A method and system for determining the cracking tendency of a multi-material interface in additive manufacturing

Abstract

This invention discloses a method and system for determining the cracking tendency of multi-material interfaces in additive manufacturing, comprising: constructing a multi-factor cracking tendency determination model; setting the composition of target dissimilar materials at different mixing ratios, calculating the value of each cracking factor at each mixing ratio, and plotting the curves of each cracking factor changing with the mixing ratio; identifying the component regions where the peak values ​​of each cracking factor overlap based on the curves of each cracking factor changing with the mixing ratio, and determining the high-risk component range for cracking; determining the cracking tendency of components at different mixing ratios to obtain a cracking tendency level; guiding the material selection and process design of additive manufacturing multi-material components based on the cracking tendency level; verifying the model prediction results through additive manufacturing experiments, and correcting the model based on experimental data. This invention integrates crack sensitivity factors, harmful phase precipitation factors, and liquid phase separation factors into the same evaluation model, overcoming the limitations of a single criterion.

Description

Technical Field

[0001] This invention relates to the field of additive manufacturing technology, and in particular to a method and system for determining the tendency of multi-material interfaces to crack in additive manufacturing. Background Technology

[0002] Multimaterial additive manufacturing (MMC) is a method that uses additive manufacturing to form different materials in different parts of the same component. It offers advantages such as rapid prototyping of complex structures and multimaterial components, and has significant application prospects in aerospace, energy and power, and electronics and information technology fields. However, differences in thermophysical properties between different materials (such as melting point, coefficient of thermal expansion, and thermal conductivity) can easily generate residual stress in the interface region, leading to interface cracking. Furthermore, certain alloy combinations within specific composition ranges can form low-melting-point eutectic phases, brittle intermetallic compounds, or undergo liquid-phase separation due to the immiscibility of the two alloys, further exacerbating the risk of interface cracking and limiting the engineering application of multimaterial additive manufacturing components.

[0003] To date, significant progress has been made in research reports on interfacial cracking in additive manufacturing of multimaterial components. Some studies have addressed stress concentration and crack formation through interfacial gradient composition design, the addition of intermediate layer materials at the interface, and interface process optimization. Other researchers have opted for forming multimaterial components from alloys that are completely miscible in the liquid phase to reduce interfacial cracking susceptibility. However, these existing studies all begin by conducting additive manufacturing experiments to determine whether an interfacial cracking event will occur in a particular material combination, analyzing the causes of cracking, and then exploring methods to suppress cracking. They lack prior prediction of interfacial cracking behavior, resulting in a lack of material selection criteria for additively manufactured multimaterial components. Furthermore, crack suppression methods such as interfacial composition design and intermediate layer material selection lack theoretical guidance. Therefore, interfacial cracking remains a prevalent problem in additively manufactured multimaterial components.

[0004] Therefore, there is an urgent need to provide a solution for a method and system for determining the tendency of multi-material interfaces to crack in additive manufacturing. Summary of the Invention

[0005] To address the above issues, the present invention provides a method and system for determining the cracking tendency of multi-material interfaces in additive manufacturing. By constructing a multi-factor evaluation model that includes precipitation of brittle and low-melting-point phases, liquid phase separation, and cracking sensitivity, the method can determine the cracking tendency of any two alloys across the entire composition range, providing theoretical guidance for material selection, interface composition design, and process parameter optimization of multi-material components in additive manufacturing.

[0006] According to a first aspect of the present invention, a method for determining the tendency of multi-material interface cracking in additive manufacturing is provided, comprising: S1. Construct a multi-factor cracking tendency determination model, wherein the cracking factors include: liquid phase separation factor, harmful phase precipitation factor and cracking sensitivity factor; S2. Set the composition of the target dissimilar material at different mixing ratios, calculate the cracking factor value for each mixing ratio, and plot the curve of each cracking factor as a function of the mixing ratio. S3. Based on the curves of each cracking factor changing with the mixing ratio and combined with the judgment model, identify the component regions where the peak values ​​of each cracking factor overlap, and determine the high-risk component range for cracking. S4. Determine the cracking tendency of components with different mixing ratios based on the judgment model to obtain the cracking tendency level; S5. Guide the material selection and process design of additive manufacturing multi-material components based on the cracking tendency level; S6. Verify the model prediction results through additive manufacturing experiments, and revise the model based on the experimental data.

[0007] In the above scheme, in step S1, the liquid phase separation factor is determined based on the second derivative of the Gibbs free energy and composition curve of the mixed system, the harmful phase precipitation factor includes low melting point eutectic phase and brittle intermetallic compound, and the cracking sensitivity factor includes solidification temperature range, brittle temperature range, crack sensitivity coefficient and solidification cracking index.

[0008] In the above scheme, the determination criteria for the liquid phase separation factor are as follows: when the second derivative of the Gibbs free energy and composition curve of the mixed system is less than zero, it is determined that liquid phase separation has occurred; when the second derivative is greater than zero, it is determined that liquid phase separation has not occurred.

[0009] In the above scheme, the determination of the harmful phase precipitation factor includes: using thermodynamic calculation software to calculate the equilibrium phase diagram under different mixing ratios of dissimilar materials, and using a non-equilibrium solidification model to simulate the phase precipitation behavior under rapid solidification conditions, so as to identify low-melting-point eutectic phases and brittle intermetallic compounds.

[0010] In the above scheme, the solidification temperature range is the difference between the liquidus temperature and the solidus temperature; the brittle temperature range is the temperature range corresponding to a solid fraction between 0.9 and 0.99; the crack sensitivity coefficient characterizes the ratio of stress concentration time to stress release time at the end of solidification; and the solidification cracking index is based on a non-equilibrium solidification model and is evaluated by analyzing the rate of change of solid fraction with temperature.

[0011] In the above scheme, the standard for determining a single characteristic value of the crack sensitivity factor as high risk is: the characteristic value of the mixed material is greater than or equal to 1.5 times the larger characteristic value of the two individual materials.

[0012] In the above scheme, the specific rules for the comprehensive rating of cracking tendency are as follows: When a harmful phase is present, it is considered high risk; When there is no harmful phase but liquid phase separation, it is judged as medium risk; When there is no harmful phase and no liquid phase separation, the risk is determined based on the number of the four characteristic values ​​in the cracking sensitivity factor that are identified as high risk: less than or equal to 1 is low risk, 2 is medium risk, and more than or equal to 3 is high risk.

[0013] In the above scheme, step S6 specifically includes: preparing alloy powders with different mixing ratios using mechanical powder mixing method, performing additive manufacturing, observing the distribution of interface cracks, comparing the experimental results with the model rating results, and adjusting the judgment threshold or rating rules of each factor according to the comparison results.

[0014] In the above scheme, the additive manufacturing method includes: laser powder bed melting, electron beam melting, or directional energy deposition.

[0015] According to a second aspect of the present invention, a system for determining the tendency of multi-material interface cracking in additive manufacturing is provided, applied to the method described in any one of the above solutions, the system comprising: The module is used to build a multi-factor cracking tendency determination model, where the cracking factors include: liquid phase separation factor, harmful phase precipitation factor and cracking sensitivity factor. The curve plotting module is used to set the composition of the target dissimilar material at different mixing ratios, calculate the cracking factor value at each mixing ratio, and plot the curve of each cracking factor as a function of the mixing ratio. The high-risk cracking identification module is used to identify the component regions where the peak values ​​of each cracking factor overlap based on the curves of how each cracking factor changes with the mixing ratio, and to determine the high-risk cracking component range. The cracking tendency level determination module is used to determine the cracking tendency of components with different mixing ratios and obtain the cracking tendency level. The material selection and process design module is used to guide the material selection and process design of additive manufacturing multi-material components based on the cracking tendency level. The correction module is used to verify the model's prediction results through additive manufacturing experiments and to correct the model based on the experimental data.

[0016] The beneficial effects of this invention are: Comprehensive assessment: By integrating crack sensitivity factors, harmful phase precipitation factors, and liquid phase separation factors into the same assessment model, the limitations of a single criterion are overcome, and the main material science causes of multi-material interface cracking in additive manufacturing are fully covered.

[0017] Wide range of applications: The method is versatile and applicable to various material combinations such as copper-iron, titanium-aluminum, nickel-copper, and iron-copper. It can also be used in different additive manufacturing processes such as laser powder bed melting, electron beam melting, and directional energy deposition.

[0018] Prediction accuracy can be improved: By combining theoretical calculations with additive manufacturing experiments, model parameters and judgment thresholds can be corrected based on experimental data, thereby improving the accuracy of cracking tendency prediction.

[0019] High engineering guidance value: The assessment results are output intuitively in low, medium and high risk levels, which can be directly used for material selection, interface composition gradient design and process parameter optimization, effectively reducing the number of trial and error experiments and saving material and time costs. Attached Figure Description

[0020] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on the structures shown in these drawings without creative effort.

[0021] Figure 1 : Schematic diagram of the method flow of the present invention; Figure 2 Schematic diagram of Gibbs free energy curve and liquid phase separation criterion; Figure 3 Equilibrium phase diagrams and non-equilibrium solidification paths under different mixing ratios; Figure 4 Curves showing the change in cracking sensitivity factor under different Invar36 ratios; Figure 5 Comparison chart of comprehensive rating results and experimental verification; Figure 6 Gibbs free energy curves of the In718-304L bimetallic system with different 304L mixing ratios; Figure 7 SEM images of cracks and brittle phase distribution at the In718 and 304L interface; Figure 8 Cracking sensitivity factors under different 304L mixing ratios; Figure 9 The actual cracking component range at the interface of In718-304L.

[0022] The realization of the objective, functional features and advantages of the present invention will be further explained in conjunction with the embodiments and with reference to the accompanying drawings. Detailed Implementation

[0023] Exemplary embodiments will now be described in detail, examples of which are illustrated in the accompanying drawings. When the following description relates to the drawings, unless otherwise indicated, the same numerals in different drawings denote the same or similar elements. The embodiments described in the following exemplary embodiments do not represent all embodiments consistent with this disclosure. Rather, they are merely examples of apparatuses and methods consistent with some aspects of this disclosure as detailed in the appended claims.

[0024] The terms "first," "second," etc., used in this disclosure are for distinguishing similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that such use of data can be interchanged where appropriate so that the embodiments of this disclosure described herein can be implemented, for example, in orders other than those illustrated or described herein.

[0025] Furthermore, the terms “comprising” and “having”, and any variations thereof, are intended to cover non-exclusive inclusion, such that a process, method, system, product, or apparatus that includes a series of steps or units is not necessarily limited to those steps or units that are explicitly listed, but may include other steps or units that are not explicitly listed or that are inherent to such process, method, product, or apparatus.

[0026] Multiple, including two or more.

[0027] And / or, it should be understood that, for the purposes of this disclosure, the term "and / or" is merely a description of the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent three situations: A exists alone, A and B exist simultaneously, and B exists alone.

[0028] like Figure 1 As shown, one embodiment of the technical solution of the present invention provides a method for determining the tendency of multi-material interface cracking in additive manufacturing, including: S1. Construct a multi-factor cracking tendency determination model, wherein the cracking factors include: liquid phase separation factor, harmful phase precipitation factor and cracking sensitivity factor; Liquid phase separation factor: determined by the Gibbs free energy (ΔG) of the mixed system. mix The second derivative of the component (x) curve determination.

[0029] Gibbs free energy ΔG mix The calculation formula is: (1) in, This is the enthalpy of mixture, expressed in kJ / mol. This represents the interaction parameter between element i and element j. c is the enthalpy of mixture of binary liquids A and B; i This represents the atomic percentage of the i-th element. Here, is the entropy of mixing, in J / mol; R is the gas constant, taken as R = 8.314 J·mol. -1 ·K -1 ; The value is the mixing free energy, expressed in kJ / mol; T is the absolute temperature, expressed in K.

[0030] The criterion for liquid phase separation is: when When <0, it indicates that the homogeneous phase is unstable and liquid phase separation can occur in the system; when A value greater than 0 indicates that the homogeneous phase is stable and no liquid phase separation occurs in the system. However, =0 is merely a critical boundary in thermodynamic theory, and cannot be stably maintained under actual non-equilibrium solidification conditions. Therefore, this equal-zero condition does not exist in actual experiments or production, and thus does not need to be considered in subsequent risk level determinations. =0.

[0031] Harmful phase precipitation factors include low-melting-point eutectic phases and brittle intermetallic compounds. Low-melting-point eutectic phases are formed at the end of solidification. Due to their low melting point, they will form liquid films between dendrites, which are easily torn apart under residual tensile stress to form cracks. Brittle intermetallic compounds are prone to forming local stress concentrations, thus becoming crack initiation sites.

[0032] This invention employs thermodynamic software to calculate equilibrium phase diagrams for dissimilar materials at different mixing ratios, identifying potentially harmful phases. Simultaneously, the Scheil non-equilibrium solidification model is used to simulate phase precipitation behavior under actual L-PBF rapid solidification conditions, further determining the precipitation of harmful phases. Since actual phase precipitation behavior under rapid solidification conditions in additive manufacturing may differ from the equilibrium phase diagram, this invention combines the non-equilibrium solidification path (Scheil model) with the equilibrium phase diagram to identify low-melting-point phases that may form at the end of solidification, making the analysis more accurate.

[0033] Cracking susceptibility factors include the solidification temperature range ΔT, brittle temperature range BTR, crack susceptibility coefficient CSC, and solidification cracking index SCI of the mixed system. These parameters can be calculated using thermodynamic software. Details are as follows: The solidification temperature range ΔT is the liquidus temperature T. L With solidus temperature T S The larger the difference in temperature (ΔT), the easier it is for thermal cracking to occur during the solidification process.

[0034] The brittle temperature range BTR is selected based on the solid fraction f. s The temperature range corresponding to 0.9 to 0.99 is when the alloy is in a pasty state, and the liquid feeding between dendrites is difficult. This is the key stage for crack initiation. The larger the BTR value, the greater the tendency to crack.

[0035] The formula for calculating the crack sensitivity coefficient (CSC) is as follows: (2) Where t v t is the time when stress concentration at the end of solidification makes cracking more likely. r The CSC value represents the time available for stress relief; the higher the CSC value, the greater the tendency to crack.

[0036] The formula for calculating the solidification cracking index (SCI) is as follows: (3) Where f s SCI represents the solid fraction; T represents the temperature in K. Based on the Scheil nonequilibrium solidification model, crack susceptibility is assessed by analyzing solute segregation and changes in solid fraction at the end of the solidification path. The larger the SCI value, the greater the tendency to crack.

[0037] Since existing research typically focuses on a single factor, this invention integrates the liquid phase separation factor, the harmful phase precipitation factor, and the cracking sensitivity factor into a single thermodynamic model, providing a multi-faceted and quantifiable assessment framework for multi-material interface cracking. Liquid phase separation is determined using the sign of the second derivative of the Gibbs free energy curve; the harmful phase is assessed using both the equilibrium phase diagram and the Scheil non-equilibrium solidification model, fully considering the rapid solidification characteristics of additive manufacturing; the cracking sensitivity factor integrates four eigenvalue sub-indices: ΔT, BTR, CSC, and SCI, and provides their respective physical definitions and calculation formulas. This model structure, combining multiple factors and calculable criteria, fundamentally overcomes the limitations of previous single-criteria approaches, laying a theoretical foundation for subsequent quantitative risk assessment.

[0038] S2. Set the composition of the target dissimilar material at different mixing ratios, calculate the cracking factor value for each mixing ratio, and plot the curve of each cracking factor changing with the mixing ratio. The method of the present invention can be applied to a variety of material combinations, such as Cu-Fe, Ti-Al, Ni-Cu, Fe-Cu, etc.

[0039] For example, for the combination of Invar36 and M2052, the proportion of Invar36 in the mixed material is set to 0%, 20%, 40%, 60%, 80%, and 100% respectively. The cracking factor under each mixing ratio is calculated using thermodynamic calculation software, and the curves of each cracking factor changing with the mixing ratio are plotted.

[0040] This step explicitly proposes calculating the cracking factor values ​​separately according to a series of discrete mixing ratios, and plotting the curves of the factors changing with the mixing ratios, thus expanding the assessment scope from the endpoint components to the entire composition range. Furthermore, by graphically demonstrating the continuous evolution of the cracking factor with composition, the risk changes under different material combinations are clearly visible, providing a visual and quantitative basis for subsequent peak overlap identification.

[0041] S3. Based on the curves of each cracking factor changing with the mixing ratio, identify the component regions where the peak values ​​of each cracking factor overlap, and determine the high-risk component range for cracking. For example, if there is a separation of harmful phase and liquid phase within a certain mixing ratio range, and the crack sensitivity factors ΔT, BTR, CSC, and SCI are all at high levels, then this range is the range of components with high crack risk.

[0042] The criteria for classifying the crack susceptibility factor of each material system as "high" are as follows: ΔT≥1.5×ΔT max When, it is determined to be high, where ΔT max Choose the material with the larger solidification temperature range from the two materials; similarly, the criteria for BTR, CSC, and SCI to determine high risk are as follows: BTR≥1.5×BTR max CSC ≥ 1.5 × CSC max SCI ≥ 1.5 × SCI max ;BTR max CSC max SCI max These are the materials with the larger corresponding characteristics.

[0043] It should be noted that the proportions in this standard are derived from statistical data reported in the literature, and are not the result of theoretical derivation. In specific material combinations, these proportions can be adjusted according to specific circumstances, or corrected through experimental verification. This invention patent only provides a method for quantifying crack sensitivity factors.

[0044] Based on the four characteristic values ​​related to crack sensitivity, the risk levels of crack sensitivity factors are classified as follows: ① When the number of values ​​judged as "high" is ≥3, it is considered high risk; ② When the number of values ​​judged as "high" is 2, it is considered medium risk; ③ When the number of values ​​judged as "high" is ≤1, it is considered low risk.

[0045] Existing technologies mostly rely on experience or single factors to determine cracking risk. This paper proposes identifying regions where multiple factors' peak values ​​overlap as high-risk component intervals. Specifically, it considers whether the high-level regions of harmful phases, liquid phase separation, and multiple sensitivity factors overlap within a certain component range. Furthermore, it establishes quantitative high-risk threshold standards for each sub-indicator (ΔT, BTR, CSC, SCI) in the cracking sensitivity factors. A comprehensive risk level classification rule is presented. This method, combining peak overlap, unified quantitative thresholds, and multi-indicator levels, significantly differs from traditional empirical judgments or single-indicator extreme value analysis, and possesses strong engineering applicability.

[0046] S4. Determine the cracking tendency of components with different mixing ratios to obtain the cracking tendency level. The specific rules are as follows: When a harmful phase is present, it is considered high risk; When there is no harmful phase but liquid phase separation, it is judged as medium risk; When there is no harmful phase and no liquid phase separation, the risk is determined based on the number of the four characteristic values ​​in the cracking sensitivity factor that are identified as high risk: less than or equal to 1 is low risk, 2 is medium risk, and more than or equal to 3 is high risk.

[0047] The method for determining the overall risk level is shown in Table 1.

[0048] Table 1 The "-" indicates that the effect of this item does not need to be considered under this condition; The rating results can be used to guide subsequent material selection and process design.

[0049] The approach to determining the risk level is as follows: when two alloys exhibit liquid phase separation but do not form a brittle phase, the risk is classified as medium. This is mainly because liquid phase separation may lead to interfacial stress concentration due to thermal mismatch between the two alloys, increasing the risk of cracking; alternatively, it may form a two-phase alloy composite material at the interface, reducing the risk of interfacial cracking by increasing interfacial strength. Therefore, this situation is classified as medium risk.

[0050] Step S4 prioritizes the results from the three dimensions—harmful phase, liquid phase separation, and cracking sensitivity factor—in a hierarchical decision-making process. This decision establishes a priority and combination logic among multiple factors, rather than a simple weighting or averaging. For example, harmful phases are given the highest weight, which aligns with physical reality: low-melting-point eutectic phases or brittle intermetallic compounds often contribute the most direct and severe to cracking. This hierarchical and prioritized decision-making rule makes the evaluation results both rigorous and easy to implement in engineering.

[0051] S5. Guide the material selection and process design of additive manufacturing multi-material components based on the cracking tendency level; The following crack suppression measures can be taken: (1) Select low-risk material combinations; (2) Avoid or reduce the medium and high risk component ranges, such as interface component gradient design, or optimize interface laser forming parameters (such as layer thickness, line energy density, etc.) to control the interface component distribution.

[0052] This invention achieves a closed-loop guidance system from risk prediction to proactive risk avoidance and mitigation. It can predict which component ranges are prone to cracking before molding, allowing for targeted avoidance or process bypassing of these ranges, thus significantly reducing trial-and-error experimental costs and demonstrating significant engineering and economic value.

[0053] S6. Verify the model prediction results through additive manufacturing experiments, and revise the model based on the experimental data.

[0054] Step S6 specifically includes: preparing alloy powders with different mixing ratios using a mechanical powder mixing method, performing additive manufacturing, observing the distribution of interface cracks, comparing the experimental results with the model rating results, and adjusting the judgment thresholds or rating rules of each factor based on the comparison results.

[0055] Furthermore, the additive manufacturing method in this invention includes: laser powder bed melting (L-PBF), electron beam melting (EBM), or directed energy deposition (DED).

[0056] According to a second aspect of the present invention, a system for determining the tendency of multi-material interface cracking in additive manufacturing is provided, applied to the method described in any one of the above solutions, the system comprising: The module is used to build a multi-factor cracking tendency determination model, where the cracking factors include: liquid phase separation factor, harmful phase precipitation factor and cracking sensitivity factor. The curve plotting module is used to set the composition of the target dissimilar material at different mixing ratios, calculate the cracking factor value at each mixing ratio, and plot the curve of each cracking factor as a function of the mixing ratio. The high-risk cracking identification module is used to identify the component regions where the peak values ​​of each cracking factor overlap based on the curves of how each cracking factor changes with the mixing ratio, and to determine the high-risk cracking component range. The cracking tendency level determination module is used to determine the cracking tendency of components with different mixing ratios and obtain the cracking tendency level. The material selection and process design module is used to guide the material selection and process design of additive manufacturing multi-material components based on the cracking tendency level. The correction module is used to verify the model's prediction results through additive manufacturing experiments and to correct the model based on the experimental data.

[0057] Example 1: Determination of cracking tendency at the bimetallic interface of L-PBF forming Invar36-M2052 I. Material System and Mixing Ratio Setting This embodiment focuses on the Invar36-M2052 bimetallic alloy, which has important applications in the field of aerospace precision instruments. Invar36 is an Fe-Ni alloy (Ni content approximately 36%), and M2052 is a Mn-Cu alloy (Mn content approximately 70%, Cu content approximately 22.35%). The two alloys have significantly different thermophysical properties: a melting point difference of approximately 300 K and a thermal expansion coefficient difference of approximately 2.4 times, making them a typical thermally mismatched bimetallic combination.

[0058] Six mixing ratios were set for the Invar 36 mass fraction in the mixed material: 0%, 20%, 40%, 60%, 80%, and 100%, denoted as M2052, M2052-20%Invar36, M2052-40%Invar36, M2052-60%Invar36, M2052-80%Invar36, and pure Invar 36.

[0059] II. Calculation of Each Cracking Factor (1) Liquid phase separation factor To assess whether liquid phase separation would occur in the Invar36-M2052 system, the Gibbs free energy curve for this system was calculated, as follows: Figure 2 As shown. Gibbs free energy calculations show that the Invar36-M2052 system satisfies the following conditions under all mixing ratios. A value >0 indicates that the mixed liquid phase maintains thermodynamic stability and no liquid phase separation will occur.

[0060] (2) Detrimental phase precipitation factor Using Thermo-Calc thermodynamic software based on the TCFE11 database, equilibrium phase diagrams and non-equilibrium solidification paths were calculated for different Invar 36 ratios, such as... Figure 3 As shown in the figure. The results indicate that when the Invar 36 content is 70%-90%, a low-melting-point Cu-rich phase can be formed at the end of solidification. These Cu-rich phases can form a continuous liquid network structure between dendrites, which becomes the preferred crack propagation path under the tensile strain caused by solidification shrinkage.

[0061] (3) Calculation of crack sensitivity factor Using Thermo-Calc thermodynamic software and based on the TCFE11 database, the solidification temperature range ΔT, brittle temperature range BTR, crack sensitivity coefficient CSC, and solidification cracking index SCI were calculated for different Invar 36 ratios.

[0062] The results show (e.g.) Figure 4As shown in the figure, with the increase of the Invar 36 mixing ratio, ΔT, BTR, CSC, and SCI all show a trend of first increasing and then decreasing. When the Invar 36 mass fraction is 60%, ΔT reaches its maximum value of 259.73K, and the corresponding BTR is 111K. At this time, the solidification process takes place in the brittle, pasty region that is prone to cracking for about 42.74% of the time. When the Invar 36 ratio increases to 70%-90%, although ΔT and BTR decrease, the proportion of the brittle temperature range in the entire solidification range continues to rise, reaching a peak of 60.07% when the Invar 36 ratio is 90%. CSC also reaches its maximum at this ratio. The calculation of SCI shows that the slope of the curve is significantly higher when the Invar 36 ratio is 60%-80%, indicating a greater tendency to crack.

[0063] Considering all factors related to cracking sensitivity, an Invar36 content of 60%-90% indicates a high-risk range.

[0064] III. Comprehensive Assessment of Cracking Risk Based on the calculation results of the above three indicators (summarized in Table 2), it was found that in the range of 60%-90% Invar36 content, although there is no liquid phase separation, there is a brittle phase, and the four characteristic peaks of the crack sensitivity factor all overlap in this range. Therefore, this composition range is determined to be the high cracking risk range of L-PBF molded Invar36-M2052 bimetal.

[0065] Table 2 IV. Experimental Verification of Cracking Risk Based on the comprehensive rating results, in order to obtain crack-free Invar36-M2052 bimetallic parts, the proportion of Invar36 in the interface area should be controlled below 40%, avoiding the crack-prone range of 60%-90%.

[0066] Alloy powders with different Invar 36 ratios were prepared by mechanical powder mixing, and L-PBF forming experiments were conducted.

[0067] The results show (e.g.) Figure 5 As shown in the figure, when the Invar36 content is 0% and 20%, there are no cracks in the deposited microstructure; when the content is 40%, a small amount of porosity appears but no cracks; when the content is 60% and 80%, a large number of longitudinal cracks extending along the dendrite growth direction appear; when the content is 100%, there are no cracks. The experimental results are in high agreement with the model predictions, verifying the accuracy of this method. The crack-free Invar36-M2052 bimetallic part formed using optimized process parameters has a tensile strength of 403 MPa, a yield strength of 353 MPa, and an elongation of 24.4%. The fracture is located on the Invar36 matrix side, and the interface achieves good metallurgical bonding.

[0068] Example 2: Verification of the interfacial cracking tendency of the Inconel 718-304L bimetallic system I. Material System This embodiment focuses on the Inconel 718-304L bimetallic alloy, which has important applications in aerospace engines and hot-end components. Inconel 718 is a Ni-Cr-Fe based precipitation-strengthened high-temperature alloy, while 304L is an austenitic stainless steel. The two alloys differ significantly in thermophysical properties: their melting points differ by approximately 150 K, their coefficients of thermal expansion differ by approximately 1.3 times, and their thermal conductivity differs significantly, making them a typical thermal mismatch-dominated bimetallic combination.

[0069] II. Calculation of Cracking Factor (1) Liquid phase separation factor To assess whether liquid phase separation would occur in the Inconel 718-304L system, the Gibbs free energy curve for this system was calculated, as follows: Figure 6 As shown. Gibbs free energy calculations show that the Inconel 718-304L system satisfies the Gibbs free energy requirement under all mixing ratios. A value >0 indicates that the liquid phase remains thermodynamically stable and homogeneous in composition, and liquid phase separation will not occur.

[0070] (2) Harmful phase factors Thermo-Calc was used to calculate equilibrium phase diagrams and non-equilibrium solidification paths for different proportions of 304L. The results show that towards the end of solidification, compositions with proportions of 45-75% will form brittle Laves phases. These brittle phases are continuously distributed between dendrites and crack under the influence of solidification shrinkage stress. SEM characterization confirmed that the presence of the brittle Laves phases leads to crack initiation (e.g., ...). Figure 7 (As shown).

[0071] (3) Calculation of crack sensitivity factor To further comprehensively assess the accuracy of the criteria, the crack sensitivity factor for this system was recalculated, such as... Figure 8 As shown, the results indicate that when the 304L content in the mixed material is 40%-70%, it falls within the range of components prone to cracking.

[0072] III. Cracking Tendency Experiment Verification Taking into account the distribution of brittle phases and cracking sensitivity factors, a 304L content of 40%-70% was identified as a high-risk range. The overall rating of the easily cracked range was compared with the actual cracked component range, which was determined by line scan composition data (e.g., ...). Figure 9 (As shown). By dividing the actual cracked area, the mass fraction of 304L at the interface was determined to be 45-75%, which is basically consistent with the calculated range, thus demonstrating the reliability of this criterion.

[0073] Based on the above criteria, the discrete distribution of the Laves phase at the grain boundaries was achieved through process adjustments, suppressing interfacial cracking in the In718-304L bimetallic forming process. The bimetallic specimen formed after optimizing process parameters exhibited a tensile strength of 600 MPa, a yield strength of 493 MPa, and an elongation of 46% at room temperature. At 600℃, the mechanical properties were a tensile strength of 335 MPa, a yield strength of 308 MPa, and an elongation of 19%. Both room temperature and high temperature tensile tests resulted in fracture on the 304L side, indicating good interfacial metallurgical bonding.

[0074] It should be noted that, in this document, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Unless otherwise specified, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes that element.

[0075] The sequence numbers of the above embodiments of the present invention are for descriptive purposes only and do not represent the superiority or inferiority of the embodiments.

[0076] Through the above description of the embodiments, those skilled in the art can clearly understand that the above implementation methods can be implemented by means of software plus necessary general-purpose hardware platforms. Of course, they can also be implemented by hardware, but in many cases the former is a better implementation method. Based on this understanding, the technical solution of the present invention, in essence, or the part that contributes to the prior art, can be embodied in the form of a software product. This computer software product is stored in a storage medium (such as ROM / RAM, magnetic disk, optical disk), and includes several instructions to cause a terminal (which may be a mobile phone, computer, server, air conditioner, or network device, etc.) to execute the methods described in the various embodiments of the present invention.

[0077] The embodiments of the present invention have been described above with reference to the accompanying drawings. However, the present invention is not limited to the specific embodiments described above. The specific embodiments described above are merely illustrative and not restrictive. Those skilled in the art can make many other forms under the guidance of the present invention without departing from the spirit and scope of the claims. All of these forms are within the protection scope of the present invention.

Claims

1. A method for determining the tendency of multi-material interface cracking in additive manufacturing, characterized in that, include: S1. Construct a multi-factor cracking tendency determination model, wherein the cracking factors include: liquid phase separation factor, harmful phase precipitation factor and cracking sensitivity factor; S2. Set the composition of the target dissimilar material at different mixing ratios, calculate the cracking factor value for each mixing ratio, and plot the curve of each cracking factor as a function of the mixing ratio. S3. Based on the curves of each cracking factor changing with the mixing ratio and combined with the judgment model, identify the component regions where the peak values ​​of each cracking factor overlap, and determine the high-risk component range for cracking. S4. Determine the cracking tendency of components with different mixing ratios based on the judgment model to obtain the cracking tendency level; S5. Guide the material selection and process design of additive manufacturing multi-material components based on the cracking tendency level; S6. Verify the model prediction results through additive manufacturing experiments, and revise the model based on the experimental data.

2. The method for determining the tendency of multi-material interface cracking in additive manufacturing according to claim 1, characterized in that, In step S1, the liquid phase separation factor is determined based on the second derivative of the Gibbs free energy and composition curve of the mixed system. The harmful phase precipitation factor includes low melting point eutectic phase and brittle intermetallic compound. The crack sensitivity factor includes solidification temperature range, brittle temperature range, crack sensitivity coefficient and solidification cracking index.

3. The method for determining the tendency of multi-material interface cracking in additive manufacturing according to claim 2, characterized in that, The determination criteria for the liquid phase separation factor are as follows: when the second derivative of the Gibbs free energy and composition curve of the mixed system is less than zero, liquid phase separation is determined to have occurred; when the second derivative is greater than zero, liquid phase separation is determined to have not occurred, and the second derivative being equal to zero is the critical boundary.

4. The method for determining the tendency of multi-material interface cracking in additive manufacturing according to claim 2, characterized in that, The determination of the harmful phase precipitation factor includes: using thermodynamic calculation software to calculate the equilibrium phase diagram under different mixing ratios of dissimilar materials, and combining it with the simulation of phase precipitation behavior under rapid solidification conditions using a non-equilibrium solidification model, in order to identify low-melting-point eutectic phases and brittle intermetallic compounds.

5. The method for determining the tendency of multi-material interface cracking in additive manufacturing according to claim 2, characterized in that, The solidification temperature range is the difference between the liquidus temperature and the solidus temperature; the brittleness temperature range is the temperature range corresponding to a solid fraction between 0.9 and 0.99; the crack sensitivity coefficient characterizes the ratio of stress concentration time to stress release time at the end of solidification; the solidification cracking index is based on a non-equilibrium solidification model and is evaluated by analyzing the rate of change of solid fraction with temperature.

6. The method for determining the tendency of multi-material interface cracking in additive manufacturing according to claim 1, characterized in that, The standard for determining a single characteristic value of the cracking sensitivity factor as high risk is: the characteristic value of the mixed material is greater than or equal to 1.5 times the larger characteristic value of the two individual materials.

7. The method for determining the tendency of multi-material interface cracking in additive manufacturing according to claim 1, characterized in that, The specific rules for the cracking tendency level are as follows: When a harmful phase is present, it is considered high risk; When there is no harmful phase but liquid phase separation, it is judged as medium risk; When there is no harmful phase and no liquid phase separation, the risk is determined based on the number of the four characteristic values ​​in the cracking sensitivity factor that indicate high risk: less than or equal to 1 indicates low risk, 2 indicates medium risk, and 3 indicates high risk.

8. The method for determining the tendency of multi-material interface cracking in additive manufacturing according to claim 1, characterized in that, Step S6 specifically includes: preparing alloy powders with different mixing ratios using a mechanical powder mixing method, performing additive manufacturing, observing the distribution of interface cracks, comparing the experimental results with the model rating results, and adjusting the judgment thresholds or rating rules of each factor based on the comparison results.

9. The method for determining the tendency of multi-material interface cracking in additive manufacturing according to claim 1, characterized in that, Additive manufacturing methods include laser powder bed melting, electron beam melting, or directional energy deposition.

10. A system for determining the tendency of multi-material interface cracking in additive manufacturing, characterized in that, The system for implementing the method of any one of claims 1-9 comprises: The module is used to build a multi-factor cracking tendency determination model, where the cracking factors include: liquid phase separation factor, harmful phase precipitation factor and cracking sensitivity factor. The curve plotting module is used to set the composition of the target dissimilar material at different mixing ratios, calculate the cracking factor value at each mixing ratio, and plot the curve of each cracking factor as a function of the mixing ratio. The high-risk cracking identification module is used to identify the component regions where the peak values ​​of each cracking factor overlap based on the curves of how each cracking factor changes with the mixing ratio, and to determine the high-risk cracking component range. The cracking tendency level determination module is used to determine the cracking tendency of components with different mixing ratios and obtain the cracking tendency level. The material selection and process design module is used to guide the material selection and process design of additive manufacturing multi-material components based on the cracking tendency level. The correction module is used to verify the model's prediction results through additive manufacturing experiments and to correct the model based on the experimental data.

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