Friction solid-phase additive manufacturing method for improving bonding strength of dissimilar alloy through interlayer interface texturing

Abstract

The invention provides a friction solid-phase additive manufacturing method for improving the bonding strength of dissimilar alloys through interlayer interface texturing. The method comprises the following steps that an aluminum alloy or magnesium alloy plate serves as a base body; depositing a first metal layer on the polished to-be-added area by adopting a friction solid-phase additive process; processing a preset micron-sized three-dimensional texture on the surface of the first metal layer by adopting a laser scanning system so as to form a textured interface, and meanwhile, removing new oxides on the surface of the first metal layer; on the textured interface, a second metal layer which is made of a material different from that of the first metal layer is deposited again through the friction solid-phase additive process, so that a bonding interface which is characterized by micromechanical interlocking is formed between the first metal layer and the second metal layer; layer-by-layer additive manufacturing of a stacked dissimilar alloy having a plurality of dissimilar metal bonding interfaces. According to the method, the interlayer bonding mode of the dissimilar alloy is changed, and the problems of layering and cracking of dissimilar alloy fusion welding additive manufacturing components are effectively solved.

Description

TECHNICAL FIELD

[0001] The application relates to a friction solid-phase additive manufacturing method, in particular to a friction solid-phase additive manufacturing method for improving the bonding strength of dissimilar alloys through interlayer interface texturing, and belongs to the technical field of metal solid-phase additive manufacturing. BACKGROUND

[0002] Magnesium alloys and aluminum alloys have broad application prospects in the fields of lightweight structures such as aerospace, automobile manufacturing and electronic products. The preparation of magnesium / aluminum laminated composite materials by using additive manufacturing technology can realize the complementary advantages of the properties of the two materials and the integration of structure and function, and is a research hotspot in the current advanced manufacturing field. Friction solid-phase additive manufacturing (FSAM) is considered as an ideal way to prepare such composite materials as a solid-phase joining technology because it can effectively inhibit the generation of brittle intermetallic compounds between dissimilar metals due to its lower processing temperature than the melting point of the material.

[0003] However, in actual production, when directly using the FSAM technology to layer-by-layer deposit magnesium and aluminum dissimilar alloys, there are still severe technical challenges. The core technical problem lies in that due to the great difference in physical and chemical properties between magnesium and aluminum, and the easy formation of a dense oxide film on the surface, it is difficult to form stable and reliable metallurgical bonding between layers only by relying on the physical mixing effect of friction. This leads to insufficient interlayer bonding strength, and there is a risk of delamination and cracking at the interlayer interface during subsequent processing or use of the part, resulting in low product yield and high manufacturing cost. In the prior art, although there are attempts to remove the oxide film by simple mechanical polishing, the effect of improving the bonding strength is limited, and the essential problem of interface bonding cannot be fundamentally solved.

[0004] Therefore, how to effectively remove the interface oxide while enhancing the interlayer bonding strength of magnesium-aluminum dissimilar alloys through an innovative process method is a technical problem to be solved in the field. SUMMARY

[0005] Based on the above background, the purpose of the present application is to provide a friction solid-phase additive manufacturing method for improving the bonding strength of dissimilar alloys through interlayer interface texturing, to solve the technical problems of low reliability and poor yield of dissimilar alloy solid-phase additive manufacturing components caused by insufficient interlayer bonding force in the prior art.

[0006] In order to achieve the above-mentioned purpose of the application, the present application provides the following technical scheme:

[0007] A friction solid-phase additive manufacturing method for improving the bonding strength of dissimilar alloys through interlayer interface texturing, the method comprising the following steps:

[0008] S1, taking an aluminum alloy or magnesium alloy plate as a substrate, and polishing a to-be-added region of the substrate to remove a surface oxide film;

[0009] S2, depositing a first metal layer on the polished to-be-added region by using a friction solid-phase addition process, the first metal layer being a magnesium alloy or an aluminum alloy;

[0010] S3, machining a preset micron-level three-dimensional texture on the surface of the first metal layer by using a laser scanning system to form a textured interface, and simultaneously removing nascent oxides on the surface of the first metal layer;

[0011] S4, depositing a second metal layer different in material from the first metal layer on the textured interface by using the friction solid-phase addition process again, the second metal layer being an aluminum alloy or a magnesium alloy, wherein heat and forging pressure generated in the rotation and advancement of a friction solid-phase addition tool cause plastic flow of the material of the second metal layer, and the material of the second metal layer is filled into the micron-level three-dimensional texture, so as to form a bonding interface characterized by micro mechanical interlocking between the first metal layer and the second metal layer;

[0012] S5, repeatedly performing steps S3 and S4 to additively manufacture a laminated dissimilar alloy with multiple dissimilar metal bonding interfaces layer by layer.

[0013] By machining a three-dimensional texture on the interlayer interface by laser, not only is the oxide film inhibiting bonding removed, but also a large number of micron-level three-dimensional textures are constructed, and in subsequent deposition by using the friction solid-phase addition process, the plastic metal of the upper layer is forced to be extruded into these microstructures under the huge forging pressure of friction, forming a strong mechanical engagement force, so that the interlayer bonding strength is improved by orders of magnitude.

[0014] As a preferred, in the step S3, the micron-level three-dimensional texture is an asymmetric flow guide structure having a reverse geometric feature relative to the advancement direction of the friction solid-phase addition tool.

[0015] The asymmetric flow guide structure is easy to enter and difficult to exit for the inflowing plastic metal, and more efficiently converts the kinetic energy of friction into interlayer bonding energy, and compared with a symmetrical grid structure, it provides stronger shear resistance and peel resistance.

[0016] As a preferred, in the step S3, the distribution density or geometric depth of the micron-level three-dimensional texture has a spatial gradient, and the texture density or depth in the peripheral region of the addition path is greater than the texture density or depth in the central region of the addition path.

[0017] Since interlayer cracking often occurs from the edge area of stress concentration, by setting deeper and denser texture in the key edge area and standard texture in the central area with less stress, the bonding strength of the edge area can be focused on.

[0018] As preferred, the asymmetric flow guide structure is an array of fish scale-shaped dimples, an array of herringbone-shaped grooves or an array of arc-shaped grooves arranged reversely along the advancing direction of the friction solid-phase additive tool; the depth of the grooves or the dimples is 50-500 microns, and the width thereof is 100-1000 microns.

[0019] As preferred, in the step S4, during the rotation and advancement of the friction solid-phase additive tool, a non-contact infrared temperature detector is also used to monitor the temperature of the area near the bonding interface in real time, and according to the real-time temperature data monitored, the rotational speed and / or the downward pressure of the friction solid-phase additive tool are dynamically adjusted through a closed-loop control system, so as to maintain the temperature of the area near the bonding interface within the process temperature interval of 350-450℃.

[0020] If the interface temperature is too low, the metal plasticity is insufficient to fill the texture sufficiently, and if the interface temperature is too high, a large amount of brittle intermetallic compounds will be generated. Real-time monitoring and control of the interface temperature ensure that each section of the bonding interface is formed within the optimal temperature window, thereby improving the process stability.

[0021] As preferred, between the step S3 and the step S4, the method further comprises the following steps:

[0022] S3.5, on the textured interface, a nanoscale-thickness metallurgical active intermediate medium is coated by physical vapor deposition or magnetron sputtering.

[0023] This step introduces an active medium into the interface bonding, which can react with magnesium and aluminum in situ under the thermal force of friction to form a flexible metallurgical transition layer, further fill the micro gaps, passivate the crack tips, and make the interface bonding mode form a composite bonding of mechanical bonding and metallurgical bonding.

[0024] As preferred, the metallurgical active intermediate medium is at least one of zinc, silicon, tin or an alloy thereof.

[0025] Zinc, silicon, tin and other elements that can form low eutectic reactions with magnesium and aluminum at low melting points can promote metallurgical bonding at lower temperatures, effectively avoiding the risk of generating a large amount of brittle aluminum-magnesium compounds at high temperatures.

[0026] As preferred, after the step S5, the method further comprises the following steps:

[0027] S6, the layered dissimilar alloy completed by the solid phase additive manufacturing is subjected to low-temperature annealing treatment at 150-250 DEG C for 30-120 minutes.

[0028] The purpose of this step is to eliminate the residual stress of the layered dissimilar alloy, further promote the uniform diffusion of the interface element, and inhibit the excessive growth of the brittle intermetallic compound at the bonding interface.

[0029] Compared with the prior art, the present application has the following advantages:

[0030] The friction solid phase additive manufacturing method for improving the bonding strength of dissimilar alloys by interlayer interface texturing can effectively prevent the delamination and cracking of the dissimilar alloy solid phase additive manufacturing component by forming a micro mechanical interlocking structure through laser texturing interface treatment, changing the interlayer bonding mode of the dissimilar alloy, and further enhancing the interlayer bonding strength of the dissimilar alloy through optional metallurgical active intermediate medium and gradient distribution of the texture design. BRIEF DESCRIPTION OF DRAWINGS

[0031] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the drawings needed to be used in the embodiments or the prior art description will be briefly introduced below. Obviously, the drawings in the following description are only embodiments of the present application, and other drawings can be obtained by those skilled in the art without creative labor on the basis of the provided drawings.

[0032] Figure 1 is a flowchart of the friction solid phase additive manufacturing method for improving the bonding strength of dissimilar alloys by interlayer interface texturing of the present application;

[0033] Figure 2 is a schematic diagram of the interface microstructure of the present application processed with the preset micron-level three-dimensional texture. DETAILED DESCRIPTION

[0034] The technical solutions of the present application will be further specifically described below by means of specific embodiments and in combination with the drawings. It should be understood that the implementation of the present application is not limited to the following embodiments, and any form of modification and / or change of the present application will fall within the scope of protection of the present application.

[0035] In the present application, unless otherwise specified, all parts and percentages are weight units, and the equipment and raw materials used can be purchased from the market or are commonly used in the art. The methods in the following examples are conventional methods in the art, unless otherwise specified. The components or equipment in the following examples are general standard components or components known to those skilled in the art, and their structure and principles are known to those skilled in the art through technical manuals or conventional experimental methods.

[0036] The embodiments of the present application will be described in detail below with reference to the drawings. In the following detailed description, numerous specific details are set forth in order to provide a thorough understanding of the embodiments of the present application. However, one or more embodiments can also be practiced without these specific details.

[0037] The embodiments of the present application disclose a friction solid-phase additive manufacturing method for improving the bonding strength of dissimilar alloys by interlayer interface texturing, which comprises the following steps:

[0038] S1, taking an aluminum alloy or magnesium alloy plate as a substrate, and polishing a region to be additively manufactured of the substrate to remove a surface oxide film;

[0039] S2, depositing a first metal layer on the polished region to be additively manufactured by using a friction solid-phase additive manufacturing process, the first metal layer being a magnesium alloy or an aluminum alloy;

[0040] S3, processing a preset micron-level three-dimensional texture on the surface of the first metal layer by using a laser scanning system to form a textured interface, and simultaneously removing nascent oxides on the surface of the first metal layer;

[0041] S4, depositing a second metal layer different in material from the first metal layer on the textured interface by using the friction solid-phase additive manufacturing process again, the second metal layer being an aluminum alloy or a magnesium alloy, in the process of rotation and advancement of a friction solid-phase additive manufacturing tool, heat and forging pressure generated by the tool cause plastic flow of the material of the second metal layer, and the material fills into the micron-level three-dimensional texture, so that a bonding interface characterized by micro-mechanical interlocking is formed between the first metal layer and the second metal layer;

[0042] S5, repeatedly performing steps S3 and S4 to additively manufacture a laminated dissimilar alloy with multiple dissimilar metal bonding interfaces.

[0043] The steps of the method will be described in detail below by taking the additive manufacturing of a multilayer magnesium / aluminum dissimilar alloy composite component by using AZ31 magnesium alloy on a 6061 aluminum alloy substrate as an example, and a method flow chart is shown in Figure 1 .

[0044] Step S1, substrate preparation. Select a 6061 aluminum alloy plate as a substrate, mechanically polish the region planned to be additively manufactured to remove a dense Al2O3 oxide film and contaminants on the surface, and provide a clean active surface for subsequent deposition.

[0045] Step S2: Deposit the first metal layer. The treated aluminum alloy substrate is fixed to the workbench of the FSAM equipment. Using a friction solid-phase additive manufacturing process, a layer of AZ31 magnesium alloy is deposited on the polished area as the first metal layer. The friction tool is set to a rotation speed of 800-1200 rpm and a forward speed of 50-150 mm / min.

[0046] Step S3, interface texturing treatment. On the surface of the first metal layer, a high-precision fiber laser scanning system is used to process a preset micron-level three-dimensional texture. In this embodiment, the processed texture is a Figure 2 The asymmetric herringbone groove array shown. The opening direction of the "herringbone" is opposite to the forward direction of the friction solid phase additive tool in step S4. In the subsequent friction process, the material of the second metal layer, under the action of the additive tool, forms a plastic metal flow that rotates at high speed and propels forward, similar to a high-viscosity fluid. Since the opening direction of the herringbone texture is set in the opposite direction of the metal flow, when the plastic metal flow hits the opening, it is forcibly guided and wedged into the deep groove, and its reverse geometric characteristics greatly hinder the backflow or slippage of the material. This design actively utilizes the kinetic energy of the material flow driven by friction and converts it into potential energy and pressure for efficient filling of the texture, thereby forming a denser and stronger mechanical meshing than a symmetrical grid structure. The interface finally formed by solidification shows a significant anisotropic strengthening effect when resisting interlayer shear force, especially resisting peeling force along the additive direction. Laser processing can not only accurately etch the grooves, but its instantaneous high temperature can also vaporize and remove the newly formed MgO oxide film on the surface of the magnesium alloy.

[0047] In addition, the texture is designed with a gradient. In the 20mm wide additive path, grooves with a depth of 300 microns and a spacing of 400 microns are processed in the 5mm wide peripheral areas on both sides. In the central area with a width of 10mm, grooves with a depth of 150 microns and a spacing of 800 microns are processed. This design concentrates the strongest locking force on the edges that are most prone to cracking. For layered composite materials, the failure behavior of interlaminar delamination does not occur uniformly. According to fracture mechanics theory, cracks are most likely to initiate at the free edges or geometric discontinuities of components because these locations are typical stress concentration areas. In this case, the peripheral areas on both sides of the additive path are the most dangerous stress concentration areas. Using a gradient texture design, deeper and denser textures are arranged in these key areas, which is equivalent to local reinforcement of the weak parts of the component.

[0048] Step S3.5: Applying an active intermediate medium. After the laser texturing is completed, the workpiece is moved into a magnetron sputtering device to deposit a zinc film with a thickness of approximately 100 nanometers on the textured interface as a metallurgically active intermediate medium.

[0049] Step S4, depositing the second metal layer and forming the bonding interface. The workpiece treated in step S3.5 is re-fixed. The FSAM process is used again to deposit a second metal layer, in this case 6061 aluminum alloy, on the textured interface. In this process, the friction heat generated by the high-speed rotation of the friction solid-phase additive tool and the huge downward forging pressure cause the aluminum alloy feed wire to undergo severe plastic deformation. The aluminum alloy material in the plastic state is forced to extrude and completely fill into the micron-level three-dimensional texture on the surface of the magnesium alloy, and after cooling, a mechanical interlocking structure is formed.

[0050] At the same time, in this step, the interface temperature is monitored in real time by a non-contact infrared temperature measuring instrument, and the speed of the additive tool is adjusted by feedback through a closed-loop system to ensure that the interface temperature is stable within the range of 400℃±5℃. This not only ensures that the aluminum has sufficient plasticity, but also avoids the generation of a large amount of brittle aluminum-magnesium compounds. Moreover, the zinc intermediate layer coated in step 3.5 will react with magnesium and aluminum at this temperature to form a more ductile Mg-Zn-Al ternary eutectic phase, further strengthening the interface.

[0051] Step S5, layer-by-layer additive. Steps S3 and S4 are repeated to deposit an aluminum alloy layer on the magnesium alloy layer or a magnesium alloy layer on the aluminum alloy layer, and finally a magnesium / aluminum dissimilar alloy composite material component with the required thickness and layering sequence is manufactured.

[0052] Step S6, low-temperature annealing post-treatment. The finished component is placed in an annealing furnace filled with argon protection, heated to 200℃, and held for 60 minutes before cooling with the furnace. This step is designed to eliminate residual stress in the component, improve its dimensional accuracy and fatigue performance.

[0053] The principles and embodiments of the present application are described herein using specific examples. The above examples are only used to help understand the method and core idea of the present application. It should be noted that for those skilled in the art, without departing from the principles of the present application, the present application can be improved and modified in several ways, and these improvements and modifications also fall within the scope of the claims of the present application.

Claims

1. A friction solid phase additive manufacturing method for improving the bonding strength of dissimilar alloys by texturing the interlayer interface, characterized by: The method comprises the following steps: S1. Using an aluminum alloy or magnesium alloy plate as a substrate, and grinding the area of ​​the substrate to be added to remove the surface oxide film; S2. Depositing a first metal layer on the polished area to be added by a friction solid phase additive process, wherein the first metal layer is a magnesium alloy or an aluminum alloy; S3, using a laser scanning system to process a preset micron-scale three-dimensional texture on the surface of the first metal layer to form a textured interface, and simultaneously removing new oxides on the surface of the first metal layer; S4. Depositing a second metal layer made of a different material from the first metal layer on the textured interface again using a friction solid phase additive process, wherein the second metal layer is an aluminum alloy or a magnesium alloy. During the rotation and advancement of the friction solid phase additive tool, the heat and forging pressure generated therefrom cause the material of the second metal layer to undergo plastic flow and fill the micron-scale three-dimensional texture, thereby forming a bonding interface characterized by microscopic mechanical interlocking between the first and second metal layers. S5. Repeat steps S3 and S4 to additively manufacture a stacked dissimilar alloy having multiple dissimilar metal bonding interfaces layer by layer.

2. The friction solid phase additive manufacturing method for improving the bonding strength of dissimilar alloys by texturing the interlayer interface according to claim 1, characterized in that: In step S3, the micron-scale three-dimensional texture is an asymmetric flow-guiding structure having reverse geometric features relative to the forward direction of the friction solid-phase additive tool.

3. The friction solid phase additive manufacturing method for improving the bonding strength of dissimilar alloys by texturing the interlayer interface according to claim 2, characterized in that: In step S3, the distribution density or geometric depth of the micron-scale three-dimensional texture has a spatial gradient, and the texture density or depth in the peripheral area of ​​the additive path is greater than the texture density or depth in the central area of ​​the additive path.

4. The friction solid phase additive manufacturing method for improving the bonding strength of dissimilar alloys by texturing the interlayer interface according to claim 2, characterized in that: The asymmetric guide structure is a fish-scale pit array, a herringbone groove array or an arc groove array arranged in the opposite direction of the forward direction of the friction solid phase additive tool; the depth of the groove or the pit is 50-500 microns, and the width is 100-1000 microns.

5. The friction solid phase additive manufacturing method for improving the bonding strength of dissimilar alloys by texturing the interlayer interface according to claim 1, characterized in that: In step S4, during the rotation and advancement of the friction solid phase additive tool, a non-contact infrared thermometer is used to monitor the temperature of the area near the bonding interface in real time. Based on the monitored real-time temperature data, the rotation speed and / or downward pressure of the friction solid phase additive tool are dynamically adjusted through a closed-loop control system to maintain the temperature of the area near the bonding interface within the process temperature range of 350°C to 450°C.

6. The friction solid phase additive manufacturing method for improving the bonding strength of dissimilar alloys by texturing the interlayer interface according to claim 1, characterized in that: Between step S3 and step S4, the method further comprises the following steps: S3.

5. Coating a metallurgically active intermediate medium with a nanometer thickness on the textured interface by physical vapor deposition or magnetron sputtering.

7. The friction solid phase additive manufacturing method for improving the bonding strength of dissimilar alloys by texturing the interlayer interface according to claim 6, characterized in that: The metallurgically active intermediate medium is at least one of zinc, silicon, tin or alloys thereof.

8. The friction solid phase additive manufacturing method for improving the bonding strength of dissimilar alloys by texturing the interlayer interface according to claim 1, characterized in that: After step S5, the method further comprises the following steps: S6. Performing a low-temperature annealing treatment at 150° C. to 250° C. with a holding time of 30 to 120 minutes on the stacked dissimilar alloys manufactured by solid phase additive manufacturing.

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