Aluminum / iron bimetallic composite material based on micro-textured intermediate layer and preparation method thereof

Abstract

The present invention belongs to the field of composite casting technology and relates to an aluminum / iron bimetallic composite material based on a micro-textured intermediate layer and its preparation method. A micro-textured intermediate layer is pre-deposited on the surface of an iron substrate through a combination of electrodeposition and laser etching. During the liquid-solid composite casting process, the intermediate layer serves to isolate the liquid aluminum alloy melt from direct contact with the solid iron substrate, while the microtexture on the intermediate layer surface induces a coordinated stress distribution. The present invention effectively addresses the problem of interface cracking by dually controlling the interfacial phase composition and interface structure of the aluminum / iron bimetallic composite material, thereby achieving a stable improvement in the interfacial bonding strength of the aluminum / iron bimetallic composite material.

Description

Technical Field

[0001] The present invention relates to the technical field of composite material casting, in particular to an aluminum / iron bimetallic composite material based on a micro-textured intermediate layer and a preparation method thereof. Background Art

[0002] Aluminum / iron bimetallic composites, formed by casting a liquid aluminum alloy melt onto an iron-based material using a liquid-solid composite casting method and then cooling it, combine the low density, high thermal conductivity, toughness, and good corrosion resistance of aluminum alloy with the excellent mechanical properties, high yield strength, and good wear resistance of iron-based materials. Therefore, aluminum / iron bimetallic composites have become one of the preferred materials for lightweight vehicle engine design. However, as engines evolve towards higher explosive pressures and higher loads, the interface bonding strength and cracking of aluminum / iron bimetallic composites produced by liquid-solid composite casting have become increasingly weak. This is primarily due to two factors: First, the significant difference in the thermophysical properties of aluminum and iron makes it very easy to generate stress at the interface during the composite casting process, leading to cracking; second, the aluminum and iron react easily to form a hard and brittle aluminum-iron binary intermetallic compound, which, upon exposure to external forces, undergoes brittle fracture.

[0003] To solve the above problems, a commonly used method is to use hot-dip low-melting-point alloys, such as hot-dip a layer of aluminum or zinc on the surface of the iron substrate to reduce or avoid contact between the aluminum melt and the iron substrate, thereby reducing the formation of large-area continuous intermetallic compounds at the aluminum-iron interface. The hot-dip method protects the pre-treated iron substrate surface from contamination and oxidation on the one hand, and reduces the temperature difference between the liquid aluminum alloy melt and the solid iron substrate on the other hand, thereby promoting the interfacial reaction between the aluminum alloy melt and the iron substrate. However, it has little effect in suppressing the binary aluminum-iron brittle intermetallic compounds at the interface. Therefore, although an aluminum / iron bimetallic composite material with a metallurgical bond at the interface is obtained, the problem of easy cracking of the interface during stress is still quite significant. Summary of the Invention

[0004] In order to solve the problems existing in the prior art, the main purpose of the present invention is to provide an aluminum / iron bimetallic composite material based on a micro-textured intermediate layer and a preparation method thereof.

[0005] To solve the above technical problems, according to one aspect of the present invention, the present invention provides the following technical solutions:

[0006] A method for preparing an aluminum / iron bimetallic composite material based on a micro-textured intermediate layer comprises the following steps:

[0007] S1. Activate the surface of the iron substrate;

[0008] S2. preparing an intermediate layer on the surface of the iron substrate;

[0009] S3, performing micro-texturing on the surface of the intermediate layer;

[0010] S4. Liquid-solid composite casting is performed using an aluminum solution and an iron substrate with a micro-textured intermediate layer surface to obtain an aluminum / iron bimetallic composite material based on a micro-textured intermediate layer.

[0011] As a preferred embodiment of the method for preparing an aluminum / iron bimetallic composite material based on a micro-textured intermediate layer according to the present invention, in step S1, the activation treatment includes polishing, cleaning, and drying, specifically comprising the following steps:

[0012] S11. Use sandpaper to polish the surface of the iron substrate to remove surface rust;

[0013] S12, placing the iron substrate in a NaOH solution for ultrasonic alkaline cleaning to remove oil stains on the surface of the substrate;

[0014] S13, rinsing the iron substrate under running water to remove residual NaOH solution on the surface;

[0015] S14, placing the iron substrate in an HCl solution for ultrasonic pickling to further remove the surface oxide scale to expose a fresh metal surface;

[0016] S15, rinsing the iron substrate under running water to remove residual HCl solution on the surface;

[0017] S16. Use cold air to dry the surface of the iron substrate and set aside for use.

[0018] As a preferred embodiment of the method for preparing an aluminum / iron bimetallic composite material based on a micro-textured intermediate layer according to the present invention, in step S1, the iron substrate includes iron and steel, such as ductile iron QT500, carbon steel, etc.

[0019] As a preferred embodiment of the method for preparing an aluminum / iron bimetallic composite material based on a micro-textured intermediate layer according to the present invention, wherein: in step S2, the intermediate layer is prepared by electrodeposition, specifically comprising the following steps:

[0020] S21, connecting the iron substrate to the negative electrode of a DC power supply, and connecting the positive electrode of the DC power supply to the graphite plate;

[0021] S22, fixing the iron substrate and the graphite plate at both ends of the container, respectively, and pouring the prepared intermediate layer plating solution into the container so that the height of the plating solution exceeds the position to be plated of the iron substrate;

[0022] S23, turning on the DC power supply to start depositing the intermediate layer;

[0023] S24, turn off the power after the deposition reaches the target thickness;

[0024] S25. Take out the iron substrate from the container, clean it ultrasonically with alcohol, and blow dry it with cold air.

[0025] As a preferred embodiment of the method for preparing an aluminum / iron bimetallic composite material based on a micro-textured intermediate layer described in the present invention, in step S23, the composition of the intermediate layer is not limited, and any metal intermediate layer that can form a uniform and dense metal intermediate layer on the surface of the iron substrate can be used, such as a copper intermediate layer, a chromium intermediate layer, a nickel intermediate layer, a high entropy alloy intermediate layer, etc.

[0026] As a preferred embodiment of the method for preparing an aluminum / iron bimetallic composite material based on a micro-textured intermediate layer according to the present invention, in step S3, micro-texturing is performed by laser etching, specifically comprising the following steps:

[0027] S31. Place the iron substrate on the workbench of the laser etching machine, with the side where the intermediate layer is deposited facing the laser gun head;

[0028] S32, drawing a micro-texture pattern on an operating interface of a laser etching device;

[0029] S33, setting laser etching parameters;

[0030] S34. Start the laser equipment system, and the laser generator etches on the surface of the intermediate layer according to the input laser scanning path to obtain an iron substrate with a micro-textured intermediate layer on the surface.

[0031] As a preferred embodiment of the method for preparing an aluminum / iron bimetallic composite material based on a micro-textured intermediate layer described in the present invention, in step S32, any micro-texture pattern that can increase the contact area between the liquid aluminum alloy melt and the solid iron substrate can be used, such as: a pit-shaped pattern, a grid-shaped pattern, a hexagonal pattern, an irregular pattern, etc.

[0032] As a preferred embodiment of the method for preparing an aluminum / iron bimetallic composite material based on a micro-textured intermediate layer according to the present invention, wherein: in step S4, the iron substrate having the micro-textured intermediate layer on its surface is placed in a mold, and the aluminum melt is cast into the mold for liquid-solid composite casting, specifically comprising the following steps:

[0033] S41, using a silicon carbon rod furnace to melt aluminum, and degas the aluminum melt;

[0034] S42, controlling the melt temperature and keeping it warm to make the melt temperature uniform;

[0035] S43. Place the iron substrate with the micro-textured intermediate layer on the surface in an insulation box for insulation and then place it in a metal mold. Quickly pour the aluminum melt in the silicon carbon rod furnace into the mold to completely solidify the aluminum melt, thereby completing the liquid-solid composite casting of the aluminum / iron bimetallic.

[0036] As a preferred embodiment of the method for preparing an aluminum / iron bimetallic composite material based on a micro-textured intermediate layer according to the present invention, in step S4, the aluminum material is pure aluminum or a cast aluminum alloy.

[0037] To solve the above technical problems, according to another aspect of the present invention, the present invention provides the following technical solutions:

[0038] An aluminum / iron bimetallic composite material based on a micro-textured intermediate layer is prepared by adopting the preparation method of the aluminum / iron bimetallic composite material based on a micro-textured intermediate layer.

[0039] As a preferred solution of the aluminum / iron bimetallic composite material based on the micro-textured intermediate layer described in the present invention, the thickness of the intermediate layer is 20-60 μm.

[0040] The beneficial effects of the present invention are as follows:

[0041] This invention proposes an aluminum / iron bimetallic composite material based on a microtextured interlayer and its preparation method. By combining electrodeposition and laser etching, a microtextured interlayer is pre-deposited on the surface of an iron substrate. During the liquid-solid composite casting process, the interlayer isolates the liquid aluminum alloy from direct contact with the solid iron substrate, while the surface microtexture of the interlayer induces a coordinated stress distribution. By dually controlling the interfacial phase composition and interfacial structure of the aluminum / iron bimetallic composite material, the invention effectively addresses the problem of interface cracking, thereby steadily improving the interfacial bonding strength of the aluminum / iron bimetallic composite material. BRIEF DESCRIPTION OF THE DRAWINGS

[0042] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on the structures shown in these drawings without paying any creative work.

[0043] Figure 1 This is a cross-sectional photograph of an iron substrate having an intermediate layer on its surface according to Example 1 of the present invention;

[0044] Figure 2 This is the interface morphology of the aluminum / iron bimetallic composite material of Example 1 of the present invention.

[0045] The purpose, features and advantages of the present invention will be further described with reference to the accompanying drawings and in conjunction with the embodiments. DETAILED DESCRIPTION

[0046] The following will be a clear and complete description of the technical solutions in the embodiments. Obviously, the embodiments described are only part of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making any creative efforts are within the scope of protection of the present invention.

[0047] The present invention proposes an aluminum / iron bimetallic composite material based on a micro-textured interlayer and its preparation method. After the micro-textured interlayer is pre-installed, the aluminum and iron are prevented from directly contacting each other. The brittle aluminum-iron binary phase at the interface is replaced by other new phases or mixed phases, achieving interface composition control. Furthermore, the presence of microtexture falls within the scope of interface structure design. On the one hand, it increases the contact area between the interface reaction layer and the substrate. On the other hand, it affects the growth path of the interface reaction layer, reduces interfacial stress concentration, and enables artificial intervention of interfacial stress. Therefore, under the dual protection of interface composition control and interface structure design, the interfacial bonding strength of the aluminum / iron bimetallic is steadily improved.

[0048] According to one aspect of the present invention, the present invention provides the following technical solutions:

[0049] A method for preparing an aluminum / iron bimetallic composite material based on a micro-textured intermediate layer comprises the following steps:

[0050] S1. Activate the surface of the iron substrate;

[0051] S2. preparing an intermediate layer on the surface of the iron substrate;

[0052] S3, performing micro-texturing on the surface of the intermediate layer;

[0053] S4. Liquid-solid composite casting is performed using an aluminum solution and an iron substrate with a micro-textured intermediate layer surface to obtain an aluminum / iron bimetallic composite material based on a micro-textured intermediate layer.

[0054] Preferably, in step S1, the activation treatment includes polishing, cleaning, and drying, and specifically includes the following steps:

[0055] S11. Use sandpaper to polish the surface of the iron substrate to remove surface rust;

[0056] S12, placing the iron substrate in a 5-10 wt% NaOH solution and ultrasonically cleaning it for 3-5 minutes to remove oil stains on the surface of the substrate;

[0057] S13. Rinse the iron substrate under running water for 1 to 2 minutes to remove residual NaOH solution on the surface;

[0058] S14, placing the iron substrate in a 5-10 wt% HCl solution and ultrasonically pickling for 3-5 minutes to further remove the surface oxide scale to expose a fresh metal surface;

[0059] S15. Rinse the iron substrate under running water for 1-2 minutes to remove residual HCl solution on the surface;

[0060] S16. Use cold air to dry the surface of the iron substrate and set aside for use.

[0061] Preferably, in step S1, the iron substrate includes iron and steel, such as ductile iron QT500, carbon steel, etc. Further preferably, the iron substrate is ductile iron QT500, which has high yield strength, tensile strength, high-temperature oxidation resistance, creep resistance, and good high-temperature strength. Its composition, by weight percentage, is as follows: C: 3.6-3.8wt%, Si: 2.5-2.9wt%, Mn <0.6wt%, S <0.025wt%, P <0.08wt%, Mg: 0.03-0.05wt%, RE: 0.03-0.05wt%, and the balance is Fe and unavoidable impurities.

[0062] Preferably, in step S2, the intermediate layer is prepared by electrodeposition, which specifically includes the following steps:

[0063] S21, connecting the iron substrate to the negative electrode of a DC power supply, and connecting the positive electrode of the DC power supply to the graphite plate;

[0064] S22, fixing the iron substrate and the graphite plate at both ends of the container, respectively, and pouring the prepared intermediate layer plating solution into the container so that the height of the plating solution exceeds the position to be plated of the iron substrate;

[0065] S23, turning on the DC power supply to start depositing the intermediate layer;

[0066] S24, turn off the power after 10~40min of deposition;

[0067] S25. Take out the iron substrate from the container, clean it ultrasonically with alcohol for 1 to 5 minutes, and blow dry it with cold air.

[0068] Preferably, in step S2, the composition of the intermediate layer is not limited, and any metal intermediate layer that can form a uniform and dense metal intermediate layer on the surface of the iron substrate can be used, such as a copper intermediate layer, a chromium intermediate layer, a nickel intermediate layer, a high entropy alloy intermediate layer, etc.

[0069] Preferably, in step S3, micro-texturing is performed by laser etching, which specifically includes the following steps:

[0070] S31. Place the iron substrate on the workbench of the laser etching machine, with the side where the intermediate layer is deposited facing the laser gun head;

[0071] S32, drawing a micro-texture pattern on an operating interface of a laser etching device;

[0072] S33, setting the laser spot diameter, laser power and laser scanning speed parameters, the spot is a 0.1 mm circular focused spot, the laser power is 15-20 W, the scanning speed is 500-1000 mm / s, and the number of processing times for each pattern is 1-3;

[0073] S34. Start the laser equipment system, and the laser generator etches on the surface of the intermediate layer according to the input laser scanning path to obtain an iron substrate with a micro-textured intermediate layer on the surface.

[0074] Preferably, in step S3, any micro-texture pattern that can increase the contact area between the liquid aluminum alloy melt and the solid iron substrate can be used, such as a pit-shaped pattern, a grid-shaped pattern, a hexagonal pattern, an irregular pattern, etc.

[0075] Preferably, in step S4, the iron substrate having a micro-textured intermediate layer on its surface is placed in a mold, and the aluminum alloy melt is cast into the mold for liquid-solid composite casting, which specifically includes the following steps:

[0076] S41, using silicon carbon rod furnace to melt aluminum, aluminum melt is degassed at 725 ~ 735 ℃;

[0077] S42, control the melt temperature to 700~720℃, keep it warm for 10~20min to make the melt temperature uniform;

[0078] S43. Place the iron substrate with a micro-textured intermediate layer on its surface in an insulation box. After keeping the temperature for 5 to 8 minutes, place it in a metal mold at a temperature of 200°C. Quickly pour the aluminum melt from the silicon carbon rod furnace into the mold. After the aluminum melt is completely solidified, the liquid-solid composite casting of the aluminum / iron bimetallic is completed.

[0079] Preferably, in step S4, the aluminum material is pure aluminum or a cast aluminum alloy. Further preferably, the aluminum material is Al-Si alloy ZL702A, which has good fluidity and excellent performance, and its composition, by weight percentage, is as follows: Si: 6.0-8.0wt%, Mg: 0.25-0.50wt%, Cu: 1.2-1.8wt%, Mn: 0.1-0.25wt%, Fe≤0.15wt%, and the balance is Al and unavoidable impurities.

[0080] Preferably, in step S4, when the iron substrate is cast iron, the holding temperature is 250°C; when the iron substrate is steel, the holding temperature is 300°C.

[0081] According to another aspect of the present invention, the present invention provides the following technical solutions:

[0082] An aluminum / iron bimetallic composite material based on a micro-textured intermediate layer is prepared by adopting the above-mentioned preparation method of the aluminum / iron bimetallic composite material based on a micro-textured intermediate layer, and the thickness of the intermediate layer is 20-60 μm.

[0083] The technical solution of the present invention is further described below with reference to specific embodiments.

[0084] Example 1

[0085] In this embodiment, the iron substrate is ductile iron QT500, whose composition, by weight percentage, is: C: 3.7wt%, Si: 2.7wt%, Mn: 0.2wt%, S: 0.015wt%, P: 0.05wt%, Mg: 0.04wt%, RE: 0.04wt%, with the balance being Fe and inevitable impurities. The aluminum material is Al-Si alloy ZL702A, whose composition, by weight percentage, is: Si: 7.11wt%, Mg: 0.39wt%, Cu: 1.5wt%, Mn: 0.16wt%, Fe: 0.08wt%, with the balance being Al and inevitable impurities. The preparation method of the aluminum / iron bimetallic composite material based on the micro-textured intermediate layer includes the following steps:

[0086] S1. Activate the surface of the iron substrate;

[0087] S11. Use sandpaper to polish the surface of the iron substrate to remove surface rust;

[0088] S12, placing the iron substrate in a 10wt% NaOH solution and ultrasonically cleaning for 5 minutes to remove oil stains on the surface of the substrate;

[0089] S13, rinsing the iron substrate under running water for 1 minute to remove residual NaOH solution on the surface;

[0090] S14, placing the iron substrate in a 10 wt % HCl solution and ultrasonically pickling for 5 min to further remove the surface oxide scale to expose a fresh metal surface;

[0091] S15. Rinse the iron substrate under running water for 1 minute to remove residual HCl solution on the surface;

[0092] S16. Use cold air to dry the surface of the iron substrate and set aside for use.

[0093] S2. preparing a chromium intermediate layer on the surface of the iron substrate;

[0094] S21, connecting the iron substrate to the negative electrode of a DC power supply, and connecting the positive electrode of the DC power supply to the graphite plate;

[0095] S22, fixing the iron substrate and the graphite plate at both ends of the container, respectively, pouring the prepared chromium intermediate layer plating solution into the container so that the height of the plating solution exceeds the position to be plated of the iron substrate;

[0096] S23, turning on the DC power supply to start depositing the chromium intermediate layer;

[0097] S24, after 40 minutes of deposition, the power supply is turned off to obtain a chromium intermediate layer with a thickness of about 50 μm;

[0098] S25. Take out the iron substrate from the container, clean it with alcohol ultrasonically for 1 minute, and blow dry it with cold air (the cross-sectional photo of the iron substrate with a chromium intermediate layer on the surface is shown in the figure). Figure 1 shown).

[0099] S3, performing micro-texturing on the surface of the chromium intermediate layer;

[0100] S31. Place the iron substrate on the workbench of the laser etching machine, with the side with the chromium intermediate layer deposited facing the laser gun head;

[0101] S32, drawing a micro-texture pattern on the operating interface of the laser etching device, wherein the center spacing of the grooves of the micro-texture is 450 μm, the groove width is 80 μm, and the depth is 50 μm;

[0102] S33, setting the laser spot diameter, laser power, and laser scanning speed parameters: the spot is a 0.1 mm circular focused spot, the laser power is 17 W, the laser scanning speed is 700 mm / s, and each groove is processed 3 times;

[0103] S34. Start the laser equipment system, and the laser generator etches the surface of the chromium intermediate layer according to the input laser scanning path to obtain an iron substrate with a micro-textured chromium intermediate layer on the surface.

[0104] S4, performing liquid-solid composite casting using an aluminum solution and an iron substrate with a micro-textured chromium intermediate layer surface to obtain an aluminum / iron bimetallic composite material based on a micro-textured chromium intermediate layer;

[0105] S41, using a silicon carbon rod furnace to melt aluminum, and degassing the aluminum melt at 730°C;

[0106] S42, control the melt temperature to 710 ° C, keep it warm for 10 minutes to make the melt temperature uniform;

[0107] S43. Place the iron substrate with a micro-textured chromium intermediate layer on its surface in an insulation box. After keeping the temperature for 5 minutes, place it in a metal mold at a temperature of 200°C. Quickly pour the aluminum melt from the silicon carbon rod furnace into the mold. Completely solidify the aluminum melt within 60 seconds to complete the liquid-solid composite casting of the aluminum / iron bimetallic.

[0108] The interface morphology of aluminum / iron bimetallic composite material is shown in the figure Figure 2 As shown in the figure, the left side is the iron substrate and the right side is the aluminum alloy. The narrow strip at the interface is the interface reaction layer formed by the reaction of the chromium intermediate layer with the iron substrate and aluminum on both sides. The thickness of the interface reaction layer is 20~25μm. It can be clearly seen from the black dotted circle in the figure that the interface reaction layer containing microtexture is distributed in a discontinuous state, and the reaction layer is bent at the microtexture. In addition, the composition of the interface reaction layer was identified, and the results are shown in Table 1. The three elements Al, Cr and Si are mainly enriched on the side close to the aluminum alloy, and Al and Cr are mainly enriched on the side close to the iron substrate. Combined with the ratio of element content, it can be inferred that Al5Cr binary new phase is formed on the iron side, and Al is formed on the aluminum side. 13 Compared with the aluminum / iron bimetallic without micro-textured chromium interlayer, after the introduction of the "groove-shaped" chromium interlayer, the bimetallic interface is composed of a mixed layer of Al-Cr phase and Al-Cr-Si phase instead of a hard and brittle Al-Fe binary phase (Al5Fe2, Al 13 The present invention achieves dual control of interface composition and structure, ultimately increasing the shear strength of the bimetallic interface from 9 MPa without a micro-textured chromium interlayer to 126 MPa for the aluminum / iron bimetallic composite material with a micro-textured chromium interlayer.

[0109] Table 1 Main element composition of the interface reaction layer (at%)

[0110]

[0111] Compared with the traditional liquid-solid composite casting technology, the present invention innovatively pre-deposits a micro-textured intermediate layer on the surface of the iron substrate. On the one hand, the intermediate layer effectively prevents direct contact between the aluminum melt and the solid iron substrate during the liquid-solid composite process, thereby suppressing the Al bimetallic interface produced by the traditional technology. 13 The problem of large-scale formation of brittle phases such as Fe4 and Al5Fe2 is addressed. On the other hand, the presence of microtexture can disrupt the continuity of the interfacial reaction layer and reduce interfacial stress concentration. By combining interface composition control with interface structure design, interfacial cracking is reduced and the interfacial bonding strength is steadily improved. This provides a theoretical basis and application foundation for the subsequent replacement of aluminum / iron bimetallic materials in vehicle engines and other products.

[0112] The above description is only a preferred embodiment of the present invention and does not limit the patent scope of the present invention. All equivalent structural transformations made by using the contents of the present invention specification under the inventive concept of the present invention, or direct / indirect application in other related technical fields are included in the patent protection scope of the present invention.

Claims

1. A method for preparing an aluminum / iron bimetallic composite material based on a micro-textured intermediate layer, characterized in that: The steps include: S1. Activate the surface of the iron substrate; the iron substrate is ductile iron QT500, and its composition, by weight percentage, is C: 3.7wt%, Si: 2.7wt%, Mn: 0.2wt%, S: 0.015wt%, P: 0.05wt%, Mg: 0.04wt%, RE: 0.04wt%, and the balance is Fe and unavoidable impurities; S11. Use sandpaper to polish the surface of the iron substrate to remove surface rust; S12, placing the iron substrate in a 10wt% NaOH solution and ultrasonically cleaning for 5 minutes to remove oil stains on the surface of the substrate; S13, rinsing the iron substrate under running water for 1 minute to remove residual NaOH solution on the surface; S14, placing the iron substrate in a 10 wt % HCl solution and ultrasonically pickling for 5 min to further remove the surface oxide scale to expose a fresh metal surface; S15. Rinse the iron substrate under running water for 1 minute to remove residual HCl solution on the surface; S16. Use cold air to dry the surface of the iron substrate for later use; S2. preparing an intermediate layer on the surface of the iron substrate; S21, connecting the iron substrate to the negative electrode of a DC power supply, and connecting the positive electrode of the DC power supply to the graphite plate; S22, fixing the iron substrate and the graphite plate at both ends of the container, respectively, and pouring the prepared intermediate layer plating solution into the container so that the height of the plating solution exceeds the position to be plated of the iron substrate; S23, turning on the DC power supply to start depositing the chromium intermediate layer; S24, after 40 minutes of deposition, the power supply is turned off to obtain an intermediate layer with a thickness of 50 μm; S25. Take out the iron substrate from the container, clean it ultrasonically with alcohol for 1 minute, and blow dry it with cold air; S3, performing micro-texturing on the surface of the intermediate layer; S31. Place the iron substrate on the workbench of the laser etching machine, with the side on which the chromium intermediate layer is deposited facing the laser gun head; S32, drawing a micro-texture pattern on the operating interface of the laser etching device, wherein the center spacing of the grooves of the micro-texture is 450 μm, the groove width is 80 μm, and the depth is 50 μm; S33, setting the laser spot diameter, laser power, and laser scanning speed parameters: the spot is a 0.1 mm circular focused spot, the laser power is 17 W, the laser scanning speed is 700 mm / s, and each groove is processed 3 times; S34, starting the laser equipment system, and the laser generator etches the surface of the intermediate layer according to the input laser scanning path, thereby obtaining an iron substrate having a micro-textured intermediate layer on the surface; S4. Liquid-solid composite casting is performed using an aluminum solution and an iron substrate with a micro-textured intermediate layer surface to obtain an aluminum / iron bimetallic composite material based on a micro-textured intermediate layer; the aluminum material is Al-Si alloy ZL702A, whose composition, by weight percentage, is Si: 7.11wt%, Mg: 0.39wt%, Cu: 1.5wt%, Mn: 0.16wt%, Fe: 0.08wt%, and the balance is Al and unavoidable impurities; S41, using a silicon carbon rod furnace to melt aluminum, and degassing the aluminum melt at 730°C; S42, control the melt temperature to 710 ° C, keep it warm for 10 minutes to make the melt temperature uniform; S43. Place the iron substrate with a micro-textured intermediate layer on the surface in an insulation box. After keeping warm for 5 minutes, put it into a metal mold at a temperature of 200°C. Quickly cast the aluminum melt in the silicon carbon rod furnace into the mold. Completely solidify the aluminum melt within 60 seconds to complete the liquid-solid composite casting of the aluminum / iron bimetallic to obtain an aluminum / iron bimetallic composite material. The thickness of the interface reaction layer of the aluminum / iron bimetallic composite material is 20~25μm. The interface reaction layer is formed by the reaction of the intermediate layer with the iron substrate and the aluminum on both sides. The interface shear strength of the aluminum / iron bimetallic composite material is 126MPa.

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