Strengthening method of low-melting-point metal matrix material

Abstract

The invention discloses a strengthening method of a low-melting-point metal matrix material, which comprises the following steps of: connecting an internal strengthening body with a cathode and externally applying voltage between the strengthening body and a matrix which are tightly combined to generate a hollow cathode glow discharge effect for synchronous heating so as to finish mutual diffusion of the strengthening body and the matrix and uniform sintering of the matrix material; therefore, the interface bonding strength and the overall performance of the composite material are improved. The obtained composite structure is high in bonding strength, is suitable for an interface heating strengthening process of a low-melting-point metal matrix and a high-melting-point reinforcement, and has the advantages of being simple in process, low in cost and easy to produce on a large scale.

Description

Technical Field

[0001] The present invention relates to the technical field of metal material processing, and in particular to a heating strengthening method for achieving mutual diffusion and homogenized sintering of a reinforcement body and a matrix through internal and external synchronous heating. Background Art

[0002] In metal-matrix composites, the interfacial bonding strength between the reinforcement and the matrix is ​​a key factor in determining material performance. Traditional heat strengthening methods typically rely on a single external heating method, resulting in uneven interfacial bonding between the reinforcement and the matrix. This is particularly true when combining a low-melting-point metal matrix with a high-melting-point reinforcement, which can lead to problems such as poor interfacial bonding and uneven sintering. Furthermore, traditional sintering methods struggle to achieve interdiffusion between the reinforcement and the matrix, resulting in insufficient interfacial bonding strength and compromising the overall material performance. Summary of the Invention

[0003] The present invention aims to address the shortcomings of the prior art by providing a heat-strengthening method that achieves interdiffusion and homogenized sintering of reinforcements and matrix materials through simultaneous internal and external heating. This method achieves both interdiffusion and homogenized sintering of the matrix material in a single step by applying simultaneous internal and external heating between the reinforcements and matrix, thereby improving the interfacial bonding strength and overall performance of the composite material.

[0004] In order to achieve the above-mentioned objectives, the present invention provides a method for strengthening a low-melting-point metal matrix, wherein the strengthening method places a reinforcement body in a hole adapted in the center of a low-melting-point metal matrix material, connects the internal reinforcement body to a cathode, and applies a voltage externally between the reinforcement body and the low-melting-point metal matrix material to generate a hollow cathode glow discharge effect for internal heating; at the same time, a cylindrical target material is arranged on the periphery of the low-melting-point metal matrix material, connected to a source electrode and placed in a plasma sintering device for external heating; by simultaneously performing internal and external heating, a dense composite material is generated; wherein, the low-melting-point metal matrix material is zinc or a zinc-based alloy.

[0005] The present invention achieves mutual diffusion between the reinforcement and the matrix material through internal and external synchronous heating, and at the same time the matrix material is uniformly sintered at high temperature, thereby forming a dense composite material, thereby improving the interface bonding strength and overall performance of the composite material.

[0006] More specifically, the strengthening method includes the following steps:

[0007] (1) drilling a hole in the low-melting-point metal matrix material along the height direction, and grinding the reinforcement according to the hole size so that the reinforcement fits the hole; then inserting the reinforcement into the hole;

[0008] (2) connecting the reinforcement to the cathode as an internal heating source, and setting a cylindrical target around the substrate and connecting it to the source as an external heating source; and placing the low-melting-point metal substrate material, the reinforcement and the cylindrical target as a whole in a plasma sintering furnace;

[0009] (3) Turn on the plasma sintering furnace and its matching cold water pump, use a mechanical pump to pump the plasma sintering furnace body pressure to 2-5 Pa, and then use a molecular pump to further pump the furnace body pressure to 4×10 -4 ~6×10 -4 Pa, to keep the furnace in high vacuum state;

[0010] (4) Fill the furnace with argon and then pump it back to the ultimate vacuum to expel the air in the furnace;

[0011] (5) By adjusting the heating power of the cathode and the cylindrical target, the internal and external synchronous heating of the reinforcement and the low-melting-point metal matrix material is achieved;

[0012] (6) Under the action of internal and external synchronous heating, mutual diffusion occurs between the reinforcement and the matrix, and at the same time, the matrix material undergoes homogenized secondary sintering at high temperature to form a dense composite material;

[0013] (7) Turn off the source power supply, cathode power supply and gas source in sequence, and then evacuate the vacuum furnace to 2×10 -4 ~5×10 - 4 Pa vacuum degree, cooled to room temperature and taken out, thus obtaining a composite material in which a low-melting-point metal matrix material and a reinforcement body diffuse with each other.

[0014] Furthermore, the matrix material is made of low-melting-point metal (pure zinc or zinc-based alloy), which can be prepared by powder metallurgy; the reinforcement material is any high-melting-point metal, which can be prepared by mechanical processing.

[0015] In some embodiments, preferably, the low-melting-point metal matrix material is zinc or a zinc-based alloy; the reinforcement material is a metal material such as iron, titanium or tantalum whose mechanical strength is better than that of zinc.

[0016] In some embodiments, more preferably, the low-melting-point metal matrix material is zinc; and the reinforcement is iron rod.

[0017] Furthermore, the heating temperature of the internal and external synchronous heating in the above step (5) is 400-700°C, and the heating time is 1-4 hours, which is implemented as follows: adjust the source voltage to 400-800V, the duty cycle to 40%-80%, and control the cathode voltage to 100-400V, the duty cycle to 40%-80%.

[0018] Furthermore, the low-melting-point metal matrix material is a zinc rod with a diameter of 5mm to 20mm; the reinforcement is an iron rod with a diameter of 1mm to 8mm; the size of the hole in the middle of the low-melting-point metal matrix material is set so that the gap between the reinforcement and the low-melting-point metal matrix material is controlled at 0.01mm to 0.05mm after insertion.

[0019] The size of the low-melting-point metal matrix material only needs to ensure that holes that match the size of the reinforcement can be smoothly processed, and there is no requirement for the thickness of the remaining hollow columnar material after processing.

[0020] Furthermore, in step (4), argon gas is filled into the furnace to 25-35 Pa, and the vacuum is re-evacuated to the ultimate vacuum degree, and this process is repeated 2-3 times to expel as much air as possible from the furnace.

[0021] Furthermore, the above strengthening method further comprises the following steps:

[0022] (8) The cooled composite material is surface polished and heat treated to further improve the performance of the composite material.

[0023] Furthermore, the processed composite material is stripped of excess reinforcement on the upper portion and excess low-melting-point metal matrix material on the lower portion (ie, portions not diffused between the two).

[0024] Compared with the prior art, the present invention has the following advantages:

[0025] The present invention obtains a dense composite material by a heating-strengthening preparation method that realizes the mutual diffusion of reinforcement and matrix and homogenization secondary sintering through dual-cathode internal and external synchronous heating. The present invention connects the cathode through a tightly combined internal reinforcement, applies a voltage externally between the reinforcement and the matrix, generates a hollow cathode glow discharge effect and synchronous heating, completes the mutual diffusion of reinforcement and matrix and the homogenization sintering of the matrix material, thereby improving the interface bonding strength and overall performance of the composite material. The composite material obtained by the present invention has high bonding strength and is suitable for the interface heating strengthening process of any low-melting-point metal matrix and high-melting-point reinforcement, and has the advantages of simple process, low cost, and easy large-scale production. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 Schematic diagram of the implementation of the method for strengthening the low-melting-point metal matrix of the present invention;

[0027] In the figure, 1-low melting point metal matrix material, 2-reinforcement body, 3-cylindrical target material, 4-first bracket, 5-second bracket, 6-first electrode rod, 7-second electrode rod, 8-tray, 9-stainless steel sheet, 10-insulating ceramic sheet, 11-heat-insulating cover;

[0028] Figure 2 for Figure 1A perspective schematic diagram of the strengthening device shown;

[0029] Figure 3 This is a SEM image of the composite material prepared in Example 2 of the present invention;

[0030] Figure 4 The mechanical properties test results of the composite materials prepared in Example 1 and Example 2 of the present invention are as follows: Figure 4 a is the stress-strain curve of the composite material, Figure 4 b is the elastic modulus and compressive strength of the composite material;

[0031] Figure 5 This is the SEM image of the composite material prepared in Comparative Example 1. DETAILED DESCRIPTION

[0032] The present invention will be described in detail below with reference to the accompanying drawings and specific embodiments.

[0033] like Figure 1 、 Figure 2 As shown, the strengthening method of the low-melting-point metal matrix of the present invention is as follows: first, a hole is punched in the low-melting-point metal matrix material 1 along the z direction (the hole is not through-hole, so as to avoid the reinforcement from contacting the insulating ceramic gasket 10 below after insertion), and then a reinforcement 2 is prepared by a mechanical processing method, which is polished to a size matching the matrix hole, and inserted into the matrix hole to ensure a close fit with the matrix. The gap after insertion is between 0.01mm and 0.05mm (the low-melting-point metal matrix material and the reinforcement are placed on the insulating ceramic gasket 10 as a whole, and the reinforcement does not contact the ceramic gasket. The gasket below is stainless steel sheet 9-insulating ceramic gasket 10-stainless steel sheet 9-insulating ceramic gasket 10-tray 8 from top to bottom ( The trays are made of stainless steel) and are stacked to prevent arcing and insulation. The height of the reinforcement 2 is slightly greater than the depth of the hole. The raised part above is connected to the cathode through the first bracket 4 and connected to the first electrode rod 6 as an internal heating source. At the same time, a cylindrical target material 3 (a pure tantalum target is used in this example) is arranged around the substrate and fixed above the gasket through the second bracket 5, and connected to the source through the second electrode rod 7 as an external heating source. The outermost part is covered with a heat preservation cover 11 to prevent temperature loss. The entire device is placed in a plasma sintering device (the cavity of the sintering device acts as an anode), the plasma sintering device is turned on, and the sintering furnace body pressure is pumped to 3Pa using a mechanical pump, and then the furnace body pressure is further pumped to 5×10 -4Pa, so that the furnace is maintained in a high vacuum state. Fill the furnace with argon to 30Pa, and re-evacuate to the ultimate vacuum to expel the air in the furnace. Afterwards, by adjusting the heating power of the cathode and the cylindrical target, the internal and external synchronous heating of the reinforcement and the matrix is ​​achieved. Under the action of internal and external synchronous heating, mutual diffusion occurs between the reinforcement and the matrix, and at the same time, the matrix material undergoes homogenized secondary sintering at high temperature to form a dense composite material. The density of the sintered composite material reaches more than 98%. After the sintering is completed, turn off the source power supply, cathode power supply and gas source in turn, and then evacuate the vacuum furnace to 3×10 -4 After the composite material is removed, the protruding portion of the reinforcement and the portion of the low-melting-point metal matrix material not inserted into the reinforcement are removed, and the composite material is surface polished and heat-treated to further improve its performance.

[0034] Embodiment 1:

[0035] In this embodiment, a hole is first punched in the z direction in a low-melting-point pure zinc rod with a hole diameter of 3 mm and a depth of 10 mm. The size of the matrix material is 10 mm in diameter and 20 mm in height. Subsequently, an iron rod reinforcement is prepared by mechanical processing. The iron rod is polished to a size that matches the hole in the matrix, that is, a diameter of 3 mm and a length of 20 mm (the length is slightly larger than the depth of the hole, and the extra part is suitable for convenient connection of the electrode). The reinforcement is inserted into the hole in the matrix to ensure a close fit with the matrix. The gap after insertion is between 0.01 mm and 0.05 mm. The reinforcement is connected to the cathode as an internal heating source, and a cylindrical target material is set around the matrix to connect the source as an external heating source. Turn on the plasma sintering equipment, use a mechanical pump to pump the sintering furnace body pressure to 3 Pa, and then use a molecular pump to further pump the furnace body pressure to 5×10 -4 Pa, so that the furnace is maintained in a high vacuum state. Fill the furnace with argon to 30Pa, and re-evacuate to the ultimate vacuum to expel the air in the furnace. Afterwards, by adjusting the heating power of the cathode and the cylindrical target, the internal and external synchronous heating of the reinforcement and the matrix is ​​achieved. The source voltage is set to 600V, the duty cycle is 60%, and the cathode voltage is less than the source voltage by 200V, and the duty cycle is 60%. The heating temperature is 400℃, and the heating time is 2 hours. Under the action of internal and external synchronous heating, mutual diffusion occurs between the reinforcement and the matrix, and at the same time, the matrix material undergoes homogenized secondary sintering at high temperature to form a dense composite material. The density of the sintered composite material reaches more than 98%. After sintering is completed, turn off the source power supply, cathode power supply and gas source in turn, and then evacuate the vacuum furnace to 3×10 -4The composite material was then removed and the protruding portion of the reinforcement and the portion of the low-melting-point metal matrix material below the reinforcement were removed. The composite material was then surface polished and heat treated at 200°C for 1 hour to further improve its performance.

[0036] Example 2:

[0037] In this embodiment, a hole is first punched in the z direction in a low-melting-point pure zinc rod with a hole diameter of 5 mm and a depth of 12 mm. The size of the matrix material is 15 mm in diameter and 25 mm in height. Subsequently, an iron rod reinforcement is prepared by a mechanical processing method. The iron rod is polished to a size that matches the hole in the matrix, that is, a diameter of 5 mm and a length of 22 mm. The reinforcement is inserted into the hole in the matrix to ensure a close fit with the matrix, and the gap after insertion is between 0.01 mm and 0.05 mm. The reinforcement is connected to the cathode as an internal heating source, and a cylindrical target material is set around the matrix to connect the source as an external heating source. Turn on the plasma sintering equipment, use a mechanical pump to pump the sintering furnace body pressure to 4 Pa, and then use a molecular pump to further pump the furnace body pressure to 5×10 -4 Pa, so that the furnace is maintained in a high vacuum state. Fill the furnace with argon to 35Pa, and re-evacuate to the ultimate vacuum to expel the air in the furnace. Afterwards, by adjusting the heating power of the cathode and the cylindrical target, internal and external synchronous heating of the reinforcement and the matrix is ​​achieved. The source voltage is set to 700V, with a duty cycle of 70%, and the cathode voltage is less than the source voltage by 300V, with a duty cycle of 70%. The heating temperature is 500°C, and the heating time is 3 hours. Under the action of internal and external synchronous heating, mutual diffusion occurs between the reinforcement and the matrix, and at the same time, the matrix material undergoes homogenized secondary sintering at high temperature to form a dense composite material. The density of the sintered composite material reaches more than 99%, such as Figure 3 After sintering is completed, turn off the source power supply, cathode power supply and gas source in sequence, and then evacuate the vacuum furnace to 4×10 -4 The composite material was then removed and the protruding portion of the reinforcement and the portion of the low-melting-point metal matrix material not inserted into the reinforcement were removed. The composite material was then surface polished and heat treated at 250°C for 2 hours to further improve its performance.

[0038] Example 3:

[0039] In this embodiment, firstly, a low melting point metal matrix material (zinc-based alloy, Ca 10-x Zn x(PO4)6(OH)2, zinc powder and zinc-loaded hydroxyapatite (Zn-HA) were mixed in a mass ratio of 19:1 by high-energy mechanical ball milling, and holes were punched in the z direction with a hole diameter of 2 mm and a depth of 8 mm. The size of the matrix material is 8 mm in diameter and 15 mm in height. Subsequently, a titanium rod reinforcement was prepared by mechanical processing. The titanium rod was polished to a size that matches the matrix hole, that is, a diameter of 2 mm and a length of 16 mm. The reinforcement was inserted into the matrix hole to ensure a close fit with the matrix. The gap after insertion was between 0.01 mm and 0.05 mm. The reinforcement was connected to the cathode as an internal heating source, and a cylindrical target was set around the matrix to connect the source as an external heating source. Turn on the plasma sintering equipment, use a mechanical pump to pump the sintering furnace pressure to 2 Pa, and then use a molecular pump to further pump the furnace pressure to 4×10 -4 Pa, so that the furnace is maintained in a high vacuum state. Fill the furnace with argon to 25Pa, and re-evacuate to the ultimate vacuum to expel the air in the furnace. Afterwards, by adjusting the heating power of the cathode and the cylindrical target, the internal and external synchronous heating of the reinforcement and the matrix is ​​achieved. The source voltage is set to 500V, the duty cycle is 50%, and the cathode voltage is 100V less than the source voltage, and the duty cycle is 50%. The heating temperature is 600℃, and the heating time is 2 hours. Under the action of internal and external synchronous heating, mutual diffusion occurs between the reinforcement and the matrix, and at the same time, the matrix material undergoes homogenized secondary sintering at high temperature to form a dense composite material. The density of the sintered composite material reaches more than 98%. After sintering is completed, turn off the source power supply, cathode power supply and gas source in turn, and then evacuate the vacuum furnace to 2×10 -4 The composite material was then removed and the protruding portion of the reinforcement and the portion of the low-melting-point metal matrix material below the reinforcement were removed. The composite material was then surface polished and heat treated at 200°C for 1 hour to further improve its performance.

[0040] Embodiment 4:

[0041] In this embodiment, firstly, a low melting point metal matrix material (zinc-based alloy, Ca 10-x Zn x(PO4)6(OH)2) is drilled along the z direction with a hole diameter of 3mm and a depth of 10mm. The size of the matrix material is 10mm in diameter and 20mm in height. Subsequently, a titanium rod reinforcement is prepared by mechanical processing. The titanium rod is polished to a size that matches the hole in the matrix, that is, 3mm in diameter and 20mm in length. The reinforcement is inserted into the hole in the matrix to ensure a close fit with the matrix. The gap after insertion is between 0.01mm and 0.05mm. The reinforcement is connected to the cathode as an internal heating source, and a cylindrical target is set around the matrix to connect the source as an external heating source. Turn on the plasma sintering equipment, use a mechanical pump to pump the sintering furnace pressure to 3Pa, and then use a molecular pump to further pump the furnace pressure to 5×10 -4 Pa, so that the furnace is maintained in a high vacuum state. Fill the furnace with argon to 30Pa, and re-evacuate to the ultimate vacuum to expel the air in the furnace. Afterwards, by adjusting the heating power of the cathode and the cylindrical target, the internal and external synchronous heating of the reinforcement and the matrix is ​​achieved. The source voltage is set to 600V, the duty cycle is 60%, and the cathode voltage is 200V less than the source voltage, and the duty cycle is 60%. The heating temperature is 400℃, and the heating time is 4 hours. Under the action of internal and external synchronous heating, mutual diffusion occurs between the reinforcement and the matrix, and at the same time, the matrix material undergoes homogenized secondary sintering at high temperature to form a dense composite material. The density of the sintered composite material reaches more than 98%. After sintering is completed, turn off the source power supply, cathode power supply and gas source in turn, and then evacuate the vacuum furnace to 3×10 -4 The composite material was then removed and the protruding portion of the reinforcement and the portion of the low-melting-point metal matrix material below the reinforcement were removed. The composite material was then surface polished and heat treated at 200°C for 1 hour to further improve its performance.

[0042] Example 5:

[0043] In this embodiment, firstly, a low melting point metal matrix material (zinc-based alloy, Ca 10-x Zn x (PO4)6(OH)2) is drilled in the z direction with a hole diameter of 3mm and a depth of 10mm. The size of the matrix material is 10mm in diameter and 20mm in height. Subsequently, a tantalum rod reinforcement is prepared by mechanical processing. The tantalum rod is polished to a size that matches the hole in the matrix, that is, 3mm in diameter and 20mm in length. The reinforcement is inserted into the hole in the matrix to ensure that it fits tightly with the matrix. The gap after insertion is between 0.01mm and 0.05mm. The reinforcement is connected to the cathode as an internal heating source, and a cylindrical target is set around the matrix to connect the source as an external heating source. Turn on the plasma sintering equipment, use a mechanical pump to pump the sintering furnace pressure to 3Pa, and then use a molecular pump to further pump the furnace pressure to 5×10 -4Pa, so that the furnace is maintained in a high vacuum state. Fill the furnace with argon to 30Pa, and re-evacuate to the ultimate vacuum to expel the air in the furnace. Afterwards, by adjusting the heating power of the cathode and the cylindrical target, the internal and external synchronous heating of the reinforcement and the matrix is ​​achieved. The source voltage is set to 600V, the duty cycle is 60%, and the cathode voltage is less than the source voltage by 200V, and the duty cycle is 60%. The heating temperature is 400℃, and the heating time is 3 hours. Under the action of internal and external synchronous heating, mutual diffusion occurs between the reinforcement and the matrix, and at the same time, the matrix material undergoes homogenized secondary sintering at high temperature to form a dense composite material. The density of the sintered composite material reaches more than 98%. After sintering is completed, turn off the source power supply, cathode power supply and gas source in turn, and then evacuate the vacuum furnace to 3×10 -4 The composite material was then removed and the protruding portion of the reinforcement and the portion of the low-melting-point metal matrix material below the reinforcement were removed. The composite material was then surface polished and heat treated at 200°C for 1 hour to further improve its performance.

[0044] Example 6:

[0045] In this embodiment, firstly, a low melting point metal matrix material (zinc-based alloy, Ca 10-x Zn x (PO4)6(OH)2) is drilled in the z direction with a hole diameter of 3mm and a depth of 10mm. The size of the matrix material is 10mm in diameter and 20mm in height. Subsequently, a tantalum rod reinforcement is prepared by mechanical processing. The tantalum rod is polished to a size that matches the hole in the matrix, that is, 3mm in diameter and 20mm in length. The reinforcement is inserted into the hole in the matrix to ensure that it fits tightly with the matrix. The gap after insertion is between 0.01mm and 0.05mm. The reinforcement is connected to the cathode as an internal heating source, and a cylindrical target is set around the matrix to connect the source as an external heating source. Turn on the plasma sintering equipment, use a mechanical pump to pump the sintering furnace pressure to 3Pa, and then use a molecular pump to further pump the furnace pressure to 5×10 -4 Pa, so that the furnace is maintained in a high vacuum state. Fill the furnace with argon to 30Pa, and re-evacuate to the ultimate vacuum to expel the air in the furnace. Afterwards, by adjusting the heating power of the cathode and the cylindrical target, the internal and external synchronous heating of the reinforcement and the matrix is ​​achieved. The source voltage is set to 600V, the duty cycle is 60%, and the cathode voltage is less than the source voltage by 200V, and the duty cycle is 60%. The heating temperature is 400℃, and the heating time is 1 hour. Under the action of internal and external synchronous heating, mutual diffusion occurs between the reinforcement and the matrix, and at the same time, the matrix material undergoes homogenized secondary sintering at high temperature to form a dense composite material. The density of the sintered composite material reaches more than 98%. After sintering is completed, turn off the source power supply, cathode power supply and gas source in turn, and then evacuate the vacuum furnace to 3×10-4 The composite material was then removed and the protruding portion of the reinforcement and the portion of the low-melting-point metal matrix material below the reinforcement were removed. The composite material was then surface polished and heat treated at 200°C for 1 hour to further improve its performance.

[0046] Performance test case

[0047] The mechanical properties of the pure zinc rod and the composite materials prepared in Example 1 and Example 2 were tested. The test results are as follows: Figure 4 shown.

[0048] from Figure 4 In a, it can be seen that when the strain is ≤8%, the stress of the pure Zn rod (pure Zn in the figure) is always the largest; when 8%<strain<24%, the stress of the composite material (5mmFe in the figure) prepared by using the 5mm diameter Fe rod as the reinforcement in Example 2 is the largest, followed by the stress of the pure Zn rod; when the strain is ≥24%, the stress of the 5mm diameter Fe rod is still the largest, but the stress of the composite material (3mmFe in the figure) prepared by using the 3mm diameter Fe rod as the reinforcement in Example 1 is second.

[0049] from Figure 4 As can be seen from Figure 2, as the diameter of the iron rod used to reinforce the composite increases, the elastic modulus and compressive strength of the composite also increase. When the diameter of the iron rod in the sample is 5 mm, that is, when the reinforcement is made of 5 mm diameter iron rods, the composite material obtained has an elastic modulus of 3866 MPa and a compressive strength of 390 MPa.

[0050] It can be seen that the mechanical properties of the composite materials prepared by the method of the present invention are improved.

[0051] Comparative Example 1:

[0052] In this embodiment, a hole is first punched in the z direction in a low-melting-point metal matrix material (pure zinc is used in this embodiment) with a hole diameter of 5 mm and a depth of 12 mm. The dimensions of the matrix material are 15 mm in diameter and 25 mm in height. Subsequently, an iron rod reinforcement is prepared by a mechanical processing method. The iron rod is polished to a size that matches the matrix hole, that is, a diameter of 5 mm and a length of 20 mm. The reinforcement is inserted into the matrix hole to ensure a close fit with the matrix, and the gap after insertion is between 0.01 mm and 0.05 mm. A cylindrical target is set around the matrix as an external heating source. Turn on the plasma sintering equipment, use a mechanical pump to pump the sintering furnace body pressure to 4 Pa, and then use a molecular pump to further pump the furnace body pressure to 5×10 -4Pa, so that the furnace is kept in a high vacuum state. Fill the furnace with argon to 35Pa, and then pump it back to the ultimate vacuum to expel the air in the furnace. After that, the external heating of the reinforcement and the matrix is ​​achieved by adjusting the heating power of the cylindrical target. The source voltage is set to 700V and the duty cycle is 70%. Under the action of external heating, mutual diffusion occurs between the reinforcement and the matrix, and at the same time, the matrix material undergoes secondary sintering at high temperature to form a composite material, such as Figure 5 After sintering is completed, turn off the source power supply and gas source in turn, and then evacuate the vacuum furnace to 4×10 -4 After the composite material is removed, the protruding portion of the reinforcement and the portion of the low-melting-point metal matrix material not inserted into the reinforcement are removed, and the composite material is surface polished and heat-treated at 250°C for 2 hours.

[0053] contrast Figure 3 and Figure 5 It can be seen that the use of the internal and external synchronous heating method of the present invention to prepare composite materials can significantly improve the interface bonding uniformity between the reinforcement and the matrix material and improve the interface bonding strength.

Claims

1. A method for strengthening a low-melting-point metal matrix, characterized in that: The strengthening method comprises placing a reinforcement in a hole adapted to the center of a low-melting-point metal matrix material, connecting the internal reinforcement to a cathode, and applying a voltage externally between the reinforcement and the low-melting-point metal matrix material to generate a hollow cathode glow discharge effect for internal heating; simultaneously, a cylindrical target is arranged on the periphery of the low-melting-point metal matrix material, connected to a source electrode, and placed in a plasma sintering device for external heating; by simultaneously performing the internal and external heating, a dense composite material is generated; the low-melting-point metal matrix material is zinc or a zinc-based alloy.

2. The method for strengthening a low-melting-point metal matrix according to claim 1, wherein: The strengthening method comprises the following steps: (1) drilling a hole in the low-melting-point metal matrix material along the height direction, and grinding the reinforcement according to the hole size so that the reinforcement fits the hole; then inserting the reinforcement into the hole; (2) connecting the reinforcement to the cathode as an internal heating source, and setting a cylindrical target around the substrate and connecting it to the source as an external heating source; and placing the low-melting-point metal substrate material, the reinforcement and the cylindrical target as a whole in a plasma sintering furnace; (3) Turn on the plasma sintering furnace and its matching cold water pump, use a mechanical pump to pump the plasma sintering furnace body pressure to 2-5 Pa, and then use a molecular pump to further pump the furnace body pressure to 4×10 -4 ~6×10 -4 Pa, to keep the furnace in high vacuum state; (4) Fill the furnace with argon and then pump it back to the ultimate vacuum to expel the air in the furnace; (5) By adjusting the heating power of the cathode and the cylindrical target, the internal and external synchronous heating of the reinforcement and the low-melting-point metal matrix material is achieved; (6) Under the action of internal and external synchronous heating, mutual diffusion occurs between the reinforcement and the matrix, and at the same time, the matrix material undergoes homogenized secondary sintering at high temperature to form a dense composite material; (7) Turn off the source power supply, cathode power supply and gas source in sequence, and then evacuate the vacuum furnace to 2×10 -4 ~5×10 -4 Pa vacuum degree, cooled to room temperature and taken out, thus obtaining a composite material in which a low-melting-point metal matrix material and a reinforcement body diffuse with each other.

3. The method for strengthening a low-melting-point metal matrix according to claim 2, wherein: The reinforcement is made of iron, titanium or tantalum.

4. The method for strengthening a low-melting-point metal matrix according to claim 2, wherein: The low melting point metal matrix material is zinc; the reinforcement is an iron rod.

5. The method for strengthening a low-melting-point metal matrix according to claim 2 or 3, characterized in that: The heating temperature of the internal and external synchronous heating in step (5) is 400-700°C, and the heating time is 1-4 hours. The implementation method is as follows: adjust the source voltage to 400-800V, the duty cycle to 40%-80%, and control the cathode voltage to 100-400V, the duty cycle to 40%-80%.

6. The method for strengthening a low-melting-point metal matrix according to claim 5, wherein: The low-melting-point metal matrix material is a zinc rod with a diameter of 5mm to 20mm; the reinforcement is an iron rod with a diameter of 1mm to 8mm; the size of the middle hole of the low-melting-point metal matrix material is set so that the gap between the reinforcement and the low-melting-point metal matrix material is controlled to be 0.01mm to 0.05mm after insertion.

7. The method for strengthening a low-melting-point metal matrix according to claim 6, wherein: In the step (4), argon gas is filled into the furnace to 25-35 Pa, and the vacuum is re-evacuated to the ultimate vacuum degree, and this is repeated 2-3 times to exhaust the air in the furnace as much as possible.

8. The method for strengthening a low-melting-point metal matrix according to claim 2 or 3, characterized in that: The strengthening method further comprises the following steps: (8) The cooled composite material is surface polished and heat treated.

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