Method for evaluating macroscopic non-uniformity of bulk amorphous alloy casting based on equivalent thickness

Abstract

The invention discloses a method for evaluating macroscopic non-uniformity of a block amorphous alloy casting based on equivalent thickness, and belongs to the technical field of amorphous alloy casting determination. The method comprises the following steps: step 1, preparing a plurality of amorphous alloy reflector small wafer castings with the diameter of 3 mm and the thickness of 0.8 mm, wherein the small wafer castings achieve mirror surface smoothness; 2, the thermal history of the amorphous alloy reflector small wafer casting obtained in the step 1 in the solidification process is quantitatively recorded; 3, all parts of the casting are determined to be all-volume amorphous, and thermodynamic parameters are obtained; 4, analyzing a cooling curve based on the thermodynamic parameters in the step 3; 5, after the solidification time and the equivalent thickness value of different typical characteristic areas of the amorphous alloy casting are obtained, structure property characterization is conducted on different areas of the casting, a relation is established with the structure property characterization, and evaluation of the macroscopic non-uniformity of the block amorphous alloy casting is achieved. The method aims at the problem of measurement of the macroscopic non-uniformity of the block amorphous alloy casting.

Description

Technical Field

[0001] This invention belongs to the field of amorphous alloy casting measurement technology, specifically relating to a method for evaluating the macroscopic inhomogeneity of bulk amorphous alloy castings based on equivalent thickness. Background Technology

[0002] Bulk amorphous alloys possess excellent mechanical and functional properties, demonstrating significant application potential in high-tech fields such as aerospace, information technology, and energy. After decades of research, significant progress has been made in their formation mechanisms, microstructure, and material properties, and they have achieved initial applications in mobile communication equipment, motor rotors, and electromagnetic shielding, showing promising engineering prospects. However, limited by their glass-forming capabilities, bulk amorphous alloys are currently unable to achieve large-scale engineering applications of large-size complex components. Integrated casting is considered a key approach to manufacturing such components, and breakthroughs in related core technologies and improvements in technological maturity are crucial prerequisites for promoting the practical engineering applications of bulk amorphous alloys as structural materials.

[0003] In traditional crystalline alloy casting, differences in heat transfer conditions (such as casting structure, wall thickness, and mold characteristics) across different parts of the casting lead to uneven distribution of microstructures (including composition, grain morphology, grain size, and phase structure) on a macroscopic scale, resulting in macroscopic inhomogeneities in mechanical and other service properties. Controlling this inhomogeneity has always been a core issue in the field of crystalline alloy casting. For amorphous alloy castings, theoretically, as long as the cooling rate of each part is higher than its glass transition critical cooling rate, overall amorphous forming can be achieved. However, in actual casting processes, differences in solidification heat history (temperature field changes caused by different heat transfer conditions such as casting structure, wall thickness, and mold properties) due to variations in casting structure, wall thickness, and mold conditions may lead to macroscopic structural or property inhomogeneities in different parts or even within the same casting. What is the extent to which this inhomogeneity affects the overall and local properties of the casting? These questions have become critical scientific issues that urgently need to be clarified in the casting and engineering applications of amorphous alloys.

[0004] To explore the relationship between macroscopic inhomogeneities and solidification thermal history of complex amorphous alloy castings, the concept of equivalent thickness, used in crystalline casting research, is introduced. First, the solidification time of different typical characteristic regions within the casting needs to be determined. When calculating the solidification time of complex castings, they can be decomposed into combinations of simple shapes such as plates, cylinders, spheres, cuboids, and cubes. The equivalent thickness of each simple shape needs to be calculated separately, and the solidification time corresponding to the shape with the largest equivalent thickness value represents the overall solidification time of the casting. This method can be used to estimate the solidification behavior of castings with arbitrary geometric shapes, thus greatly simplifying the analysis of complex-shaped components. This research method for studying crystalline alloy castings is applied to the study of amorphous alloy castings. A novel method for evaluating the macroscopic inhomogeneity of bulk amorphous alloy castings based on equivalent thickness is proposed. This method can be used to systematically study the influence of thermal history on the macroscopic structure and properties of amorphous alloy castings, establish certain relationships, clarify the generation mechanism and control law of macroscopic structural and property inhomogeneity in amorphous alloy castings, guide the process design for controlling macroscopic inhomogeneity in amorphous alloy castings, and promote the development of amorphous alloy casting forming technology and its engineering application as a structural material. Summary of the Invention

[0005] This invention provides a method for evaluating the macroscopic inhomogeneity of bulk amorphous alloy castings based on equivalent thickness, addressing the problem of measuring the macroscopic inhomogeneity of bulk amorphous alloy castings.

[0006] This invention is achieved through the following technical solution: A method for evaluating the macroscopic inhomogeneity of bulk amorphous alloy castings based on equivalent thickness, the method comprising the following steps: Step 1: Prepare multiple amorphous alloy mirror disc castings with a diameter of 3 mm and a thickness of 0.8 mm to achieve a mirror finish; Step 2: Quantitatively record the thermal history of the amorphous alloy mirror disc casting obtained in Step 1 during the solidification process; Step 3: Confirm that all parts of the casting are full-volume amorphous and obtain thermodynamic parameters; Step 4: Analyze the cooling curve based on the thermodynamic parameters from Step 3; Step 5: After obtaining the solidification time and equivalent thickness values ​​of different typical characteristic regions of the amorphous alloy casting, characterize the microstructure and properties of different regions of the casting and establish a relationship with them to evaluate the macroscopic inhomogeneity of the bulk amorphous alloy casting.

[0007] Furthermore, step 2 specifically involves dividing the typical characteristic areas of significant temperature changes inside the casting into regions 1, 2, 3 and 4 according to the order of solidification. Four K-type thermocouples are inserted through the holes in the side wall of the mold, located at different distances from the center of the cavity. The sampling points are selected from representative areas of the casting to facilitate subsequent equivalent thickness calculation. Specifically, region 1 is taken from the thinnest part of the casting; region 2 is taken from the support rib of the casting; region 3 is taken from the outer support ring of the casting; and region 4 is taken from the joint between the gate and the casting. A high-speed data acquisition system is used, with a sampling rate of 100Hz for each channel, to quantitatively record the thermal history of the amorphous alloy casting during the solidification process.

[0008] Furthermore, step 3 specifically involves characterizing the microstructure of the amorphous alloy casting using X-ray diffraction (XRD); measuring the non-isothermal curves using differential scanning calorimetry (DSC); observing a single broad peak in each spectrum, indicating the absence of any crystalline phase; and the gradual narrowing of the full width at half maximum (FWHM) of the XRD peaks as the cooling rate decreases. The results confirmed that all the MG samples studied were amorphous; The thermodynamic parameters include the glass transition temperature. T g Crystallization temperature T x Melting temperature T m Liquid phase temperature T l and the extension of the liquid phase region Δ T = T x - T g .

[0009] Furthermore, step 4 specifically involves determining the melting point. T m regarded as solidification temperature T s In the corresponding coordinate system, the liquidus temperature T l solidification temperature line T s Glass transition temperature T g All intersections were marked; different typical characteristic regions were determined at different solidification times. τ The equivalent thickness below M Value; solidification time is defined as the time interval from filling the cavity to complete solidification.

[0010] Furthermore, for the one-dimensional heat transfer model, the solidification time follows the following relationship, where the solidified layer thickness... From solidification coefficient K Decide:

[0011] in K It can be represented as:

[0012] in K 2 represents the solidification coefficient of a crystalline alloy; ε This refers to the thickness of the solidified layer; ρ 1 represents the melt density. C 1 represents the specific heat capacity of the melt; λ 2 represents the thermal conductivity of the mold material; the casting temperature is... T c express, T i This refers to the melt-mold interface temperature. T 20 This is the initial mold temperature.

[0013] Furthermore, to control the solidification direction of the casting, equation (1) can be rewritten as:

[0014] in V Indicates the volume of the casting. S Represents its surface area; M The standard value is calculated from equation (4), and we get: M Standard value vs. actual value vs. setting time τ The relationship between them.

[0015] Further, step 5 specifically involves the following: the microstructure and elemental distribution are characterized by field emission scanning electron microscopy (SEM); the MCIH phenomenon exhibits increasingly significant characteristics in different typical feature regions of large bulk metallic glass castings; the cooling curves of the Vit1 BMG melt show an average cooling rate of approximately 31.4–112.4 ℃ / s, all exceeding the critical cooling rate required for Vit1; mechanical properties are tested using nanoindentation at room temperature with an MTS Nano Indenter XP device equipped with a Berkovich diamond probe, and the sample cross-section is polished; the indentation progresses from the sample edge to the center, with 12 measurement points set for each sample, spaced 50 μm apart; hardness values ​​are determined using the Oliver-Fal method; Furthermore, quantitative analysis showed that the values ​​of hardness and elastic modulus were positively correlated with macroscopic chemical element inhomogeneity (MCIH). As the solidification rate decreased, both hardness and modulus showed an increasing trend, and the average value variation pattern was consistent with previous research results.

[0016] A system for evaluating macroscopic inhomogeneity of bulk amorphous alloy castings based on equivalent thickness, characterized in that the system uses the method described above for evaluating macroscopic inhomogeneity of bulk amorphous alloy castings based on equivalent thickness, and the system includes... Parameter acquisition module: Obtains the thermodynamic parameters of the full-volume amorphous casting for each part; Curve Analysis Module: Analyzes cooling curves based on thermodynamic parameters; Microstructure and property characterization test module: After obtaining the solidification time and equivalent thickness values ​​of different typical characteristic regions of the amorphous alloy casting, the microstructure and property of different regions of the casting are characterized and a relationship is established with them, so as to realize the evaluation of the macroscopic non-uniformity of the bulk amorphous alloy casting.

[0017] A method for evaluating the macroscopic inhomogeneity of bulk amorphous alloy castings based on equivalent thickness, as described above, is applied to mold design, forming process, and subsequent microstructure and property testing of amorphous alloy castings.

[0018] The beneficial effects of this invention are: This invention fills the gap in the analysis of macroscopic inhomogeneity of amorphous alloy castings and proposes a systematic research method for crystalline alloy castings.

[0019] This invention intuitively links the macroscopic inhomogeneity of amorphous alloy castings with their solidification thermal history and mechanical properties.

[0020] The criteria proposed in this invention can guide the mold design, forming process, and subsequent microstructure and property testing of amorphous alloy castings. Attached Figure Description

[0021] Figure 1 (a) Sampling method for testing bulk amorphous alloy castings.

[0022] Figure 1 (b) Temperature field distribution diagram displayed by infrared thermometer.

[0023] Figure 2 (a) XRD patterns of the four regions.

[0024] Figure 2 (b) Full width at half maximum (FWHM) of each XRD pattern.

[0025] Figure 2 (c) DSC curves of samples with different typical characteristic regions.

[0026] Figure 2 (d) Glass transition temperature T g Crystallization temperature T x Melting temperature T m Liquid phase temperature T l A summary table of the liquid phase region ΔT.

[0027] Figure 3 (a) Schematic diagram of the four typical characteristic regions of the casting.

[0028] Figure 3 (b) Temperature curves during the solidification process of amorphous alloy castings.

[0029] Figure 4This is a schematic diagram illustrating the calculation process of the actual value of M in different feature areas of the casting according to the present invention.

[0030] Figure 5 (a) SEM images and corresponding EDS results are taken from four regions on the casting and typical characteristic regions of the sample.

[0031] Figure 5 (b) is the average Zr elemental mass taken from different sampling positions of an amorphous alloy mirror with a diameter of 130 mm.

[0032] Figure 5 (c) is the average elemental mass of Ti taken from different sampling positions of an amorphous alloy mirror with a diameter of 130 mm.

[0033] Figure 5 (d) is the average elemental mass of Cu taken from different sampling positions of an amorphous alloy mirror with a diameter of 130 mm.

[0034] Figure 5 (e) is the average Ni elemental mass taken from different sampling positions of the amorphous alloy mirror with a diameter of 130 mm. Figure 6 (a) is the nanohardness of the Zr-based bulk amorphous alloy casting of the present invention in four regions.

[0035] Figure 6 (b) represents the elastic modulus of the Zr-based bulk amorphous alloy casting of the present invention in four regions.

[0036] Figure 7 (a) is a graph showing the relationship between the equivalent thickness of different typical characteristic regions in the Zr-based bulk amorphous alloy casting of the present invention and the macroscopic chemical inhomogeneity of (a).

[0037] Figure 7 (b) is a graph showing the relationship between the equivalent thickness of different typical characteristic regions in the Zr-based bulk amorphous alloy casting of the present invention and the mechanical properties of (a).

[0038] Figure 8 This is a schematic diagram of the method flow of the present invention. Detailed Implementation

[0039] In the following description, specific details such as particular system architectures and techniques are set forth for illustrative purposes and not for limitation, in order to provide a thorough understanding of the embodiments of this application. However, those skilled in the art will understand that this application may also be implemented in other embodiments without these specific details. In other instances, detailed descriptions of well-known systems, apparatuses, circuits, and methods are omitted so as not to obscure the description of this application with unnecessary detail.

[0040] It should be understood that, when used in this specification and the appended claims, the term "comprising" indicates the presence of the described features, integrals, steps, operations, elements and / or components, but does not exclude the presence or addition of one or more other features, integrals, steps, operations, elements, components and / or collections thereof.

[0041] It should also be understood that the terminology used in this application specification is for the purpose of describing particular embodiments only and is not intended to limit the application. As used in this application specification and the appended claims, the singular forms “a,” “an,” and “the” are intended to include the plural forms unless the context clearly indicates otherwise.

[0042] The technical solutions in the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of this application, and not all of the embodiments. Based on the embodiments of this application, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of this application.

[0043] Many specific details are set forth in the following description in order to provide a full understanding of this application. However, this application may also be implemented in other ways different from those described herein. Those skilled in the art can make similar extensions without departing from the spirit of this application. Therefore, this application is not limited to the specific embodiments disclosed below.

[0044] Implementation like Figure 1-8 As shown, Zr is first selected. 41.2 Ti 13.8 Cu 12.5 Ni 10 Be 22.5 (Vit1) An amorphous alloy mirror with a diameter of 130 mm and a thickness of 10 mm was cast by induction heating remelting of the alloy in a quartz crucible under an argon atmosphere. This casting serves as an introduction to illustrate the research method. Figure 1As shown in (a), the removed amorphous alloy casting was cut into eight small circular pieces, each 3 mm in diameter and 0.8 mm thick, from the center of the mold outwards. These pieces were then polished to a mirror finish for subsequent experiments. Previous studies have attempted to characterize the thermal history of bulk amorphous alloy casting by embedding thermocouples within the mold cavity. However, this method only provides localized temperature-time data and has several unresolved issues: the thermocouples have limited spatial resolution, can disturb melt flow, and exhibit thermal hysteresis due to their limited mass and heat capacity. In contrast, high-speed infrared thermal imaging, with its megapixel spatial resolution and kHz-level acquisition rate, has become a powerful tool for probing transient thermal processes. This technique has been successfully applied to elucidate the deformation behavior of bulk amorphous alloy castings under non-uniform flow conditions. Figure 1 (b) The results of infrared temperature mapping using a high-performance Optris PI 1M thermal imager are presented. A customized visual mold was used to observe the solidification thermal history of the casting and to divide typical characteristic areas with significant internal temperature changes into regions 1, 2, 3, and 4, labeled according to the order of solidification. Four K-type thermocouples were inserted through holes in the mold sidewall, located at different distances from the center of the cavity (regions 1-4). Sampling points were selected from representative areas of the casting to facilitate subsequent equivalent thickness calculations: region 1 was taken from the thinnest part of the casting; region 2 from the casting support ribs; region 3 from the outer support ring; and region 4 from the junction of the gate and the casting. A high-speed data acquisition system (EM9104C, ZTIC) with a sampling rate of 100Hz per channel was used to quantitatively record the thermal history of the amorphous alloy casting during solidification.

[0045] Secondly, it was determined that all parts of the casting were entirely amorphous and thermodynamic parameters were obtained to support subsequent research on the thermal history during solidification. The microstructure of the amorphous alloy casting was characterized using X-ray diffraction (XRD, Panalytical X-PERT). Non-isothermal curves were measured using differential scanning calorimetry (DSC, NETZSCH STA449F3). Figure 2 (a) Shows the X-ray diffraction (XRD) patterns of four selected MG samples from different locations (2 θ The peaks are approximately 10°–90°, and a single broad peak is observed in each spectrum, indicating the absence of any crystalline phase. Furthermore, the full width at half maximum (FWHM) of the XRD peaks gradually narrows with decreasing cooling rate (e.g., approximately 10°–90°). Figure 2 (b) These results confirm that all the studied MG samples are amorphous and that the atomic structure is more stable at lower cooling rates. Figure 2 (c) Differential scanning calorimetry (DSC) curves of samples at different casting temperatures (heating rate 20 K / min) are shown. Glass transition temperature T g Crystallization temperatureT x Melting temperature T m Liquid phase temperature T l and the extension of the liquid phase region Δ T = T x - T g Summary Figure 2 (d) facilitates subsequent analysis of the cooling curve.

[0046] Figure 3 This study demonstrates the temperature field distribution and cooling rate variations in four regions during the solidification process of an amorphous alloy casting. Delineating typical characteristic regions within the casting not only facilitates subsequent equivalent thickness calculations but also provides both qualitative and quantitative evidence for the thermal history. (Most commonly, the melting point...) T m regarded as solidification temperature T s In the corresponding coordinate system, the liquidus temperature T l solidification temperature line T s Glass transition temperature T g All intersections were marked. The most crucial step in analyzing castings is determining the different typical feature regions at different solidification times. τ The equivalent thickness below M Value. Solidification time is defined as the time interval from mold cavity filling to complete solidification. Studies have found that for a one-dimensional heat transfer model, solidification time follows the following relationship, where the solidified layer thickness... From solidification coefficient K Decide.

[0047]

[0048] in t The value was obtained using the cooling profile, and K The value derivation consists of the steps above, which are the complete steps highlighted in red below, including a pair. K The value is simplified because bulk amorphous alloys do not release latent heat during solidification. L It is 0, this is M The standard value. The second method is to define the equivalent thickness. M = V / S To obtain it, it is necessary to calculate the equivalent part. V and S , specifically Figure 4 As shown, this is MThe actual value. By matching the standard value and the actual value, the value of this application can be obtained. M Then M The horizontal axis is used to characterize the microstructure and properties of different regions of the casting.

[0049] in K It can be represented as:

[0050] Here, K 1 represents the solidification coefficient of a crystalline alloy, defined as the thickness of the solidified layer formed per unit time ( ). τ = 1, K = ε ). K The value is a function of multiple parameters, reflecting the specific solidification conditions determined by the melt characteristics and the mold environment. The heat storage coefficient of the mold is represented by, where ε For the thickness of the solidified layer, ρ 1 and ρ 2 represents the density of the melt and the density of the mold, respectively. L The latent heat of fusion of the alloy, C 1 and C 2 represents the specific heat capacity of the melt and the mold, respectively. λ 2 represents the thermal conductivity of the mold material. The casting temperature is used... T c express, T i This refers to the melt-mold interface temperature. T 20 The initial mold temperature is given. It should be noted that the above theoretical model is derived under several simplifying assumptions to maintain compatibility with the idealized one-dimensional heat transfer framework, and these assumptions are rarely fully satisfied in actual casting processes. Therefore, the coefficients... K The solidification time and corresponding solidified layer thickness are usually determined experimentally (as shown in Equation (1)). Introduction K This provides a convenient way to estimate the solidification time during the casting process of sheet metal. Since bulk amorphous alloys do not release latent heat during solidification, equation (2) can be reconstructed into equation (3).

[0051]

[0052] When the pouring temperature is 950 ℃, Vit1 K The value of 2 is greater than that of conventional crystalline alloys, and its K The value is 3.18 cm / min¹ / ². In actual production, to control the solidification direction of the casting, it is not necessary to calculate the solidification time of each part of the casting structure; only their equivalent thickness needs to be compared. Therefore, equation (1) can be rewritten as:

[0053] Here, V Indicates the volume of the casting. S It represents its surface area. M The standard value is calculated by equation (4), while the actual value is determined by defining the equivalent thickness. M = V / S To obtain and characterize the solidification behavior of irregularly shaped castings. Based on the above two methods, the solidification behavior of irregularly shaped castings was determined. M Standard value vs. actual value vs. setting time τ The relationships between them are shown in Table 1. This table can, to some extent, guide the forming process and subsequent microstructure and property testing of amorphous alloy castings.

[0054] Table 1. Solidification time and equivalent thickness values ​​of different typical characteristic regions of castings

[0055] After obtaining the solidification time and equivalent thickness values ​​of different typical characteristic regions of the amorphous alloy casting, the microstructure and properties of different regions of the casting were characterized, and a relationship was established with the solidification time and equivalent thickness values ​​of different typical characteristic regions. The microstructure and elemental distribution were characterized by field emission scanning electron microscopy (SEM, TESCAN MAGNA). Figure 5 (a) EDS results of four regions sampled from typical characteristic areas of the casting are shown. Except for Be, which cannot be identified in the EDS (elemental distribution map), the other four elements show uniform distribution, indicating that no crystalline phase has formed in any part of the casting. However, no macroscopic compositional inhomogeneity can be observed from the EDS results, so macroscopic chemical inhomogeneity was characterized by inductively coupled plasma atomic emission spectrometry (ICP, iCAP 7400). Figure 5 The ICP spectral curves in (b) clearly reveal the macroscopic compositional inhomogeneity within the amorphous phase. The MCIH phenomenon exhibits increasingly pronounced characteristics in different typical regions of the large bulk metallic glass casting. Cooling curves of the Vit1 BMG melt show an average cooling rate of approximately 31.4–112.4 °C / s, all exceeding the critical cooling rate required for Vit1 (approximately 1 °C / s). Mechanical properties were determined using nanoindentation testing at room temperature with an MTS Nano Indenter XP device equipped with a Berkovich diamond probe, and the sample cross-sections were polished. Indentations were made from the sample edge towards the center, with 12 measurement points spaced 50 μm apart per sample. Hardness values ​​were determined using the Oliver-Fal method. Figure 6The nanoindentation hardness and elastic modulus values ​​for four measurement regions are presented. Quantitative analysis shows that the values ​​of hardness and elastic modulus are positively correlated with macroscopic chemical elemental inhomogeneity (MCIH). This indicates that both hardness and modulus increase with decreasing solidification rate, and the average variation pattern is consistent with the results of previous studies on hardness and modulus values ​​in Zr-based amorphous alloys.

[0056] Figure 7 This figure shows the relationship between the equivalent thickness of different typical characteristic regions in Zr-based bulk amorphous alloy castings and their macroscopic chemical inhomogeneity and mechanical properties. The red and green bars represent the Zr and Ti elemental proportions in regions with different equivalent thicknesses, while the blue and yellow line graphs represent the nanoscale hardness and elastic modulus values ​​in different equivalent regions. It can be observed that when the equivalent thickness value... M When the thickness reaches 0.7, corresponding to an average nanoindentation value of 9.95425 GPa, the macroscopic inhomogeneity within the casting is significantly enhanced. This indicates that the concept of equivalent thickness in this method can intuitively reflect the macroscopic inhomogeneity phenomenon in bulk amorphous alloy castings.

[0057] The above embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit them. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention, and should all be included within the protection scope of the present invention.

Claims

1. A method for evaluating the macroscopic inhomogeneity of bulk amorphous alloy castings based on equivalent thickness, characterized in that, The method includes the following steps: Step 1: Prepare multiple amorphous alloy mirror disc castings with a diameter of 3 mm and a thickness of 0.8 mm to achieve a mirror finish; Step 2: Quantitatively record the thermal history of the amorphous alloy mirror disc casting obtained in Step 1 during the solidification process; Step 3: Confirm that all parts of the casting are full-volume amorphous and obtain thermodynamic parameters; Step 4: Analyze the cooling curve based on the thermodynamic parameters from Step 3; Step 5: After obtaining the solidification time and equivalent thickness values ​​of different typical characteristic regions of the amorphous alloy casting, characterize the microstructure and properties of different regions of the casting and establish a relationship with them to evaluate the macroscopic inhomogeneity of the bulk amorphous alloy casting.

2. The method according to claim 1, characterized in that, Step 2 specifically involves dividing the typical characteristic areas of significant temperature changes inside the casting into regions 1, 2, 3 and 4 according to the order of solidification. Four K-type thermocouples are inserted through the holes in the side wall of the mold and located at different distances from the center of the cavity. The sampling points are selected from representative areas of the casting to facilitate subsequent equivalent thickness calculation. That is, region 1 is taken from the thinnest part of the casting; region 2 is taken from the supporting rib of the casting; Region 3 was taken from the outer support ring of the casting; Region 4 was taken from the joint between the gate and the casting; a high-speed data acquisition system was used, with a sampling rate of 100Hz for each channel, to quantitatively record the thermal history of the amorphous alloy casting during the solidification process.

3. The method according to claim 1, characterized in that, Step 3 specifically involves characterizing the microstructure of the amorphous alloy casting using X-ray diffraction (XRD); measuring the non-isothermal curves using differential scanning calorimetry (DSC); observing a single broad peak in each spectrum, indicating the absence of any crystalline phase; and the gradual narrowing of the full width at half maximum (FWHM) of the XRD peaks as the cooling rate decreases. The results confirmed that all the MG samples studied were amorphous; The thermodynamic parameters include the glass transition temperature. T g Crystallization temperature T x Melting temperature T m Liquid phase temperature T l and liquid phase extension Δ T = T x - T g .

4. The method according to claim 1, characterized in that, Step 4 specifically involves determining the melting point. T m regarded as solidification temperature T s In the corresponding coordinate system, the liquidus temperature T l solidification temperature line T s Glass transition temperature T g All intersections were marked; different typical characteristic regions were determined at different solidification times. τ The equivalent thickness below M Value; solidification time is defined as the time interval from filling the cavity to complete solidification.

5. The method according to claim 4, characterized in that, For a one-dimensional heat transfer model, the solidification time follows the following relationship, where the thickness of the solidified layer is... From solidification coefficient K Decide: in K It can be represented as: in K 2 represents the solidification coefficient of a crystalline alloy; ε This refers to the thickness of the solidified layer. ρ 1 represents the melt density. C 1 represents the specific heat capacity of the melt; λ 2 represents the thermal conductivity of the mold material; the casting temperature is used for... T c express, T i This refers to the melt-mold interface temperature. T 20 This is the initial mold temperature.

6. The method according to claim 5, characterized in that, To control the solidification direction of the casting, equation (1) can be rewritten as: in V Indicates the volume of the casting. S Represents its surface area; M The standard value is calculated from equation (4), and we get: M Standard value vs. actual value vs. setting time τ The relationship between them.

7. The method according to claim 1, characterized in that, Specifically, step 5 involves characterizing the microstructure and elemental distribution using field emission scanning electron microscopy (SEM); the MCIH phenomenon exhibits increasingly prominent characteristics in different typical feature regions of large bulk metallic glass castings. Cooling curves of the Vit1 BMG melt showed an average cooling rate of approximately 31.4–112.4 °C / s, all exceeding the critical cooling rate required for Vit1. Mechanical properties were determined using nanoindentation testing at room temperature with an MTS Nano Indenter XP device equipped with a Berkovich diamond probe, and the sample cross-section was polished. The indentation was performed from the edge of the sample towards the center, with 12 measurement points set for each sample at 50 μm intervals. Hardness values ​​were determined using the Oliver-Fal method.

8. The method according to claim 7, characterized in that, Quantitative analysis showed that the values ​​of hardness and elastic modulus were positively correlated with macroscopic chemical element inhomogeneity (MCIH). As the solidification rate decreased, both hardness and modulus showed an increasing trend, and the average value variation pattern was consistent with previous research results.

9. A system for evaluating the macroscopic inhomogeneity of bulk amorphous alloy castings based on equivalent thickness, characterized in that, The system uses the method for evaluating macroscopic inhomogeneities of bulk amorphous alloy castings based on equivalent thickness as described in any one of claims 1-8, and the system comprises, Parameter acquisition module: Obtains the thermodynamic parameters of the full-volume amorphous casting for each part; Curve Analysis Module: Analyzes cooling curves based on thermodynamic parameters; Microstructure and property characterization test module: After obtaining the solidification time and equivalent thickness values ​​of different typical characteristic regions of the amorphous alloy casting, the microstructure and property of different regions of the casting are characterized and a relationship is established with them, so as to realize the evaluation of the macroscopic non-uniformity of the bulk amorphous alloy casting.

10. A method for evaluating the macroscopic inhomogeneity of bulk amorphous alloy castings based on equivalent thickness, as described in any one of claims 1-8, which is applied to mold design, forming process and subsequent microstructure and property testing of amorphous alloy castings.

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