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Article

Magnetic Properties and Coercivity Mechanism of Nanocrystalline Rare-Earth-Free Co74Zr16Mo4Si3B3 Alloys

by
Aida Miranda
and
Israel Betancourt
*
Instituto de Investigaciones en Materiales, Universidad Nacional Autónoma de México, México City 04510, Mexico
*
Author to whom correspondence should be addressed.
Magnetochemistry 2025, 11(9), 78; https://doi.org/10.3390/magnetochemistry11090078
Submission received: 18 July 2025 / Revised: 25 August 2025 / Accepted: 28 August 2025 / Published: 2 September 2025
(This article belongs to the Section Magnetic Materials)
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Abstract

The microstructure and magnetic properties of rare-earth-free, melt-spun Co74Zr16Mo4Si3B3 alloys were investigated to enhance their hard magnetic response and elucidate their coercivity mechanism. The alloys exhibit a polycrystalline microstructure composed of randomly oriented, equiaxed grains, predominantly comprising the rhombohedral hard magnetic Co11Zr2 phase (92.4 wt.%). These materials display a favorable combination of magnetic properties, with coercive fields up to 581 kA/m, maximum magnetization reaching 0.30 T, and Curie temperatures as high as 751 K. An interpretation of the results, based on microstructural features, intrinsic magnetic parameters, and micromagnetic simulations, indicates that the coercivity mechanism of these melt-spun alloys can be attributed to the nucleation of reverse magnetic domains.

1. Introduction

Permanent magnets (PMs) are materials that retain their magnetization in the absence of an external applied magnetic field [1]. PMs are used in a wide variety of technological applications, including electronic devices (like mobile phones and audio gadgets), motors and power generators (for instance, hybrid car engines and wind turbines), data processing (such as hard drives), medical equipment (e.g., magnetic resonance imaging apparatuses), and even in common household appliances (like washing machines) [2,3,4]. Rare-earth (RE)-based alloys are the most employed components in PM technology, owing to their outstanding inherent hard magnetic characteristics [5,6]. Over the past decades, there has been significant research regarding the fabrication of novel PMs based on RE alloys [6,7], but due to the growing price of RE elements [8], the reduction in the usage of these elements in currently known alloys is of great scientific and industrial interest nowadays. For instance, one of the development methods focuses on finding new hard magnetic phases with similar performance to the ones used, with reduced RE content, such as those with ThMn12-type structure (1:12-type structure) [9,10,11] or 2:17-type structure (based on Sm–Co) [12]. On the other hand, scientists are trying to develop RE-free hard magnetic phases with competitive performance for technological applications, e.g., hard magnetic alloys such as Al–Ni–Co (which is already used and being optimized every year) [13,14] or alloys based on Fe–Ni [15,16,17] (a phase known from iron meteorites [18,19]), which has not yet been synthesized in bulk form in industrial amounts [19,20]. Other magnetic materials based on Mn or Co like Mn–Bi [21,22], Mn–Al [23], Mn–Ga [24], and Co–Zr-based alloys [25,26,27,28] have also been studied as alternatives for RE-free PM technology. Among these, Co–Zr alloys based on the Co11Zr2-phase as the main constituent are interesting candidates for designing competitive permanent magnets, owing to their favorable combination of magnetic properties, including a high magnetocrystalline anisotropy of 1.1 M J/m3 and Curie temperature of around 773 K, alongside noticeable saturation magnetization of up to 0.60 T [29,30,31,32].
Concerning the preparation techniques of materials, rapid solidification by the melt-spinning process has important advantages over the conventional casting of alloys, such as the formation of fine-grained microstructures with a mean diameter of the grains being within nanometric range (i.e., below 100 nm) in as-spun conditions. Hence, high coercivity values are achievable for melt-spun ribbons compared to their bulk alloy counterparts. Accurate identification of the different Co–Zr phases for the Co11Zr2-based alloys holds fundamental significance in comprehending the coercivity mechanism of these materials [21]. According to the literature, Co11Zr2-based alloys predominantly present the following two crystalline phases: rhombohedral Co11Zr2 and cubic Co23Zr6 [33]. For PM applications, the main phase is Co11Zr2 due to its hard magnetic behavior, while the cubic Co23Zr6 phase presents soft magnetic characteristics [27,33,34].
According to the Co–Zr phase diagram, the formation of the Co11Zr2 phase occurs via a peritectic reaction at 1543 K with 15.4 at. % of Zr [26]. Consequently, to achieve high phase purity, precise control of the composition and rapid quenching after the fabrication of the alloy is necessary [2,31]. The addition of alloying elements such as Ti, Si, Mo, or B facilitates the formation of the hard magnetic Co11Zr2 phase and decreases both the average grain size and the amount of the soft Co23Zr6 phase [35,36]. Moreover, the addition of B has been found to increase the coercivity (from 262 up to 400 kA/m) and the saturation magnetization (from 0.4 to 0.5 T) for Co80Zr20−xBx alloys [29], and it also decreases the average grain sizes of Co82.5−x Zr16Mo1.5Bx alloys within an interval of 10–30 nm [30]. In addition, the inclusion of Si and Ti atoms for Co83Zr17−xTix and Co82−yZr18Siy alloys also increased the Hc values up to a maximum of 318 A/m [35]. Depending on the preparation route, the Co11Zr2 phase crystallizes in rhombohedral or orthorhombic structures [31,32,33,37]. However, the rhombohedral structure (equivalent to a hexagonal unit cell) has the proper magnetocrystalline anisotropy for developing hard magnetic properties [31,38,39]. In this study, we examined the microstructural and magnetic properties of nanocrystalline Co74Zr16Mo4Si3B3 alloys synthesized with the melt-spinning technique, followed with heat treatments at 903 K. The structure of the melt-spun alloys with the rhombohedral Co11Zr2 hard magnetic phase as the main constituent was confirmed with X-ray diffraction analysis and electron microscopy. The magnetic measurements performed with a vibrating-sample magnetometer revealed that these alloys had coercivity values well over 500 k A/m, which fits them into the values of magnetically hard nanocomposite α-Fe/Nd2Fe14B alloys.

2. Materials and Methods

Pure Co (99.80%), Zr (99.90%), Mo (99.97%), Si (99.99%), and B (99.70%) were employed as initial constituent pure elements (Sigma Aldrich, St. Louis, MO, USA). Alloy ingots with a nominal composition of Co74Zr16Mo4Si3B3 were prepared in arc-melting equipment (Arc Melter MAM-1, Bodelshausen, Edmund Bühler, Munich, Germany) under an argon atmosphere. Alloy ingots were remelted eight times to achieve a homogeneous composition. Alloy ribbons were obtained by a continuous casting of ingots (i.e., melt-spinning process), using melt spinner equipment (SC System, Edmund Bühler, Munich, Germany) under a helium atmosphere at a tangential speed of 16 m/s and an injection pressure of 0.2 Bar. Subsequently, the obtained Co74Zr16Mo4Si3B3 ribbons were heat-treated in a quartz tube in an argon atmosphere under two different conditions as follows: (i) 903 K for 90 min, followed by quenching in water (heat treatment labeled as “T1”) and (ii) 903 K for 180 min, followed by quenching in water (heat treatment labeled “T2”).
The phase distribution of the melt-spun ribbons was examined by X-ray diffraction (XRD) using a D5000 diffractometer (Siemens, Munich, Germany) with Co-Kα radiation, λ = 1.7903 Å. Rietveld refinement was carried out by means of GSAS software Version 5182 [40]. The microstructure characteristics of alloys were analyzed through transmission electron microscopy (TEM) in JEOL ARM 200F (Tokyo, Japan) operating at 200 kV. The magnetic properties of the melt-spun alloys were studied by means of a vibrating-sample magnetometer (VSM) in MPMS-3 SQUID (Quantum Design, Troy, MI, USA) with a maximum applied field of 2500 kA/m for hysteresis measurements at room temperature. Additionally, the Curie temperature was determined by using magnetic thermogravimetric analysis (mTGA) in a TA Q500 thermobalance (New Castle, DE, USA) with a heating rate of 10 K/min, coupled with an electromagnet.
Micromagnetic simulations were carried out by using the time integration of the Landau–Lifshitz–Gilbert equation together with a hybrid finite element/boundary element method [41] on realistic microstructure models in the form of cubic structures with edge lengths between 100 and 413 nm, comprising 216 irregular grains in intimate contact with the following intrinsic magnetic properties for the Co11Zr2 phase: Ms = 477.7 kA/m, A  = 3.98 × 10 − 12 J m , and K 1 = 1.1 × 1 0 6 J m 3 [30,38,39].

3. Results

3.1. Phase Distribution and Microstructural Characterization

X-ray patterns of the melt-spun ribbons of Co74Zr16Mo4Si3B3 alloys for as-spun, T1, and T2 conditions are shown in Figure 1. For as-spun conditions, the observed phases were identified as the cubic phase Co23Zr6 and rhombohedral phase Co11Zr2 through comparison with the JCPDS database (01-071-7527) and database reported for similar alloys with the same phase [33]. Precipitation of the secondary Co23Zr6 phase is attributed to the peritectic formation of the compound Co11Zr2 from Co23Zr6 [29]. For the present alloy samples, the hard magnetic phase Co11Zr2 predominates with a substantial 84.2 wt.%, whereas the secondary Co23Zr6 phase has a minority content of 15.8 wt.%, according to Rietveld analysis. Equivalent composite phase distribution combining hard/soft magnetic phases has been reported for similar alloys [42]. For the T1 condition, the identified phases are consistent with those observed in the as-spun state, namely Co23Zr6 and Co11Zr2. However, there is a noticeable 7.4 wt.% increase for the hard magnetic phase Co11Zr2, together with a significant reduction in the secondary phase. A similar trend is observed for the T2 condition, with an additional reduction in the Co23Zr6 phase, down to 7.6 wt.%, suggesting that the temperature and duration of the heat treatment were optimal to achieve the hard magnetic phase as a majority component. The variation in phase content under different conditions is attributed to atomic ordering. It is well known that high-temperature annealing followed by quenching is one of the most common alloy processing methods used to modify atomic order [43]. This process redistributes atoms between present phases through diffusion driven by thermal energy. Since XRD analysis shows the formation of Co11Zr2 and Co23Zr6 phases only, the alloying elements Mo, Si, and B must have been incorporated into the crystal structure, as the variation in Curie temperature (described within Section 3.2) clearly suggests. Lattice parameters for the Co11Zr2 and Co23Zr6 crystal structures, as well as the amount formed for each phase, derived from Rietveld refinement, are summarized in Table 1 for all the alloys’ processing conditions. The lattice parameter c exhibits an increasing tendency for the following sequence of conditions: as-spun, T1, and T2. For the as-spun alloy, residual stresses strongly influence lattice deformations. These stresses are induced by the rapid cooling rate of the melt-spinning process followed by quenching in water [44]. Subsequent heat treatments produce stress relief within alloy samples, which in turn facilitate the expansion of lattice parameters.
Microstructural characterization by TEM was carried out for the as-spun Co74Zr16Mo4Si3B3 alloy. The micrograph shown in Figure 2 reveals a polycrystalline structure of randomly oriented equiaxed grains. The mean grain size, determined as 9.6 ± 2.3 nm, was calculated from the histogram of distribution shown as an inset in Figure 2a. A similar microstructure was observed for alloys under T1 and T2 conditions. Complementarily, Figure 2b displays HRTEM images combined with fast Fourier transform (FFT) analysis (inset) of the lattice fringe spacing, corresponding to the {160} (with d = 0.2397 nm), {0411} (with d = 0.1940 nm), and {121} (with d = 0.3920 nm) family planes of the hard magnetic phase Co11Zr2.
The cooling rate for melt-spun alloys has been estimated, in general, to be between 105 and 106 K/s [45]. This high cooling speed significantly affects the solidification of alloys (in particular, the nucleation process as the initial step in the solidification of undercooled melts), determining grain size as well as the formation of a crystalline phase that can be either stable or metastable [46]. The formation of very fine polycrystalline microstructures as a result of the melt-spinning process can be explained as follows: during the nucleation process, the transformation into a specific crystalline phase requires activation energy to facilitate the formation of a nucleus with a critical size in the undercooled melt [47]. In this case, the high degree of undercooling and the presence of active nucleation sites result in the initiation of nucleation. However, the growth of grains is limited due to the rapid heat extraction, which restricts atomic diffusion and hence results in a very small grain size.

3.2. Magnetic Properties

Figure 3 displays magnetic thermogravimetric (mTGA) curves of weight W vs. temperature T for Co74Zr16Mo4Si3B3 alloys for all processing conditions studied. The inflection points of each W(T) curve correspond to the Curie temperature, TC, of the Co11Zr2 phase and thus, each TC was determined by means of the minimum of the derivative dW/dT (see insets of Figure 3). TC values for the hard magnetic phase were located at 746 K, 751 K, and 676 K for the as-spun, T1, and T2 conditions, respectively. These TC variations are consistent with the interval of Curie temperatures of 670–820 K reported for Co11Zr2 crystal structures [34,35,48]. According to Table 1, the highest cell volume of the Co11Zr2 phase (469.4 Å3) corresponds to the lowest TC (676 K) under the T2 condition. Conversely, the lowest cell volume (462.6 Å3) corresponds to the highest TC (751 K) of the alloy under T1 conditions. Intermediate TC = 746 K corresponds to the intermediate V = 466.9 Å3 for the as-spun condition. Such variations in TC values can originate from atom ordering [49,50] and internal stresses [51,52]. For instance, previous reports on (Sm,Ce)Co5-based magnetic materials [53] indicate that alloying with other transition metals produced variations in the atomic volume associated with internal strain of the unit cell (due to the differences in the atomic radius between the elements involved), which in turn promotes variation in Co–Co atomic distances and hence changes in their exchange coupling interactions, which strongly influences their Curie transition temperatures [51,52,53]. For the alloys in this study, these results suggest that more compacted crystal structures facilitate higher Curie temperatures. The correlation between internal stress and magnetic properties is an important factor for developing high-performance permanent magnets, for which specific sintering and thermal processes have been designed [54,55].
Hysteresis curves for Co74Zr16Mo4Si3B3 alloys are shown in Figure 4. Typical hard magnetic behavior is manifested for all samples, with coercivity field values well above 500 kA/m for T1 and T2 alloys. This coercivity is comparable to high-performance nanocomposite α-Fe/Nd2Fe14B alloys [2,56]. The properties (coercivity field Hc, maximum magnetization μ0Mmax, remanence magnetization μ0Mr, Mmax/Mr ratio, and TC) are reported in Table 2. An increasing tendency of Hc is observed for the following sequence of alloy processing conditions: as-spun, T1, and T2, with a noticeable peak in Hc = 581 kA/m for the T2 alloy sample. This coercivity tendency can be attributed to the increasing amount of the hard magnetic Co11Zr2 phase (from 84.2% to 94.2%, Table 1). Bearing in mind the magnetic character of the secondary Co23Zr6 phase and its nanometric dimension, “exchange–spring magnet” behavior is expected [57,58,59,60] for the studied alloys, as their smooth second quadrant suggests. Exchange–spring interaction implies a coherent rotation of the magnetic moment of hard and soft particles at the beginning of the demagnetization process (i.e., at the second quadrant) and hence a smooth, progressive decrease in magnetization (i.e., without steps) is observed on the demagnetization section of the hysteresis curve. The main beneficial effect of this coupling is the improvement in the remanence magnetization, which in turn favors the hard magnetic response of the material.
Complementarily, maximum magnetization exhibits an initial significant increase of 66% from the as-spun to T1 condition, followed by a decrease of 33% for the T2 condition. The initial increment of μ0Mmax can be attributed to the higher content of the hard magnetic phase, whereas the decrease in μ0Mmax with T2 can be associated with variations in the magnetic coupling between Co–Co and Co–Zr atoms [35] afforded by the more open crystal structure of the T2 alloy, for which the largest unit cell volume was identified by Rietveld analysis (Table 1), as well as the lowest TC (Table 2). Curie temperature is an intrinsic property that is sensitive to exchange interaction variations between magnetic atoms. In addition, the ratio Mmax/Mr is over 0.5 for all the samples, which according to the Stoner–Wohlfarth model [61] is indicative of intergranular exchange-coupling interaction affording remanence enhancement and hence improved magnetic performance.

4. Discussion

In general, the coercivity mechanism for hard magnetic alloys can be explained in terms of two primary approaches, namely inverse domain nucleation processes and magnetic domain wall pinning [61,62,63]. For the nucleation of inverse domains, achieving significant Hc values rely on the nucleation field (HN) necessary for initiating magnetization inversion after the maximum applied field. This inversion typically occurs at grain boundaries or within the grains of secondary non-magnetic phases at significantly misaligned magnetic grains, within defects like vacancies, at dislocations, or at grain boundaries [61].
An essential characteristic for describing the coercivity of magnetic materials is the formation of single-domain particles in the magnetically saturated state. The critical diameter (Dcrit) below which the magnetically saturated state is energetically most favorable is given in [61].
D c r i t = 72 μ 0 M s 2 A K 1
where A represents the exchange constant of the material and K1 denotes the magnetocrystalline anisotropy constant. When the grain diameter D exceeds D c r i t , magnetic domain formation is favored to reduce the total magnetostatic energy of the material. Conversely, for D ≤ Dcrit, the magnetic structure of each grain corresponds to a saturated state, i.e., single-domain particles. For our Co74Zr16Mo4Si3B3 alloys, we have the following intrinsic magnetic properties: Ms = 477.7 kA/m, A  = 3.98 × 10 − 12 J m , and K 1 = 1.1 × 1 0 6 J m 3 [18,26,27] and hence, the critical diameter can be calculated as D c r i t = 525   nm . Therefore, bearing in mind that the average grain sizes determined for all our alloy samples are well below 100 nm, the presence of single-domain particles is clear. Consequently, the coercivity mechanism for these melt-spun Co74Zr16Mo4Si3B3 alloys corresponds to the nucleation of inverse domains, for which the beginning of magnetization reversal (or demagnetization) occurs at the interface between the Co11Zr2 magnetic phase and the surrounding areas with the secondary Co23Zr6 phase and defects since at such interfaces, a reduction in the magnetocrystalline anisotropy K1 takes place, which in turn facilitates the nucleation of reverse domains.
Micromagnetically simulated M/Ms vs. H curves are shown in Figure 5 for different mean grain sizes within the cubic model, at 127 ± 24 nm, 85 ± 20 nm, and 20 ± 5 nm. All the calculated plots resulted in considerably higher Hc values (around double with respect to the experimental ones) due to the fact that the microstructure model reflects the ideal nucleation field for reverse domains. This difference between theoretical Hc values and experimental data is known as Brown’s paradox [55,61]. Nevertheless, the simulated plots replicate the experimentally observed intergranular exchange coupling, with Mr/Ms ratios (between 0.54 and 0.64) very similar to the measured ones. In addition, the lowest Hc value corresponds to the model with a mean size around 20 nm, which is consistent with experimental data (Table 2), since alloys samples T1, and T2 have mean sizes over 20 nm due to the heat treatment used for such processing conditions. A summary of the calculated magnetic properties is shown in Table 3. Although consistently higher Hc, µ0Mmax, and µ0Mr values were obtained compared with the experimental curves, these calculated results are indicative of the feasibility of attaining an attractive combination of high coercivity together with remanence enhancement for the fine-grained melt-spun Co74Zr16Mo4Si3B3 alloys with mean grain sizes beyond 100 nm, which in turn suggests the possibility for obtaining consolidated hard magnetic materials with competitive performance based on the Co11Zr2 phase as the main constituent.

5. Conclusions

Nanocrystalline Co74Zr16Mo4Si3B3 alloys were obtained by the melt-spinning technique and further processing, including heat treatments of 900 K for 90 min and 180 min. Phase distribution characterization exhibited a predominant Co11Zr2 hard phase (over 90 wt.%) and a polycrystalline assembly of single-domain, randomly oriented grains with an average size below the critical diameter for the formation of single-domain particles. The coercivity mechanism for the studied alloys was described within the frame of the nucleation of reverse domains, for which micromagnetic calculations revealed the possibility for achieving high coercivity and enhanced remanence for fine-grained alloys with mean grain sizes beyond 100 nm. Experimentally, an attractive combination of hard magnetic properties at room temperature included coercive field values of up to 581 kA/m, alongside a maximum magnetization of 0.30 T and Curie temperatures of up to 751 K, rendering these alloys as an interesting option to develop RE-free, cost-effective permanent magnets based on Co11Zr2 as the principal hard magnetic component.

Author Contributions

Conceptualization, I.B.; methodology, I.B. and A.M.; validation, I.B.; formal analysis, I.B. and A.M.; investigation, I.B.; resources, I.B.; data curation, A.M.; writing—original draft preparation, A.M.; writing—review and editing, I.B.; supervision, I.B. All authors have read and agreed to the published version of the manuscript.

Funding

This research received no external funding.

Institutional Review Board Statement

Not applicable.

Informed Consent Statement

Not applicable.

Data Availability Statement

The original contributions presented in this study are included in the article. Further inquiries can be directed to the corresponding author.

Acknowledgments

Aida Miranda acknowledges the financial support from CONAHCYT, Mexico (CVU 1042641), through a Ph.D. scholarship. I. Betancourt is grateful to Thomas Schrefl (University of Krems for Continuing Education, Austria) for providing access to his micromagnetic simulation code. The authors thank Edilso Reguera and Marlene Gutiérrez (CICATA-IPN) for their valuable support with VSM measurements. Technical assistance for materials characterization is also gratefully acknowledged for the following individuals: Adriana Tejeda (XRD), Carlos Flores (ion milling), Josué Romero (TEM), and Eriseth Reyes (mTGA), all of them from IIM-UNAM.

Conflicts of Interest

The authors declare no conflicts of interest.

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Magnetochemistry 11 00078 g001
Figure 1. X-ray diffraction patterns of the Co74Zr16Mo4Si3B3 alloys, showing the phase distribution (namely cubic Co23Zr6 and rhombohedral Co11Zr2 phases) for all processing conditions: as-spun alloy; heat treated alloy T1; and heat treated alloy T2.
Figure 1. X-ray diffraction patterns of the Co74Zr16Mo4Si3B3 alloys, showing the phase distribution (namely cubic Co23Zr6 and rhombohedral Co11Zr2 phases) for all processing conditions: as-spun alloy; heat treated alloy T1; and heat treated alloy T2.
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Magnetochemistry 11 00078 g002
Figure 2. (a) TEM image of the as-spun Co74Zr16Mo4Si3B3 alloy and corresponding grain size histogram (inset) indicating an average grain size of 9.6 ± 2.3 nm. (b) HRTEM image showing lattice fringes corresponding to the {160}, {0411}, and {121} family planes as well as FFT pattern (inset) taken from the dashed rectangle marked in white (indexed to the Co11Zr2 phase).
Figure 2. (a) TEM image of the as-spun Co74Zr16Mo4Si3B3 alloy and corresponding grain size histogram (inset) indicating an average grain size of 9.6 ± 2.3 nm. (b) HRTEM image showing lattice fringes corresponding to the {160}, {0411}, and {121} family planes as well as FFT pattern (inset) taken from the dashed rectangle marked in white (indexed to the Co11Zr2 phase).
Magnetochemistry 11 00078 g002
Magnetochemistry 11 00078 g003
Figure 3. mTGA curves of Co74Zr16Mo4Si3B3 alloys: (a) as-spun (TC = 746 K); (b) T1 (TC = 751 K); and (c) T2 (TC = 676 K).
Figure 3. mTGA curves of Co74Zr16Mo4Si3B3 alloys: (a) as-spun (TC = 746 K); (b) T1 (TC = 751 K); and (c) T2 (TC = 676 K).
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Magnetochemistry 11 00078 g004
Figure 4. Room-temperature hysteresis loops (M–H curves) of Co74Zr16Mo4Si3B3 alloys under all processing conditions.
Figure 4. Room-temperature hysteresis loops (M–H curves) of Co74Zr16Mo4Si3B3 alloys under all processing conditions.
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Magnetochemistry 11 00078 g005
Figure 5. Micromagnetic simulations of normalized hysteresis curves (M/Ms vs. H) for Co74Zr16Mo4Si3B3 alloys with Co11Zr2 as the main phase and varying average grain sizes.
Figure 5. Micromagnetic simulations of normalized hysteresis curves (M/Ms vs. H) for Co74Zr16Mo4Si3B3 alloys with Co11Zr2 as the main phase and varying average grain sizes.
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Table 1. Lattice parameters and phase composition of melt-spun Co74Zr16Mo4Si3B3 alloys from Rietveld refinement (including error parameters Rw = 7.63, χ2 = 4.78) for all processing conditions studied.
Table 1. Lattice parameters and phase composition of melt-spun Co74Zr16Mo4Si3B3 alloys from Rietveld refinement (including error parameters Rw = 7.63, χ2 = 4.78) for all processing conditions studied.
Processing ConditionsPhase (wt.%)a (Å)c (Å)V (Å3)
Co11Zr2Co23Zr6Co11Zr2Co23Zr6Co11Zr2Co11Zr2Co23Zr6
As-spun84.215.84.752 ± 0.002711.4671 ± 0.001923.8695 ± 0.0039466.9 ± 0.241507.8 ± 0.23
T1 (903 K, 90 min)91.68.44.7152 ± 0.001311.5415 ± 0.002824.0266 ± 0.0038462.6 ± 0.141537.4 ± 0.19
T2 (903 K, 180 min)92.47.64.7494 ± 0.002311.5802 ± 0.001724.0324 ± 0.0058469.4 ± 0.241552.9 ± 0.13
Table 2. Room-temperature magnetic properties of Co74Zr16Mo4Si3B3 alloys for all processing conditions.
Table 2. Room-temperature magnetic properties of Co74Zr16Mo4Si3B3 alloys for all processing conditions.
Processing
Conditions		Hc (kA/m)μ0Mmax (T)μ0Mr (T)Mmax/MrTC (K)
As-spun4770.180.100.55746
T15570.300.170.56751
T25810.200.120.60676
Table 3. Calculated magnetic properties of the cubic model with the Co11Zr2 phase as the main constituent with different mean grain sizes.
Table 3. Calculated magnetic properties of the cubic model with the Co11Zr2 phase as the main constituent with different mean grain sizes.
Mean Grain Size
(nm)		Hc (kA/m)μ0Mmax (T)μ0Mr (T)Mr/Ms
127 ± 249710.350.250.54
85 ± 2010500.360.260.56
20 ± 59640.380.300.64
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Miranda, A.; Betancourt, I. Magnetic Properties and Coercivity Mechanism of Nanocrystalline Rare-Earth-Free Co74Zr16Mo4Si3B3 Alloys. Magnetochemistry 2025, 11, 78. https://doi.org/10.3390/magnetochemistry11090078

AMA Style

Miranda A, Betancourt I. Magnetic Properties and Coercivity Mechanism of Nanocrystalline Rare-Earth-Free Co74Zr16Mo4Si3B3 Alloys. Magnetochemistry. 2025; 11(9):78. https://doi.org/10.3390/magnetochemistry11090078

Chicago/Turabian Style

Miranda, Aida, and Israel Betancourt. 2025. "Magnetic Properties and Coercivity Mechanism of Nanocrystalline Rare-Earth-Free Co74Zr16Mo4Si3B3 Alloys" Magnetochemistry 11, no. 9: 78. https://doi.org/10.3390/magnetochemistry11090078

APA Style

Miranda, A., & Betancourt, I. (2025). Magnetic Properties and Coercivity Mechanism of Nanocrystalline Rare-Earth-Free Co74Zr16Mo4Si3B3 Alloys. Magnetochemistry, 11(9), 78. https://doi.org/10.3390/magnetochemistry11090078

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