Method and device for preparing mixed crystal structure material by friction stir solid phase deposition

Abstract

The application discloses a method and device for preparing a mixed crystal structure material by using a friction stir solid-phase deposition, and belongs to the technical field of preparing a heterogeneous structure material. The method first uses a deposition head to perform single-layer friction stir solid-phase deposition on a required material, then uses a special corrugated roller to perform cold roller pressing, so that different positions on the surface of the deposited material are subjected to different degrees of cold deformation, thereby introducing uneven high dislocation density to the deposited layer, and then performing next-layer friction stir solid-phase deposition on the surface. In the friction stir solid-phase deposition process, the local high-dislocation-density area rapidly undergoes static recrystallization and static recovery to maintain fine grains, and the low-dislocation-density area rapidly undergoes grain growth under heat, so that the whole deposited layer exhibits the mixed crystal structure characteristic of coexisting fine grains and coarse grains. Through the circulation of the friction stir solid-phase deposition and the cold roller pressing, the bulk mixed crystal structure material can be prepared.

Description

Technical Field

[0001] This invention belongs to the field of heterogeneous structure material preparation technology, specifically relating to a method and apparatus for preparing mixed crystal structure materials by stir-friction solid-phase deposition. Background Technology

[0002] Heterogeneous metals refer to metals with two or more microstructures and different properties. The synergistic effect of the different microstructures within heterogeneous metals can typically significantly improve their overall performance. Typical heterostructures include gradient heterostructures, two-phase heterostructures, lamellar heterostructures, defect heterostructures, reinforcing phase heterostructures, and multi-level heterostructures. Mixed-grain structures are a typical example of heterostructures. Mixed-grain materials usually exhibit significant differences in grain size, primarily composed of coarse and fine grains. During tensile deformation, the coarse and fine grains in mixed-grain materials can coordinate strain distribution, achieving a simultaneous increase in strength and plasticity.

[0003] Existing methods for preparing mixed-crystalline materials include heteroparticle-induced mixed-crystalline structures and those induced by special heat treatments. For example, Chinese patent CN115074646B discloses a multi-scale gradient mixed-crystalline aluminum alloy, its construction method, and its application. This method obtains an aluminum alloy with a gradient mixed-crystalline structure by introducing heteroparticles. Its main principle is to pin recrystallized grains by controlling the distribution position and number of heteroparticles, thereby obtaining a mixed-crystalline structure. Furthermore, Chinese patent CN113005317A discloses a high thermal stability mixed-crystalline magnesium alloy and its controllable preparation method and application. This method mainly involves mechanically mixing magnesium-based powder and titanium powder, ball milling to refine the magnesium-based powder, and then pressing and extruding the refined mixed powder with coarse magnesium-based powder to obtain a magnesium alloy with a mixed-crystalline structure. However, while introducing heteroparticles achieves the preparation of a mixed-crystalline structure, it alters the material composition, significantly reducing its purity. Furthermore, Chinese patent CN118291900A discloses a titanium material and its preparation method based on the synergistic strengthening and plasticizing of mixed crystals and twins. Its main principle is to achieve the preparation of titanium materials with a mixed crystal structure through the synergistic effect of hot rolling—cold rolling—annealing—deep cryogenic rolling—recrystallization annealing. However, this method typically involves a long preparation process, low production efficiency, and high cost. To achieve high-quality, high-efficiency, and low-cost preparation of mixed crystal structure materials, it is necessary to seek a novel method for preparing mixed crystal structure materials. Summary of the Invention

[0004] The technical problem to be solved by the present invention is to provide a method and apparatus for preparing mixed crystal structure materials by stir-friction solid-phase deposition, which is used to achieve a mixed crystal structure feature in which fine and coarse grains coexist on the deposition layer.

[0005] The technical solution adopted by this invention to solve its technical problem is a method for preparing mixed-crystal structure materials by stir-friction solid-phase deposition, comprising the following steps:

[0006] S1. A metal substrate identical to the deposition material is placed in the working position. The outlet of the deposition head is opposite to the metal substrate and can move along the length of the metal substrate. The deposition material is placed inside the deposition head. The deposition head includes a friction cylinder and a spiral rod. The spiral rod is coaxially arranged inside the friction cylinder and can rotate relative to the friction cylinder. The lower end of the spiral rod has a gap with the lower end of the friction cylinder, forming the outlet of the deposition head.

[0007] S2. The deposited material is extruded from the outlet of the deposition head to form the first deposited layer on the metal substrate, and the first deposited layer is cooled by the cooling material.

[0008] S3. Place the corrugated roller above the first deposited layer. The corrugated roller is provided with a protruding forming part. The first deposited layer is cold rolled. The protruding forming part forms a high dislocation density region above the first deposited layer, and the rest of the corrugated roller forms a low dislocation density region above the first deposited layer.

[0009] S4. The discharge port of the deposition head is aligned with the upper surface of the Nth deposition layer. The deposited material is extruded from the discharge port of the deposition head to form the N+1th deposition layer on the Nth deposition layer. The N+1th deposition layer is cooled using a cooling material. A corrugated roller is placed above the N+1th deposition layer. The corrugated roller is provided with a protruding forming part to cold roll the N+1th deposition layer. The protruding forming part forms a high dislocation density region above the N+1th deposition layer, and the remaining part of the corrugated roller forms a low dislocation density region above the N+1th deposition layer. Wherein, N is an integer ≥1.

[0010] S5. Repeat step S4 until the deposition layer thickness reaches the designed thickness.

[0011] Furthermore, the deposition material is one of aluminum, magnesium, zinc, or an alloy, the alloy is formed from two or three of aluminum, magnesium, and zinc, and the deposition material is in the form of one or two of filaments or particles.

[0012] Furthermore, in steps S2 and S4, when the deposited material is extruded from the outlet of the deposition head, the downward pressure load on the deposition head is 2~6KN;

[0013] Furthermore, the thickness of each deposition layer is 1~3mm; the amount of pressure applied by the corrugated roller on each deposition layer is 1 / 2 of the thickness of each deposition layer;

[0014] Furthermore, the cooling material is one of water, liquid carbon dioxide, or liquid nitrogen.

[0015] Furthermore, the length L of the corrugated roller is K. D, in mm, where K is an empirical coefficient (ranging from 1 to 1.5); D is the diameter of the bottom end of the friction cylinder, in mm;

[0016] Furthermore, the ratio of the rotational speed of the screw to the moving speed of the deposition head is 3 to 5.

[0017] An apparatus for preparing mixed-crystal structure materials by friction stir solid-state deposition (FSS), and a method for preparing mixed-crystal structure materials by FSS, comprising a mounting base, a deposition head and a rolling base vertically disposed below the mounting base, the deposition head comprising a friction cylinder and a helical rod, the helical rod being coaxially disposed inside the friction cylinder and rotatable relative to the friction cylinder, the lower end of the helical rod having a gap with the lower end of the friction cylinder forming a discharge port of the deposition head; the bottom of the rolling base is provided with two opposing mounting plates, and a corrugated roller is rotatably connected between the two mounting plates, the outer circumferential surface of the corrugated roller being provided with a protruding forming part.

[0018] Furthermore, the protruding forming part can be a hemispherical or cylindrical protrusion arranged in an array on the outer peripheral surface of the corrugated roller, a forming ring arranged coaxially on the outer peripheral surface of the corrugated roller and spaced apart along the axis of the corrugated roller, a wave forming rib arranged spaced apart along the circumference of the corrugated roller, or a spiral rib arranged coaxially on the outer peripheral surface of the corrugated roller.

[0019] The beneficial effects of this invention are:

[0020] 1. A single-layer friction-stirred solid-state deposition (FSS) is performed on the desired material using a deposition head. Subsequently, a corrugated roller is used for cold rolling, causing varying degrees of cold deformation at different locations on the deposition layer surface. This creates high dislocation density regions and low dislocation density regions on the deposition layer. The next FSS is then deposited on the surface of the deposition layer. During the FSS process, the high dislocation density regions undergo rapid static recrystallization and static recovery due to the frictional heat of the second deposition layer. This results in the high dislocation density regions maintaining fine grains, while the low dislocation density regions experience rapid growth of their fine equiaxed grains after the frictional heat of the second deposition layer. This leads to the entire deposition layer exhibiting a mixed-crystal structure characterized by the coexistence of fine and coarse grains.

[0021] 2. Dynamic recrystallization during friction-stirred solid-state deposition refines grains. These fine, dynamically recrystallized grains generate a high dislocation density due to cold deformation. Subsequently, regions with high dislocation density undergo static recrystallization upon heating, maintaining their fine, equiaxed shape. Conversely, regions with lower dislocation density experience rapid growth of these fine, equiaxed grains upon heating. Compared to traditional methods of introducing heterogeneous particles to pin grain boundaries to obtain mixed-crystalline structures, this method does not alter the composition of the mixed-crystalline material, resulting in a purer internal structure and greater potential application value in areas requiring high-purity mixed-crystalline materials. Compared to traditional methods using special heat treatments to prepare mixed-crystalline structures, this method has a shorter preparation process. It utilizes "heat reuse" during subsequent material deposition by the deposition head, shortening the preparation process, significantly improving production efficiency, and reducing production costs. Furthermore, this method can alter the deposition head's path, directly enabling additive manufacturing of components with mixed-crystalline structures.

[0022] 3. This invention also discloses an apparatus for preparing mixed-crystalline structure materials by friction stir solid-state deposition, mainly comprising a deposition head, a corrugated roller, and protruding forming parts on the surface of the corrugated roller. The deposition head and the corrugated roller are independently controlled, and the protruding forming parts on the surface of the corrugated roller are of various forms. By using different corrugated rollers, the distribution positions of fine and coarse grains in the mixed-crystalline structure material can be adjusted. By using the deposition head and the corrugated roller in conjunction, personalized preparation of mixed-crystalline structure materials can be achieved. The apparatus of this invention has a simple composition, is easy to operate, and has a high degree of system integration. Attached Figure Description

[0023] Figure 1 This is a flowchart of the method of the present invention;

[0024] Figure 2 This is a schematic diagram of the device of the present invention;

[0025] Figure 3 This is a schematic diagram of the deposition head of the present invention;

[0026] Figure 4 This is a schematic diagram of the corrugated roller of the present invention;

[0027] Figure 5 This is a schematic diagram of a typical mixed crystal structure prepared by the method of the present invention.

[0028] Reference numerals: 1-Deposition head; 101-Friction cylinder; 102-Screw rod; 2-Metal substrate; 3-Mounting seat; 4-Rolling seat; 5-Mounting plate; 6-Corrugated roller; 601-Protruding forming part. Detailed Implementation

[0029] Embodiments of the present invention are described in detail below. Examples of these embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the present invention, and should not be construed as limiting the present invention.

[0030] like Figure 1 As shown, the present invention discloses a method for preparing mixed-crystal structure materials by friction stir solid-state deposition, comprising the following steps:

[0031] S1. A metal substrate 2 identical to the deposition material is placed in the working position. The outlet of the deposition head 1 is opposite to the metal substrate 2 and can move along the length of the metal substrate 2. Deposition material is placed inside the deposition head 1. The deposition head 1 includes a friction cylinder 101 and a spiral rod 102. The spiral rod 102 is coaxially arranged inside the friction cylinder 101 and can rotate relative to the friction cylinder 101. The lower end of the spiral rod 102 has a gap with the lower end of the friction cylinder 101, forming the outlet of the deposition head 1. The spiral rod 102 of the deposition head 1 rotates relative to the friction cylinder 101. When the spiral rod 102 is rotating, the deposition material in the deposition head 1 enters the grinding space between the spiral rod 102 and the friction cylinder 101. The deposition material in the grinding space enters a local thermoplastic state under shearing and extrusion. The deposition material in the local thermoplastic state continues to be conveyed downward and conveyed to the surface of the metal substrate 2 through the outlet. The thermoplastic material accumulates.

[0032] S2. The deposition material is extruded from the outlet of the deposition head 1, forming a first deposition layer on the metal substrate 2. The first deposition layer is then cooled using a cooling material. The thermoplasticized deposition material is extruded from the outlet of the deposition head 1, while the deposition head 1 moves along the length of the metal substrate 2, thus forming a long strip-shaped deposition layer on the metal substrate 2. Water cooling, liquid carbon dioxide cooling, or liquid nitrogen cooling can be used during the deposition process.

[0033] S3. Place the corrugated roller 6 above the first deposited layer. The corrugated roller 6 is provided with a protruding forming part 601. The first deposited layer is cold rolled. The protruding forming part 601 forms a high dislocation density region above the first deposited layer, and the rest of the corrugated roller 6 forms a low dislocation density region above the first deposited layer.

[0034] S4. The discharge port of the deposition head 1 is aligned with the upper surface of the Nth deposition layer. The deposition material is extruded from the discharge port of the deposition head 1 to form the N+1th deposition layer on the Nth deposition layer. The N+1th deposition layer is cooled using a cooling material. The corrugated roller 6 is placed above the N+1th deposition layer. The corrugated roller 6 is provided with a protruding forming part 601. The N+1th deposition layer is cold-rolled. The protruding forming part 601 forms a high dislocation density region above the N+1th deposition layer, and the remaining part of the corrugated roller 6 forms a low dislocation density region above the N+1th deposition layer. Wherein, N is an integer ≥1.

[0035] See Figure 4 and Figure 5 The corrugated roller 6 is cold-rolled to form high dislocation density regions and low dislocation density regions on the surface of the deposited layer. The high dislocation density region is the area where the protruding forming part 601 on the surface of the corrugated roller 6 functions, while the low dislocation density region is the area on the surface of the corrugated roller 6 other than the protruding forming part 601. Subsequently, the "heat" generated during the formation of the next deposited layer promotes static recovery and static recrystallization in the high dislocation density region to maintain fine equiaxed grains. At the same time, the "heat" promotes the rapid growth of fine equiaxed grains in the low dislocation density region, thereby making the entire deposited material exhibit a mixed crystal structure. It should also be noted that the shape of the protruding forming part 601 on the corrugated roller 6 can be a hemispherical or cylindrical protrusion arrayed on the outer peripheral surface of the corrugated roller 6, a forming ring coaxially arranged on the outer peripheral surface of the corrugated roller 6 and spaced apart along the axis of the corrugated roller 6, a wave forming rib spaced apart along the circumference of the corrugated roller 6, or a spiral rib coaxially arranged on the outer peripheral surface of the corrugated roller 6. During the cold roll pressing process, the corrugated rollers 6 used for each deposition layer have different shapes, which creates differences in each deposition layer. This results in different positions of high dislocation density regions and low dislocation density regions on each deposition layer, which in turn makes the grains in the final formed bulk mixed crystal structure material more complex and the grains more fully interlaced.

[0036] S5. Repeat step S4 until the deposition layer thickness reaches the designed thickness.

[0037] To reduce production costs, the deposition material is further selected from aluminum, magnesium, zinc, or an alloy, wherein the alloy is formed from two or three of aluminum, magnesium, and zinc, and the deposition material is in the form of filaments or particles, or two of these. Since the deposition material is output from the outlet of deposition head 1 in a thermoplastic state, pressure needs to be applied to the thermoplastic deposition material using deposition head 1 to ensure the thickness of the deposition layer. Furthermore, in steps S2 and S4, when the deposition material is extruded from the outlet of deposition head 1, the downward pressure load on deposition head 1 is 2~6KN.

[0038] Furthermore, the thickness of each deposited layer is 1~3mm; the amount of pressure applied by the corrugated roller 6 on each deposited layer is 1 / 2 of the thickness of each deposited layer; that is, when the corrugated roller 6 performs cold rolling pressing on each deposited layer, the depth of pressing is 1 / 2 of the thickness of each deposited layer.

[0039] To ensure that the corrugated roller 6 can completely cover the width of the deposited layer, the length of the corrugated roller 6 is further L=K. D, in mm, where K is an empirical coefficient (value 1~1.5); D is the bottom diameter of the friction cylinder 101, in mm; the bottom diameter of the friction cylinder 101 is the width of the deposition layer.

[0040] The rotational speed of the screw 102 is directly proportional to the discharge speed of the outlet. If the rotational speed is too fast, the discharge speed will be fast, resulting in a deposition layer that is high on both sides and low in the middle. If the rotational speed is too slow, the discharge speed will be slow, resulting in uneven thickness of the deposition layer or failure to reach the theoretical thickness. In order to ensure the formation of the deposition layer, the ratio of the rotational speed of the screw 102 to the moving speed of the deposition head 1 is 3 to 5.

[0041] See Figures 2-4 An apparatus for preparing mixed-crystal structure materials by friction stir solid-state deposition (FSS), and a method for preparing mixed-crystal structure materials by FSS, comprising a mounting base 3, a deposition head 1 and a rolling base 4 vertically disposed below the mounting base 3, the deposition head 1 comprising a friction cylinder 101 and a helical rod 102, the helical rod 102 being coaxially disposed inside the friction cylinder 101 and rotatable relative to the friction cylinder 101, the lower end of the helical rod 102 having a gap with the lower end of the friction cylinder 101 forming the discharge port of the deposition head 1; the bottom of the rolling base 4 is provided with two opposing mounting plates 5, and a corrugated roller 6 is rotatably connected between the two mounting plates 5, the outer peripheral surface of the corrugated roller 6 being provided with a protruding forming part 601. The screw 102 of the deposition head 1 rotates relative to the friction cylinder 101. While the screw 102 is rotating, the deposition material inside the deposition head 1 enters the grinding space between the screw 102 and the friction cylinder 101. Under shearing and extrusion, the deposition material in the grinding space enters a locally thermoplasticized state. This locally thermoplasticized material continues to be conveyed downwards and through the discharge port to the surface of the metal substrate 2, where it accumulates. The rolling seat 4 is located behind the deposition head 1. After the deposition head 1 outputs the thermoplasticized deposition material, a deposition layer is formed. During the deposition process, water cooling, liquid carbon dioxide cooling, or liquid nitrogen cooling can be used. Two opposing mounting plates 5 are provided at the bottom of the rolling seat 4. A corrugated roller 6 is rotatably connected between the two mounting plates 5. This rotatable connection can be achieved using bearings, allowing for cold rolling on the upper surface of the deposition layer.

[0042] Example 1

[0043] S1: Select 6061 aluminum alloy substrate as the metal substrate for the first deposition layer, and use a deposition head to perform frictional solid-phase deposition on 6061 aluminum alloy particles.

[0044] S2: The first deposition layer is formed on a 6061 aluminum alloy substrate. The thickness of the first deposition layer is 2mm. During the deposition process, the downward pressure load of the deposition head is 4KN. The rotation speed of the deposition head is 400r / min and the forward speed is 100mm / min. The diameter of the friction cylinder is 30mm. Liquid cooling water is used to cool the surface of the deposition layer during the deposition process.

[0045] S3: A corrugated roller is used to cold roll the surface of the first deposited layer. The protruding forming part forms a high dislocation density region above the first deposited layer, and the rest of the corrugated roller forms a low dislocation density region above the first deposited layer. The length of the corrugated roller is 40mm, and the cold rolling pressing amount is 1 / 2 of the thickness of a single deposited material, which is 1mm.

[0046] S4: The discharge port of the deposition head is aligned with the upper surface of the first deposition layer. The deposition material is extruded from the discharge port of the deposition head, forming a second deposition layer on the first deposition layer. The thickness of the second deposition layer is 2 mm. During the deposition process, the downward pressure load of the deposition head is 4 kN. The rotation speed of the deposition head is 400 r / min, and the forward speed is 100 mm / min. The diameter of the friction cylinder is 30 mm. Liquid cooling water is used to water-cool the surface of the deposition layer during the deposition process. A corrugated roller is placed above the second deposition layer. The corrugated roller is equipped with a protruding forming part to cold roll the second deposition layer. The protruding forming part forms a high dislocation density region above the second deposition layer, and the rest of the corrugated roller forms a low dislocation density region above the second deposition layer. The length of the corrugated roller is 40 mm, and the cold roll pressing amount is 1 / 2 of the thickness of a single layer of deposition material, which is 1 mm.

[0047] S5: The discharge port of the deposition head is aligned with the upper surface of the second deposition layer. The deposition material is extruded from the discharge port of the deposition head, forming the final deposition layer on the second deposition layer. The thickness of the final deposition layer is 2 mm. During the deposition process, the downward pressure load of the deposition head is 4 kN. The rotation speed of the deposition head is 400 r / min, and the forward speed is 100 mm / min. The diameter of the friction cylinder is 30 mm. Liquid cooling water is used to water-cool the surface of the final deposition layer during the deposition process. A corrugated roller is placed above the final deposition layer. The corrugated roller is equipped with a protruding forming part to cold roll press the final deposition layer. The protruding forming part forms a high dislocation density region above the final deposition layer, and the rest of the corrugated roller forms a low dislocation density region above the final deposition layer. The length of the corrugated roller is 40 mm, and the cold roll pressing amount is 1 / 2 of the thickness of a single layer of deposition material, which is 1 mm.

[0048] In this embodiment, optimized stirring friction solid-state deposition parameters and optimized special corrugated roller parameters were used to prepare a 6mm thick 6061 aluminum alloy mixed crystal material. The tensile strength of the mixed crystal material reached 188MPa and the elongation reached 32%.

[0049] Example 2

[0050] S1: Select 6061 aluminum alloy substrate as the metal substrate for the first deposition layer, and use a deposition head to perform frictional solid-phase deposition on 6061 aluminum alloy particles.

[0051] S2: The first deposition layer is formed on a 6061 aluminum alloy substrate. The thickness of the first deposition layer is 1mm. During the deposition process, the downward pressure load of the deposition head is 2KN. The rotation speed of the deposition head is 300r / min and the forward speed is 100mm / min. The diameter of the friction cylinder is 30mm. Liquid cooling water is used to cool the surface of the deposition layer during the deposition process.

[0052] S3: A corrugated roller is used to cold roll the surface of the first deposited layer. The protruding forming part forms a high dislocation density region above the first deposited layer, and the rest of the corrugated roller forms a low dislocation density region above the first deposited layer. The length of the corrugated roller is 30mm, and the cold rolling pressing amount is 1 / 2 of the thickness of a single deposited material, which is 0.5mm.

[0053] S4: The discharge port of the deposition head is aligned with the upper surface of the first deposition layer. The deposition material is extruded from the discharge port of the deposition head, forming a second deposition layer on the first deposition layer. The thickness of the second deposition layer is 1 mm. During the deposition process, the downward pressure load of the deposition head is 2 kN. The rotation speed of the deposition head is 300 r / min, and the forward speed is 100 mm / min. The diameter of the friction cylinder is 30 mm. Liquid cooling water is used to cool the surface of the deposition layer during the deposition process. A corrugated roller is placed above the second deposition layer. The corrugated roller is equipped with a protruding forming part to cold roll the second deposition layer. The protruding forming part forms a high dislocation density region above the second deposition layer, and the rest of the corrugated roller forms a low dislocation density region above the second deposition layer. The length of the corrugated roller is 30 mm, and the cold roll pressing amount is 1 / 2 of the thickness of a single layer of deposition material, which is 0.5 mm.

[0054] S5 aligns the outlet of the deposition head with the upper surface of the second deposition layer, extruding the deposition material from the outlet of the deposition head to form the final deposition layer on the second deposition layer, with a thickness of 1 mm. During deposition, the deposition head experiences a downward pressure load of 2 kN; the deposition head rotates at 300 r / min and advances at 100 mm / min; the friction cylinder diameter is 30 mm; liquid cooling water is used to water-cool the surface of the final deposition layer during deposition; a corrugated roller is placed above the final deposition layer, featuring protruding forming sections that cold-roll press the final deposition layer. The protruding forming sections create a high dislocation density region above the final deposition layer, while the remaining portion of the corrugated roller creates a low dislocation density region above the final deposition layer; the corrugated roller is 30 mm long, and the cold-roll pressing amount is half the thickness of a single deposition layer, i.e., 0.5 mm.

[0055] In this embodiment, optimized stirring friction solid-state deposition parameters and optimized special corrugated roller parameters were used to prepare a 3mm thick 6061 aluminum alloy mixed crystal material. The tensile strength of the mixed crystal material reached 183MPa and the elongation reached 33%.

[0056] Example 3

[0057] S1: Select 6061 aluminum alloy substrate as the metal substrate for the first deposition layer, and use a deposition head to perform frictional solid-phase deposition on 6061 aluminum alloy particles.

[0058] S2: The first deposition layer is formed on a 6061 aluminum alloy substrate. The thickness of the first deposition layer is 3mm. During the deposition process, the downward pressure load of the deposition head is 6KN. The rotation speed of the deposition head is 500r / min and the forward speed is 100mm / min. The diameter of the friction cylinder is 30mm. Liquid cooling water is used to cool the surface of the deposition layer during the deposition process.

[0059] S3: A corrugated roller is used to cold roll the surface of the first deposited layer. The protruding forming part forms a high dislocation density region above the first deposited layer, and the rest of the corrugated roller forms a low dislocation density region above the first deposited layer. The length of the corrugated roller is 45mm, and the cold rolling pressing amount is 1 / 2 of the thickness of a single deposited material, which is 1.5mm.

[0060] S4: The discharge port of the deposition head is aligned with the upper surface of the first deposition layer. The deposition material is extruded from the discharge port of the deposition head, forming a second deposition layer on the first deposition layer. The thickness of the second deposition layer is 3mm. During the deposition process, the downward pressure load of the deposition head is 6KN. The rotation speed of the deposition head is 500r / min, and the forward speed is 100mm / min. The diameter of the friction cylinder is 30mm. Liquid cooling water is used to cool the surface of the deposition layer during the deposition process. A corrugated roller is placed above the second deposition layer. The corrugated roller is equipped with a protruding forming part to cold roll the second deposition layer. The protruding forming part forms a high dislocation density region above the second deposition layer, and the rest of the corrugated roller forms a low dislocation density region above the second deposition layer. The length of the corrugated roller is 45mm, and the cold roll pressing amount is 1 / 2 of the thickness of a single layer of deposition material, which is 1.5mm.

[0061] S5 aligns the outlet of the deposition head with the upper surface of the second deposition layer, extruding the deposition material from the outlet of the deposition head to form the final deposition layer on the second deposition layer, with a thickness of 3 mm. During deposition, the deposition head experiences a downward pressure load of 6 kN; the deposition head rotates at 500 r / min and advances at 100 mm / min; the friction cylinder has a diameter of 30 mm; liquid cooling water is used to water-cool the surface of the final deposition layer during deposition; a corrugated roller is placed above the final deposition layer, featuring protruding forming sections that cold-roll press the final deposition layer. The protruding forming sections create a high dislocation density region above the final deposition layer, while the remaining portion of the corrugated roller creates a low dislocation density region above the final deposition layer; the corrugated roller is 45 mm long, and the cold-roll pressing amount is half the thickness of a single deposition layer, i.e., 1.5 mm.

[0062] In this embodiment, optimized stirring friction solid-state deposition parameters and optimized special corrugated roller parameters were used to prepare a 9mm thick 6061 aluminum alloy mixed crystal material. The tensile strength of the mixed crystal material reached 190MPa and the elongation reached 32%.

[0063] Comparative Example 1

[0064] The comparative example uses the same method as Example 1, except that the cold rolling process was not performed in Comparative Example 1. The 6061 aluminum alloy sheet prepared in Comparative Example 1 has a uniform microstructure, a tensile strength of 173 MPa, and an elongation of 24%.

[0065] Comparative Example 2

[0066] The comparative example uses the same method as Example 2, except that the cold rolling process was not performed in Comparative Example 2. The 6061 aluminum alloy sheet prepared in Comparative Example 2 has a uniform microstructure, a tensile strength of 170 MPa, and an elongation of 25%.

[0067] Comparative Example 3

[0068] The comparative example uses the same method as Example 3, except that the cold rolling process was not performed in Comparative Example 3. The 6061 aluminum alloy sheet prepared in Comparative Example 3 has a uniform microstructure, a tensile strength of 175 MPa, and an elongation of 23%.

[0069] Compared with Comparative Examples 1, 2 and 3, the tensile strength and elongation of the mixed-crystal 6061 aluminum alloy plates prepared in Examples 1, 2 and 3 were simultaneously improved.

[0070] The embodiments described herein are preferred embodiments of the present invention and are not intended to limit the scope of protection of the present invention. Therefore, all equivalent changes made in accordance with the structure, shape, and principle of the present invention should be covered within the scope of protection of the present invention.

Claims

1. A method for preparing mixed-crystal structure materials by stir-friction solid-phase deposition, characterized in that, Includes the following steps: S1. A metal substrate (2) identical to the deposition material is placed in the working position. The outlet of the deposition head (1) is opposite to the metal substrate (2) and moves along the length of the metal substrate (2). The deposition material is placed inside the deposition head (1). The deposition head (1) includes a friction cylinder (101) and a screw rod (102). The screw rod (102) is coaxially arranged inside the friction cylinder (101) and rotates relative to the friction cylinder (101). The lower end of the screw rod (102) has a gap with the lower end of the friction cylinder (101) to form the outlet of the deposition head (1). S2. The deposited material is extruded from the outlet of the deposition head (1) to form a first deposited layer on the metal substrate (2), and the first deposited layer is cooled by a cooling material. S3. Place the corrugated roller (6) above the first deposited layer. The corrugated roller (6) is provided with a protruding forming part (601). The first deposited layer is cold rolled. The protruding forming part (601) forms a high dislocation density region above the first deposited layer. The rest of the corrugated roller (6) forms a low dislocation density region above the first deposited layer. S4. The outlet of the deposition head (1) is aligned with the upper surface of the Nth deposition layer. The deposition material is extruded from the outlet of the deposition head (1) to form the N+1th deposition layer on the Nth deposition layer. The N+1th deposition layer is cooled using a cooling material. The corrugated roller (6) is placed above the N+1th deposition layer. The corrugated roller (6) is provided with a protruding forming part (601). The N+1th deposition layer is cold-rolled. The protruding forming part (601) forms a high dislocation density region above the N+1th deposition layer. The remaining part of the corrugated roller (6) forms a low dislocation density region above the N+1th deposition layer. During the cold-rolling process, the shape of the corrugated roller (6) used for each deposition layer is different, and the positions of the high dislocation density region and the low dislocation density region on each deposition layer are different. Wherein, N is an integer ≥1. S5. Repeat step S4 until the deposition layer thickness reaches the designed thickness.

2. The method for preparing mixed-crystal structure materials by friction stir solid-state deposition according to claim 1, characterized in that, The deposition material is one of aluminum, magnesium, zinc or an alloy, the alloy is formed from two or three of aluminum, magnesium and zinc, and the deposition material is in the form of one or two of filaments or particles.

3. The method for preparing mixed-crystal structure materials by stir-friction solid-phase deposition according to claim 1, characterized in that, In steps S2 and S4, when the deposited material is extruded from the outlet of the deposition head (1), the pressure load on the deposition head (1) is 2~6KN.

4. The method for preparing mixed-crystal structure materials by friction stir solid-state deposition according to claim 1, characterized in that, The thickness of each deposition layer is 1~3mm; the amount of pressure applied by the corrugated roller (6) on each deposition layer is 1 / 2 of the thickness of each deposition layer.

5. The method for preparing mixed-crystal structure materials by friction stir solid-state deposition according to claim 1, characterized in that, The cooling material is one of water, liquid carbon dioxide, or liquid nitrogen.

6. The method for preparing mixed-crystal structure materials by friction stir solid-state deposition according to claim 1, characterized in that, The length L of the corrugated roller (6) is L=K*D, in mm, where K is an empirical coefficient with a value of 1~1.5; D is the bottom diameter of the friction cylinder (101), in mm.

7. The method for preparing mixed-crystal structure materials by stir-friction solid-phase deposition according to claim 1, characterized in that, The ratio of the rotational speed of the screw (102) to the moving speed of the deposition head (1) is 3 to 5.

8. The method for preparing mixed-crystal structure materials by stir-friction solid-phase deposition according to claim 1, characterized in that, An apparatus for preparing mixed-crystal structure materials using friction stir solid-state deposition includes a mounting base (3). A deposition head (1) and a rolling base (4) are vertically arranged below the mounting base (3). The deposition head (1) includes a friction cylinder (101) and a spiral rod (102). The spiral rod (102) is coaxially arranged inside the friction cylinder (101) and can rotate relative to the friction cylinder (101). The lower end of the spiral rod (102) has a gap with the lower end of the friction cylinder (101), forming the outlet of the deposition head (1). The rolling base (4)... 4) has two opposing mounting plates (5) at its bottom, and a corrugated roller (6) is rotatably connected between the two mounting plates (5). The corrugated roller (6) has a protruding forming part (601) on its outer circumferential surface. The protruding forming part (601) is a hemispherical or cylindrical protrusion arranged in an array on the outer circumferential surface of the corrugated roller (6), a forming ring arranged coaxially on the outer circumferential surface of the corrugated roller (6) and spaced apart along the axis of the corrugated roller (6), a wave forming rib arranged spaced apart along the circumference of the corrugated roller (6), or a spiral rib arranged coaxially on the outer circumferential surface of the corrugated roller (6).

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