FE-NI nanocomposite alloy

Abstract

1. A nanocomposite comprising: crystalline particles in an amorphous matrix, the crystalline particles comprising an iron (Fe)-nickel (Ni) compound and separated from one another by the amorphous matrix; and one or more barriers between the crystalline particles and the amorphous matrix, the barriers configured to inhibit growth of the crystalline particles during their formation, one of the one or more barriers being between the crystalline particles and the amorphous matrix; wherein the amorphous matrix has an increased resistivity compared to the resistivity of the crystalline particles, and the amorphous matrix is ​​configured to reduce loss of the crystalline particles caused by a change in a magnetic field applied to the crystalline particles compared to loss of the crystalline particles that would occur in the absence of the amorphous matrix.

Description

[Technical Field]

[0001] (Claiming priority) This application claims priority to U.S. Patent Application No. 16 / 434,869, filed on 7 June 2019, under Section 120 of the U.S. Patent Act, the entire contents of which are incorporated herein by reference.

[0002] (Government rights) This invention was made with the support of the U.S. Government under contract number DMR0804020, awarded by the National Science Foundation. This invention was made with the support of the U.S. Government under contract number W911NF-14-1-0184, awarded by the Army Research Laboratory. The U.S. Government has certain rights in this invention.

[0003] (background) This disclosure generally relates to nanocomposite alloys. More specifically, this disclosure relates to Fe-Ni nanocomposite alloys.

[0004] Materials exhibiting ferromagnetism have a Curie temperature of T C A magnetic material is a material in which electron spin dipole moments are ordered within a volume called a magnetic domain, in the absence of a magnetic field, below a temperature called . At a sufficiently strong applied magnetic field, a magnetically saturated material has a single magnetic domain encompassing the sample volume. At zero magnetic field, having multiple magnetic domains is energetically advantageous in order to minimize the demagnetizing field. When an external magnetic field is applied, there are two ways in which magnetic domains can be aligned in the direction of the magnetic field: (1) domain growth, or (2) domain rotation. In domain growth, magnetic domains that are already aligned in the direction of the magnetic field expand by moving domain walls, reducing (or sacrificing) their adjacent domains. Domain rotation is when, instead of domain wall movement, the individual atomic moments rotate to align with the applied magnetic field.

[0005] Magnetic materials are broadly divided into two groups: soft magnets and hard / permanent magnets. The two groups are distinguished by their coercivity; soft magnets have much lower values, while permanent magnets are difficult to demagnetize. Other important magnetic properties are saturation magnetization and permeability. Saturation magnetization is the magnitude of magnetization in a single magnetic domain, while permeability relates to the strength of the external magnetic field relative to the magnitude of the induced internal magnetic field. Developing the correct balance of these properties for various applications facilitates the study of magnetic materials.

[0006] Michael Faraday was the first to demonstrate the law of induction (or electromagnetic induction) using an iron core. When the power industry developed and adopted AC current, it was found that the low resistivity of iron cores resulted in excessive losses, leading to the high losses of standard eddy currents. For this reason, silicon steel was studied from the 1880s and became dominant in the market by the 1930s. Silicon steel remains the industry standard for high-voltage AC power transformers. More specialized applications require higher induction, leading to the development of Fe-Co alloys, which have been found in military applications and have fewer cost issues. Fe-Co alloys have the highest induction of all transition metal alloys, which can be understood in relation to the Slater-Pauling curve. Other applications, such as sensors and motors, require higher permeability than Si steel. For these applications, Fe-Ni alloys, or permalloy, were developed. [Overview of the project]

[0007] (overview) The nanocomposite includes: crystalline particles in an amorphous matrix, where the crystalline particles comprise an iron (Fe)-nickel (Ni) compound and are separated from each other by the amorphous matrix; and one or more barriers between the crystalline particles and the amorphous matrix, where the barriers are configured to inhibit the growth of the crystalline particles during their formation, and the barriers of the one or more barriers are located between the crystalline particles and the amorphous matrix; wherein the amorphous matrix comprises an increased resistivity compared to the resistivity of the crystalline particles; wherein the amorphous matrix is ​​configured to reduce the loss of crystalline particles caused by changes in the magnetic field applied to the crystalline particles compared to the loss of crystalline particles that would occur without the amorphous matrix.

[0008] Furthermore, this paper demonstrates that it possesses good glass formation ability (GFA) based on thermocalc simulations and experimentally validated models (Fe 70 Ni 30 ) 80 (B-Si-Nb) 20A series of compositions in the system are described. In particular, the range of B=14-18%, Si=0-7%, and Nb=0-6% has excellent GFA and is a preferred embodiment of the present application. Furthermore, some of these alloys have a large ΔTxg=(Tx-Tg), where Tx corresponds to the primary crystallization temperature and Tg corresponds to the glass transition temperature of the amorphous phase, which will enable processing by various thermomechanical means at high temperatures, including stamping, rolling, and die forming. Examples of advanced manufacturing process embodiments that are uniquely suited to these alloys include: (1) a step of hot rolling at a temperature above the Tg of the amorphous precursor to thin it before ribbon nanocrystallization; (2) a step of hot stamping the ribbon above the Tg of the amorphous precursor to form a laminate of a desired geometry; (3) an induction rolling step of generating a heat source by RF excitation of rollers using eddy currents in the ribbon; and (4) a step of hot rolling simultaneously with nanocrystallization of the alloy composition in which grain boundary amorphous phases are designed to maintain a low Tg as the crystallization process progresses, even after partial crystallization of the amorphous precursor, which still has a large ΔT xg These alloys can be treated thermomechanically, even after nanocrystallization.

[0009] In some implementations, the crystalline particles contain metastable, face-centered cubic Fe-Ni groups. In some implementations, the Fe-Ni groups contain γ-FeNi nanocrystals.

[0010] In some implementations, the barrier contains niobium (Nb). There, the amorphous matrix contains boron (B) and silicon (Si) which are configured together to enable the amorphous matrix's glass-forming ability. In some implementations, the nanocomposite material contains a copper (Cu) nucleating agent configured to increase the nucleation of crystalline particles during the molding process compared to the nucleation of crystalline particles during the molding process without the copper nucleating agent, where the crystalline particles are reduced by more than 10% as a result of the increased nucleation.

[0011] In some implementations, crystalline particles have an average diameter of 5–20 nm.

[0012] In some implementations, the nanocomposite forms ribbons with a thickness of 15–30 μm. In some implementations, the nanocomposite exhibits magnetic anisotropy that is longitudinal along the ribbon.

[0013] In some implementations, the nanocomposite material contains 50 atomic percent or less of one or more metals, including boron (B), carbon (C), phosphorus (P), silicon (Si), chromium (Cr), tantalum (Ta), niobium (Nb), vanadium (V), copper (Cu), aluminum (Al), molybdenum (Mo), manganese (Mn), tungsten (W), and zirconium (Zr). The nanocomposite also contains 30 atomic percent or less of cobalt (Co). In some implementations, the nanocomposite contains approximately 30 atomic percent of Ni. In some implementations, the resistivity of the crystalline particles is approximately 100 μΩ·cm, and the resistivity of the amorphous matrix is ​​approximately 150 μΩ·cm. In some implementations, the amorphous matrix is ​​annealed to enable the superplastic response of the nanocomposite. In some implementations, the amorphous matrix and crystalline particles within the diffusion barrier include a strain-annealed structure, tuned to a relative permeability of over 10,000. The changes in the magnetic field applied to the crystalline particles occur at frequencies between 400 Hz and 5 kHz. In some implementations, losses include eddy current losses.

[0014] In some embodiments, the rotor comprises one or more layers, each comprising: γ-FeNi nanocrystals in an amorphous matrix, where the γ-FeNi nanocrystals have an average resistivity of less than 100 μΩ·cm and the amorphous matrix has a resistivity of 100 μΩ·cm or more; and one or more boron diffusion barriers between each of the one or more γ-FeNi nanocrystals and the amorphous matrix, each of the one or more diffusion barriers configured to inhibit the diffusive growth of the γ-FeNi nanocrystals during their formation; where the γ-FeNi nanocrystals are approximately 70 atomic % Ni; where the average diameter of the γ-FeNi nanocrystals is 5 nm to 30 nm; and where the thickness of each of the one or more composite layers is less than approximately 25 μm.

[0015] In some implementations, each composite layer is a strain-annealed composite with a relative permeability of over 10,000. In some implementations, each composite layer further contains copper.

[0016] In some implementations, the electric motor includes a rotor and a stator configured to drive the rotor, the stator comprising a number of laminates less than 30 μm thick. Each laminate comprises an iron (Fe)-nickel (Ni) compound and crystalline particles in an amorphous matrix, separated from each other by an amorphous matrix; and one or more barriers between the crystalline particles and the amorphous matrix, the barriers configured to inhibit the growth of crystalline particles during their formation, and one of the one or more barriers is between the crystalline particles and the amorphous matrix; wherein the rotor is configured to operate at frequencies greater than 400 Hz.

[0017] Some implementations involve fabricating amorphous precursors of nanocomposites through heat treatment with and without stress, resulting in unique metastable multiphase metallic structures (or microstructures).

[0018] The stress applied during annealing induces anisotropy that depends on the chemical properties. The anisotropy induced in Fe-rich alloys follows the ribbon axis, increasing permeability. The anisotropy induced in Ni-rich alloys transverses the ribbon axis, resulting in lower permeability. Furthermore, alloying additions can improve resistivity by approximately 40% without significantly affecting magnetic properties. Adding Cu alters the crystallization rate, refining the microstructure and producing smaller particles. Using different glass-forming agents alters formability and affects the mechanical properties of the nanocomposite. Applications of these alloys include high-switching-frequency electric motors, such as axial motors with rare-earth-free permanent magnets, and motor designs using only soft magnetic materials, such as switched reluctance motors.

[0019] In some implementations, the nanocomposite is made of a material in the range of Ni 20% to 80%. The microstructure can be controlled by melt spinning and various post-treatment methods such as strain annealing, allowing the properties to be tuned to meet the requirements of various applications.

[0020] The nanocomposites described below offer several advantages. Certain alloy compositions described below possess an attractive superplastic response that enables more practical stamping of useful shapes. In iron-rich compositions, strain annealing induces anisotropy along the ribbon direction, thereby increasing permeability along the ribbon direction. The crystallization product is γ-FeNi, which is metastable in Fe-rich compositions, in addition to α-FeNi in Fe-rich compositions. The nanocomposites described below improve the efficiency of motors operating at high rotational speeds.

[0021] The nanocomposites described below are useful for high-frequency applications. For example, laminated (or thin-sheet) silicon steel has traditionally been used in motors. However, laminated silicon steel becomes inefficient at high frequencies due to conventional anomalous eddy current losses. Using higher frequencies is attractive due to the potential for higher power output (motor power is the product of torque and rotational frequency). The nanocomposites described below have reduced losses during high-frequency switching of the magnetic field. This allows high frequencies to be applied to motor stators containing nanocomposites without compromising power efficiency and without requiring larger motors. Higher frequencies would allow for a reduction in the size and mass of inductive components. Reduced motor size can result in cost savings. Many motor designs use permanent magnets to generate or induce magnetic flux. Since motor size can be reduced at high frequencies, devices using rare-earth permanent magnets may require significantly less rare-earth material. This is attractive given the cost and procurement concerns of rare-earth metals.

[0022] Details of one or more implementations are described in the attached drawings and the following description. Other features, purposes, and advantages will become apparent from the description, drawings, and claims. [Brief explanation of the drawing]

[0023] [Figure 1]Figure 1 shows a diagram of crystallites (or microcrystals) surrounded by a diffusion barrier in an amorphous matrix. [Figure 2] Figures 2A-2B show examples of Fe-Ni alloys. [Figure 3] Figure 3 shows a comparison of motors. [Figure 4] Figure 4 shows a graph of losses during the magnetic switching cycle. [Figure 5] Figure 5 shows the T0 diagram configuration of a binary alloy. [Figure 6] Figure 6 shows various amorphous alloy matrices. [Figure 7] Figure 7 shows the Fe-Ni binary phase diagram. [Figure 8] Figure 8 shows the saturation magnetization as a function of the composition of the as-cast alloy. [Figure 9] Figure 9 shows the X-ray diffraction pattern. [Figure 10] Figure 10 shows Tg, primary, and secondary crystallization temperatures as a function of composition. [Figure 11] Figure 11 shows the MH data for Fe70Ni30 after casting and after strain annealing. [Figure 12] Figure 12 shows graphs illustrating the HTXRD for each of the Fe-rich Fe-Ni alloys. [Figure 13] Figures 13A-13B show examples of motors. [Figure 14] Figures 14A-14B show the simulation results of glass formation capability (GFA) for various material compositions. [Figure 15] Figure 15 shows an example of a hot rolling mill system for processing one or more alloy compositions. [Figure 16] Figure 16 shows an example of a roll bonding scheme for applying heat to an alloy composition. [Figure 17] Figure 17 shows a graph that includes the change in glass transition temperature Tg with respect to the change in annealing temperature.

[0024] (Detailed explanation) Figure 1 shows a nanocomposite material 100 comprising one or more crystalline particles 110, an amorphous matrix 120, and a diffusion barrier 130. The crystalline particles 110 are formed by a crystallization process, which is described in more detail below. Generally, each crystalline particle 110 (also known as crystallite) contains a small or microscopic "crystal" formed during the cooling of a metallic material, such as an Fe-Ni alloy. The crystalline particles 110 generally contain a regular or nearly regular lattice of atoms, as seen in Figure 1. Grain boundaries are interfaces where crystalline particles come into contact with other materials, such as an amorphous matrix. Generally, the crystalline particles 110 are embedded (e.g., embedded) within an amorphous matrix containing a relatively high resistivity material between crystalline particles with relatively low resistivity. The crystalline particles 110 have an average diameter of 5–30 nm and are formed from Fe-Ni alloys. In some implementations, the nanocomposite contains materials ranging from 20% to 80% Ni. The crystalline particles 110 may have an average size of 5 to 20 nm embedded in the amorphous matrix 120. In some implementations, the crystalline particles 110 include Fe-Ni alloys. The properties of the crystalline particles 110 (e.g., magnetic or resistive properties) can be tuned by adding additional materials. Other metals such as cobalt or copper are included in the crystalline particles 110, as will be described in more detail below. In some implementations, the resistivity, permeability, or other properties of the nanocomposite are tuned using crystalline particles 110 formed from various alloys, such as various Fe-Ni alloys. In some implementations, each crystalline particle 110 is formed from the same material or alloy as the nanocomposite 100. In some implementations, the crystalline particles 110 have a different composition throughout the nanocomposite 100.

[0025] Generally, the amorphous matrix 120 contains metals or metalloids that form amorphous solids, such as solids lacking the long-range order characteristic of crystals. The amorphous matrix 120 has a relatively high resistivity compared to crystalline particles 110. The crystalline particles 110 are located within the amorphous matrix 120 and are generally separated from each other by the amorphous matrix. The resistivity, relative permeability, and other properties of the amorphous matrix 120 can be tuned by adjusting the composition of the amorphous matrix. In some implementations, the amorphous matrix 120 contains one or more metalloids or early transition metals, as described in relation to Figure 6. Generally, the average spacing between crystalline particles 110 provided by the amorphous matrix 120 is smaller than the average diameter of the crystalline particles (e.g., <10-15 nm).

[0026] Generally, the diffusion barrier 130 is a metal or metalloid configured to inhibit the growth of crystalline particles 110 during annealing or other molding processes. By including the material of the diffusion barrier 130, the size of the crystalline particles 110, and therefore the resistivity, relative permeability, etc., of the nanocomposite 100 can be adjusted. In some implementations, the diffusion barrier 130 prevents collisions between the crystalline particles 110.

[0027] Crystallization is a phase transformation controlled by nucleation and growth kinetics. The function of glass-forming agents is to control the crystallization rate. From the Johnson-Mehl-Avrami-Kolmogorov (JMAK) kinetics, the transformed volume fraction (X) can be expressed as a function of temperature (T) and time (t) in a TTT diagram. The JMAK equation is as follows:

[0028]

number

[0029] Here, ti is the incubation (or constant temperature standing: incubation) period, n varies from 1 to 4, and k is the rate constant, which can be expressed as follows.

[0030]

Formula

[0031] From the determination of X at various temperatures, k and Q can be calculated. The JMAK kinetics is based on the following three assumptions that do not hold for nanocomposite systems: 1) growth stops when precipitates collide with each other; 2) 100% of the volume is transformed; and 3) nucleation is uniform.

[0032] However, in the case of nanocrystallization, early transition metal atoms are released from the crystal phase, form a diffusion barrier around the crystal, and delay further growth. This invalidates assumptions 1 and 2, making it necessary to adopt soft impingement corrections. There are several feasible methods for determining X. The T of the amorphous phase C is lower than the T of the crystallite C , crystallization can be confirmed from magnetization data. The magnetization of the sample will initially come only from the amorphous phase. As approaching the T of the amorphous phase C , the magnetization will decrease. When primary crystallization occurs, the magnetization will increase. During cooling, the remaining amorphous phase will contribute to the total magnetization again. By comparing the magnetizations of the initial amorphous phase, the crystalline phase, and the residual amorphous phase, the volume fraction of crystallites can be determined.

[0033] Another method for determining the volume fraction of crystallites is to use XRD. By fitting a Gaussian curve to the peaks present in the diffraction pattern, the peak area can be determined. By comparing the amorphous peak area with the crystalline peak area, the relative proportion can be determined. This is particularly feasible when using synchrotron radiation because the data can have high time resolution.

[0034] Primary crystallization from amorphous materials is beneficial from a device perspective, while secondary crystallization is detrimental to magnetic properties. In secondary crystallization, metalloid and glass-forming elements form crystalline intermetallic compound phases with transition metals. Due to their adverse effects that enable rapid particle growth, it is important to determine the rate of secondary crystallization so that it can be prevented during device use. In some implementations, the crystalline particles 110 in Figure 1 contain metastable face-centered cubic Fe-Ni groups as shown in Figures 2A-2B. Figure 2A shows alloy 200 containing disordered γ-FeNi (white Ni, gray Fe). Figure 2B shows alloy 210 containing L12 FeNi3.

[0035] Phase diagram:

[0036] The binary Fe-Ni phase diagram is shown in Figures 8a-b. The phase boundary is where the Gibbs free energies of the two phases are equal. However, due to the glass-forming agent of the alloy, this system is not in equilibrium. Thus, when the system crystallizes from the amorphous structure after casting, as was the case with the nearly isoatomic FeCo system, it is not possible to confirm whether the resulting crystallites are FeNi3 or γ-FeNi without TEM evidence from XRD or superlattice reflections.

[0037] In addition to the equilibrium phase, Figure 8B shows the T of the γ-FeNi phase and α-Fe phase as a function of composition. C This plots the values. In conventional motor applications, high T C Therefore, the region where Ni is close to 70% is important. Furthermore, when crystallizing Ni3Fe instead of the γ phase, T C The value will be even higher on the Fe-rich side of the diagram, T C It can be quite expensive for motor applications.

[0038] Fe-Ni nanocomposite materials enable a wide range of compositions. Metastable γ-FeNi nanocrystals can be used rather than α-Fe nanocrystals, and they can be used even in Fe-rich compositions. In Ni-rich Fe-Ni nanocomposites, crystallization results in a regular L12 (Figure 1) structure of γ-FeNi or Ni3Fe.

[0039] Some Fe-Ni alloys possess properties that are attractive for specific applications. For example, 50-50Fe-Ni alloys have the highest saturation magnetization. For Ni-rich alloys, 78%Ni permalloy is important because it has a magnetostriction coefficient of zero and a high permeability of approximately 100,000. Since it is not possible to optimize all properties at once, the composition is usually selected considering the specific device application. Recently, Fe-rich Fe-Ni alloys have been found to be suitable for near room temperature temperatures. C Therefore, it has been studied for use in magnetocaloric cooling applications.

[0040] Nanocomposite 100 includes Fe-Ni-based metallic amorphous nanocomposite (MANC) materials for motors with compositions ranging from 20% to 80% Ni. Interestingly, certain iron-rich alloys have evidence of asperomagnetism. Changing the composition of the glass-forming agent also affects castability and mechanical properties. Of the pre-period transition elements, Nb can usually be cast in air, while Hf and Zr cannot. Modifying the metalloid mixture can also improve formability and allow for adjustment of the magnetostrictive coefficient.

[0041] The principle of electric motor operation can be explained by referring to equation (1), which relates Faraday's law of induction to the voltage response of an ideal core driven by an AC current.

[0042]

number

[0043] Here, ω = 2πf, where f is the frequency. Increasing f while keeping all other variables constant allows A to be reduced at a constant voltage. This means that the device size can be reduced by increasing the frequency. However, increasing the frequency increases the losses incurred. Therefore, if a smaller device is desired, materials with low losses at high frequencies must be designed. A motor is measured by its power density, i.e., the amount of power per unit volume of the motor. Figure 3 shows three rotors designed to have equivalent power. The top two are made of Si steel, and the bottom rotor is made of HITPERM alloy. As can be seen, using HITPERM alloy and a larger magnetization allows for a smaller rotor design and a higher power density. A preliminary design by COMSOL Multiphysics suggests that switching from Si steel operating at 60 Hz to Fe-Ni MANC operating at 1 kHz can reduce the motor size by almost 50%. Figure 3 shows a comparison of a Si steel rotor (top) to a HITPERM alloy (bottom) with the same power.

[0044] The nanocomposites described herein include materials for improving the efficiency of motors operating at high rotational speeds by using Fe-Ni nanocomposites, which are more economical than their Co-Fe counterparts for motor applications. The microstructure is controlled by various post-treatment methods such as melt-spinning and strain annealing, as described in more detail below. This process adjusts the properties of various alloys (e.g., permeability, induced anisotropy, grain size) to meet the requirements of various motor applications. For example, in Fe-rich compositions, strain annealing induces anisotropy in the ribbon direction. Furthermore, certain alloy compositions described below have attractive superplastic responses that enable more practical stamping of shapes useful for motor laminates.

[0045] loss:

[0046] Figure 4 shows Graph 400, which represents the three loss sources as a function of frequency. The AC losses of magnetic materials can be divided into those arising from (1) magnetic hysteresis, (2) conventional eddy currents, and (3) anomalous eddy currents. Each of these losses has a different frequency dependence. Hysteresis loss is the energy / volume lost in one magnetic cycle, relating to the area within the hysteresis loop of the material. Since it is constant per cycle, the total power loss is linear with respect to time. The coercivity (H) of the material C When the crystallite size decreases, the hysteresis loss can decrease. This is one reason why using nanocomposite materials is beneficial. When the crystallite size decreases to below a certain amount, H C This decreases significantly, which reduces losses.

[0047] Conventional eddy current losses are related to the fact that AC currents generate an alternating magnetic field that induces eddy currents in the material. These currents heat the material. 2 This causes R power loss. Conventional eddy current loss is described in Equation 2:

[0048]

number

[0049] It has a coefficient b given by Equation 3.

[0050]

number

[0051] Here, t is the thickness and ρ is the resistivity. Therefore, to minimize conventional eddy currents, a thin cross-section and high resistivity are desirable. A thin cross-section can be obtained by melt-spinning the alloy. Relevant variables are wheel speed, casting temperature, discharge pressure, and nozzle-wheel gap distance. Standard silicon steel used in motors has a laminate thickness of nearly 0.6 mm. Using a 25 μm thick ribbon reduces eddy losses by approximately two orders of magnitude. Nanocomposite 100 makes it possible to fabricate ribbons of approximately 15–30 μm. Hysteresis loss and eddy current loss are often expressed by Steinmetz's equation:

[0052]

number

[0053] P is the power loss, and k, α, and β are empirical fits to the data.

[0054] To model the resistivity of nanocomposites, it is beneficial to consider three phases: a crystalline phase, an amorphous phase, and a shell phase consisting mainly of glass-forming agent and growth inhibitor atoms. The advantage of the amorphous structure is that, because it has higher resistivity than the chemically identical crystalline phase, the resistivity of the nanocomposite is higher, thereby reducing conventional eddy current losses. Of the three, the crystalline phase has the lowest resistivity, and the shell has the highest resistivity because it has the highest concentration of glass-forming agent. For example, the resistivity of an amorphous ribbon nanocomposite after casting is approximately 150 μΩ·cm. The resistivity of a crystalline nanocomposite is approximately 100 μΩ·cm. Without a shell, it is assumed that the path to minimize resistance would be to maximize the distance traveled within the crystallite relative to the amorphous matrix. However, a high-resistivity shell complicates this. From previous modeling, it is known that to maximize resistivity, small grain size (e.g., <10-15 nm), high glass-forming agent concentration in the shell, and a thick shell around the crystal are all desirable.

[0055] A third cause of loss is abnormal eddy currents. Abnormal losses are due to the movement of domain walls when the magnetization of the material is switched. Domain wall movement is reduced when magnetic anisotropy is induced so that the magnetic domains align transversely to the ribbon direction in the absence of a magnetic field.

[0056] Relationships in Fe-Ni pseudo-binary systems:

[0057] Glass formation:

[0058] Before tackling the Fe-Ni pseudo-binary system, we investigate the glass-forming ability and nanocrystallization kinetics. The glass-forming ability (GFA) of a material explains the nucleation and suppression of growth of stable crystalline phases. This includes preventing elements in the liquid from being distributed into the crystalline phase. The GFA of a material is determined by its glass-forming temperature (T rg This is related to a decline in ) and can be expressed as follows:

[0059]

number

[0060] Here, T g is the glass transition temperature, T L is the liquidus temperature. g Below this level, the structure freezes, but T g Beyond a certain point, the material becomes capable of viscous flow. To facilitate glass formation, T g We should maximize T L This should be minimized. The thermodynamics of glass formation are shown in Figures 500 and 510. The T0 curves indicate all points where the free energies of the liquid and solid phases are equal. For compositions between the T0 curves, the liquid can only reduce its free energy by diffusion into the α and β phases. Outside the T0 curves, the liquid can form solid crystals without diffusion. Within the T0 curves, the molten material is T g If cooled rapidly enough to a temperature below a certain level, diffusion does not occur, and the atomic structure of the liquid freezes.

[0061] Suzuki has created the first amorphous alloy matrix that can be used to develop nanocrystalline alloys. The matrix is ​​a graphical representation of the Inoue rule for forming magnetic glass. The glass should contain three components with vastly different atomic radii and negative heat of mixing.

[0062] Various combinations of alloys can be seen in Matrix 600 in Figure 6. In Figure 6, FM is a ferromagnetic post-period transition metal element, EM is an early-period transition metal, and ML is a metalloid. Nb is a common EM used as a diffusion growth inhibitor because it allows casting in air, which is important for industrial scale. The diffusion barrier limits primary crystallization, so the resulting crystallites are small. Boron is a preferred metalloid because its solubility in the FM crystals formed during primary crystallization is virtually zero, and T C This increases in the amorphous matrix due to the resulting B enrichment. Silicon is required along with boron to ensure glass-forming ability. The use of other transition metals and metalloids in different amounts is expected to alter the formability of the glass and the mechanical properties of the resulting alloy. Nanocomposites may contain one or more metals, including boron (B), carbon (C), phosphorus (P), silicon (Si), chromium (Cr), tantalum (Ta), niobium (Nb), vanadium (V), copper (Cu), aluminum (Al), molybdenum (Mo), manganese (Mn), tungsten (W), and zirconium (Zr), in amounts of 50 atomic percent or less. In some implementations, the nanocomposites contain 30 atomic percent or less of cobalt (Co).

[0063] Examples of manufacturing and experimental tools:

[0064] The nanocomposite material is (Fe x Ni 1-x ) 80 Nb4Si2B 14It follows the general chemical formula, where x will vary over a wide range. All materials are arc-melted several times from pure elements in a controlled atmosphere to obtain chemical homogeneity. The ingot is then melt-spinned in a controlled atmosphere. To produce amorphous ribbons, all casting conditions such as wheel speed, discharge temperature, discharge pressure, and nozzle wheel distance are controlled. Amorphousness is first checked by a simple bending test. Usually, if the sample is not amorphous, the sample will be very brittle and will break when bent. If it passes the bending test, X-ray diffraction (XRD) will be performed to confirm that the casting is amorphous.

[0065] Once the amorphous ribbon is fabricated, differential scanning calorimetry (DSC) measurements are used to determine the primary and secondary crystallization temperatures, and, if possible, the glass transition temperature. DSC measures the heat supplied to the sample and the reference. The reference and sample are maintained at the same temperature. During the transition, the amount of heat required to maintain the equivalent temperature increases or decreases depending on whether the transition is endothermic or exothermic. By measuring the change in the heat supply rate, the transformation temperature can be estimated.

[0066] By determining the transformation temperature, the activation energy for crystallization can be calculated. The amorphous phase is metastable, and a certain amount of energy is required to nucleate the crystalline phase. This yields the activation energy Q shown in equation (6). The most convenient method for determining the activation energy for crystallization is to use Kissinger's kinetics. Kissinger's equation can be expressed as follows:

[0067]

number

[0068] Here, α is the heating rate, T x Q is the crystallization temperature, and KThis is the activation energy (do not confuse it with the activation energy derived using the Kissinger equation and JMAK kinetics). Next Q K is 1 / T x This is the slope of the line plotting equation (7) on the left side against . One energy barrier contributing to Q is the energy required to nucleate a critical nucleus size. Below the critical size, the formed crystal will be unstable, and due to the solid-liquid interface energy, the free energy will decrease if the crystal dissolves in the liquid. If nuclei larger than the critical size are formed, they will grow during crystallization. During primary crystallization, growth is a temperature-dependent diffusion process and represents another contribution to Q. Primary crystallization is thought to be controlled by volume diffusion that grows parabolic over time, at least until soft impingement occurs. During primary crystallization, the amorphous matrix becomes enriched with the glass-forming elements (or is enriched with the glass-forming elements). Other factors contributing to Q are the decrease in volume free energy from crystallization and the misfit strain energy.

[0069] Because the magnetic properties of the material are important, a vibrating sample magnetometer (VSM) is used to determine the MH loop and MT curve at the relevant magnetic field and temperature, respectively. The operation of the VSM is described by applying Faraday's induction method. A magnetic field is applied to the sample to magnetize it. The sample is connected to a drive head that vibrates the sample at 60 Hz. This generates a spatiotemporally varying magnetic field, which induces a current in a series of pickup coils proportional to the induced magnetization of the sample.

[0070] Using magnetization data, the volume fraction of the crystallized ribbon can also be estimated by utilizing Brillouin function fitting. The function simplifies the spin-only dipole moment into the following form:

[0071]

number

[0072] Here, M is the magnetization and T is the temperature. The magnetization curve can be extrapolated to 0 K using the Brillouin function. If the specific magnetization of the crystalline phase is known, the proportion of the sample that is crystalline can be determined. The amorphous phase is usually T, which is the temperature of primary crystallization. x1 Lower T C It has. Therefore, the amorphous phase of the ribbon after casting is T C The magnetization becomes zero. x1 When this value is reached, the magnetization increases as a function of the transformed volume fraction. After crystallization, the sample is cooled, and the amorphous phase again contributes to the magnetization. By fitting the Brillouin function to the crystalline phase, the magnetization obtained from the presence of crystallites is determined. By comparing this value with the specific magnetization value of the crystallites, the mass percentage of the crystalline phase can be calculated. This technique has been demonstrated in recent publications.

[0073] As mentioned earlier, XRD is used to ensure the amorphous nature of the ribbon after casting, but it is also used to check for phase transformations that occur during annealing. X-ray diffraction instruments basically rely on Bragg's law:

[0074]

number

[0075] As shown in Figure 900 of Figure 9, where n is an integer, λ is the X-ray wavelength, d is the atomic lattice spacing, and θ is the angle between the X-ray and the atomic plane. Conventional XRD devices use a single λ and vary the θ value. Advanced Photon Sources make available energy-dispersive XRD that uses a range of wavelengths and has a fixed θ value.

[0076] The crystallite size after crystallization can also be estimated using Scherrer analysis based on the XRD crystallite size. The diffraction peaks are first fitted to a Gaussian curve. For a Gaussian distribution, the peak width is related to the integral width as follows:

[0077]

number

[0078] Here, β is the integral width and w is the width. Next, instrumental broadening is removed from the peak integral width by quadratic subtraction. The resulting integral width may be attributable to the crystal size. Calculated integral width β s This is used to estimate crystal size using Scherrer's formula:

[0079]

number

[0080] Here, d is the average grain size, and K is a shape factor typically between 0.9 and 1. Generally, the cast material is expected to have a broad amorphous halo. The material that has undergone primary crystallization should have a significantly reduced amorphous halo, but the crystal peaks will still be broad due to the small crystallite size.

[0081] The material can also be subjected to strain annealing, which has multiple effects. Primary and secondary crystallization temperatures are determined from DSC. Next, the cast ribbon is strain annealed between the two temperatures. The ribbon is annealed in a tubular furnace under atmospheric conditions. This creates a nanocomposite, improving the magnetic inductance of the metal flake (or foil). Furthermore, the permeability of the ribbon can be adjusted by changing the stress applied during annealing. After strain annealing, XRD data is collected to confirm crystallization, and magnetic data is collected to confirm the effects of strain annealing. Strain annealing is also used to demonstrate the superplasticity of the amorphous phase. Superplasticity can be simply defined as the ability of a material to undergo large plastic deformation in tensile conditions without fracture. g Metallic glasses exceeding a certain threshold become viscous, supercooled liquids capable of viscous flow.g The viscosity between quenching and crystallization can vary by seven orders of magnitude. These supercooled liquids can experience large plastic strains under applied stress. The processing (or processing) is similar to that of thermoplastics, and moldability is temperature-dependent. The main difference is that, because amorphous glass is metastable, the superplastic formation region of this system is easily limited by the secondary crystallization temperature. Elongation is measured by marking a ribbon with a high-temperature marker before strain annealing and measuring how much the mark moves after the sample has been annealed. The results for the example are (Fe 60 Ni 40 ) 80 Nb4Si2B 14 It shows nearly 100% elongation of the sample.

[0082] Experimental results:

[0083] DSC:

[0084] Glass transition temperature (T g ), primary crystallization temperature (T x1 ) and secondary crystallization temperature (T x2 DSC curves were collected for a wide range of Fe-Ni compositions in which ) was measured. These alloys are brittle at room temperature after primary crystallization, so T g This is important. g Beyond that point, it becomes possible to stamp them into shape for use as motor stators. Furthermore, to know the maximum temperature the material can tolerate before irreparable property damage occurs, T x1 and T x2 It is important to know the temperature range between these points. These results can be seen in Graph 1000 in Figure 10.

[0085] Superplasticity distinguishes certain metallic glasses from other metals by allowing them to be molded and processed like thermoplastics. Stamping allows for stacking many layers to construct components. Figure 13A shows an example of an electric motor 1300 from above, showing the stator 1310 and rotor 1320 containing nanocomposite (e.g., nanocomposite 100 in Figure 1). Figure 13B shows an example of an electric motor 1330 from a side perspective view. The stator 1310 is constructed from a stack 1340 of nanocomposite layers 1340a-n. As described above, layers 1340a-n each have a thickness of less than 30 μm to reduce losses during high-frequency operation. Stacking the nanocomposite layers 1340 is a less expensive manufacturing method than laser cutting, which would otherwise need to be used.

[0086] VSM:

[0087] Figure 800 in Figure 8 shows how the saturation induction of Fe-Ni alloy depends on the Ni content. As expected from the Slater-Pauling curve, induction increases with higher Fe content. The data in Figure 800 in Figure 8 are for the post-cast sample. Towards the Ni-rich end, M S The M of the material after primary crystallization begins to fall below the value required for the application. S This is expected to be higher compared to amorphous material.

[0088] Furthermore, as can be seen in Figure 1000 of Figure 10, an example (Fe 70 Ni 30 ) 80 Nb4Si2B 14For the alloy, MT curves were collected. While magnetization is typically expected to increase with decreasing temperature, it is observed that magnetization eventually begins to decrease with temperature. This can be explained as the spin glass phenomenon. When cooled to temperatures below the ferromagnetic-asperomagnetic (or non-blocking magnetic) transition, the spins freeze tilted toward each other, but all tilt angles are within the hemisphere. Upon heating, the asperomagnetic phase becomes metastable, and as the temperature approaches room temperature, the magnetization approaches the cooling curve. The tilted spins reduce the magnetization usable for motor applications. Due to its temperature dependence, this is a greater concern for cryomotor applications.

[0089] Figure 1100 of Figure 11 shows (Fe 70 Ni 30 ) 80 Nb4Si2B 14 The MH curves are shown for samples cast and strain-annealed at 200 MPa and 470°C. The permeability of the strain-annealed samples is almost an order of magnitude higher than that of the cast samples. We demonstrated an increase in permeability from 4000 to 16000. Since the sign of the magnetostriction coefficient is opposite, Ni-rich ribbons are expected to have the opposite effect. MH data were collected for several other Fe-rich alloys that were cast and strain-annealed. All other alloys show an increase in permeability with strain annealing.

[0090] XRD:

[0091] High-temperature XRD (HTXRD) is shown in Graph 1200 of Figure 12, after casting (Fe 65 Ni 35 ) 80 Nb4Si2B 14The experiment was conducted on alloys. Peaks are matched using a crystal model in CrystalDiffract. Peaks from the corundum background are marked in orange, FCC peaks in green, and BCC peaks in blue. The presence of CuKα1 and Kα2 radiation doubles the corundum peak. As can be seen, the ribbon starts mostly amorphous, but there is a prominent broad FCC{002} peak. Primary crystallization occurs at 500°C, and both FCC and BCC peaks are observed. From previous studies, it is expected that further heating above the α-γ transition temperature of Fe will convert α-Fe to γ-Fe, which will not revert even upon cooling. The phase fractions of crystallites and amorphous matrix can also be determined by fitting Gaussian curves or pseudo-Voigt curves to the peaks. The ratio of peak areas provides the proportion of the phases. (Fe 75 Ni 25 ) 80 Nb4Si2B 14 The values ​​for the base alloy are shown in Graph 1210 of Figure 12.

[0092] Virtual Bound State (VBS) and Resistivity:

[0093] The VBS theory shows that d electrons from dilute transition elements (TEs) transfer the Fermi energy of the parent alloy composed of later-period transition metals (TLs) and are added to empty spin states. Each TE atom will contribute to an empty TL3d state. The TE atoms create perturbation energy wells that scatter conduction electrons, thereby increasing resistivity.

[0094] (Fe 70 Ni 30 ) 80 Nb4Si2B 14 Vanadium was added to the base alloy, and the resistivity was measured in the range of V content from 0.5% to 5%, sacrificing (FeNi). It was found that adding V could increase the resistivity by approximately 40% without significantly degrading the magnetic properties.

[0095] Addition of Cu:

[0096] DSC can provide activation energy for crystallization and abrasion index. (Fe 70 Ni 30 ) 80 Nb4Si2B 14 The abrasion index of the alloy is 2.5, which corresponds to continuous nucleation and three-dimensional crystal growth. However, (Fe 70 Ni 30 ) 79 Nb4Si2B 14 The abrasion index of the Cu1 alloy is 1.5, which corresponds to instantaneous nucleation and three-dimensional growth. This will provide a finer crystalline structure and further reduce losses.

[0097] Figures 14A-14B show simulation results of glass-forming ability (GFA) for various material compositions. As previously mentioned, amorphous metallic nanocomposites (MANCs) are soft magnetic materials consisting of nanocrystalline particles surrounded by an amorphous matrix. They combine higher saturation induction than amorphous metallic ribbons (AMRs) with lower coercivity and higher electrical resistance than crystalline materials, reducing hysteresis and eddy current losses. MANCs are fabricated by planar flow casting in the form of amorphous ribbons and then annealed to induce crystallization. Due to the amorphous precursor to the nanocrystalline state, glass-forming ability (GFA) is important in alloy development. Typically, in AMR and MANA alloys, magnetic induction is sacrificed for glass-forming ability (and resistivity) because the addition of glass-forming elements degrades these properties compared to crystalline materials (e.g., Si steel). Optimization of GFA allows for a reduction in the content of glass-forming agents, resulting in better performance. Advances in MANCE alloys with higher GFA values ​​in the amorphous phase affect the formability of such materials in applications such as hot-stamped motor laminates (e.g., in the case of the motor described in relation to Figures 13A-13B).

[0098] Glass-forming alloys (GFAs) are defined by the minimum cooling rate (Rc) required to form an amorphous material. Because experimentally measuring Rc is difficult, several parameters have been developed to rank the GFAs of amorphous materials. Glass-forming alloys are designed according to three empirical guidelines. First, the material generally contains at least three atomic species. Second, the material contains more than 12% difference in atomic size. Third, there is negative enthalpy of elemental mixing in the liquid phase. The first two rules also stem from the "confusion principle," which states that additional alloy complexity and difference in atomic size complicates the crystallization process, slowing the crystallization rate and increasing the likelihood of amorphous phase formation. In addition to the slow rate, multiple atomic species also reduce the free energy advantage of forming a crystalline phase. Because the alloy has four or more components, the equilibrium structure can have very large unit cells. The long-range order of these phases minimizes the loss of free energy (compared to the liquid) from crystallization. The third rule is based on the need to prevent elements from falling apart in a liquid.

[0099] Models based on atomic size differences have been proposed to explain and predict GFA based on the maximization of liquid density, resulting in the formation of an amorphous phase. As the density of the amorphous phase increases, the driving force for crystallization decreases. Generally, alloys with the smallest volume change during solidification and therefore higher density in the liquid have the highest GFA. Higher density in the liquid phase leads to higher viscosity and a decrease in the free volume of the supercooled liquid; both of these decrease the diffusion rate and slow the rate of crystallization. Such models predict the required concentrations of alloying elements based on the atomic sizes of binary and ternary alloys, but become overly complex for higher-order systems. Another model is the Maximum Possible Amorphization Range (MPAR) model, which correlates the GFA of an alloy system to the compositional range between the maximum solid solubility of the eutectic. This, too, is not practical beyond ternary alloys.

[0100] Kinetic-based predictions of GFA are also possible. High-viscosity alloys tend to have improved GFA because the high viscosity reduces the diffusion rate, slowing down nucleation and growth of crystalline phases. The effect of additional alloying elements on GFA is strongly dependent on the viscosity of the elements in the liquid state. However, measuring viscosity is difficult and therefore cannot be easily used to predict GFA.

[0101] As described above, theories based on the three empirical rules, as well as kinetics, are unable to predict GFA or serve as nothing more than relative guidelines in alloy development. Furthermore, due to significant differences in metallic glass structures, all proposed rules have exceptions, indicating that many possible alloys remain unspecified. The ability to sample a large compositional space and identify superior glass-forming agents would be extremely advantageous for alloy development.

[0102] Furthermore, compositions near or within the eutectic have good GFA (Gross Form Factor). In eutectic alloys, the liquid phase is stable down to lower temperatures, at which point viscosity increases, diffusion slows down, and amorphous structures are formed more easily. In addition, since the material crystallizes into two phases in equilibrium, the alloying elements need to be separated between the phases, resulting in a slower crystallization rate.

[0103] Based on the idea of ​​improving GFA by identifying the eutectic composition, thermodynamic calculations can be used to determine the minimum liquidus temperature for a certain range of compositions.

[0104] Soft magnetic alloys have several key differences from other amorphous alloys. Most amorphous alloys are bulk metallic glass (BMG) containing a very high percentage (>40%) of alloying elements, which allows them to maintain their amorphous state at low cooling rates. In contrast, magnetic alloys typically contain less than 30% alloying elements, and the goal is to reduce this as much as possible. Reducing the amount of alloying elements increases the saturation magnetization and decreases coercivity due to the increased content of magnetic elements. Therefore, soft magnetic alloys fall into the category of limiting glass-forming agents, or alloys that require rapid solidification techniques for their fabrication. This is generally not a significant issue, as thin materials produced by rapid solidification are ideal for reducing eddy current losses. However, the alloy must have sufficient GFA to maintain its amorphous state at cooling rates achievable by rapid solidification.

[0105] Applying the method described above, (Fe 70 Ni 30 ) 80 (B-Si-Nb) 20 Compositions with good glass-forming agent (GFA) in soft magnetic alloy systems were rapidly identified. These systems were investigated using a combination of thermodynamic models and experimental verification, as described below. Using Thermocalc simulations, regions exhibiting minimal liquidus temperature and solidification range were identified by varying Nb, Si, and B across the entire range up to 20%. Furthermore, since one goal in increasing the GFA of soft magnetic alloys is to increase the proportion of magnetic elements, simulations were repeated for alloys with low concentrations of glass-forming agents.

[0106] Furthermore, the fact that the ribbons can be processed into laminates by hot stamping, and that the ribbon thickness, material structure, and anisotropy can be controlled by the rolling process, is advantageous for power magnetic applications. Hot forming of amorphous materials can be performed by blow forming. Alternatively, forming can be performed by pressing into a die at high temperatures. Suitability for such processes can be determined by analyzing the temperature range between the glass transition temperature and the crystallization temperature, and preferred alloy systems are T to allow for a suitable processing temperature window.x T that is significantly lower than g a value is displayed. When the temperature is below T g , the material cannot be deformed, but when the temperature exceeds T g , the material can exhibit viscous flow. When the temperature exceeds T x , crystallization will hinder further deformation. However, in some compositions, high-temperature formability can be maintained by the T of the grain boundary amorphous precursor below the target processing temperature during or after the crystallization stage. Therefore, the effect of the concentration of three glass formers on these temperatures is measured. g Composition selected based on the model

[0107] As shown in graphs 1400 and 1410 respectively, the results of Thermocalc simulations for liquidus temperature and solidification range are shown in Figures 14A and 14B. Graph 1400 shows the liquidus temperature of various compositions. Graph 1410 shows the solidification range of various compositions. GRA ranking is represented by shaded points. As shown in graph 1400, the minimum values of both the liquidus and the solidification range are identified from 0-7% Si, 14-18% B and 0-6% Nb, which are found to have the highest GFA and are considered exemplary embodiments. GFA is ranked by the parameter T

[0108] = (T rg / T g / T l ), and the temperature range ΔT xg = (T x -T g ) was measured. As mentioned above, alloys with a large positive ΔT xg have a wide thermomechanically formable temperature range, but tend to have low GFA related to T rg , so they are promising for hot forming applications. Nevertheless, several exemplary alloys having both good GFA and a large ΔT xg have been identified in this composition range. The T rg , GFA ranking, and ΔT xg are shown in Table 1 below.

[0109] Table 1

[0110] Large ΔT xg Advanced manufacturing processes utilizing alloys

[0111] ΔT xg The unique advantage of alloys with a large positive value is their compatibility with advanced manufacturing processes, including stamping, forming, rolling, and related processes, which can be used to modify the shape of the laminate, the thickness of the ribbon, the anisotropy of the material, and the structure in ways that would otherwise be impossible with existing conventional MANC alloy systems. Several exemplary embodiments are described below, along with the performance advantages of the components for their potential applications and end-uses, and the advanced manufacturing processes enabled by this unique alloy property.

[0112] Hot stamping process

[0113] Laminate stamping is an established process for crystalline soft magnetic alloys used in transformer and motor applications. However, its application to amorphous alloys on a manufacturing scale is severely limited by the extremely hard mechanical properties of the rapidly solidifying ribbon, which tends to cause high wear of the stamping die. g The value of is relatively low (i.e., ΔT xg Amorphous alloys (high) g This offers the possibility of a high-temperature stamping process that is higher but lower than the crystallization temperature. The stamped laminate can then be subjected to a post-stamping annealing treatment to optimize its microstructure and magnetic properties.

[0114] Hot rolling process:

[0115] Rolling is a standard process in the optimization of large-scale soft magnetic crystalline alloys, but its application to amorphous alloys has also been limited by the mechanical properties of amorphous soft magnetic ferromagnets. A particularly attractive aspect of applying the rolling process to amorphous and MANCE alloy systems for soft magnetic applications is the potential to significantly reduce eddy current losses by reducing the ribbon thickness without adversely affecting the overall quality and continuity of the ribbon. Thickness reduction by adjusting the rapid solidification process is limited to about 10-15 microns, as pinholes and other ribbon defects are formed during the casting process as the ribbon thickness decreases, thereby limiting the frequency performance to an upper limit of about 100 kHz. A rolling process to further reduce the thickness of the cast ribbon offers the potential to further reduce eddy current losses and increase the maximum operating frequency of this class of rapidly solidified alloys.

[0116] In addition to reducing thickness, rolling can enable the use of novel anisotropy mechanisms, including crystallographic texture and slip-induced anisotropy. ΔT xg High-quality alloys are T g and T x It is highly suitable for hot rolling applications at temperatures between [temperature range], where viscous flow is activated without crystallization, and successful thickness reduction can be ensured without ribbon breakage or defects. Subsequent heat treatment can be applied to the ribbon to optimize its magnetic properties. In some cases, the grain boundary amorphous phase is sufficiently low T g Designed to retain magnetic properties, MANCE alloys are compatible with hot rolling processes without requiring a two- or multi-step process scheme to reduce thickness before partial devitrification to optimize magnetic properties. In some cases, a unique induced anisotropy mechanism can be utilized by controlling the shape of embedded nanocrystals, crystallographic texture, bond orientation configuration, and defect structure through hot rolling combined with or following a crystallization process.

[0117] Figure 15 shows a schematic diagram of a hot rolling mill system 1500 in which a driven heated nip roller pulls the material away from the dancer and rewinds it into a slip clutch rewinding device. A height-adjustable heated nip roller 1518 is supplied with pneumatic pressure to contact and feed the strip 1506 through the roll assembly. The system 1500 includes a feed spool 1502 and a rewind spool 1504. Ribbon material 1506 is fed through the system 1500. The ribbon material 1506 is fed onto a dancer arm 1510 driven by a motor control 1512. The ribbon material 1506 moves through a guide roller 1508a to a height-adjustable heated nip roller 1518. The heated nip roller presses the ribbon material 1506 onto the idler roller 1514 and across the drive roller 1516. The ribbon material 1506 is immediately annealed and then guided through guide rollers 1508b and 1508c to the rewind spool 1504.

[0118] Inductive rolling process / roll bonding process:

[0119] In some implementations, it is desirable to avoid direct heating of rolls requiring large thermal mass, and rolls specially designed to retain mechanical properties, as well as oxidation during long-term operation of the hot rolling process. Another processing approach involves directly inductively heating the material being processed by applying an RF electromagnetic potential to the entire roll, which induces heating associated with highly localized eddy current losses within the strip material. In this way, combined with the application of mechanical stress due to the presence of the roll, very fast heating rates can be achieved within the ribbon. This alternative processing scheme does not require providing continuous thermal excitation to the roll or maintaining a constant high operating temperature, thus reducing wear, oxidation, and degradation of mechanical properties, making the process scalable and manufacturable.

[0120] Local induction annealing also offers advantages in that it further optimizes the heat treatment, which can result in a favorable, predetermined optimized metal structure, achieved in other MANCE compositions with significant associated saturation induction through rapid thermal annealing procedures. In addition to hot rolling of rapidly solidifying metal strip materials, more advanced processes are also conceivable, including roll bonding with other metals to optimize mechanical, electrical, and / or magnetic properties. For example, to produce an optimized MANCE metal structure, roll bonding with a thin Al foil or other oxidizable metal, followed by an oxidation step during thermal annealing, may increase stack resistance, reduce associated eddy current losses, and raise the maximum operating temperature for performance.

[0121] Figure 16 shows an example of a roll bonding system 1600. The rollers 1602a and 1602b can be directly heated thermally, or an applied RF potential can be applied to the rollers to induce heating of the base material 1606 and cladding material 1604 through eddy currents.

[0122] Hot forming and blow forming processes:

[0123] The formation of conventional soft magnetic crystalline alloys is a significant challenge due to the degradation of magnetic properties caused by mechanical formation, as an ideal metallic structure exhibits large particles with minimal defects to avoid pinning of magnetic domain walls and associated magnetic losses. The formation of amorphous alloys above the glass transition temperature has been an advantage utilized in many structural material applications, such as bulk metallic glasses. However, the forming process is T g Because crystallization occurs at a temperature where formability is improved by viscous flow exceeding ΔT, this has not been used in soft magnetic amorphous alloys until now. The newly developed MANCE alloy mentioned above has a high ΔT xg This provides an opportunity for forming and blow forming soft magnetic alloys, and a subsequent crystallization process allows for the successful optimization of the metallic structure and magnetic properties to the desired final shape.

[0124] Molding after nanocrystallization

[0125] Since MANC materials have a residual amorphous phase, the above process can be applied to materials that have already undergone nanocrystallization. Because the crystalline particles are too small to be significantly deformed, this requires a large ΔT in the residual amorphous phase. xg This will be necessary. During the nanocrystallization process, glass-forming elements are released from the crystal into the residual amorphous matrix, changing its composition. Therefore, even if it is large in the amorphous precursor, a large ΔT will be required. xg The existence of is not clear. As shown in Graph 1700 in Figure 17, a large ΔT xg To confirm, (Fe 70 Ni 30 ) 80 B 15 Si0Nb5 and (Fe 70 Ni 30 ) 80 B 12 The Si3Nb5 sample was crystallized to various degrees, T g The following was measured. Graph 1700 shows the T due to annealing temperature. g This shows a change, indicating that the change in glass transition temperature due to crystallization is relatively small. In a completely crystallized sample, T g Although it could not be identified, in the partially crystallized sample, T g No significant changes were observed in T x This has not changed. As a result, the ΔT of the crystallized sample xg It is confirmed that it is large.

[0126] Fe-Ni nanocomposite materials are a relatively unexplored alloy system, more affordable than Fe-Co alloys, and still guaranteed to possess excellent soft magnetism. Nanocomposite alloys can be used in motor applications where maximum saturation magnetization is desired. Sufficiently high Curie and secondary crystallization temperatures are also important. Because nanocomposite alloys are deformable above their glass transition temperature, they can be easily molded into motor rotors or stators. These alloys offer higher efficiency at high frequencies than Si steel, which is commonly used in motors.

[0127] Other embodiments are within the scope of the specification, claims, and ideas. Furthermore, due to the nature of software, the above functions can be implemented using software, hardware, firmware, hardwiring, or a combination thereof. The features implementing the functions can also be physically located in various locations, including being distributed so that some of the functions are implemented in different physical locations. The use of the term “one(a)” in this specification and throughout the application is not used in an restrictive manner and therefore does not mean to exclude multiple meanings of the term “one(a)” or the meaning of “one or more.” Furthermore, to the extent that priority is claimed to the provisional patent application, it should be understood that the provisional patent application is not restrictive and includes examples of how the technology described herein may be implemented.

[0128] Therefore, it will be apparent that the above objectives are efficiently achieved among those revealed above, and that certain modifications may be made when implementing the above methods and in the above structure. Without departing from the spirit and scope of this disclosure, all matters included in the above description and shown in the accompanying drawings are intended to be interpreted as illustrative rather than restrictive.

[0129] Several exemplary implementations of nanocomposites have been described. Nevertheless, those skilled in the art will understand that various modifications can be made without departing from the ideas and scope of the described embodiments. The disclosures in this specification may include the following aspects: [Aspect 1] Crystalline particles in an amorphous matrix, wherein the crystalline particles contain an iron (Fe)-nickel (Ni) compound and are separated from each other by the amorphous matrix; and A nanocomposite comprising one or more barriers between the crystalline particles and the amorphous matrix, wherein the barriers are configured to inhibit the growth of the crystalline particles during their formation, and one of the barriers is located between the crystalline particles and the amorphous matrix; The amorphous matrix contains an increased resistivity compared to the resistivity of the crystalline particles. A nanocomposite in which the amorphous matrix is ​​configured to reduce the loss of crystalline particles caused by changes in the magnetic field applied to the crystalline particles, compared to the loss of crystalline particles that would occur in the absence of the amorphous matrix. [Aspect 2] The nanocomposite according to embodiment 1, wherein the crystalline particles contain metastable, face-centered cubic Fe-Ni groups. [Aspect 3] The nanocomposite according to embodiment 2, wherein the Fe-Ni group includes γ-FeNi nanocrystals. [Aspect 4] The nanocomposite according to Embodiment 1, wherein the barrier comprises niobium (Nb), and the amorphous matrix comprises boron (B) and silicon (Si) configured together to enable the glass-forming ability of the amorphous matrix. [Aspect 5] The nanocomposite according to embodiment 1, further comprising a copper (Cu) nucleating agent configured to increase the nucleation of crystalline particles during a molding process compared to the nucleation of crystalline particles during a molding process without a copper nucleating agent, wherein, as a result of the increased nucleation, the number of crystalline particles is reduced by 10% or more. [Aspect 6] The nanocomposite according to embodiment 1, wherein the crystalline particles include an average diameter of 5 to 20 nm. [Aspect 7] The nanocomposite according to embodiment 1, which forms a ribbon with a thickness of 15 to 30 μm. [Aspect 8] The nanocomposite according to embodiment 7, which includes magnetic anisotropy that is longitudinal along the ribbon. [Aspect 9] Furthermore, the nanocomposite according to Embodiment 1 contains 50 atomic percent or less of one or more metals, including boron (B), carbon (C), phosphorus (P), silicon (Si), chromium (Cr), tantalum (Ta), niobium (Nb), vanadium (V), copper (Cu), aluminum (Al), molybdenum (Mo), manganese (Mn), tungsten (W), and zirconium (Zr). [Aspect 10] The nanocomposite according to embodiment 1, comprising 30 atomic percent or less of cobalt (Co). [Aspect 11] The nanocomposite according to embodiment 1, comprising approximately 30 atomic percent Ni. [Aspect 12] The nanocomposite according to embodiment 1, wherein the resistivity of the crystalline particles is about 100 μΩ·cm and the resistivity of the amorphous matrix is ​​about 150 μΩ·cm. [Aspect 13] The nanocomposite according to embodiment 1, wherein the amorphous matrix is ​​annealed to enable the superplastic response of the nanocomposite. [Aspect 14] The nanocomposite according to embodiment 1, wherein the crystalline particles and diffusion barrier in the amorphous matrix include a strain-annealed structure adjusted to a relative permeability of more than 10,000. [Aspect 15] The nanocomposite according to embodiment 1, wherein the change in the magnetic field applied to the crystalline particles occurs at a frequency of 400 Hz to 5 kHz. [Aspect 16] The nanocomposite according to embodiment 1, wherein the loss includes eddy current loss. [Aspect 17] One or more composite layers, each of which is a composite layer comprising γ-FeNi nanocrystals in an amorphous matrix having an average resistivity of less than 100 μΩ·cm, and the amorphous matrix having a resistivity greater than 100 μΩ·cm; and The present invention comprises one or more boron diffusion barriers located between one or more γ-FeNi nanocrystals and the amorphous matrix, each of which is configured to inhibit the diffusive growth of the γ-FeNi nanocrystals during their formation; The aforementioned γ-FeNi nanocrystal has Ni at approximately 70 atomic percent. The average diameter of the γ-FeNi nanocrystals is 5 nm to 30 nm. A rotor laminate in which one or more composite layers each have a thickness of less than approximately 25 μm. [Aspect 18] The rotor laminate according to embodiment 17, wherein each composite layer is a strain-annealed composite having a relative permeability of more than 10,000. [Aspect 19] The rotor laminate according to embodiment 17, wherein each of the composite layers further contains copper. [Aspect 20] An electric motor comprising a rotor and a stator configured to drive the rotor, The stator comprises a number of laminates with a thickness of less than 30 μm, and each laminate is: Crystalline particles in an amorphous matrix, wherein the crystalline particles contain an iron (Fe)-nickel (Ni) compound and are separated from each other by the amorphous matrix; and One or more barriers between the crystalline particles and the amorphous matrix, wherein the barriers are configured to inhibit the growth of the crystalline particles during their formation, and one of the one or more barriers is located between the crystalline particles and the amorphous matrix; The rotor is an electric motor configured to operate at a frequency exceeding 400 Hz.

Claims

1. Crystalline particles in an amorphous matrix, wherein the crystalline particles contain an iron (Fe)-nickel (Ni) compound and are separated from each other by the amorphous matrix; and A nanocomposite comprising one or more barriers between the crystalline particles and the amorphous matrix, wherein the barriers are configured to inhibit the growth of the crystalline particles during their formation, and one of the one or more barriers is located between the crystalline particles and the amorphous matrix; The amorphous matrix contains an increased resistivity compared to the resistivity of the crystalline particles. The amorphous matrix is ​​configured to reduce the loss of crystalline particles caused by changes in the magnetic field applied to the crystalline particles, compared to the loss of crystalline particles that would occur in the absence of the amorphous matrix. (Fe ７０ Ni ３０ ) ８０ (B ｘ -Si ｙ -Nb ｚ ) ２０ A nanocomposite having the following composition, where 20x / 100 = 12 to 18, 20y / 100 = 0 to 7, 20z / 100 = 0 to 6, and x + y + z = 100, A nanocomposite in which a portion of the composition is substituted so as to be included in the nanocomposite, wherein the copper nucleating agent is configured to increase the nucleation of the crystalline particles during the molding process compared to the nucleation of the crystalline particles during the molding process without the copper nucleating agent, and as a result of the increased nucleation, the number of crystalline particles is reduced by 10% or more.

2. The nanocomposite according to claim 1, wherein the crystalline particles contain metastable, face-centered cubic Fe-Ni groups.

3. The nanocomposite according to claim 2, wherein the Fe-Ni group comprises γ-FeNi nanocrystals.

4. The nanocomposite according to claim 1, wherein the barrier comprises niobium (Nb), and the amorphous matrix comprises boron (B) and silicon (Si) configured together to enable the glass-forming ability of the amorphous matrix.

5. The nanocomposite according to claim 1, wherein the crystalline particles include an average diameter of 5 to 20 nm.

6. The nanocomposite according to claim 1, comprising a ribbon with a thickness of 15 to 30 μm.

7. The nanocomposite according to claim 6, comprising magnetic anisotropy that is longitudinal along the ribbon.

8. The nanocomposite according to claim 1, wherein the resistivity of the crystalline particles is about 100 μΩ·cm and the resistivity of the amorphous matrix is ​​about 150 μΩ·cm.

9. The nanocomposite according to claim 1, wherein the amorphous matrix is ​​annealed to enable the superplastic response of the nanocomposite.

10. The nanocomposite according to claim 1, wherein the crystalline particles and diffusion barrier in the amorphous matrix include a strain-annealed structure adjusted to a relative permeability of more than 10,000.

11. The nanocomposite according to claim 1, wherein the change in the magnetic field applied to the crystalline particles occurs at a frequency of 400 Hz to 5 kHz.

12. The nanocomposite according to claim 1, wherein the loss includes eddy current loss.

13. One or more composite layers, each of which comprises γ-FeNi nanocrystals in an amorphous matrix having an average resistivity of less than 100 μΩ·cm, and the amorphous matrix having a resistivity greater than 100 μΩ·cm; and The present invention comprises one or more boron diffusion barriers located between one or more γ-FeNi nanocrystals and the amorphous matrix, each of which is configured to inhibit the diffusive growth of the γ-FeNi nanocrystals during their formation; The γ-FeNi nanocrystals have Ni content of approximately 70 atomic percent. The average diameter of the γ-FeNi nanocrystals is 5 nm to 30 nm. Each of the aforementioned one or more composite layers has a thickness of less than approximately 25 μm. The one or more composite layers are (Fe ７０ Ni ３０ ) ８０ (B ｘ -Si ｙ -Nb ｚ ) ２０ having a composition where 20x / 100 = 12 to 18, 20y / 100 = 0 to 7, 20z / 100 = 0 to 6, and x+y+z = 100, A rotor laminate in which a portion of the composition is substituted so that a copper (Cu) nucleating agent is included in one or more composite layers, the copper nucleating agent is configured to increase the nucleation of the crystalline particles during the molding process compared to the nucleation of the crystalline particles during the molding process without the copper nucleating agent, and as a result of the increased nucleation, the number of crystalline particles is reduced by 10% or more.

14. The rotor laminate according to claim 13, wherein each composite layer is a strain-annealed composite having a relative permeability of more than 10,000.

15. An electric motor comprising a rotor and a stator configured to drive the rotor, The stator comprises a number of laminates with a thickness of less than 30 μm, each laminate being: Crystalline particles in an amorphous matrix, wherein the crystalline particles contain an iron (Fe)-nickel (Ni) compound and are separated from each other by the amorphous matrix; and One or more barriers between the crystalline particles and the amorphous matrix, wherein the barriers are configured to inhibit the growth of the crystalline particles during their formation, and one of the one or more barriers is located between the crystalline particles and the amorphous matrix; The rotor is configured to operate at a frequency exceeding 400 Hz. Each of the aforementioned laminates is (Fe ７０ Ni ３０ ) ８０ (B ｘ -Si ｙ -Nb ｚ ) ２０ It has the following composition: 20x / 100 = 12 to 18, 20y / 100 = 0 to 7, 20z / 100 = 0 to 6, and x + y + z = 100. An electric motor wherein a portion of the composition is substituted so that a copper (Cu) nucleating agent is included in each of the laminates, and the copper nucleating agent is configured to increase the nucleation of the crystalline particles during the molding process compared to the nucleation of the crystalline particles during the molding process without the copper nucleating agent, and as a result of the increased nucleation, the number of crystalline particles is reduced by 10% or more.

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