High Saturation Magnetic Flux Research Articles

Obtaining extremely low coercivity of high Bs FeCoBSiCPCu nanocrystalline alloys through modulation of magnetic anisotropy

Longitudinal magnetic field annealing is utilized for modifying the magnetic anisotropy and enhancing the magnetic softness of Fe75Co8(B10Si3C3P1)1-x/17Cux (x = 0.5, 0.75, 1, 1.25) nanocrystalline alloys. All of the magnetic field-annealed nanocrystalline alloys with Cu content more than 0.5 at.% exhibit significantly improved soft-magnetic properties, including high saturation magnetic flux density up to 1.87 T, effective permeability of 13000-16000 under the condition of 1 A/m and 1 kHz, coercivity as low as 1.6 A/m, and core loss of 0.11-0.45 W/kg under the condition of 1.0 T and 50 Hz. The application of a magnetic field promotes the nucleation and inhibits the growth of grains, leading to an increase in the number density of nanocrystals and the crystalline volume fraction, and a reduction in the grain size. The magnetic field annealing reduces the effective magneto-crystalline anisotropy energy to 2-4 J/m3, and induces longitudinal magnetic anisotropy with anisotropy energy density of 400-900 J/m3 which shows dependence on the crystalline volume fraction. The field-induced magnetic anisotropy dominates over the random local magnetic anisotropies, and results in the formation of regular magnetic domains aligned longitudinally, pinning-free domain wall displacement, and thus enhanced soft-magnetic properties.

Laminated nanocrystalline-ferrite high saturation magnetic flux density composite core for use in high-frequency transformers

Laminated nanocrystalline-ferrite high saturation magnetic flux density composite core for use in high-frequency transformers

Effect of Nb addition and annealing treatment on structural and magnetic properties of Fe–Si–B–P–Cu alloy ribbons

Thermal and magnetic properties of Fe85-xSi2B8P4Cu1Nbx (0 ≤ x ≤ 4) alloy ribbons of different microstructures were systematically investigated. Increase in Nb content raised the first crystallization onset temperature from 646 to 701 K suggesting improved thermal stability. XRD results on the as-spun ribbons also suggested the role of Nb increasing the thermal stability and glass-forming ability by showing fully amorphous patterns for all alloys with Nb addition. However, Nb addition turned out to decrease the saturation magnetic flux density from 1.74 to 1.17 T. To further optimize the properties, annealing treatment was carried out to find the optimized condition as Fe84Si2B8P4Cu1Nb1 processed at 793 K for 10 min resulting in nanocrystalline microstructure with a high saturation magnetic flux density of 2.03 T. Transmission electron microscopy confirmed the formation of nanocrystalline α-Fe phase in the annealed ribbons.

Influence of Ge doping on the magnetic properties and microstructure of Fe-Si-B-P-Cu alloys prepared with industrial raw materials

With the increasing demand for energy efficiency and miniaturization, there is a growing need for magnetic materials with high saturation magnetic flux density (Bs) and low coercivity (Hc). Here, Fe82.3Si4B9P4-xCu0.7Gex (x = 0, 1, 2) nanocrystalline ribbons were prepared using industrial raw materials (IRMs). We found that appropriate Ge doping can optimize Bs by enhancing the crystallization volume fraction of α-Fe phase, and refine grain size by increasing the energy barriers for the growth of α-Fe and Fe(B, P) phases, which ultimately reduces Hc. However, Ge doping can also induce surface crystallization of the ribbons due to the enrichment of Cu elements. Excessive diffusion of Cu into the crystalline layer is not favorable for grain refinement, which deteriorates the soft magnetic properties of the ribbons.

Effects of B/P and Co/Fe substitutions on glass-forming ability and soft magnetic properties of a Fe80P13C7 metallic glass

New soft magnetic Fe-based Fe–Co–P–B–C bulk metallic glasses (BMGs) with the highest saturation magnetic flux density (Bs) up to 1.68 T among current Fe-based BMGs have been developed. Initial replacement of P by 2–6 at.% B enhances the thermal stability, glass-forming ability (GFA), and soft magnetic properties of a Fe80P13C7 alloy. A Fe80P9B4C7 BMG with a supercooled liquid region of 38 K, Bs of 1.63 T, and coercivity (Hc) of 0.9 A/m has been obtained by copper mold casting. Substitution of Fe by 5–10 at.% Co in the Fe80P9B4C7 alloy further enhances the GFA and Bs, but leads to a moderate increase in Hc. A critical sample diameter of 1.5 mm, Bs of 1.68 T, and Hc of 6.2 A/m can be achieved for a Fe70Co10P9B4C7 BMG. The improvement of the GFA is attributed to the enhanced stability of alloy melts achieved by similar B/P and Co/Fe substitution.

Affable thermal treatment process to overcome the trade-off relation via interface engineering in an Fe-based amorphous film

As pre-eminent soft magnetic materials, Fe-based amorphous alloys have been extensively studied due to adjustable composition, low cost, and low iron core loss. The soft magnetic properties could be further improved after thermal annealing, which achieve a low coercive force (Hc) due to the low magnetic anisotropy and a high saturation magnetic flux density (Bs) on account of the precipitation of soft magnetic nanocrystalline phases. However, it is a key difficulty to control the nucleation and growth procedures of nanocrystals during annealing, resulting in rapid deterioration of Hc. Here, a soft magnetic Fe76Si8B13Nb3 film with ultra-fine amorphous/crystalline (a/c) core–shell structure is achieved from an amorphous precursor with the nanoscale phase separation. The pre-existing nanoscale phase separation provides vast nucleation sites and interphase boundaries, which could generate high concentration of nanocrystals and depresses the subsequent coarsening behavior even for long-time heat treatment. In consequence, the a/c core–shell soft magnetic film breaks the general trade-off relation in the soft magnetic material family with the highest Bs and lowest Hc simultaneously. This work provides a new perspective to design a/c alloys by amorphous precursor with dual phase structure, and importantly, it supplies effortless thermal treatment requirement to conveniently regulate the microstructures and soft magnetic properties of metallic glasses.

Iron Losses Comparison of Two Kinds of Permendurs under Rotating Magnetic Flux Density Conditions

Vector magnetic properties of permendurs have been investigated by using a vector magnetic property measurement apparatus to select a magnetic material suitable as a motor core material. When a motor is rotated at high speed by high-frequency excitation to increase power of a motor, a magnetic material with a high saturation magnetic flux density and a low iron loss is useful for a motor core. However, iron loss versus frequency characteristics under rotating magnetic flux density conditions of permendurs have not been sufficiently investigated. Moreover, the magnetic characteristics of permendurs made by different manufacturers have not been compared. Therefore, in this paper, the vector magnetic properties under rotating magnetic flux density conditions of two kinds of permendur made by different manufacturers are measured and compared for iron losses.

Convolutional neural network guided prediction of saturation magnetic flux density of Fe-based metallic glasses

Fe-based metallic glasses (FeMGs) have recently garnered considerable research attention due to their unique characteristics, such as low core loss and high saturation magnetic flux density (Bs). They also have promising applications in modern electrical machines, such as inductors, motors, and transformers. For FeMGs with high Bs, a trial-and-error approach using various metalloid elements as constituents has been intensively carried out to consider satisfactory thermal stability. However, this approach is time-consuming and expensive because it requires a huge compositional space and results in a lack of understanding of metalloid effects on magnetic properties and thermal stability. In this study, we established a deep learning model using a convolutional neural network (CNN) based only on compositional descriptors of FeMG constituent elements to predict Bs as the representative magnetic property. In addition, an artificial neural network was applied with the same compositional descriptors for comparison, resulting in a lower prediction performance than that of the CNN model. The CNN model demonstrated high-performance metrics that included a determination coefficient (R2) of 0.960 and a low root-mean-square error of 0.067 T, indicating that the material composition-to-property map is well-defined. We further applied the CNN model to unseen datasets for Bs prediction and compared it with results reported in the existing literature. The predicted Bs values are in excellent agreement with the reported experimental results.

Relationship between blanking performance and microstructure of annealed Fe–Si–B–Cr amorphous alloy sheets

The high saturation magnetic flux density, low coercivity, and high permeability of iron-based amorphous alloys make them excellent magnetic core materials for electrical devices. Their local embrittlement and high fracture strength, however, make them difficult to machine. To overcome these difficulties, we have developed a new machining method with optimized heat treatment to improve the machinability of amorphous alloys. We conducted a series of blanking tests on melt-spun and post-annealed Fe–Si–B–Cr amorphous alloys with as-quenched, relaxed, partially or fully crystallized, and grain-grown microstructures. SEM examinations of the fractured surfaces of the blanked specimens and TEM observations revealed that the blanking resistance and overall machining performance correlated with these microstructures. The as-quenched sample showed the largest blanking resistance, and the fracture surface exhibited a drooped top edge, vertical marks, and the formation of horizontal voids, suggesting that plastic deformation occurred. For the samples annealed up to 763 K, the blanking resistance decreased and fractographic examination indicated that the blanking occurred in a brittle manner. Annealing at higher temperatures (773–873 K) increased the blanking resistance and changed the fracture morphology, exhibiting intragranular and intergranular fractures of crystalline precipitates. After complete crystallization, several burrs appeared at the bottom of the sample. Annealing at 1073 K led to a further decrease in blanking resistance related to the intergranular fracture of large grains. The plastic deformation of the sheet deteriorated the blanking quality. Based on these findings, the optimum microstructure and post-treatment of the amorphous alloy for ideal blanking performance are proposed.

Development of novel FeCo based amorphous FeCoBPSiCr alloy with high Bs of 1.71 T and high corrosion resistance

Metallic ribbons of different compositions were prepared using a single-roller melt-spinning method. The (Fe0.8Co0.2)83B11P4Si2 alloy without Cr showed both high saturation magnetic flux (Bs) of 1.78 T and high corrosion resistance, with a corrosion potential of −607 mV and a corrosion current density of 29 μA/cm2 compared to those of a conventional high-Bs Fe79B13.5Si5.5C2 amorphous alloy. The (Fe0.7Co0.3)82B11P4Si2Cr1 alloy with Cr also exhibited a high Bs of 1.71 T and high corrosion resistance at the same level as that of a conventional Fe73B11Si11C3Cr2 amorphous alloy. The (Fe0.7Co0.3)82B11P4Si2Cr1 alloy showed a corrosion potential of −509 mV and a corrosion current density of 18 μA/cm2. Furthermore, the (Fe0.7Co0.3)82B11P4Si2Cr1 alloys exhibited a high amorphous forming ability because of a single amorphous phase in the metallic ribbon at a thickness of >60 μm. Based on these results, the (Fe0.7Co0.3)82B11P4Si2Cr1 amorphous alloy with the possibility of powderization was confirmed to be a suitable material for the magnetic core that is widely used in metallic inductive components.

Effects of Nb microalloying on the magnetic properties and microstructure of Fe-Si-B-P-Cu-Nb nanocrystalline alloys prepared with pure and industrial raw materials

Fe-based nanocrystalline alloys with high saturation magnetic flux density (Bs) and low coercivity (Hc) are highly desirable, especially if they can be prepared with industrial raw materials (IRMs). Here, Fe82.3Si4B9P4Cu0.7 and Fe82.3Si4B9P3Cu0.7Nb1 nanocrystalline ribbons were prepared with IRMs and pure raw materials (PRMs). It was found that Nb microalloying broadens the annealing process window of the ribbons due to the suppressed precipitation of Fe(B, P) phase. In addition, the soft magnetic properties of the Fe82.3Si4B9P3Cu0.7Nb1 ribbons prepared with IRMs are insensitive to impurities and surface-crystallized layer. Compared to the PRMs-prepared ribbons, the IRMs increase the Hc of the Nb-free ribbons, whereas having little effect on the Hc of the Nb-doped ribbons with dendritic-crystallites in the surface layer. These results originate from the former forming coarse α-Fe grains and narrow magnetic domains, while the latter mainly forming fine α-Fe grains and broad magnetic domains. This work provides a valuable reference for the development and industrialization of nanocrystalline alloys with high Bs and low Hc.

Historical Perspectives on Evolution from Elctrodeposition to Electrochemistry

Among numerous findings by human beings, electrodeposition is of great importance in the whole invention and is getting to be a core technology to date. The applications of electroplating used in electronics devices, magnetic recording heads and media, chemical biosensors, and batteries are some typical examples surrounding our present world. Looking back on the history of electrodeposition, the first trial was carried out in the Mesopotamian-era in 1500 BC, which was a Sn plating on iron wares. For Japan, the beginning of plating was performed back in the 6th century for a Au amalgam plating on the Buddha statue at Asuka-era Temple. Hence, the technology of electrodeposition has been developed and evolved for a long period of time along with humankind.While electrodeposition is known to be a traditional way to form metal or non-metal ions on various substrates, it is still kept being one of the cutting edge technologies to date. Because desired thin films, such as CoFeNi for hard disk and Cu wiring for silicon devices, can be easily obtained by the fine control of the chemistry on the interface between the electrode and electrolyte. The sequential high-throughput with outstanding cost effectiveness also push forward this technology to practical applications in various industrial fields. An example of the fine control of deposited films popped up in our mind is the idea of UPD (underpotential deposition) by ad-atom in 1978. Such an idea of ppm or ppt content of metal ions in the plating bath resulted in the practical realization of electroless plating disk for PATTY HDD device (1981 NEC,NTT). Electrodeposition is also known to be a game-changer in the scientific history as well. For the fabrication of soft magnetic materials, the electrodeposited thin film of Co65Ni23Ni12 achieved low-Hc with high-Bs for the first time, which was breaking the common sense that high-Bs is incompatible with low-Hc in soft magnetic materials. [1, 2] Such an electroplating technology is on going to the next stage for 3D memories. Ever since electrodeposition was conducted in earnest by Jacobi et al in 1837, its practical use in sub-micron scale was established in 1997 as damascene process to ULSI internal wiring technology and is now available to handle atomic-scale of fabrication in various fields.This year marks the 100th anniversary of the establishment of the ECS Electrodeposition Division. There is no doubt that ECS has contributed significantly to the development of the Electrodeposition field since 1922. In today's lecture, we will introduce our research concept on electrodeposition in the various fields based on electrochemistry, such as magnetism, sensors, and electronics on the basis of our achievements of their practical use for future industrial usage including battery devices. [3][1] T. Osaka et al., “A soft magnetic CoNiFe film with high saturation magnetic flux density and low coercivity”, Nature, 392, 796 (1998).[2] T. Osaka et al., “Influence of crystalline structure and sulfur inclusion on corrosion properties of electrodeposited CoNiFe soft magnetic films”, Journal of the Electrochemical Society, 146, 2092 (1999).[3] T. Osaka, “Spotlight on Japanese Battery Technologies”, Nature jobs, 2015. Figure 1

(Invited) Chemistry Effects on the Electrodeposition of Re, Co, and Alloys

Electrodeposition has been adopted in various metallization processes. It allows conformal and super-conformal deposition on curved and recessed substrates, enables the fabrication of metals and alloys with well controlled composition, impurity, and grain structure, and provides fast growth rate, high throughput, and low cost of ownership. Organic additives have been used in electrolytes to tune not only the growth behavior, but also the impurity and grain structure of the deposited material. The most well-known cases are those used for magnetic alloy plating[1,2] in storage and MEMS industry and for damascene copper plating[3,4] in microelectronic industry. On the other hand, the electrolyte itself has largely remained aqueous for most cases. Organic solvents, room temperature ionic liquids, and deep eutectic systems have been widely studied with, however, relatively limited success in large scale adoption.The first part of this talk will introduce some studies on the electrodeposition of Cobalt as an alternative metal for semiconductor interconnect applications. Organic additives that tailor the deposition rate of cobalt are used to enable the Co filling in sub-micron structures. The effect of such additives on the impurity incorporation and film grain structure will be discussed. The second part of the talk will discuss some recent studies on the electrodeposition from “water-in-salt” electrolytes, where the hydration of a super high concentration of supporting salt depletes the free water molecules in the aqueous solution, thus limiting the hydrogen evolution reaction. The discussion will be in a context of Re and ReCo alloy deposition for superconducting connector applications for quantum devices. REFERENCES T. Osaka, M. Takai, K. Hayashi, K. Ohashi, M. Saito, and K. Yamada, A soft magnetic CoNiFe film with high saturation magnetic flux density and low coercivity, Nature, 1998, 392(6678), 796. E.I. Cooper, C. Bonhôte, J. Heidmann, Y. Hsu, P. Kern, J.W. Lam, M. Ramasubramanian, N. Robertson, L.T. Romankiw, and H. Xu, Recent developments in high-moment electroplated materials for recording heads, IBM Journal of Research and Development, 2005, 49(1), 103. P. Andricacos, C. Uzoh, J. Dukovic, J. Horkans, and H. Deligianni, Damascene copper electroplating for chip interconnections, IBM Journal of Research and Development, 1998, 42(5), 567. T.P. Moffat, J.E. Bonevich, W.H. Huber, A. Stanishevsky, D.R. Kelly, G.R. Stafford, and D. Josell, Superconformal Electrodeposition of Copper in 500–90 nm Features, Journal of The Electrochemical Society, 2000, 147, 4524.

Excellent soft magnetic properties and enhanced glass forming ability of Fe-Si-B-C-Cu nanocrystalline alloys

In the present investigation, the glass forming ability (GFA), thermal stability, and soft magnetic properties of Fe85Si6-xB8Cu1Cx alloys are investigated by the substitution of C for Si. It was found that the GFA of C-containing alloys is remarkably enhanced when a certain amount of Si is replaced by C in a C-free alloy. The temperature interval between the first and second crystallization temperatures is also improved by C addition and reaches a maximum value of 169 °C for the as-spun Fe85Si2B8Cu1C4 amorphous alloy. The Fe85Si4B8Cu1C2 nanocrystalline alloy exhibits the best soft magnetic properties with the highest saturation magnetic flux density (Bs) of 1.95 T and the lowest coercivity (Hc) of 4.1 A/m, which corresponds to the highest grain number density (Nd). The high GFA, large annealing window, low cost, and excellent soft magnetic properties enable the Fe85Si2B8Cu1C4 nanocrystalline alloy as a material with wide applicability. Moreover, this work is highly beneficial in balancing the relationship between a high Bs and sufficient GFA in the production of Fe-rich nanocrystalline alloys.

Exceptionally High Saturation Magnetic Flux Density and Ultralow Coercivity via an Amorphous-Nanocrystalline Transitional Microstructure in an FeCo-Based Alloy.

High saturation magnetic flux density (Bs ) of soft magnetic materials is essential for increasing the power density of modern magnetic devices and motor machines. Yet, increasing Bs is always at the expense of high coercivity (Hc ), presenting a general trade-off in the soft magnetic material family. Here, superior comprehensive soft magnetic properties, i.e., an exceptionally high Bs of up to 1.94 T and Hc as low as 4.3 A m-1 are unprecedentedly combined in an FeCo-based alloy. This alloy is obtained through a composition design strategy to construct a transitional microstructure between amorphous and traditional nanocrystalline alloys, with nanocrystals (with < 5 nm-sized crystal-like regions around) sparsely dispersed in an amorphous matrix. Such transitional microstructure possesses extremely low magnetic anisotropy caused by the annihilation of quasi-dislocation dipoles, and a strong magnetic exchange interaction, which leads to excellent comprehensive magnetic properties. The results provide useful guidelines for the development of the next generation of soft magnetic materials, which are promising for applications of high-frequency, high-efficiency, and energy-saving devices.

Investigation of glass forming ability, crystallization behavior, and soft magnetic properties of Fe–B–P–C–Cu alloy ribbons

The effect of Cu content on GFA, crystallization behavior, and soft magnetic properties in high P Fe84+xB6P6C3Cu1−x (x = 0, 0.2, 0.4, 0.6, and 1.0 at. %) alloy ribbons were systematically investigated to balance the relationship between glass forming ability (GFA), heat treatment window, and soft magnetic properties of high saturation magnetic flux density (Bs) Fe-based nanocrystalline alloys. It was discovered that lowering Cu promotes the formation of an amorphous structure. The GFA of alloys rises from 23 μm for Fe84B6P6C3Cu1 to 29 μm for Fe84.4B6P6C3Cu0.6. Analysis of thermal physical properties shows that when Cu content is between 1.0 at. % and 0.6 at. %, reducing Cu in the alloys does not affect the onset temperature of the first crystallization peak (Tx1), the second one (Tx2), and ΔT (ΔT = Tx2 − Tx1), whereas when Cu content is less than 0.6 at. %, reducing Cu leads to an increase in Tx1 and a decrease in Tx2 and ΔT, which is not conducive to obtaining a wide temperature range of precipitation of a single α-Fe phase. The alloys have a wide range of crystallization annealing temperature (693–753 K) and annealing time (60–6 min) to obtain a low coercivity (Hc) of about 8.0 A/m, high Bs of about 1.80 T, and high effective magnetic permeability (μe) of about 10000 when Cu is between 1.0 at. % and 0.6 at. %. The Bs, Hc, and μe of Fe84.4B6P6C3Cu0.6 alloy annealed at 723 K for 30 min are 1.82 T, 8.1 A/m, and 10820, respectively.

Vibration and Noise Measurement of Medium-High Frequency Transformer Cores Under Non-Sinusoidal Excitation

Vibration and acoustic noise are essential in electrical equipment. Amorphous alloy is widely used in the medium- to high-frequency transformer due to its low loss, but its significant vibration and noise cannot be ignored, which will even reduce the reliability of the equipment. Ultra-thin grain-oriented silicon steel (≤0.2 mm) is expected to design medium- to high-frequency transformers due to its high magnetic permeability, high saturation magnetic flux density, and high stability. In this article, the loss characteristic, three-dimensional vibration acceleration, and noise level of three C-type core samples made of ultra-thin grain-oriented silicon steels (GT-050, GT-100) and amorphous alloy CACC30 are measured and analyzed under sinusoidal and rectangular excitations. The mathematic analysis predicts that the vibration acceleration increases with duty cycle decrease under rectangular excitation, which is consistent with the experimental results. The ultra-thin grain-oriented silicon steel has lower vibration and noise under medium- to high-frequency excitation compared with amorphous alloy when the transformer is operated on the non-saturated state. The experimental results and analysis can promote the application of new high-efficiency magnetic materials in medium- to high-frequency electrical equipment.

Advances in Fe-based amorphous/nanocrystalline alloys

Fe-based amorphous/nanocrystalline alloys exhibit excellent soft magnetic properties, including high saturation magnetic flux density (Bs), high permeability, low coercivity (Hc), and low magnetostriction. They are utilized in distribution transformers, transformers, reactors, and other devices. As green, energy-saving, and environmentally friendly materials, their application fields have more possibilities. In this paper, the development history, composition design principle, heat treatment process, magnetic properties, and annealing brittleness of Fe-based amorphous/nanocrystalline alloys are introduced.

Excellent magnetic softness-magnetization synergy and suppressed defect activation in soft magnetic amorphous alloys by magnetic field annealing

Fe-based amorphous alloys with high saturation magnetic flux density (Bs) are increasingly attractive from both scientific and technological points of view, however, they usually suffer from the trade-off between magnetization and softness. In this work, we explore the soft magnetic properties (SMPs), magnetic and atomic structures, and defect activation during creep deformation of as-quenched and annealed Fe82.65-xCoxSi2B14Cu1.35 (x = 0–20) amorphous alloys (AAs). Improved magnetic softness-magnetization synergy has been realized in all these alloys by field annealing. Particularly, superb SMPs with super-high Bs of 1.86 T, low coercivity of 1.2 A/m and high effective permeability of 16300 are obtained in the Fe66.65Co16Si2B14Cu1.35 AA. The locally regularized arrangement of domains, homogenized structure with less structural/magnetic defects and suppressed crystal-like ordering by field annealing contribute synergistically to the superb SMPs. Besides, the relaxation time spectra obtained from creep deformation indicate less liquid-like and solid-like defects activated in the field-annealed AA, which is correlated with the structural homogenization and superb SMPs. This work provides new and comprehensive insight into the interplay among external field, heterogeneous structure, SMPs and defect activation of Fe-based AAs, and offers a promising pathway for softening amorphous alloys with high Bs.

Role of Fe substitution for Co on thermal stability and glass-forming ability of soft magnetic Co-based Co-Fe-B-P-C metallic glasses

Soft magnetic Co-based bulk metallic glasses (BMGs) with large supercooled liquid region (ΔTx) of 47 K and high saturation magnetic flux density (Bs) up to 1.21 T have been developed in a new Co-Fe-B-P-C alloy system without early transition metal and rare earth elements. Substitution of Co by 10–35 at.% Fe in a Co75B10P7.5C7.5 alloy promotes the occurrence of glass transition and enhances the stability of supercooled liquid and glass-forming ability (GFA). The ΔTx of 37–47 K and a critical sample diameter up to 1.2 mm can be achieved for Co40–55Fe20–35B10P7.5C7.5 BMGs. The improved thermal stability and GFA are attributed to complicated primary crystallization phases and stabilized alloy melts, respectively. The addition of Fe enhances the Bs of the Co-based BMGs from 0.79 to 1.21 T, and increases coercivity from 1.1 to 7.2 A/m. The Co-based BMGs also exhibit high yield strength of 3243–3665 MPa with plastic strain up to 2.3% and low viscosity of around 3.0 × 109 Pa·s in the supercooled liquid state.