Calculation method and device for a multi-component heterogeneous powder laser in-situ alloying process

Abstract

The present application relates to a calculation method and device for a multi-component heterogeneous powder laser in-situ alloying process. Based on the collected heterogeneous powder data set, a random powder dropping model for the heterogeneous powder bed is constructed, a powder scraping model for the heterogeneous powder is constructed, and a molten state diffusion model for the printing process of the heterogeneous powder is constructed. Then, component deviation and component uniformity analysis, heterogeneous powder component selection and printing are carried out to obtain a printed sample with alloying and uniform composition. By predicting the alloying degree and component uniformity of samples with different components and process combinations, the present application guides the design of process systems for in-situ alloying of different materials, improves the development efficiency of the SLM in-situ alloying preparation process technology for different materials, and further improves the development and iteration efficiency of new alloys. It effectively solves the problems of specific defects such as cracks, pores, solidification segregation, unmelted particles and interphase boundaries in traditional SLM samples, and provides an innovative method for the development of special alloys for additive manufacturing.

Description

Technical Field

[0001] The present application relates to the fields of laser additive manufacturing and numerical simulation technology, and particularly relates to a calculation method and device for a multi-component heterogeneous powder laser in-situ alloying process. Background Art

[0002] SLM (Selective Laser Melting) in-situ alloying is a new type of additive manufacturing technology, that is, heterogeneous powders are used for real-time mixing for SLM printing, and the micro-area alloying process is completed during the printing process and a high-density bulk sample is formed synchronously. Compared with using pre-alloyed powders as raw materials, heterogeneous powders can flexibly and quickly adjust the alloy composition through various powder mixing methods. Different alloy compositions can be designed and manufactured in a short time to quickly study the relationship between composition changes and material properties, which is suitable for the accelerated research and development of special material systems for additive manufacturing.

[0003] The SLM in-situ alloying technology not only has the process characteristics of traditional SLM processes, such as point-by-point, line-by-line, and layer-by-layer, but also has the characteristics of synchronous alloying during the melting and solidification process. The particularity of the process makes the sample not only have common defects such as cracks, pores, and solidification segregation that appear in traditional SLM samples, but also have specific defects such as unmelted particles and interface phases. These defects will greatly reduce the composition uniformity and tissue densification of the sample, thereby damaging the service performance of the material. Summary of the Invention

[0004] To at least overcome to some extent the problems of cracks, pores, solidification segregation, and specific defects such as unmelted particles and interface phases that appear in traditional SLM samples in related technologies, the present application provides a calculation method and device for a multi-component heterogeneous powder laser in-situ alloying process.

[0005] The solution of the present application is as follows:

[0006] A calculation method for a multi-component heterogeneous powder laser in-situ alloying process includes: collecting a dataset of heterogeneous powders to be tested;

[0007] Based on the dataset of heterogeneous powders, constructing a random powder dropping model for a heterogeneous powder bed to obtain a mixed powder bed;

[0008] Based on the mixed powder bed, constructing a powder scraping model for heterogeneous powders to obtain a vibration-compacted stacked heterogeneous powder layer;

[0009] Based on the vibration-compacted stacked heterogeneous powder layer, constructing a temperature field model for the multi-layer and multi-pass printing process of heterogeneous powders to obtain the melting time and temperature of the micro-areas of the vibration-compacted stacked heterogeneous powder layer after multi-pass laser scanning;

[0010] Based on the melting state time and temperature of the micro-region of the vibration-compacted heterogeneous powder layer after multi-pass laser scanning, construct a diffusion kinetics model for the high-speed melting and solidification process, conduct melting state diffusion analysis, and obtain the diffusion conditions of the heterogeneous powder data set under different melting states;

[0011] Based on the vibration-compacted heterogeneous powder layer, conduct composition deviation and composition uniformity analysis, and obtain the composition deviation parameter and the composition non-uniformity parameter;

[0012] Based on the diffusion conditions of the heterogeneous powder data set under different melting states, as well as the composition deviation parameter and the composition non-uniformity parameter, conduct selection and printing of the heterogeneous powder composition to obtain a printed sample with alloying and uniform composition.

[0013] Further, construct a random powder dropping model for the heterogeneous powder bed, including:

[0014] Based on the heterogeneous powder data set, by simulating the free fall under the action of gravity after mixing the distribution ratio and particle size ratio of the heterogeneous powder data set, obtain a mixed powder bed.

[0015] Further, construct a powder scraping model for the heterogeneous powder, including:

[0016] Based on the mixed powder bed, move the scraper unidirectionally from the initial end to the end of the mixed powder bed at a preset moving speed. Assume that the thickness of the mixed powder bed after vibration compaction is the preset height, and scrape off the powder higher than the preset height from the mixed powder bed to obtain a vibration-compacted heterogeneous powder layer.

[0017] Further, construct a temperature field model for the multi-layer and multi-pass printing process of the heterogeneous powder, including:

[0018] Based on the vibration-compacted heterogeneous powder layer, by applying a moving laser heat source and setting the laser heat source parameters of the moving laser heat source, calculate the melting state time and temperature of the micro-region of the vibration-compacted heterogeneous powder layer after multi-pass laser scanning at a specified micro-region on the laser scanning path.

[0019] Further, construct a diffusion kinetics model for the high-speed melting and solidification process, including:

[0020] Based on the melting state time and temperature of the micro-region of the vibration-compacted heterogeneous powder layer after multi-pass laser scanning, calculate the degree of liquid diffusion of the heterogeneous particles in the molten state during the laser melting process, and calculate the alloying degree of different elements through the diffusion percentage;

[0021] The calculation formula for the diffusion percentage is:

[0022]

[0023] Among them, D distance represents the diffusion percentage, A and B represent two elements, and D iAB represents the diffusion distance of the element in A into B, and R B is the radius of element B.

[0024] Furthermore, performing the component deviation and component uniformity analysis includes:

[0025] Component deviation analysis and component non-uniformity analysis;

[0026] The component deviation analysis is based on the tapped packed heterogeneous powder layer, and is the ratio of the absolute value of the difference between the calculated component and the designed component of the element to be tested of the particles in the tapped packed heterogeneous powder layer to the designed component. The formula for calculating the component deviation analysis is:

[0027]

[0028] Among them, x represents component deviation analysis, n represents the number of components in the system, Wi calculation represents the calculated component, and Wi design represents the designed component;

[0029] The component non-uniformity is based on the tapped packed heterogeneous powder layer. The tapped packed heterogeneous powder layer is equally divided into a specified number of regions with the same area in the length direction, and the average value of the deviation between the component and the designed component is calculated. The formula for calculating the component non-uniformity is:

[0030]

[0031] Among them, ω represents component non-uniformity, m represents the number of equal divisions of the powder bed along the x-axis, and χ j represents the component deviation analysis of the micro-region j.

[0032] Furthermore, performing the molten state diffusion analysis includes:

[0033] Based on the molten state time and temperature of the micro-regions of the tapped packed heterogeneous powder layer after multi-pass laser scanning and the diffusion kinetics model of the high-speed melting and solidification process, calculate the diffusion situation of the particles in the tapped packed heterogeneous powder layer at different molten state temperatures and molten state durations, and obtain the diffusion situation of the particles in the tapped packed heterogeneous powder layer under different molten states.

[0034] Furthermore, performing the selection and printing of the heterogeneous powder components includes:

[0035] Based on the diffusion situation of the particles in the vibrated and packed heterogeneous powder layer in different molten states, as well as the composition deviation parameter and the composition non-uniformity parameter, select the laser process parameters that obtain the maximum value of the diffusion percentage. The laser process parameters include laser power, scanning speed, scanning spacing, and scanning times, and use them as the optimal process design scheme for the composition of the heterogeneous powder, and perform printing to obtain a printed sample with alloying and uniform composition.

[0036] The present application also provides a calculation device for a multi-component heterogeneous powder laser in-situ alloying process, including: a heterogeneous powder data set acquisition module for acquiring a heterogeneous powder data set to be tested;

[0037] A heterogeneous powder bed powder dropping module for constructing a random powder dropping model of the heterogeneous powder bed based on the heterogeneous powder data set to obtain a mixed powder bed;

[0038] A scraping module for heterogeneous powder for constructing a scraping model for heterogeneous powder based on the mixed powder bed to obtain a vibrated and packed heterogeneous powder layer;

[0039] A multi-layer and multi-pass printing process module for heterogeneous powder for constructing a temperature field model of the multi-layer and multi-pass printing process of heterogeneous powder based on the vibrated and packed heterogeneous powder layer to obtain the melting state time and temperature of the micro-region of the vibrated and packed heterogeneous powder layer after multi-pass laser scanning;

[0040] A melting state diffusion analysis module for constructing a diffusion kinetics model of the high-speed melting and solidification process based on the melting state time and temperature of the micro-region of the vibrated and packed heterogeneous powder layer after multi-pass laser scanning, performing melting state diffusion analysis, and obtaining the diffusion situation of the heterogeneous powder data set in different melting states;

[0041] A composition deviation and composition uniformity analysis module for performing composition deviation and composition uniformity analysis based on the vibrated and packed heterogeneous powder layer to obtain a composition deviation parameter and a composition non-uniformity parameter; a heterogeneous powder composition selection and printing module for performing heterogeneous powder composition selection and printing based on the diffusion situation of the heterogeneous powder data set in different melting states, the composition deviation parameter, and the composition non-uniformity parameter to obtain a printed sample with alloying and uniform composition.

[0042] The technical solution provided by the present application may include the following beneficial effects: By predicting the alloying degree and composition uniformity of samples with different compositions and process combinations, the present application guides the design of the process system for in-situ alloying of different materials, improves the development efficiency of the SLM in-situ alloying preparation process technology for different materials, and further improves the development and iteration efficiency of new alloys, effectively solving the problems of specific defects such as cracks, pores, solidification segregation, unmelted particles, and interphase boundaries in traditional SLM samples, and providing an innovative method for the development of special alloys for additive manufacturing.

[0043] It should be understood that the above general description and the following detailed description are merely exemplary and explanatory, and do not limit this application. BRIEF DESCRIPTION OF THE DRAWINGS

[0044] The drawings herein are incorporated into the specification and constitute a part of this specification, showing embodiments consistent with this application, and are used together with the specification to explain the principles of this application.

[0045] Figure 1 It is a schematic flow chart of a method for a multi-component heterogeneous powder laser in-situ alloying process provided by an embodiment of this application;

[0046] Figure 2 It is a schematic diagram of a one-dimensional diffusion model of heterogeneous liquid particles constructed based on DICTRA software provided by another embodiment of this application;

[0047] Figure 3 It is a schematic diagram of the calculation result of the composition deviation of an in-situ alloying sample of Fe-Ni binary heterogeneous powder provided by another embodiment of this application;

[0048] Figure 4 It is a schematic diagram of the calculation result of the composition non-uniformity of an in-situ alloying sample of Fe-Ni binary heterogeneous powder provided by another embodiment of this application;

[0049] Figure 5 It is a schematic diagram of the device composition of a multi-component heterogeneous powder laser in-situ alloying process provided by an embodiment of this application;

[0050] Figure 6 It is a schematic diagram of the designed composition and the percentage of the number of particles of Fe-Ni binary heterogeneous particles provided by an embodiment of this application;

[0051] Figure 7 It is a schematic diagram of the cyclic melting temperature field data of finite element calculation of SLM printing Fe-Ni provided by an embodiment of this application;

[0052] Figure 8 It is a schematic diagram of the percentage of the diffusion distance of Fe-Ni heterogeneous powder with different particle radii provided by an embodiment of this application. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0053] Here, exemplary embodiments will be described in detail, and examples thereof are shown in the accompanying drawings. When the following description refers to the accompanying drawings, unless otherwise indicated, the same numbers in different drawings represent the same or similar elements. The embodiments described in the following exemplary embodiments do not represent all embodiments consistent with the present application. On the contrary, they are merely examples of devices and methods consistent with some aspects of the present application as detailed in the appended claims.

[0054] In the prior art, due to the particularity of the process, not only common defects such as cracks, pores, and solidification segregation that appear in traditional SLM samples will exist in the samples, but also unique defects such as unmelted particles and interface phases will appear. These defects will significantly reduce the compositional uniformity and tissue densification of the samples, thereby damaging the service performance of the materials.

[0055] In view of this, the purpose of the present application is to provide a calculation method and device for a multi-component heterogeneous powder laser in-situ alloying process to overcome the problems of common defects such as cracks, pores, and solidification segregation that appear in traditional SLM samples in the current prior art, as well as unique defects such as unmelted particles and interface phases.

[0056] Embodiment 1

[0057] Figure 1 It is a schematic flow chart of a method for a multi-component heterogeneous powder laser in-situ alloying process provided by an embodiment of the present application. Please refer to Figure 1 , this embodiment provides a calculation method for a multi-component heterogeneous powder laser in-situ alloying process, including the following steps:

[0058] S1. Collect a dataset of heterogeneous powders to be tested;

[0059] S2. Based on the dataset of heterogeneous powders, construct a random powder dropping model for the heterogeneous powder bed to obtain a mixed powder bed;

[0060] S3. Based on the mixed powder bed, construct a powder scraping model for the heterogeneous powders to obtain a vibration-compacted stacked heterogeneous powder layer;

[0061] S4. Based on the vibration-compacted stacked heterogeneous powder layer, construct a temperature field model for the multi-layer and multi-pass printing process of the heterogeneous powders to obtain the melting time and temperature of the micro-regions of the vibration-compacted stacked heterogeneous powder layer after multi-pass laser scanning;

[0062] S5. Based on the melting time and temperature of the micro-regions of the vibration-compacted stacked heterogeneous powder layer after multi-pass laser scanning, construct a diffusion kinetics model for the high-speed melting and solidification process, conduct melting-state diffusion analysis, and obtain the diffusion conditions of the dataset of heterogeneous powders under different melting states;

[0063] S6. Based on the vibration-compacted heterogeneous powder layer, perform analysis on composition deviation and composition uniformity to obtain a composition deviation parameter and a composition non-uniformity parameter;

[0064] S7. Based on the diffusion conditions of the heterogeneous powder dataset in different molten states, as well as the composition deviation parameter and the composition non-uniformity parameter, perform selection and printing of the heterogeneous powder composition to obtain a printed sample with alloying and uniform composition.

[0065] In real life, the full-process technology of the SLM in-situ alloying technology can be divided into three main links: powder mixing, powder spreading, and printing. These three technological links will all bring problems of composition uniformity. Different from the traditional SLM process using pre-alloyed powder for printing, the composition and quality of the heterogeneous mixed powder bed generated by in-situ alloying powder spreading are the primary factors for controlling composition uniformity. If macroscopic-scale regional composition non-uniformity is caused during the powder spreading process, it is very difficult to improve through process adjustment. Its second factor is the alloying process controlled by process parameters, which mainly depends on the phase transformation process controlled by diffusion. The diffusion process in the micro-region of in-situ alloying materials will undergo multiple cycles of liquid diffusion, solidification diffusion, and solid diffusion. Among them, the liquid diffusion coefficient is several orders of magnitude higher than the solidification diffusion, and the diffusion coefficient during the solid-phase transformation process is almost 0. Therefore, the degree of diffusion in the molten state controlled by process parameters under high-speed printing conditions is the physical essence of realizing SLM in-situ alloying. To obtain a fully alloyed and composition-uniform printed sample, on the one hand, it is to achieve complete diffusion of heterogeneous particles during the molten state process through laser process parameter regulation, and on the other hand, it is to achieve uniform laying of the mixed powder through control of the physical properties of the raw materials.

[0066] In one embodiment, to achieve, on the one hand, complete diffusion of heterogeneous particles during the molten state process through laser process parameter regulation, and on the other hand, uniform laying of the mixed powder through control of the physical properties of the raw materials, the present application provides a calculation method for the laser in-situ alloying process of multi-component heterogeneous powder. Specifically, through a function that characterizes the in-situ alloying degree and composition uniformity of heterogeneous powder particles, a random mixing and powder spreading model of multi-component heterogeneous powder particles is established according to the discrete element method, and the influence results of the material properties / particle size / scraping speed and scraping thickness of the powder particles on the composition uniformity of the powder bed can be calculated. According to the finite element method, a multi-layer and multi-pass scanning temperature field model of the powder bed is established, and combined with the diffusion kinetics calculation method, a molten state diffusion model of heterogeneous powder particles in the micro-region during high-speed printing is established, and the influence results of laser process parameters such as laser power / scanning speed / scanning spacing / scanning times on the laser in-situ alloying degree of the sample can be calculated. Through the calculation method provided by the present application, the design of laser process parameters for selective laser melting of heterogeneous powder can be guided, and the composition uniformity of the sample can be predicted more accurately, thereby accelerating the development and optimization efficiency of such preparation processes, reducing experimental costs, and maximizing the tissue performance of the final sample.

[0067] For step S2, in one embodiment, a random powder dropping model for a heterogeneous powder bed is constructed, including: based on a heterogeneous powder data set, by simulating the distribution ratio and particle size ratio of the heterogeneous powder data set after mixing and freely falling under the action of gravity, a mixed powder bed is obtained.

[0068] In this embodiment, the specific operation steps for constructing the random powder dropping model of the heterogeneous powder bed include:

[0069] S2.1 Convert the preset distribution ratio and particle size ratio of the multi-component heterogeneous powder into a particle number ratio as the initial material parameter.

[0070] S2.2 Design the solution size (length L, width W, and height H) of the heterogeneous powder bed, and set the generation time of the mixed powder particles as t1. Input the property parameters of the particles, including density, generation time, generation speed, relative displacement, elastic constant, deformation coefficient, and friction coefficient, as the inherent attribute parameters of the particles in the calculation process into the software.

[0071] S2.3 The heterogeneous powder particles freely fall on a rectangular substrate under the action of gravity to form a loosely packed and randomly mixed powder bed.

[0072] In this embodiment, for step S3, a powder scraping model M2 of the heterogeneous powder is constructed through discrete element software based on the powder dropping model in S2. Since the particles falling in the first step are loosely packed, a moving scraper is applied above them. This model is used to simulate the formation of a vibrated and packed powder layer with a preset height, with a length of L, a width of W, and a height of H1.

[0073] In this embodiment, the specific steps are as follows:

[0074] S3.1 Apply a moving scraper to the initial end of the loosely packed powder bed formed in S2, and set a baffle at the end.

[0075] S3.2 The clearance value between the bottom of the scraper and the substrate is preset as H1, which is the thickness of the powder layer after compaction. The bottom position of the baffle is flush with the substrate position, and the preset height value is n1;

[0076] S3.3 The scraper is a cuboid, and its thickness should be ≤ L (the length of the powder bed solution domain) / 10, the width is equal to W (the width of the powder bed solution domain), and the height is ≥ 5*H (the height of the powder bed solution domain);

[0077] S3.4 The scraper moves unidirectionally from the starting end to the ending end of the powder bed at a preset moving speed v, and the ending end is set as the outlet;

[0078] The S3.5 blade interacts with the powder bed to scrape off the powder above the preset value H1 from the original powder bed, forming a heterogeneous powder layer with a fixed length, width, and height.

[0079] In this embodiment, for step S4, a moving laser heat source is applied to the powder layer established in S2 through a calculation software based on the finite volume method or the finite element method to construct a temperature field model for the multi-layer and multi-pass printing process of heterogeneous powder. The construction of this model is used to obtain the melting state time and temperature of the micro-region of the powder bed after multi-pass laser scanning.

[0080] In this embodiment, the specific operation steps are as follows:

[0081] S4.1 Take the dimensions of the single-layer powder bed formed in S2, including length L, width W, and height H1, as the geometric model dimensions for temperature field calculation. The material properties can be simplified to a homogeneous alloy entity with a preset distribution ratio. On this basis, set model parameters such as material properties, ambient temperature, and mesh size.

[0082] S4.2 Designate the area not covered by the powder bed as air and set convective heat transfer.

[0083] S4.3 The heat source model preferably uses a Gaussian volume heat source, and set laser heat source parameters, including scanning strategy, laser power, scanning speed, laser source diameter, overlap rate, and number of scanning passes.

[0084] S4.4 Parameters such as absorptivity, solidification phase change, vapor back pressure, and multiple reflections can be set for the model to further improve the calculation accuracy.

[0085] S4.5 Calculate and select any micro-region on the laser scanning path, calculate the temperature change curve over time, and obtain the average temperature value T and duration t in the melting state (greater than or equal to the melting point temperature).

[0086] In this embodiment, for S5, a diffusion kinetics model of the micro-region during the high-speed melting and solidification process is constructed through DICTRA software based on the diffusion kinetics method to analyze the melting state diffusion kinetics process of heterogeneous powder under the action of different laser process parameters.

[0087] Specifically, it includes the following steps:

[0088] S5.1 Adopt a single-phase one-dimensional diffusion model, as follows Figure 2 As shown, the molten heterogeneous particles are simplified into two spheres with different melting points. One sphere represents the single-element particle A with a radius of 25 μm, and the other sphere represents the alloy particle B composed of other components according to the composition ratio except A with a radius of 75 μm. When the heterogeneous powder system is a binary system, A and B respectively represent single-element particles.

[0089] S5.2 Calculate the liquid diffusion that occurs between two spheres during the laser melting process. The input temperature for the diffusion is the average temperature value T calculated in Step 4, and the input time is the duration t calculated in Step 4.

[0090] S5.3 Based on diffusion kinetics software, obtain the distribution of the composition of all elements with respect to the diffusion distance by solving the diffusion equation. The diffusion distance is the sum of the radii of particle A and particle B.

[0091] S5.4 To quantitatively measure the alloying degree of different elements, define the diffusion distance percentage (DiffusionDistance, D distance ):

[0092]

[0093] In the formula, D i is the diffusion distance of the element in A into B. D model is the maximum diffusion distance of the element in A into B, which is equal to the radius R B of particle B. If the element in particle A can diffuse to the core of particle B under the action of the laser melting process, it is considered that in-situ alloying has been achieved in this system, that is, the value of D distance is equal to 1, and it can be considered that the in-situ alloying process of the heterogeneous powder particles has been completed in the molten state.

[0094] S5.5 Analyze the diffusion kinetics process in the molten state that occurs under different laser process parameters for the heterogeneous powder. Based on the molten state time and temperature of the micro-region of the vibrated and packed heterogeneous powder layer after multi-pass laser scanning and the diffusion kinetics model of the high-speed melting and solidification process, calculate the diffusion of powder particles under multiple groups of different molten state temperatures (T + ΔT), molten state durations (t + Δt), powder particle sizes, and scanning times.

[0095] In one embodiment, for S6, based on the vibrated and packed heterogeneous powder layer obtained in S2, use.stl file conversion software to perform statistical analysis on the results of the discrete element method calculation to obtain the number and position data of the heterogeneous powder layer particles. Use two parameters, the composition deviation χ and the composition non-uniformity ω, to characterize the composition uniformity of the powder bed.

[0096] In this embodiment, the specific operation steps are as follows:

[0097] S6.1 The overall composition segregation of the powder bed is the ratio of the absolute value of the difference between the calculated composition and the designed composition of a certain element to the designed composition, represented by χ, where n represents the number of components in the system.

[0098]

[0099] S6.2 Divide the powder bed into m regions of the same area along the length (x-axis) direction. The average value of the deviation between the calculated composition and the designed composition of the ten regions characterizes the overall composition segregation of the powder bed, denoted by ω. Here, m represents the number of equal divisions of the powder bed along the x-axis, w represents the mass fraction of the element, and χ j represents the composition segregation of the micro-region j.

[0100]

[0101] S6.3 The sum of the composition uniformity and the composition non-uniformity is equal to 1. If the sample prepared with the preset powder characteristics in the calculation model achieves complete alloying, the composition uniformity between micro-regions is equal to 1 - ω.

[0102] In this embodiment, for S7, based on the diffusion situation of the heterogeneous powder dataset under different molten states obtained through S5 and the calculation formulas for composition deviation and composition non-uniformity analysis obtained through S6, select the laser process parameters that can obtain the maximum D distance value (diffusion distance percentage), including laser power, scanning speed, scanning spacing, and scanning times, as the optimal process design scheme for the composition of this heterogeneous powder. The predicted value of the composition uniformity of the prepared sample is equal to the composition deviation χ and the composition non-uniformity ω calculated in S6. Perform the selection and printing of the heterogeneous powder composition to obtain a printed sample with alloying and uniform composition.

[0103] This application provides a general, convenient, efficient, and low-cost process development method for the novel SLM in-situ alloying preparation technology. This method can predict the influence law of the composition ratio and particulate physical properties on the composition uniformity of the final sample for various multi-element heterogeneous powder particles, so as to give an optimized scheme according to the characteristics of the raw materials. This method can predict the influence law of the laser process parameters on the in-situ alloying degree of samples with different compositions, so as to give an optimized scheme in the huge process parameter range.

[0104] For the sample actually prepared by using the process scheme designed in this application, there are no obvious unmelted particles or composition segregation regions, and the composition uniformity can reach more than 95%. The density of the optimized process sample can reach more than 98%.

[0105] The SLM in-situ alloying technology can realize the development of the composition of new materials through the free ratio of multiple elements, thus eliminating the raw material powder pre-alloying process and bypassing the problem of limited sources of special new powders for additive manufacturing. Using this application can increase the development efficiency of different material composition-process combinations by several times, thus breaking through the bottleneck of the limited material types of the SLM technology itself and accelerating the industrial application process of SLM materials.

[0106] Example Two

[0107] This embodiment provides a calculation method for a multi - optimized Fe - Ni - based heterogeneous powder laser in - situ alloying process, including the following steps:

[0108] S1. Collect the Fe - Ni heterogeneous powder data set to be tested;

[0109] S2. Based on the collected Fe - Ni heterogeneous powder data set, construct a random mixing model of Fe - Ni heterogeneous powder bed through general discrete element software. In this embodiment, the DEM discrete element module in Flow - 3D is used. The calculation process of this model includes:

[0110] S2.1 Generate a particle cloud of no less than 100,000 Fe - Ni heterogeneous spherical particles directly above the rectangular substrate, randomly distributed according to the preset particle size and designed composition. In this embodiment, a total of 5 component ratios are designed. The powder of each component is composed of particles with diameters of 15μm, 30μm, and 53μm mixed in equal proportion. Convert the preset component ratio and particle size ratio of Fe - Ni heterogeneous powder into a particle number ratio as the initial material parameter, as Figure 6 shown.

[0111] S2.2 Design the solution size (length L, width W, and height H) of the Fe - Ni heterogeneous powder bed, and set the generation time of the mixed powder particles as t1. In this embodiment, the solution size of the powder bed is 0.2 cm×0.06 cm×0.06 cm (L×W×H), and the production time of the mixed powder is 0.2 s. Input the property parameters of the particles, including density, generation time, generation speed, relative displacement, elastic constant, deformation coefficient, and friction coefficient, as the inherent attribute parameters of the particles during the calculation process into the software.

[0112] S2.3 The heterogeneous powder particles freely fall on the rectangular substrate under the action of gravity.

[0113] S3. On the basis of the random powder - falling model in S2, continue to construct a powder - scraping model of Fe - Ni heterogeneous powder through discrete element software. Since the particles falling in S1 are loosely piled up, a moving scraper is given above them. The height gap between the scraper and the substrate is 85μm, and it moves unidirectionally from left to right to form a vibrated powder layer with a preset thickness; in this embodiment, the formed vibrated piled powder layer has a length L of 0.2 cm, a width W of 0.06 cm, and a height H1 of 85μm. The construction process of this model includes:

[0114] S3.1 Apply a moving scraper to the initial end of the loosely piled powder bed formed in S2, and set a baffle at the end;

[0115] S3.2 The gap between the bottom of the scraper and the substrate is preset to 85μm, which is the thickness of the powder layer after compaction. The bottom of the baffle is flush with the substrate, and the preset height is consistent with the thickness of the powder layer, which is 85μm;

[0116] S3.3 In this embodiment, the scraper is in the shape of a rectangular plate with a thickness of 0.01 cm, a width of 0.06 cm, and a height of 0.3 cm;

[0117] S3.4 In this embodiment, the scraper moves unidirectionally from the starting end to the ending end of the powder bed at a preset moving speed v=0.5 cm / s, and the ending end is set as an outlet;

[0118] The S3.5 scraper interacts with the powder bed, scraping the Fe-Ni mixed powder higher than the preset value of 85μm away from the original powder bed, forming a compacted heterogeneous powder layer with a fixed length, width and height of 0.2cm*0.06cm*0.0085cm.

[0119] S4. A moving laser heat source is applied to the powder layer established in step 2 by using the ABAQUS calculation software based on the finite element method to construct a temperature field model of the Fe-Ni heterogeneous powder 2-layer 5-pass printing process. The model is used to obtain the melting time and temperature of the powder bed micro-area after multiple laser scans.

[0120] S4.1 takes the size of the single-layer powder bed formed by S2 as the size of the finite element temperature field calculation model, simplifies the material properties to a homogeneous alloy entity with a Fe-wt.%Ni composition ratio, and sets the ambient temperature to 180°C.

[0121] S4.2 Designate the area not covered by the powder bed as air and set the convection heat transfer coefficient to 15W / (m 2 ·℃).

[0122] S4.3 selects Gaussian body heat source, sets scanning strategy to reentry type, laser power 150W, scanning speed 500mm / s, laser source diameter 50μm, scanning spacing 80μm, and overlap rate 0.

[0123] S4.4 Select any micro-area on the laser scanning path, calculate the temperature change curve over time, and obtain the average temperature value T and duration t of the molten state (greater than or equal to the melting point temperature). The calculation results in this embodiment are as follows Figure 7 shown.

[0124] S5 uses DICTRA software based on the diffusion kinetics method to build a diffusion kinetics model of micro-regions during high-speed melting and solidification. The construction of this model is mainly used to obtain the composition distribution of the sample micro-region after multi-pass laser scanning.

[0125] In S5.1, a one-dimensional diffusion model of single-phase (LIQUID) is adopted. The molten heterogeneous particles are simplified into two spheres with different melting points. Sphere A represents the elemental Fe, and sphere B represents the elemental Ni. The radii of the Fe powder and Ni powder particles are set to 7μm, 15μm, and 25μm respectively.

[0126] In S5.2, liquid diffusion occurs to the Fe powder and Ni powder during the laser melting process. The input temperature for diffusion is the average temperature value calculated in S4, and the input time is the duration t calculated in step four.

[0127] In S5.3, the distributions of the compositions of all elements with the diffusion distance are obtained by solving the diffusion equation. The percentage of the diffusion distance corresponding to different powder particle sizes of the Fe-Ni heterogeneous particles is as Figure 8 shown.

[0128] In S5.4, the kinetic process of the molten state diffusion occurring under different laser process parameters for the heterogeneous powder is analyzed. Based on the molten state temperature T and molten state duration t obtained in S4, a one-dimensional diffusion model is adopted to calculate the diffusion conditions of the powder particles under multiple groups of different molten state temperatures (T + ΔT), molten state durations (t + Δt), powder particle sizes, and 5 scans respectively. The calculation results are as Figure 8 shown.

[0129] In S6, an stl file conversion software is used to statistically analyze the discrete element calculation results to obtain the data of the number and position of the heterogeneous powder layer particles. Two parameters, the composition deviation χ and the composition non-uniformity ω, are used to characterize the composition uniformity of the powder bed.

[0130] The overall composition deviation χ is equal to the ratio of the absolute value of the difference between the content of the heterogeneous powder particles (mass percentage wt.%) in the calculated tapped powder bed and the designed composition to the designed composition, represented by χ. Here, n represents the number of components in the system, and in this embodiment, n = 2. The calculation results are as Figure 3 shown.

[0131] The tapped powder bed is equally divided into 10 regions with the same area (0.02cm * 0.06cm * 0.0085cm) along the length (x-axis) direction. The average value of the deviation between the calculated composition and the designed composition in the ten regions represents the overall composition non-uniformity of the powder bed, represented by ω. Here, m represents the number of equal divisions of the powder bed along the x-axis, w represents the mass fraction of the element, and χ j represents the composition deviation of the micro-region j. The calculation results of the composition non-uniformity of the Fe-Ni heterogeneous particles are shown in Figure 4 shown.

[0132] The sum of the component uniformity and the component non-uniformity of S6.3 is equal to 1. Therefore, after the complete alloying of Fe-Ni samples with different components, the component uniformity in the micro-regions varies between 97.5% and 99.7%.

[0133] S7. Select the laser process parameters that can obtain the maximum D distance value, including laser power, scanning speed, scanning spacing, and scanning times, as the optimal process design scheme for the composition of the heterogeneous powder. The predicted value of the component uniformity of the prepared sample is equal to the component deviation χ and the component non-uniformity ω calculated in S6. Through the above operations, the selection and printing of the heterogeneous powder composition are carried out to obtain an alloyed and compositionally uniform printed sample.

[0134] Example 3

[0135] Figure 5 It is a schematic diagram of the device composition of a laser in-situ alloying process for multi-component heterogeneous powder provided by an embodiment of the present application. This embodiment provides a calculation device for a laser in-situ alloying process of multi-component heterogeneous powder, including: a heterogeneous powder data set acquisition module for acquiring a heterogeneous powder data set to be tested;

[0136] a heterogeneous powder bed powder dropping module for constructing a random powder dropping model of the heterogeneous powder bed based on the heterogeneous powder data set to obtain a mixed powder bed;

[0137] a scraping module for heterogeneous powder for constructing a scraping model of the heterogeneous powder based on the mixed powder bed to obtain a vibration-compacted heterogeneous powder layer;

[0138] a multi-layer and multi-pass printing process module for heterogeneous powder for constructing a temperature field model of the multi-layer and multi-pass printing process of the heterogeneous powder based on the vibration-compacted heterogeneous powder layer to obtain the melting time and temperature of the micro-regions of the vibration-compacted heterogeneous powder layer after multi-pass laser scanning;

[0139] a melting state diffusion analysis module for constructing a diffusion kinetics model of the high-speed melting and solidification process based on the melting time and temperature of the micro-regions of the vibration-compacted heterogeneous powder layer after multi-pass laser scanning, performing melting state diffusion analysis, and obtaining the diffusion conditions of the heterogeneous powder data set under different melting states;

[0140] a component deviation and component uniformity analysis module for performing component deviation and component uniformity analysis based on the vibration-compacted heterogeneous powder layer to obtain component deviation parameters and component non-uniformity parameters;

[0141] A heterogeneous powder composition selection and printing module for performing heterogeneous powder composition selection and printing based on the diffusion of the heterogeneous powder dataset in different molten states, as well as the composition deviation parameter and the composition non-uniformity parameter, to obtain a printed sample with alloying and uniform composition.

[0142] It can be understood that the same or similar parts in the above embodiments can be referred to each other, and the content not detailed in some embodiments can be seen in the same or similar content in other embodiments.

[0143] It should be noted that in the description of the present application, terms such as "first" and "second" are only used for descriptive purposes and cannot be understood as indicating or implying relative importance. In addition, in the description of the present application, unless otherwise specified, the meaning of "a plurality of" refers to at least two.

[0144] Any process or method description in the flowchart or described in other ways herein can be understood as representing a module, segment, or part of code including one or more executable instructions for implementing a specific logical function or process. The scope of the preferred embodiments of the present application includes additional implementations, where the functions can be executed in a substantially simultaneous manner or in a reverse order according to the involved functions, rather than in the order shown or discussed, which should be understood by those skilled in the technical field of the embodiments of the present application.

[0145] It should be understood that each part of the present application can be implemented by hardware, software, firmware, or a combination thereof. In the above embodiments, multiple steps or methods can be implemented by software or firmware stored in a memory and executed by a suitable instruction execution system. For example, if implemented by hardware, as in another embodiment, any one or a combination of the following well-known technologies in the art can be used: discrete logic circuits with logic gate circuits for implementing logical functions on data signals, application-specific integrated circuits with appropriate combinational logic gate circuits, programmable gate arrays (PGAs), field-programmable gate arrays (FPGAs), etc.

[0146] Those of ordinary skill in the technical field of the present application can understand that all or part of the steps carried by the methods in the above embodiments can be completed by instructing relevant hardware through a program. The program can be stored in a computer-readable storage medium, and when the program is executed, it includes one or a combination of the steps of the method embodiments.

[0147] In addition, each functional unit in various embodiments of the present application may be integrated into a processing module, may exist physically alone for each unit, or two or more units may be integrated into one module. The above integrated module may be implemented in the form of hardware or in the form of a software functional module. When the integrated module is implemented in the form of a software functional module and sold or used as an independent product, it may also be stored in a computer-readable storage medium.

[0148] The above-mentioned storage medium may be a read-only memory, a magnetic disk, an optical disc, etc.

[0149] In the description of this specification, the description with reference to terms such as "one embodiment", "some embodiments", "example", "specific example", or "some examples" means that the specific features, structures, materials, or characteristics described in connection with the embodiment or example are included in at least one embodiment or example of the present application. In this specification, the schematic representation of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials, or characteristics described may be combined in any one or more embodiments or examples in a suitable manner.

[0150] Although the embodiments of the present application have been shown and described above, it can be understood that the above embodiments are exemplary and should not be construed as limiting the present application. Those of ordinary skill in the art can make changes, modifications, substitutions, and variations to the above embodiments within the scope of the present application.

Claims

1. A calculation method for a laser in-situ alloying process of multi-component heterogeneous powder, characterized in that, Including: Collecting a heterogeneous powder data set to be tested; Based on the heterogeneous powder data set, constructing a random powder dropping model for the heterogeneous powder bed to obtain a mixed powder bed; Based on the mixed powder bed, constructing a powder scraping model for the heterogeneous powder to obtain a vibration-compacted heterogeneous powder layer; Based on the vibration-compacted heterogeneous powder layer, constructing a temperature field model for the multi-layer and multi-pass printing process of the heterogeneous powder to obtain the melting time and temperature of the micro-region of the vibration-compacted heterogeneous powder layer after multi-pass laser scanning; Based on the melting time and temperature of the micro-region of the vibration-compacted heterogeneous powder layer after multi-pass laser scanning, constructing a diffusion kinetics model for the high-speed melting and solidification process, performing melting state diffusion analysis, and obtaining the diffusion conditions of the heterogeneous powder data set under different melting states; Based on the vibration-compacted heterogeneous powder layer, performing component deviation and component uniformity analysis to obtain a component deviation parameter and a component non-uniformity parameter; Based on the diffusion conditions of the heterogeneous powder data set under different melting states, the component deviation parameter, and the component non-uniformity parameter, performing heterogeneous powder component selection and printing to obtain a printed sample with alloying and uniform composition.

2. The method according to claim 1, characterized in that, Constructing the random powder dropping model for the heterogeneous powder bed includes: Based on the heterogeneous powder data set, by simulating the free fall of the heterogeneous powder data set after mixing according to the distribution ratio and particle size ratio, a mixed powder bed is obtained.

3. The method according to claim 1, characterized in that, Constructing the powder scraping model for the heterogeneous powder includes: Based on the mixed powder bed, a scraper moves unidirectionally from the initial end to the end of the mixed powder bed at a preset moving speed. Assuming that the thickness of the mixed powder bed after vibration compaction is a preset height, the powder higher than the preset height is scraped off the mixed powder bed to obtain a vibration-compacted heterogeneous powder layer.

4. The method according to claim 1, wherein Constructing the temperature field model for the multi-layer and multi-pass printing process of the heterogeneous powder includes: Based on the vibration-compacted heterogeneous powder layer, by applying a moving laser heat source and setting the laser heat source parameters of the moving laser heat source, the melting time and temperature of the micro-region of the vibration-compacted heterogeneous powder layer after multi-pass laser scanning are calculated when the moving laser heat source passes through a specified micro-region on the laser scanning path.

5. The method according to claim 1, characterized in that Constructing the diffusion kinetics model for the high-speed melting and solidification process includes: Based on the melting time and temperature of the micro-region of the vibration-compacted heterogeneous powder layer after multi-pass laser scanning, calculating the degree of liquid diffusion of the heterogeneous particles in the molten state during the laser melting process, and calculating the alloying degree of different elements through the diffusion percentage; The calculation formula for the diffusion percentage is: Among them, D distance represents the diffusion percentage, A and B represent two elements, and D iAB represents the diffusion distance of the element in A into B, and R B is the radius of element B.

6. The method according to claim 1, characterized in that Performing the component deviation and component uniformity analysis includes: Component deviation analysis and component non-uniformity analysis; The component deviation analysis is based on the vibration-compacted heterogeneous powder layer. The ratio of the absolute value of the difference between the calculated component and the designed component of the element to be tested of the particles in the vibration-compacted heterogeneous powder layer to the designed component is calculated. The formula for calculating the component deviation analysis is: where χ represents the compositional deviation analysis, and n represents the set of the elements to be tested in the system. represents the calculated composition of the elements to be tested of the particles of the tapped bulk heterogeneous powder layer. represents the designed composition of the elements to be tested of the particles of the tapped bulk heterogeneous powder layer. The analysis of the component non-uniformity is based on the vibration-compacted heterogeneous powder layer. The vibration-compacted heterogeneous powder layer is equally divided into a specified number of regions with the same area in the length direction, and the average value of the deviation between the component and the designed component is calculated. The formula for calculating the component non-uniformity is as follows: Among them, ω represents the compositional non-uniformity, m represents the number of equal divisions of the powder bed along the x-axis, and χ j represents the compositional deviation analysis of the micro-region j.

7. The method according to claim 1, characterized in that, Performing the molten-state diffusion analysis includes: Based on the molten-state time and temperature of the micro-regions of the vibration-compacted heterogeneous powder layer after multi-pass laser scanning and the diffusion kinetic model of the high-speed melting and solidification process, calculate the diffusion situation of the particles in the vibration-compacted heterogeneous powder layer at different molten-state temperatures and molten-state durations, and obtain the diffusion situation of the particles in the vibration-compacted heterogeneous powder layer under different molten states.

8. The method according to claim 1, characterized in that Performing the selection and printing of the heterogeneous powder components includes: Based on the diffusion situation of the particles in the vibration-compacted heterogeneous powder layer under different molten states, the component deviation parameter, and the component non-uniformity parameter, select the laser process parameters that obtain the maximum diffusion percentage. The laser process parameters include laser power, scanning speed, scanning spacing, and scanning times, and use them as the optimal process design scheme for the heterogeneous powder components, and perform printing to obtain an alloyed and component-uniform printed sample.

9. A computing device for a multi-component heterogeneous powder laser in-situ alloying process, characterized in that, It includes: A heterogeneous powder data set acquisition module for acquiring a heterogeneous powder data set to be tested; A heterogeneous powder bed powder dropping module for constructing a random powder dropping model of the heterogeneous powder bed based on the heterogeneous powder data set to obtain a mixed powder bed; A scraping module for heterogeneous powder for constructing a scraping model of the heterogeneous powder based on the mixed powder bed to obtain a vibration-compacted heterogeneous powder layer; A multi-layer and multi-pass printing process module for heterogeneous powder for constructing a temperature field model of the multi-layer and multi-pass printing process of the heterogeneous powder based on the vibration-compacted heterogeneous powder layer to obtain the molten-state time and temperature of the micro-regions of the vibration-compacted heterogeneous powder layer after multi-pass laser scanning; A molten-state diffusion analysis module for constructing a diffusion kinetic model of the high-speed melting and solidification process based on the molten-state time and temperature of the micro-regions of the vibration-compacted heterogeneous powder layer after multi-pass laser scanning, performing molten-state diffusion analysis, and obtaining the diffusion situation of the heterogeneous powder data set under different molten states; A component deviation and component uniformity analysis module for performing component deviation and component uniformity analysis based on the vibration-compacted heterogeneous powder layer to obtain a component deviation parameter and a component non-uniformity parameter; A heterogeneous powder component selection and printing module for performing heterogeneous powder component selection and printing based on the diffusion situation of the heterogeneous powder data set under different molten states, the component deviation parameter, and the component non-uniformity parameter to obtain an alloyed and component-uniform printed sample.

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