetic properties with coercivity of 0.24 A/m and saturation magnetization of 1.37 T were obtained in the ribbon with x = 6 after annealed at 455 °C for 1 min. Acknowledgements This work was supported by National Natural Science Foundation of China (No. 51731003), Talents Training Project of Shanxi Graduate Joint Training Base (No. 2018JD35), The Key Research and Development Program of Shanxi Province (No. 201803D421046), “131” Leading Talents Project of Higher Education Institutions in Shanxi (2015), Overseas Students Science and Technology Activities Project Merit Funding (2016).
Fig. 5. (a) Selected area diffraction pattern and (b) high-resolution transmission electron microscope images of the x = 6 ribbon that annealed at 455 °C for 1 min. 5
Journal of Magnetism and Magnetic Materials 487 (2019) 165297
Q. Zhu, et al.
Fig. 6. The distribution of magnetostrictive coefficient in the alloys.
References
[13] Y.R. Jia, Z. Wang, F. Wang, et al., Effect of P substitution for Nb on structure and soft magnetic properties of Si-rich FeCuNbSiB nanocrystalline alloys, Mater. Sci. Eng., B 222 (2017) 55–59. [14] Makino, Nanocrystalline soft magnetic Fe-Si-B-P-Cu alloys with high Bs of 1.8–1.9 T contributable to energy saving, IEEE Trans. Magn. 48 (4) (2012) 1331–1335. [15] J.A. Moya, Nanocrystals and amorphous matrix phase studies of Finemet-like alloys containing Ge, J. Magn. Magn. Mater. 322 (13) (2010) 1784–1792. [16] Y. Li, X. Jia, Y. Xu, et al., Soft magnetic Fe-Si-B-Cu nanocrystalline alloys with high Cu concentrations, J. Alloy. Compd. 722 (2017) 859–863. [17] J.A. Moya, Improving soft magnetic properties in FINEMET-like alloys. A study, J. Alloy. Compd. 622 (2015) 635–639. [18] R. Wang, J. Liu, C. Zeng, et al., Crystallization progress and soft magnetic properties of Finemet alloy with Ge addition, Vacuum 104 (2014) 88–91. [19] A. Saad, V. Cremaschi, H. Sirkin, Influence of Al and Ge additions on magnetic properties of Finemet type alloys, J. Metastable Nanocryst. Mater. 20–21 (2004) 717–724. [20] Z. Qianke, C. Zhe, Z. Shuling, et al., Crystallization progress and soft magnetic properties of FeGaBNbCu alloys, J. Magn. Magn. Mater. 475 (2019) 88–92. [21] K. Fukamichi, T. Satoh, T. Masumoto, Magnetic moment of Fe-Ga-B amorphous alloys, J. Magn. Magn. Mater. 31–34 (83) (1983) 1589–1590. [22] N. Kawamiya, K. Adachi, Y. Nakamura, Magnetic properties and Mössabauer investigations of Fe-Ga alloys, J. Phys. Soc. Jpn. 33 (5) (2007) 1318–1327. [23] B.W. Corb, Magnetic moments and coordination symmetry in bcc Fe-M alloys, Phys. Rev. B 31 (4) (1985) 2521–2523. [24] A. Inoue, Stabilization of metallic supercooled liquid and bulk amorphous alloys, Acta Mater. 48 (1) (2000) 279–306. [25] P. Taheri, R. Barua, J. Hsu, et al., Structure, magnetism, and magnetostrictive properties of mechanically alloyed Fe81Ga19, J. Alloy. Compd. 661 (1) (2016) 306–311. [26] I.S. Golovin, Anelasticity of Fe-Ga based alloys, Mater. Des. 88 (2015) 577–587.
[1] G. Herzer, Magnetization process in nanocrystalline ferromagnets, Mater. Sci. Eng., A 133 (1) (1991) 1–5. [2] Y. Yoshizawa, S. Oguma, K. Yamauchi, New Fe-based soft magnetic alloys composed of ultrafine grain structure, J. Appl. Phys. 64 (10) (1988) 6044. [3] G. Herzer, Soft-magnetic nanocrystalline materials, Scr. Metall. Mater. 33 (10–11) (1995) 1741–1756. [4] Z. Qianke, C. Zhe, Z. Shuling, et al., Microstructure and magnetic properties of Fe79xB20NbxCu1 fibers with annealing, Vacuum 154 (2018) 154–158. [5] G. Herzer, Grain size dependence of coercivity and permeability in nanocrystalline ferromagnets, IEEE Trans. Magn. 26 (5) (2002) 1397–1402. [6] T. Gheiratmand, H.R.M. Hosseini, P. Davami, et al., The effect of mechanical milling on the soft magnetic properties of amorphous FINEMET alloy, J. Magn. Magn. Mater. 381 (2015) 322–327. [7] T. Kulik, G. Vlasák, R. Ẑuberek, Correlation between microstructure and magnetic properties of amorphous and nanocrystalline Fe73.5Cu1Nb3Si16.5B6, Mater. Sci. Eng., A 226–228 (1997) 701–705. [8] 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 (3) (1999) 997–1006. [9] H. Okumura, D.E. Laughlin, M.E. Mchenry, Magnetic and structural properties and crystallization behavior of Si-rich FINEMET materials, J. Magn. Magn. Mater. 267 (3) (2003) 347–356. [10] D. Muraca, V. Cremaschi, J. Moya, et al., FINEMET type alloy without Si: structural and magnetic properties, J. Magn. Magn. Mater. 320 (9) (2008) 1639–1644. [11] V. Cremaschi, A. Saad, J. Moya, et al., Evolution of magnetic, structural and mechanical properties in FeSiBNbCuAlGe system, Phys. B 320 (1–4) (2002) 281–284. [12] C. GómezPolo, P. Marín, L. Pascual, et al., Structural and magnetic properties of nanocrystalline Fe73.5-xCoxSi13.5B9CuNb3 alloys, Phys. Rev. B 65 (2) (2001) -.
6
Contents lists available at ScienceDirect
Journal of Magnetism and Magnetic Materials journal homepage: www.elsevier.com/locate/jmmm
Research articles
Improving soft magnetic properties in FINEMET-like alloys with Ga addition a
a
b
a
a
c
Qianke Zhu , Zhe Chen , Shuling Zhang , Qiushu Li , Yong Jiang , Peixuan Wu , Kewei Zhang a b c
a,⁎
T
School of Materials Science and Engineering, Taiyuan University of Science and Technology, Taiyuan, China School of Material of Science and Engineering, North Minzu University, Yinchuan, China Guangdong Provincial Key Laboratory of Micro-nano Manufacturing Technology and Equipment, Guangdong University of Technology, Guangzhou, China
A R T I C LE I N FO
A B S T R A C T
Keywords: Annealing Coercivity Nanocrystalline Ga Nucleation sites Amorphous
The effect of partial substitution of Si by Ga on the microstructure and soft magnetic properties of FINEMET-like Fe73.5Si13.5−xNb3B9Cu1Gax (x = 0, 3, 6, 9, 12 at.%) alloys has been investigated. It was found that the primary crystallization of ribbons was gradually changed from α-Fe (Si) into α-Fe (Ga, Si) phase with the increase of Ga content. Besides, the Fe-Ga clusters were detected in the amorphous ribbon with x = 6, which could provide nucleation sites for the α-Fe (Ga, Si) phase. In such case, the crystallization temperature of the ribbons with Ga addition was lower than that of ribbon without Ga addition. For the ribbon with x = 6, the precipitation of Ga element was priority to that of Si, which leads to the ‘increase-decrease’ tendency for the changes of lattice parameter with the increase of annealing temperature. Meanwhile, compared to the α-Fe (Si) phase with enrichment of Si for x = 0 ribbon, the α-Fe (Ga, Si) phase with high Ga and low Si concentration for the x = 6 ribbon was obtained, together with fine grain size (11 nm) of α-Fe (Ga, Si) phase, resulting to the same low coercivity (0.24 A/m), higher saturation magnetization (1.37 T) and maximum permeability after annealed at 455 °C for 1 min.
1. Introduction FINEMET alloys, with excellent soft magnetic properties such as high maximum permeability μm and very low coercivity Hc [1,2], are one of the most promising substitute materials for silicon steel sheet to reduce loss in the field of transformers. The power electronic components and every area relating to industry also call for such nanocrystalline alloys to conserve energy. Unfortunately, the application of FINEMET alloys is restricted due to the relatively low saturation magnetization Bs (1.2 T) which leads to size increase of magnetic devices [3]. According to Hc ∝ D6 and Es = 3/2λsσ (where D is grain size, Es the stress anisotropy energy, λs the saturation magnetostrictive coefficient, σ the inner stress) [4,5], the magnetic softness of the alloy is related to vanishing magnetocrystalline anisotropy K1 due to nanocrystalline α-Fe (Si) grains and low effective λs that result from the balance between negative contribution of the crystallites (λcr) and positive contribution of residual amorphous matrix (λam) [6,7]. Low value of D can be obtained by facilitating the nucleation sites and restraining the grain growth. To achieve negative value of λcr, Si is enriched in the α-Fe phase [8], which, however, can significantly reduce the Fe atomic magnetic dipole moment [9] and thus the Bs. Considering the deterioration of Bs due to the existing of much α-Fe (Si) phase, exploring
new types of α-Fe (M) (where M is the additive element) phase is a future development trend. Many researches have been done to find new FINEMET-like alloys with high μm, Bs and low Hc, such as, alloying elements like Ge, Al, P and Co [10–13], adjusting atom percentage of Si, B and Cu [14–16]. But it was hard to obtain negative λcr value that could offset positive λam, which increases the Hc [17], or some elements addition decreased the Bs of alloys after annealed [18], such as Fe85Si2B8P4Cu1 alloy [14] with high Bs of 1.85 T but high λs of 2.3 × 10−6 and Hc of 5.8 A/m, (Fe,B,Cu,Nb)84.5Si9.5Ge6 alloy [19] with low Hc of 0.41 A/m but low Bs of 0.92 T, and so on. Thus, it is necessary to find a new way of vanishing λs and increasing the magnetic contribution of α-Fe (M) phase. Our former researches [20] have found that α-Fe (Ga) phase was formed in the Fe-Ga-B-Nb-Cu alloys and its grain size was refined by Ga addition which raised the nucleation rate. Meanwhile, it has been reported that Ga addition could enhance the magnetic moment of Fe [21,22] compared to Si addition [9,23]. Consequently, by means of partial substitution of Si by Ga, it is possible to obtain a new type of FINEMET-like alloy with high Bs and low Hc. In this work, Fe73.5Si13.5-xNb3B9Cu1Gax (x = 0, 3, 6, 9, 12 at.%) alloys have been fabricated and the influence of partial substitution of Si by Ga on the microstructure and soft magnetic properties of the new FINEMET-like alloys has been investigated.
⁎ Corresponding author at: School of Materials Science and Engineering, The Key Laboratory of Magnetic and Electric Functional Materials and Their Applications of Shanxi Province, Taiyuan University of Science and Technology, 030024 Taiyuan, China. E-mail address: [email protected] (K. Zhang).
https://doi.org/10.1016/j.jmmm.2019.165297 Received 21 March 2019; Received in revised form 24 April 2019; Accepted 11 May 2019 Available online 13 May 2019 0304-8853/ © 2019 Elsevier B.V. All rights reserved.
Journal of Magnetism and Magnetic Materials 487 (2019) 165297
Q. Zhu, et al.
2. Experimental procedure Fe73.5Si13.5-xNb3B9Cu1Gax (x = 0, 3, 6, 9, 12 at.%) ribbons were fabricated using the melt spinning technique with the wheel speed of 29.9 m/s. To achieve optimal soft magnetic properties, the samples were annealed at different temperatures (from 355 to 605 °C) for 1, 2 and 3 min under vacuum at a heating rate of 100 K/min. The structural evolution of the samples were inspected by X-ray diffraction (XRD) (MiniFlex 600) using Cu Kα radiation (λ = 1.5418 Å). The mean diameters, lattice parameter of crystal phase and the crystallized fraction of the annealed samples were estimated by XRD analysis. The thermal stability was followed by differential scanning calorimetry (DSC) using a Netzsch STA 449 F3 Jupiter® calorimeter at the heating rate of 35 ℃/min under N2 protection. Magnetic properties were measured with a dc B-H loop tracer (MATS-2010SD-K50), and the samples were straight ribbons with a dimension of 50 mm × 2 mm × 30 μm. The microstructure of the selected annealed ribbon was examined by transmission electronic microscopy (TEM, JEM 2100F).
Fig. 2. DSC curves of as-spun Fe73.5Si13.5−xNb3B9Cu1Gax (x = 0, 3, 6, 9, 12 at. %) ribbons.
with x = 0, 3, 6 and 9 ribbons, which correspond to the crystallization processes. For the ribbon with x = 0, the first exothermic peak Tp1 at 555 °C is identified as the crystallization process of α-Fe (Si) phase and followed by the crystallization (Tp2) of the residual amorphous phase, as is well known for the FINEMET alloy. With the Ga content increasing to 3 at.%, an extra exothermic peak Tp1′ appears at 455 °C, which will be identified later by XRD. It is interesting that Tp1 disappears and the peak for Tp1′ turns to be broader and more asymmetric when the Ga content increases to 6 and 9 at.%. Meanwhile, the value of Tp2 decreases with the increase of Ga content. Thus, the evolution of exothermic peaks with the gradual substitution of Si by Ga can be concluded as follows:
3. Results Fig. 1 shows the XRD patterns of as-spun Fe73.5Si13.5-xNb3B9Cu1Gax (x = 0, 3, 6, 9, 12 at.%) ribbons. It can be seen from Fig. 1a that the ribbons with x = 0 and 6 consist only of a series of broad band feature without any detectable sharp peaks, meaning the fully amorphous structure of the alloys. The ribbons with x = 3, 9, and 12 exhibit obvious diffraction peaks overlapping in the amorphous phase, indicating the crystallization of the as-spun ribbons. To figure out the type of α-Fe phase, the XRD patterns of as-spun ribbons with x = 3, 9 and the annealed Fe81Nb3B15Cu1 ribbon [20] are shown in Fig. 1b. Comparing to the α-Fe phase in Fe81Nb3B15Cu1 ribbon, the diffraction peak position of x = 3 ribbon lies in higher value of 2θ, demonstrating the solubility of Si which diminishes the lattice parameter of α-Fe phase. With the gradual substitution of Si by Ga, the peak position of α-Fe phase shifts to lower value of 2θ, meaning the expanding of lattice parameter due to the increase of Ga concentration in α-Fe phase and the decrease of Si. Consequently, the crystal peaks in the ribbons with Ga addition turn out to be α-Fe (Ga, Si) phase, and the variation concentration of Si and Ga in the α-Fe (Ga, Si) phase corresponds to their content in ribbons. In Fig. 1c, the broad band for the as-spun ribbon with x = 6 slightly shifts to lower value of 2θ comparing to the x = 0 ribbon, indicating that the same Fe-Ga clusters are formed in the amorphous matrix, as in our previous report [20]. Fig. 2 displays the DSC curves acquired from as-spun Fe73.5Si13.5−xNb3B9Cu1Gax (x = 0, 3, 6, 9, 12 at.%) ribbons at the heating rate of 35 °C/min. There are exothermic peaks in the ribbons
Tp1 + Tp2 (x = 0) → Tp′ 1 + Tp1 + Tp2 (x = 3) → Tp′ 1 + Tp2 (x = 6 and 9) The endothermic peaks correspond to the melting of ribbons. With the increase of Ga content, the melting point and the liquidus temperature TL of ribbons increase, indicating that the substitution of Si by Ga diminishes the glass forming ability of the ribbons due to the decrease of reduced glass transition temperature Trg (Trg = Tg/TL) (where Tg is glass transition temperature). Thus, the as-spun ribbons with x = 9 and 12 is almost crystallized. It can be seen that the ribbon with x = 3 has a complicated broad melting process, which could diminish the glass forming ability due to the wide solid-liquid coexistence zone. That is why the microstructure of x = 3 ribbon is not complete amorphous. To seek the optimal annealing condition, the amorphous ribbons with x = 0 and 6 were annealed at different temperatures for 1, 2 and 3 min. The XRD patterns of annealed ribbons for 2 min are shown in Fig. 3, together with the mean diameters D (Fig. 3c1 and d1), crystallized fraction vcr (Fig. 3c2 and d2) and the lattice parameter a (Fig. 3c3
Fig. 1. XRD patterns of (a) as-spun Fe73.5Si13.5−xNb3B9Cu1Gax (x = 0, 3, 6, 9, 12 at.%) ribbons, (b) x = 3, 9 ribbons and Fe81Nb3B15Cu1 ribbon, (c) x = 0 and 6 ribbons. 2
Journal of Magnetism and Magnetic Materials 487 (2019) 165297
Q. Zhu, et al.
Fig. 3. XRD patterns of (a) x = 0 and (b) x = 6 ribbons that annealed for 2 min, and (c1, d1) mean diameters D, (c2, d2) crystallized fraction vcr and (c3, d3) the lattice parameter a of the annealed samples.
in x = 6 ribbon), D firstly increases at 2 min and then decreases at 3 min, and the vcr keeps increasing over annealing time, meaning that new crystal nucleus is formed with annealing time increasing from 2 to 3 min, which leads to the heterogeneity of grain size. As shown in Fig. 3d3, a of the annealed ribbon with x = 6 firstly increases and then decreases, indicating that the precipitation of Ga was priority to that of Si, since Ga has stronger driving force to partition into the α-Fe phase than Si. When the Ga element is exhausted, the precipitation of Si occurs and reduces a of α-Fe (Ga, Si) phase. In other words, the substitution of Si by Ga can suppress the partition of Si into α-Fe phase, which results in the α-Fe (Ga, Si) phase with high Ga and low Si concentration. Eventually, the exothermic peak Tp1′ appearing at the DSC curves of as-spun ribbons with Ga addition is identified as the precipitation of α-Fe (Ga, Si) phase, and its broad and asymmetric feature can be explained as the long-range atomic rearrangements of Ga and Si elements which can inhibit the initial grain growth and thus further refine the nanocrystalline. Consequently, the evolution of crystallization processes with the gradual substitution of Si by Ga can be concluded as follows:
and d3) of the precipitated nanocrystallites in the ribbons. It can be seen that the ribbon with x = 0 is still amorphous after annealed at 455 ℃ for 2 min. With the increase of annealing temperature, the ribbon starts to crystallize, and the D and vcr increase, except for D of ribbon annealed for 2 min which shows a ‘V’ curve tendency. Meanwhile, a decreases at 505 °C and then keeps almost constant, by which the nanocrystalline is identified as α-Fe (Si) and Fe3Si. Clearly, massive Si precipitates from the amorphous matrix and dissolves into the α-Fe phase once the crystallization occurs. The ribbon with x = 6 crystallizes at 355 °C, and vcr increases with rising annealing temperature. D of annealed x = 6 ribbon firstly decreases and then increases with rising annealing temperature, except for that of ribbon annealed for 3 min which presents a variation tendency of ‘increase-decrease-increase’. The minimum D of x = 6 ribbon is obtained while D of x = 0 ribbon keeps increasing. This could be attributed to the formation of Fe-Ga clusters which provide adequate nucleation sites for the precipitation of α-Fe (Ga, Si) phase, which refines the nanocrystalline [20]. It is noteworthy that, when the annealing temperature is relatively low (505 °C in x = 0 ribbon and 355 ℃ 3
Journal of Magnetism and Magnetic Materials 487 (2019) 165297
Q. Zhu, et al.
Fig. 4. Soft magnetic properties of annealed ribbons with x = 0 and 6, including (a1,b1) Hc, (a2, b2) Bs and (a3, b3) μm. (c) Hysteresis loop of as-spun and annealed ribbons with optimal soft magnetic properties.
α − Fe (Si) + Fe3 Si + Fe − B compounds (x = 0)
induce the internal stress between crystallites and residual amorphous matrix, which hinders the motion of magnetic domain walls, leading to the decrease of μm. That is why the trend of the change of the μm is opposite to that of Hc, since Hc is also relates to the λs. For the ribbon with x = 6, the trends of Hc versus annealing temperature is the same as x = 0 ribbon. The Bs firstly increases due to the crystallization and the partition of Ga into α-Fe phase then decreases owning to the precipitation of Si and Fe-B compounds. It can be seen that the Bs of the ribbon with x = 6 is higher than that of x = 0 ribbon at same vcr, indicating that Ga certainly improves the magnetic contribution of α-Fe (Ga, Si) phase. Finally, the change of μm present a complicated tendency, which is result from the variation of λs on the one hand, on the other hand, the positive effect of Bs on the μm can be confirmed since they have almost same varying tendency. Relatively low values of Hc of annealed ribbons, together with the Bs, μm, D, vcr and a, are listed in Table 1. For the x = 0 ribbon, after annealed at 505 °C for 1 and 2 min, low value of Hc is obtained due to the fine grains, but relatively low values of vcr and a lead to poor Bs,
→ α − Fe (Ga, Si) + α − Fe (Si) + Fe − B compounds (x = 3) → α − Fe (Ga, Si) + Fe − B compounds (x = 6 and 9) Fig. 4 displays the magnetic properties including Hc, Bs and μm. With the increase of annealing temperature, Hc of the ribbons with x = 0 firstly decrease due to the release of internal stress and the grain refining combining with optimal vcr, then increase as the result of the grain growth and the precipitation of Fe3Si and Fe-B compounds, except for that of ribbon annealed for 3 min, which increases at 455 °C owing to the heterogeneity of grain size as discussed above. The Bs of x = 0 ribbon firstly decreases due to the structure relaxation and the formation of α-Fe (Si), then increases as the result of high value of vcr, and finally decreases owing to the precipitation of Fe3Si and Fe-B compounds. The changes of μm present a tendency of ‘decrease-increasedecrease’ which reflects the balance between negative λcr value and positive λam value to a certain extent. Because high value of λs will 4
Journal of Magnetism and Magnetic Materials 487 (2019) 165297
Q. Zhu, et al.
Table 1 Soft magnetic and microstructure properties of annealed ribbons with low value of Hc. The published data in literatures is also listed for comparison. Alloys
Hc (A/m)
Bs (T)
μm (×103)
D (nm)
vcr (%)
a (nm)
x = 0 an. 505 °C, 1 min x = 0 an. 505 °C, 2 min x = 0 an. 555 °C, 2 min x = 6 an. 405 °C, 2 min x = 6 an. 455 °C, 1 min Fe85Si2B8P4Cu1 [14] Fe81.3Si4B13Cu1.7 [16] Fe76Al4P12B4Si4 [24] FINEMET [2] (Fe,B,Cu,Nb)84.5Si9.5Ge6 [19]
0.22 0.23 0.25 0.22 0.24 5.8 7.1 2.6 0.53 0.41
1.16 1.20 1.23 1.35 1.37 1.85 1.77 1.24 1.24 0.92
18.1 12.3 16.9 22.8 25.3
11 12 12 10 11 < 25 14
39 46 67 54 67
0.28384 0.28391 0.28355 0.28750 0.28707
10
70–80
also be achieved by the new balance between λcr and λam. Meanwhile, the α-Fe (Ga, Si) phase with Ga enrichment can improve the Bs, and the Ga addition can facilitate the nucleation of α-Fe (Ga, Si) phase. Consequently, the annealed x = 6 ribbon with low Hc and higher Bs is obtained.
since Si significantly reduces the Fe atomic magnetic dipole moment [9,23]. Thus, optimal soft magnetic properties of x = 0 ribbon are achieved after annealed at 555 °C for 2 min, which is 0.25 A/m of Hc, 1.23 T of Bs and 16.9 × 103 of μm. For the ribbon with x = 6, the optimal Hc, Bs and μm are 0.24 A/m, 1.37 T and 25.3 × 103, respectively, which belongs to the ribbon annealed at 455 °C for 1 min. The ribbon annealed at 405 °C for 2 min also has excellent soft magnetic properties. In summary, the Bs of x = 6 ribbon is higher than that of x = 0 ribbon while the Hc stays nearly the same value. Moreover, the Ga addition significantly improves the μm. The improvements are shown in Fig. 4c by hysteresis loops. Table 1 also shows the published date in literatures for comparison. It can be seen that, to achieve low value of Hc, Fe usually is substituted by metalloid elements like Si and Ge for vanishing λs, which diminishes the Bs of FINEMET [2] and (Fe,B,Cu,Nb)84.5Si9.5Ge6 [19] alloys. However, for the x = 6 ribbon in this work, the substitution of 6 at.% Si by Ga can increase the Bs by 11.4% while the Hc stays the extremely low value compared to the FINEMET alloy. Thus, a new way of improving soft magnetic properties of FINEMET-like alloys can be obtained by Ga addition. In Fig. 5(a), the results of selected area diffraction pattern show that nanocrystals with size of 11 nm is confirmed in the x = 6 ribbon that annealed at 455 °C for 1 min. Moreover, one of the interplanar spacing d of (1 1 0) in α-Fe (Ga, Si) grain is detected, which is higher than that of pure α-Fe (0.2027 nm) due to Ga enrichment, as shown in Fig. 5(b). To explain the reason why the annealed ribbon with x = 6 exhibits such soft magnetic properties, the discussion about its λs is given as follows. In FINEMET alloys, the low value of λs is due to the balance between negative λcr and positive λam, as shown in Fig. 6. To obtain negative λcr, the concentration of Si in the α-Fe phase is higher than that in the remaining amorphous matrix, which decreases the Bs to a certain extent. In this work, for the FINEMET-like alloy with partial substation of Si by Ga, the precipitation of Ga can suppress the partition of Si into α-Fe phase. Thus, it is believed that the α-Fe (Ga, Si) phase with Ga enrichment has positive λcr [25,26], and the remaining amorphous matrix with high ratio of Si/Fe has negative λam, which is opposite to that in FINEMET alloy. That is to say, low value of λs can
4. Conclusion The effect of partial substitution of Si by Ga on the microstructure and soft magnetic properties of FINEMET-like alloys has been studied. Several points are concluded as follows: During the primary crystallization, the precipitated phase changed from α-Fe (Si) into α-Fe (Ga, Si) with the gradual substitution of Si by Ga. Meanwhile, the Fe-Ga clusters were detected in the amorphous ribbon with x = 6, which could provide nucleation sites for the α-Fe (Ga, Si) phase. For the annealed ribbon with x = 6, the addition of Ga could suppress the partition of Si into α-Fe phase, and thus the α-Fe (Ga, Si) phase with high Ga and low Si concentration could be obtained at the optimal annealing condition. Compared to the FINEMET alloy, the substitution of 6 at.% Si by Ga can increase the Bs by 11.4 percent while the Hc stays nearly the same value. The optimal magnetic properties with coercivity of 0.24 A/m and saturation magnetization of 1.37 T were obtained in the ribbon with x = 6 after annealed at 455 °C for 1 min. Acknowledgements This work was supported by National Natural Science Foundation of China (No. 51731003), Talents Training Project of Shanxi Graduate Joint Training Base (No. 2018JD35), The Key Research and Development Program of Shanxi Province (No. 201803D421046), “131” Leading Talents Project of Higher Education Institutions in Shanxi (2015), Overseas Students Science and Technology Activities Project Merit Funding (2016).
Fig. 5. (a) Selected area diffraction pattern and (b) high-resolution transmission electron microscope images of the x = 6 ribbon that annealed at 455 °C for 1 min. 5
Journal of Magnetism and Magnetic Materials 487 (2019) 165297
Q. Zhu, et al.
Fig. 6. The distribution of magnetostrictive coefficient in the alloys.
References
[13] Y.R. Jia, Z. Wang, F. Wang, et al., Effect of P substitution for Nb on structure and soft magnetic properties of Si-rich FeCuNbSiB nanocrystalline alloys, Mater. Sci. Eng., B 222 (2017) 55–59. [14] Makino, Nanocrystalline soft magnetic Fe-Si-B-P-Cu alloys with high Bs of 1.8–1.9 T contributable to energy saving, IEEE Trans. Magn. 48 (4) (2012) 1331–1335. [15] J.A. Moya, Nanocrystals and amorphous matrix phase studies of Finemet-like alloys containing Ge, J. Magn. Magn. Mater. 322 (13) (2010) 1784–1792. [16] Y. Li, X. Jia, Y. Xu, et al., Soft magnetic Fe-Si-B-Cu nanocrystalline alloys with high Cu concentrations, J. Alloy. Compd. 722 (2017) 859–863. [17] J.A. Moya, Improving soft magnetic properties in FINEMET-like alloys. A study, J. Alloy. Compd. 622 (2015) 635–639. [18] R. Wang, J. Liu, C. Zeng, et al., Crystallization progress and soft magnetic properties of Finemet alloy with Ge addition, Vacuum 104 (2014) 88–91. [19] A. Saad, V. Cremaschi, H. Sirkin, Influence of Al and Ge additions on magnetic properties of Finemet type alloys, J. Metastable Nanocryst. Mater. 20–21 (2004) 717–724. [20] Z. Qianke, C. Zhe, Z. Shuling, et al., Crystallization progress and soft magnetic properties of FeGaBNbCu alloys, J. Magn. Magn. Mater. 475 (2019) 88–92. [21] K. Fukamichi, T. Satoh, T. Masumoto, Magnetic moment of Fe-Ga-B amorphous alloys, J. Magn. Magn. Mater. 31–34 (83) (1983) 1589–1590. [22] N. Kawamiya, K. Adachi, Y. Nakamura, Magnetic properties and Mössabauer investigations of Fe-Ga alloys, J. Phys. Soc. Jpn. 33 (5) (2007) 1318–1327. [23] B.W. Corb, Magnetic moments and coordination symmetry in bcc Fe-M alloys, Phys. Rev. B 31 (4) (1985) 2521–2523. [24] A. Inoue, Stabilization of metallic supercooled liquid and bulk amorphous alloys, Acta Mater. 48 (1) (2000) 279–306. [25] P. Taheri, R. Barua, J. Hsu, et al., Structure, magnetism, and magnetostrictive properties of mechanically alloyed Fe81Ga19, J. Alloy. Compd. 661 (1) (2016) 306–311. [26] I.S. Golovin, Anelasticity of Fe-Ga based alloys, Mater. Des. 88 (2015) 577–587.
[1] G. Herzer, Magnetization process in nanocrystalline ferromagnets, Mater. Sci. Eng., A 133 (1) (1991) 1–5. [2] Y. Yoshizawa, S. Oguma, K. Yamauchi, New Fe-based soft magnetic alloys composed of ultrafine grain structure, J. Appl. Phys. 64 (10) (1988) 6044. [3] G. Herzer, Soft-magnetic nanocrystalline materials, Scr. Metall. Mater. 33 (10–11) (1995) 1741–1756. [4] Z. Qianke, C. Zhe, Z. Shuling, et al., Microstructure and magnetic properties of Fe79xB20NbxCu1 fibers with annealing, Vacuum 154 (2018) 154–158. [5] G. Herzer, Grain size dependence of coercivity and permeability in nanocrystalline ferromagnets, IEEE Trans. Magn. 26 (5) (2002) 1397–1402. [6] T. Gheiratmand, H.R.M. Hosseini, P. Davami, et al., The effect of mechanical milling on the soft magnetic properties of amorphous FINEMET alloy, J. Magn. Magn. Mater. 381 (2015) 322–327. [7] T. Kulik, G. Vlasák, R. Ẑuberek, Correlation between microstructure and magnetic properties of amorphous and nanocrystalline Fe73.5Cu1Nb3Si16.5B6, Mater. Sci. Eng., A 226–228 (1997) 701–705. [8] 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 (3) (1999) 997–1006. [9] H. Okumura, D.E. Laughlin, M.E. Mchenry, Magnetic and structural properties and crystallization behavior of Si-rich FINEMET materials, J. Magn. Magn. Mater. 267 (3) (2003) 347–356. [10] D. Muraca, V. Cremaschi, J. Moya, et al., FINEMET type alloy without Si: structural and magnetic properties, J. Magn. Magn. Mater. 320 (9) (2008) 1639–1644. [11] V. Cremaschi, A. Saad, J. Moya, et al., Evolution of magnetic, structural and mechanical properties in FeSiBNbCuAlGe system, Phys. B 320 (1–4) (2002) 281–284. [12] C. GómezPolo, P. Marín, L. Pascual, et al., Structural and magnetic properties of nanocrystalline Fe73.5-xCoxSi13.5B9CuNb3 alloys, Phys. Rev. B 65 (2) (2001) -.
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