A post-processing method to simultaneously improve the plasticity and soft magnetic properties of iron-based metallic glasses

Abstract

This invention belongs to the field of heat treatment technology for iron-based metallic glasses, specifically relating to a post-treatment method that simultaneously improves the plasticity and soft magnetic properties of iron-based metallic glasses. The method is characterized by the following steps: first, subjecting the iron-based amorphous ribbon to a low-temperature thermal cycling treatment, followed by annealing; the low-temperature thermal cycling treatment involves immersing the iron-based amorphous ribbon in liquid nitrogen for 3-240 seconds, then transferring it to a drying device to dry to room temperature, which constitutes one cycle, with the low-temperature thermal cycling treatment lasting for 20-60 minutes; the annealing temperature is 700-850 K, and the annealing time is 40-80 minutes. This method achieves a synergistic improvement in the plasticity and soft magnetic properties of iron-based metallic glasses.

Description

Technical Field

[0001] This invention belongs to the field of heat treatment technology for iron-based metallic glasses, specifically relating to a post-treatment method that simultaneously improves the plasticity and soft magnetic properties of iron-based metallic glasses. Background Technology

[0002] The statements herein provide only background information in relation to this invention and do not necessarily constitute prior art.

[0003] Ferrometallic glasses (MG) exhibit excellent soft magnetic properties, making them ideal for applications in the power industry and electronic information technology. However, their widespread use is hindered by their lack of plasticity. To improve the plasticity of MG, much research has focused on compositional design, including the addition of elements with high Poisson's ratios, such as Cu, Ni, and Mo. However, this approach has been shown to reduce the glass-forming ability (GFA) and soft magnetic properties of MG.

[0004] Recently, rejuvenation processes have attracted widespread attention due to their ability to enhance the energy state of mineral gallium (MG) and improve its mechanical and functional properties. Traditional rejuvenation methods, such as high-pressure torsion, room-temperature rolling, and shot peening, are limited to large MG blocks. In contrast to these mechanical methods, low-temperature thermal cycling (CTC) treatment, as an emerging rejuvenation method, has been widely used due to its simple operation, lack of limitations on sample size, uniform rejuvenation effect, and non-destructive nature.

[0005] CTC-induced rejuvenation of MG is generally attributed to non-affine thermal strain caused by structural inhomogeneities. For iron-based MG, strictly defined soft magnetic properties are related to the annealed sample. Although existing techniques document the enhancement of annealed [(Fe] MG] by CTC treatment... 0.5 Co 0.5 ) 0.75 B 0.2 Si 0.05 ] 96 While Nb4MG exhibits improved plasticity, this improvement comes at the cost of its soft magnetic properties, and it is rare to achieve a synergistic improvement in both plasticity and soft magnetic properties in annealed iron-based MG. Summary of the Invention

[0006] In view of the shortcomings of the existing technology, the purpose of this invention is to provide a post-processing method that simultaneously improves the plasticity and soft magnetic properties of iron-based metallic glasses.

[0007] To achieve the above objectives, the present invention is implemented through the following technical solution: In a first aspect, the present invention provides a post-processing method for simultaneously improving the plasticity and soft magnetic properties of iron-based metallic glasses, comprising the following steps: The iron-based amorphous ribbon is first subjected to low-temperature thermal cycling treatment, and then annealed. The low-temperature thermal cycling treatment involves immersing the iron-based amorphous ribbon in liquid nitrogen for 3-240 seconds, then transferring it to a drying device to dry to room temperature. This constitutes one cycle, and the low-temperature thermal cycling treatment lasts for a total of 20-60 minutes. The annealing temperature is 700-850K, and the annealing time is 40-80min.

[0008] Secondly, the present invention provides an iron-based metallic glass prepared by the post-processing method.

[0009] The beneficial effects achieved by one or more embodiments of the present invention described above are as follows: The two-step heat treatment method of this invention combines CTC treatment with post-annealing treatment. In contrast to the structural relaxation caused by typical annealing, this method achieves rejuvenation in the annealed 1K107b alloy (Fe). 73.5 Cu1Nb3Si 15.5 In B7MG, the flow units increase, while large α-Fe nanocrystals are formed. The interaction between these two structural features contributes to the synergistic improvement of plasticity and soft magnetic properties.

[0010] This invention adjusts the microstructure and energy state of the quenched amorphous alloy before annealing by adjusting the cycling parameters during the low-temperature thermal cycling process, so that it forms an anti-free volume defect after annealing. This not only preserves the rejuvenating effect of the low-temperature thermal cycling process in the final annealed alloy, but also further increases the degree of rejuvenation, thereby overcoming the problem of reduced plasticity usually caused by annealing. Attached Figure Description

[0011] The accompanying drawings, which form part of this invention, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an improper limitation of the invention.

[0012] Figure 1 In the figure, (a) is a schematic diagram of the two-step heat treatment process; (b) is the XRD spectrum of the quenched and CTC-treated samples; (c) is the DSC curve of the quenched and CTC-treated samples, with the inset showing an enlarged view of the exothermic peak represented by the black dashed box; (d) is the change of the relaxation enthalpy of the CTC-treated sample with the holding time in a single cycle. Figure 2 In the figure, (a) shows the hardness (left) and elastic modulus (right) values ​​of the quenched and CTC-treated samples; (b) shows the force-depth curves of the quenched and CTC-treated samples; (c) and (b) are magnified views of the areas indicated by the black dashed boxes; (d) shows the strain rate sensitivity curves of samples HT0, HT3, HT60 and HT240, with the arrows indicating the location of their initial pop events. Figure 3In the figure, (a) is HT0, (b) is HT3, (c) is HT60, (d) is the surface morphology near the fracture of HT240 sample; (e) is a schematic diagram of the sample bending fracture. Figure 4 In the figure, (a) is the XRD pattern of the annealed sample; (b) is the high-resolution transmission electron microscope image of the sample HTO-AN; (c) is the DSC curve of the annealed sample, with the inset showing a magnified view of the α-Fe crystallization peak; and (d) is the graph showing the change of crystallization enthalpy of the annealed sample with the holding time in a single cycle. Figure 5 In the figure, (a) shows the changes in relaxation enthalpy (curve), hardness (left), and elastic modulus (right) of the annealed sample with the holding time in a single cycle; (b) shows the force-depth curve of the annealed sample.

[0013] Figure 6 In the figure, (a) shows the magnetization curve and hysteresis loop of the CTC-treated sample (see inset); (b) coercivity and (c) saturation magnetic induction values ​​of the CTC-treated and annealed samples, with the inset showing an enlarged view of the coercivity value of the annealed sample; (d) a comparison of the fluctuations between relaxation enthalpy and saturation magnetic induction of different CTC-treated samples. Figure 7 High-resolution transmission electron microscopy images of samples (a) HT0, (b) HT3, (c) HT60 and (d) HT240, with insets showing the corresponding selected area electron diffraction images; two-dimensional autocorrelation analysis images of (eh) and (ad), with crystalline ordered structures highlighted in red boxes, and percentages representing the proportion of crystalline ordered structures. Figure 8 High-resolution HAADF-STEM images of (a) HT0, (b) HT3, (c) HT60 and (d) HT240 samples; (ei) energy dispersive spectroscopy of five elements in sample HT0. Figure 9 In the image, (a-1-d-1) are bright-field images of the annealed samples (a) HT0-AN, (b) HT3-AN, (c) HT60-AN and (d) HT240-AN; (a-2-d-2) are the corresponding selected area electron diffraction images; (a-3-d-3) is the copper cluster distribution image; and (a-4-d-4) is the histogram of α-Fe nanocrystal distribution. Figure 10 The values ​​represent the relaxation enthalpy and hardness of the quenched and annealed samples, with the red line representing the rejuvenation process and the blue line representing the relaxation process. Figure 11In the figure, (a) represents the normalized relaxation enthalpy ΔHrel / ΔHrel,0 for different samples; (b) is a schematic diagram of the microstructure evolution of HT3-AN and HT240-AN samples during the entire two-step heat treatment process; and (c) is an evolution diagram of the energy state of different samples on the potential energy landscape. Detailed Implementation

[0014] It should be noted that the following detailed description is illustrative and intended to provide further explanation of the invention. Unless otherwise specified, all technical and scientific terms used in this invention have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains.

[0015] To address the technical problems mentioned in the background art, the present invention provides a post-processing method for simultaneously improving the plasticity and soft magnetic properties of iron-based metallic glasses, comprising the following steps: The iron-based amorphous ribbon is first subjected to low-temperature thermal cycling treatment, and then annealed. The low-temperature thermal cycling treatment involves immersing the iron-based amorphous ribbon in liquid nitrogen for 3-240 seconds, then transferring it to a drying device to dry to room temperature. This constitutes one cycle, and the low-temperature thermal cycling treatment lasts for a total of 20-60 minutes. The annealing temperature is 700-850K, and the annealing time is 40-80min.

[0016] The immersion time in liquid nitrogen can be 3s, 5s, 10s, 15s, 20s, 25s, 30s, 35s, 40s, 45s, 50s, 55s, 60s, 65s, 70s, 75s, 80s, 85s, 90s, 95s, 100s, 105s, 110s, 115s, 120s, 125s, 130s, 135s, 140s, 145s, 150s, 155s, 160s, 165s, 170s, 175s, 180s, 185s, 190s, 195s, 200s, 205s, 210s, 215s, 220s, 225s, 230s, 235s, or 240s.

[0017] In some embodiments, the iron-based amorphous nanoribbon is selected from 1K107b or 1K107a.

[0018] In some embodiments, the low-temperature thermal cycling treatment lasts for 30-50 minutes. For example, it can be 30 minutes, 31 minutes, 32 minutes, 33 minutes, 34 minutes, 35 minutes, 36 minutes, 37 minutes, 38 minutes, 39 minutes, 40 minutes, 41 minutes, 42 minutes, 43 minutes, 44 minutes, 45 minutes, 46 minutes, 47 minutes, 48 ​​minutes, 49 minutes, or 50 minutes.

[0019] Preferably, the low-temperature thermal cycling treatment lasts for 35-45 minutes.

[0020] In some embodiments, the drying temperature is room temperature.

[0021] In some embodiments, the annealing temperature is 750-850K. For example, it can be 750K, 755K, 760K, 765K, 770K, 775K, 780K, 785K, 790K, 795K, 800K, 805K, 810K, 815K, 820K, 825K, 830K, 835K, 840K, 845K, or 850K.

[0022] Preferably, the annealing temperature is 750-800K.

[0023] In some embodiments, the annealing time is 50-70 minutes, preferably 55-65 minutes.

[0024] For example, the annealing time can be 50 min, 55 min, 60 min, 65 min, or 70 min.

[0025] Secondly, the present invention provides an iron-based metallic glass prepared by the post-processing method.

[0026] The present invention will be further described below with reference to the embodiments.

[0027] Example 1 The nominal composition of the 1K107b alloy ingot is Fe. 73.5 Cu1Nb3Si 15.5 B7 is synthesized by arc melting a mixture of constituent elements with a purity exceeding 99.9% in a high-purity argon atmosphere. Amorphous ribbons approximately 30 μm thick and 5 mm wide are produced using single-roll melt spinning at a speed of approximately 46 m / s. The ribbons are then cut to appropriate dimensions using ceramic shears. Subsequently, CTC treatment is performed at different holding times (HT) for a total duration of 40 minutes, followed by a 60-minute post-annealing treatment at 773 K. Note that the holding time (ta) mentioned here refers to the time spent in liquid nitrogen (or at room temperature) in each cycle.

[0028] The specific process is as follows: Figure 1As shown in Figure a, during CTC treatment, the strips were initially immersed in liquid nitrogen (77 K) for a specified duration ta (ta = 3 s, 15 s, 30 s, 60 s, 120 s, and 240 s). They were then immediately dried to room temperature (300 K) using a drying apparatus (Philips, Hp8132) for the same duration ta, constituting one cycle. The maximum degree of rejuvenation induced by CTC typically occurs within a relatively short treatment time. Therefore, a total duration of 40 minutes was chosen for CTC treatment of all samples, and the number of cycles (C) was calculated using the following formula: .

[0029] The quenched and CTC-treated samples were designated as HT0, HT3, HT15, HT30, HT60, HT120, and HT240, corresponding to different holding times ta in each cycle. The associated annealed samples were labeled HT0-AN, HT3-AN, HT15-AN, etc. The ta and C values ​​for each sample are shown in Table 1, where the total CTC treatment time is 40 minutes.

[0030] Table 1. Holding time (ta) and number of cycles (C) for different samples in a single cycle.

[0031] The amorphous structure of the samples was analyzed using X-ray diffraction (XRD, DMAX-2500PC) under Cu target Kα radiation. The thermal properties of the samples were measured by differential scanning calorimetry (DSC) (Netzsch DSC404) under an argon atmosphere. Initially, an empty crucible was heated to 1073 K at a constant rate of 20 K / min, followed by cooling to room temperature. The samples were then placed in the crucible, and a second experiment was performed under the same conditions. The baseline obtained from the first run was subtracted from the DSC curves generated during the second run. The relaxation enthalpy (ΔHrel) of the samples was calculated based on the DSC curves. Each sample was measured three times to ensure the accuracy of its ΔHrel. In this invention, all error bars represent the standard deviation of the mean. The force-depth profile, hardness (H), and modulus (Er) of the samples were measured using nanoindentation testing (TI 980 Tribolndeter) under a load control mode with a peak load of 5 mN.

[0032] To further evaluate plasticity, the surface morphology near the fracture of the samples was observed using a Zeiss field emission scanning electron microscope (FSEM, Gemini 500, Zeiss). The coercivity (Hc) of the samples was measured using a DC-BH loop tracer (MATS-2010SD) at a field strength of 1000 a / m. The saturation magnetic induction density (Bs) of the samples was determined using a vibrating sample magnetometer (VSM, JDAW-2000D) at a maximum applied magnetic field of 8000 Oe (approximately 640,000 a / m). The nanoscale microstructure of various samples was analyzed using a high-resolution transmission electron microscope (HRTEM) with aberration correction (FEI Talos F200X) at 200 kV. Samples used for HRTEM analysis were thinned by ion milling under liquid nitrogen cooling conditions. The nanoscale elemental distribution was analyzed by energy-dispersive X-ray spectroscopy (EDS) in the HRTEM.

[0033] Figure 1 Figure b shows the XRD patterns of the quenched and CTC-treated samples. It indicates that all diffraction patterns exhibit a broad peak without a discernible Bragg peak, suggesting that the samples maintained their amorphous structure before and after CTC treatment. The DSC curves of various samples are shown below. Figure 1 As shown in Figure c, the inset provides a magnified view of the exothermic peak observed before crystallization. ΔHrel represents the degree of rejuvenation or the number of flow units in the CTC-treated sample, determined by calculating the area of ​​the exothermic peak. Figure 1 Figure d shows the relationship between the ΔHrel value and the holding time in each cycle ta. An increase in the ΔHrel value was found in the CTC-treated samples, thus confirming the occurrence of the rejuvenation process and the increase in flow unit. Furthermore, with the increase of ta, corresponding to a decrease in the number of cycles (C), the change in ΔHrel can be divided into four distinct phases, such as... Figure 1 As indicated by the arrow in d. This change is similar to the quasi-periodic characteristics of the ΔHrel change observed in La-based MGs, reflecting the competition between rejuvenation and relaxation processes in iron-based MGs.

[0034] The mechanical properties of quenched and CTC-treated samples were characterized by nanoindentation tests for H, Er, and typical force-depth curves. Figure 2 As shown in Figure a, the H and Er values ​​of the rejuvenated sample decreased compared to the quenched sample HT0. For these rejuvenated samples, both parameters initially increased with the increase of ta until ta reached 120 seconds, after which they began to decrease. Figure 2 The force-depth curve shown in Figure b indicates that the maximum indentation depth increases in the rejuvenated sample, and the relationship between the maximum depth and ta is the opposite of that between H and ta. Since the maximum indentation depth can be used as an indicator of the degree of plastic deformation in the sample, Figure 2The value of b indicates enhanced plasticity in the rejuvenated sample, consistent with the observed decrease in H value. Previous studies have shown that the force-depth curves of La-based, Pa-based, and Zr-based MG exhibit a step-like pattern, characterized by typical sawtooth flow behavior. In contrast, iron-based MG rarely exhibits these characteristics.

[0035] However, Figure 2 Figure b shows a small step on the rejuvenated sample curve, commonly referred to as a Pop-in event. Generally, Pop-in events are caused by pre-existing defects in the MG, such as loosely packed regions (LPRs) or flow cells. Furthermore, the occurrence of Pop-in is closely related to the activation of SBs in the MG. Figure 2 C provides Figure 2 The magnified view of the marked points in section b illustrates the first pop-in events for HT0, HT3, HT60, and HT240. To visually represent the pop-in events of the four samples, the sawtooth flow strain rate sensitivity formula proposed by Schuh and Nieh was used to calculate the relationship between indentation strain rate and indentation depth, as shown below. Figure 2 As shown in d. Under a constant loading rate, the indentation strain rate exhibits a nonlinear function of time, specifically defined as follows: , where h represents the indentation depth and t represents the time.

[0036] Figure 2 The strain rate shows a continuous decreasing trend; however, this trend is frequently interrupted by brief pulses or peaks characterized by increases in strain rate. After fitting these strain rate sensitivity curves with a fifth-order polynomial, the peaks that significantly deviate from the fitted curves and Figure 2 The Pop-in event shown in Figure c corresponds precisely to this. For HT3 and HT240, the initial Pop-in occurs at lower loading forces (as indicated by the arrows), and the frequency of Pop-in events during the initial strain phase increases.

[0037] according to Figure 3 As shown in Figure e, the strip is fully bent, and the surface morphology near the fracture is observed using SEM, such as... Figure 3As shown in Figure 1, the number of primary flow units (SBs) was highest in HT3 and HT240, and many secondary SBs were activated along the length of the primary SBs. This observation is consistent with the increase in pop-in events, confirming their intrinsic correlation and indicating an increase in flow units in HT3 and HT240. SBs are the carriers of plastic deformation in MG, with plastic strain concentrated within SBs with a thickness of 10-20 nm. The increase in SBs in HT3 and HT240 helps to accommodate a large amount of plastic deformation, which is the main reason for their significant plastic enhancement. Shear offset provides more direct evidence of plastic improvement, reflecting the stability of SB sliding. The smaller the shear offset, the greater the degree of plastic enhancement. Shear offset is clearly visible in HT0 and HT60, while it is almost non-existent in HT3 and HT240.

[0038] The XRD pattern of the annealed sample is as follows Figure 4 As shown in Figure a. These patterns exhibit distinct crystallization peaks at 2θ = 45°, 65°, and 85°, confirming the presence of the α-Fe phase in all annealed samples. HRTEM images, as shown... Figure 4 As shown in Figure b, the precipitation of α-Fe nanocrystals was confirmed. DSC analysis was performed on the annealed sample at a constant heating rate of 20 K / min, and the resulting DSC curves are shown in Figure b. Figure 4 As shown in Figure c. The inset provides a magnified view of the α-Fe crystallization peak within the DSC curve. The enthalpy of crystallization (ΔHccrystal) reflects the degree of crystallinity or volume fraction of α-Fe nanocrystals in the annealed sample and is determined by calculating the area of ​​the α-Fe crystallization peak, as shown by the shaded area in the inset. Figure 4 Figure d shows the variation of ΔHccrystal value with ta. Notably, the ΔHccrystal value of the CTC-treated annealed sample is lower than that of HTO-AN. Furthermore, the fluctuation of ΔHccrystal relative to ta is exactly the opposite of the fluctuation of ΔHrel relative to ta in the corresponding rejuvenated sample. This indicates that the CTC-induced rejuvenation process enhances crystallization and increases the volume fraction of α-Fe nanocrystals.

[0039] Similar to the ΔHrel value of the rejuvenated samples, the ΔHrel value of the annealed samples was also determined according to the method outlined in the literature, and... Figure 5 The values ​​of α-Fe nanocrystals are shown along with their H and Er values. The H and Er values ​​of the annealed samples are similar to those of the rejuvenated samples, initially decreasing, then increasing, and finally decreasing again with increasing α-Fe. The expected result is that the H and Er values ​​of the annealed samples increase with increasing α-Fe nanocrystals. However, only HT120-AN has H and Er values ​​exceeding those of HTO-AN, which is consistent with... Figure 4The ΔHccrystal value shown in d is contradictory. Analysis of the ΔHrel values ​​of the annealed samples shows that, except for HT120-AN, the ΔHrel values ​​of other CTC-pretreated annealed samples are greater than those of HT0-AN, and the H value of the annealed samples is negatively correlated with its ΔHrel.

[0040] Compared to HT0-AN, the ΔHrel values ​​of HT3-AN and HT240-AN increased by 83.58% and 71.84%, respectively, while the H values ​​decreased by 7.61% and 6.79%, respectively. In contrast, HT120-AN underwent further relaxation (indicated by a decrease in ΔHrel), resulting in a higher H value. Figure 5 Figure b shows that the fluctuation trend of the maximum indentation depth of the annealed samples is similar to that of the rejuvenated samples. Furthermore, only HT120-AN has a lower maximum indentation depth than HTO-AN.

[0041] Taking a CTC-treated sample as an example, the magnetization curve is shown as follows: Figure 6 As shown in Figure a, the hysteresis loop is as illustrated in the inset. Figure 6 Figure b shows the Hc values ​​of the CTC-treated and corresponding annealed samples, indicating that the Hc of each annealed sample was significantly reduced. Figure 6 The inset in section b shows a magnified view of the Hc values ​​of the annealed samples, demonstrating a further reduction in Hc for HT3-An and HT240-An compared to HT0-An (e.g., an 8.57% reduction in Hc for HT3-An). Bs values ​​for CTC-treated and corresponding annealed samples are shown below. Figure 6 As shown in Figure c, the Bs value increases for each annealed sample. Furthermore, compared to HTO-AN, the Bs values ​​for HT3-AN and HT240-AN show a slight increase. Notably, there is a strong correlation between the Bs value and the ΔHrel value of the CTC-treated samples, such as... Figure 6 As shown in d.

[0042] HRTEM analysis of HT0, HT3, HT60 and HT240 is as follows: Figure 7 As shown. Figure 7 The inset in the middle section shows their selected area electron diffraction (SAED) images. Both HRTEM and SAED images confirm the amorphous nature of the samples before and after CTC treatment, and... Figure 1 The XRD results in b are consistent. Figure 7 The HRTEM image in the middle ad shows that a crystalline-like ordered (CLO) structure of about 1 nm can be resolved in the amorphous substrate, which is a phenomenon previously observed on other iron-based MG.

[0043] To quantitatively assess the structural order of different samples, Figure 7The images in the ad were divided into 225 cells (15×15), each cell measuring 1.785 nm × 1.785 nm. Two-dimensional (2D) autocorrelation analysis of these cells, and the proportion of CLO structures in each sample, were performed. Figure 7 As shown in Figure eh, the CLO structure is highlighted with a red box. A decrease in the proportion of CLO structures was observed in the rejuvenated samples, a trend documented in existing literature.

[0044] The degree of this reduction is related to the ta value of the rejuvenated samples. Specifically, the proportion of CLO structures decreased by 82% in HT3 compared to HT0, while the proportion of CLO structures decreased by 76% in HT240. The reduction in CLO structures promotes the nucleation and sliding of SBs, contributing to the plastic enhancement observed in the rejuvenated samples HT3 and HT240.

[0045] The microstructure of MG consists of two parts: densely packed regions (DPRs) characterized by high structural order and loosely packed regions (LPRs) with lower structural order. In high-angle annular dark-field scanning transmission electron microscopy (HAADF-STEM) images, these regions are represented by bright and dark areas, respectively.

[0046] Figure 8 HAADF-STEM images of the samples showed a significant increase in LPR in the rejuvenated samples. Figure 8 The EDS mapping in EI shows that, taking HTO as an example, the five elements are uniformly distributed. This uniformity indicates that the increase in LPR in the rejuvenated sample stems from enhanced structural heterogeneity, and is related to... Figure 7 The reduction in CLO structures in the rejuvenated samples shown is consistent with this. The large flow units formed within the large LPR promote SB nucleation, which corresponds to the abundant presence of SB in HT3 and HT240, as... Figure 3 As shown.

[0047] HRTEM analysis of HT0-AN, HT3-AN, HT60-AN and HT240-AN is as follows Figure 9 As shown. Figure 9 Bright-field image in a-1-d-1 and Figure 9 The corresponding SAED pattern in a-2-d-2 confirms the presence of α-Fe nanocrystals on the amorphous matrix of the annealed sample, and... Figure 4 The XRD results in a are consistent with those in a. Figure 9 The copper clusters in the a-3-d-3 matrix are crucial for the formation of α-Fe nanocrystals, facilitating their nucleation and inhibiting their growth. To compare the changes in α-Fe nanocrystals in different annealed samples, [the following was done]: Figure 9The diameters (D) and numbers of all observed α-Fe nanoparticles in the a-1-d-1 sequence are tabulated, and the curves show Gaussian fitting, as shown in the figure. Figure 9 The histogram in a-4-d-4 is shown.

[0048] The number of α-Fe nanocrystals can be approximated by the width of the cylinder or the peak value of the relative frequency represented on the vertical axis of the histogram. A narrower width or a lower peak value indicates a greater number of α-Fe nanocrystals. Among the four annealed samples mentioned above, HT60-AN had the highest number of α-Fe nanocrystals. Figure 4 The ΔH crystal value shown in d is consistent. Nevertheless, its α-Fe nanocrystals do not exhibit the largest average diameter. This observation suggests that the significant rejuvenation effect induced by CTC treatment in HT60 primarily promotes the nucleation of α-Fe clusters, rather than their growth. Various studies have confirmed that annealed samples exhibit enhanced soft magnetic properties when the volume fraction of α-Fe nanocrystals is large and their average diameter is between 10-12 nm. Comparison with HTO-AN shows that both HT3-AN and HT240-AN exhibit an increased volume fraction of α-Fe nanocrystals within this specified range, which could explain the additional enhancement of soft magnetic properties in HT3-AN and HT240-AN.

[0049] Heat treatment, such as annealing, typically leads to structural relaxation in MG, thereby reducing the number of flow units. Therefore, it is generally recognized that annealing cannot simultaneously improve the ductility and soft magnetic properties of iron-based MG. However, in this invention, a two-step heat treatment, including CTC and post-annealing, resulted in a synergistic improvement in the ductility and soft magnetic properties of HT3-AN and HT240-AN. This enhancement is attributed to the simultaneous formation of a large number of flow units and large α-Fe nanocrystals. The flow units (SBs) generated by the large number of flow units help accommodate plastic deformation, while the large α-Fe nanocrystals stabilize the non-uniform slippage of the SBs, simultaneously enhancing the soft magnetic properties. The formation of α-Fe nanocrystals by annealing typically involves the annihilation of flow units, making the coexistence of a large volume fraction of α-Fe nanoparticles and a large number of flow units in iron-based MG challenging.

[0050] However, Figure 4 d and Figure 9 The study showed an increase in the number and diameter of α-Fe nanocrystals in HT3-an and HT240-an. Meanwhile, Figure 5 The ΔHrel values ​​shown in Figure a also indicate an increase in the number of flow units for HT3-an and HT240-an. Notably, HT3 and HT240, HT3-AN and HT240-AN exhibited the highest plasticity among all CTC-treated samples and all annealed samples.

[0051] These findings indicate that even after high-temperature annealing in HT3-an and HT240-an, the rejuvenating effect of CTC treatment on HT3 and HT240 (characterized by increased flow units and enhanced plasticity) still exists. Figure 10 The ΔHrel and H values ​​for quenched samples and all annealed samples are shown. The ΔHrel value decreases while the H value increases in the annealed samples, indicating that the annealing treatment induced a relaxation process. However, the ΔHrel value of the annealed samples pretreated with CTC (excluding HT120-AN) did not decrease further, nor did the H value increase. Instead, both parameters showed fluctuations similar to those observed in the rejuvenated samples. This further confirms that the rejuvenation effect induced by CTC persists despite the annealing post-treatment, which increases the number of flow units (or ΔHrel) in the annealed samples compared to the quenched samples. This phenomenon indicates the memory effect of MG during heat treatment.

[0052] Based on the above results and discussion, appropriate degrees of rejuvenation (HT3 and HT240) can promote enhanced crystallization kinetics and the growth of α-Fe nanocrystals after annealing. Simultaneously, the retained rejuvenation effect increases the number of flow units in HT3-AN and HT240-AN, exhibiting a significant memory effect. Conversely, higher degrees of rejuvenation (HT60) tend to lower the activation energy of crystallization and promote the nucleation of additional α-Fe clusters (HT60-AN) during annealing. That is, with increasing sample energy, the induced relaxation evolves into crystallization during subsequent annealing. The highest degree of rejuvenation in HT120 leads to the greatest crystallinity and loss of the memory effect (HT120-AN). When the degree of rejuvenation of the sample exceeds the critical threshold (expressed as Tf / Tg ~ 1.09, where Tf is the hypothetical temperature for regenerating the sample and Tg is the glass transition temperature), the relaxation process becomes dominant.

[0053] Figure 11 Figure a shows the normalized relaxation enthalpy ΔHrel / ΔHrel,0, representing the degree of rejuvenation or relaxation in CTC-treated and corresponding annealed samples. A ΔHrel / ΔHrel,0 value greater than 1 indicates a rejuvenation process, denoted as Mode I; conversely, a value less than 1 indicates a relaxation process, denoted as Mode II. Furthermore, a higher ΔHrel / ΔHrel,0 value indicates a greater degree of rejuvenation. Notably, the change in ΔHrel / ΔHrel,0 is more pronounced in annealed samples compared to CTC-treated samples. Among all annealed samples, HT3-AN and HT240-AN exhibit the highest degree of rejuvenation, being 1.77 times and 1.59 times that of HT3 and HT240, respectively.

[0054] This indicates that, in addition to the additional flow units formed simultaneously with the transformation of annihilated flow units into α-Fe nanocrystals, HT3-AN and HT240-AN also contain another type of defect with higher energy, called anti-free volume defects. Compared to free volume defects (flow units) with high energy and low density and loose structure, anti-free volume defects are characterized by a more compact structure while exhibiting both high energy and high density. Structural relaxation in MG is often elucidated through free volume theory, which posits that relaxation is characterized by the annihilation of free volumes within flow units. In this context, structural defects in MG are conceptualized as low-density regions with a large amount of free volume.

[0055] However, in metallic systems, local density can fluctuate in both the negative and positive directions, leading to the formation of higher-density anti-free volume defects with greater energy. In HT3-AN and HT240-AN, some flow units and α-Fe nanocrystals interact during their growth, resulting in anti-free volume defects at their interfaces. Figure 11 Figure b illustrates the evolution of their microstructure throughout the two-step heat treatment process. The energy state evolution of the samples during the entire two-step heat treatment process can be observed through… Figure 11 The potential energy landscape diagram in C is used for interpretation. Before CTC treatment, all samples were in the initial energy state (state I). HT120 initially transitioned to the highest energy metabasin within the initial megabasin (state III), as shown in the diagram. Figure 11 The long green dashed line path in C is shown. After annealing, HT120-AN descends to the adjacent megabasin (state VI), characterized by a local minimum energy, corresponding to... Figure 11 Mode II in state a. In contrast, HT3 and HT240 first transition to metabasin with different energies in another megabasin, collectively referred to as state II. After annealing, HT3-AN and HT240-AN respectively precipitate into the local lowest energy metabasin, as shown in... Figure 11 The path indicated by the red dashed line in 'c' corresponds to... Figure 11 Pattern I in a.

[0056] Although these samples occupy different energy states, they are all classified as state IV, higher than state V, which represents HTO-AN. The energy state or degree of rejuvenation of CTC-treated samples significantly affects the memory effect observed in the corresponding annealed samples. Figure 11As shown in Figure c, the memory effect disappears when the energy state exceeds a specific critical threshold. This observation is consistent with the findings in Fe77.5Si9.5B13 MG, which indicate that the memory effect can only be activated when the energy state of the sample is kept within a specified range. In lanthanum-based MGs, the energy state range favorable for the memory effect is characterized by Tf values ​​between 1.04 and 1.09 times Tg, with higher Tf values ​​corresponding to higher energy states of the sample. However, the relationship between the energy state of iron-based MGs and their memory effect, as well as the critical energy state at which the memory effect occurs, requires further investigation and clarification.

[0057] In summary, the ductility and soft magnetic properties of the 1K107b alloy (Fe73.5Cu1Nb3Si15.5B7 MG) were synergistically improved by combining CTC treatment with post-annealing in a two-step heat treatment strategy. This strategy addresses the long-standing challenge of simultaneously enhancing both properties. Unlike the general structural relaxation observed in annealed samples, this two-step heat treatment strategy activates the memory effect in the annealed samples, preserving the CTC-induced rejuvenation effect, and further enhancing the degree of rejuvenation due to the formation of anti-free volume defects. This mechanism promotes the coexistence of large α-Fe nanocrystals and abundant flow units in the annealed samples.

[0058] Large α-Fe nanocrystals contribute to excellent soft magnetic properties, while the interaction between these nanocrystals and the sigma generated by the flow units leads to excellent plasticity. Furthermore, a novel approach to enhancing the soft magnetic properties of iron-based magnetometallic compounds (MGs) is revealed from an energy state perspective, unlike traditional methods that rely on altering annealing temperature or holding time. Given the widespread application of CTC and annealing treatments, these innovations deepen the understanding of the memory effect in iron-based MGs and hold promise for providing valuable insights into the design of other iron-based MGs with superior properties.

[0059] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A post-processing method for simultaneously improving the plasticity and soft magnetic properties of iron-based metallic glasses, characterized in that: Includes the following steps: The iron-based amorphous ribbon is first subjected to low-temperature thermal cycling treatment, and then annealed. The low-temperature thermal cycling treatment involves immersing the iron-based amorphous ribbon in liquid nitrogen for 3-240 seconds, then transferring it to a drying device to dry to room temperature. This constitutes one cycle, and the low-temperature thermal cycling treatment lasts for a total of 20-60 minutes. The annealing temperature is 700-850K, and the annealing time is 40-80min.

2. The post-processing method for simultaneously improving the plasticity and soft magnetic properties of iron-based metallic glasses according to claim 1, characterized in that: The iron-based amorphous ribbon is selected from 1K107b or 1K107a.

3. The post-processing method for simultaneously improving the plasticity and soft magnetic properties of iron-based metallic glasses according to claim 1, characterized in that: The low-temperature thermal cycling treatment lasted for 30-50 minutes.

4. The post-processing method for simultaneously improving the plasticity and soft magnetic properties of iron-based metallic glasses according to claim 3, characterized in that: The low-temperature thermal cycling treatment lasted for 35-45 minutes.

5. The post-processing method for simultaneously improving the plasticity and soft magnetic properties of iron-based metallic glasses according to claim 1, characterized in that: The drying temperature is room temperature.

6. The post-processing method for simultaneously improving the plasticity and soft magnetic properties of iron-based metallic glasses according to claim 1, characterized in that: The annealing temperature is 750-850K.

7. The post-processing method for simultaneously improving the plasticity and soft magnetic properties of iron-based metallic glasses according to claim 6, characterized in that: The annealing temperature is 750-800K.

8. The post-processing method for simultaneously improving the plasticity and soft magnetic properties of iron-based metallic glasses according to claim 6, characterized in that: The annealing time is 50-70 minutes.

9. The post-processing method for simultaneously improving the plasticity and soft magnetic properties of iron-based metallic glasses according to claim 8, characterized in that: The annealing time is 55-65 minutes.

10. A type of iron-based metallic glass, characterized in that: It is prepared by the post-processing method described in any one of claims 1-9.

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