Method for connecting titanium aluminum carbide and niobium by using high-entropy alloy intermediate layer and connecting joint

Abstract

The invention provides a method for connecting titanium aluminum carbide and niobium through a high-entropy alloy interlayer and a connector, and relates to the technical field of welding. The method comprises the steps that S1, a to-be-connected assembly is prepared; the assembly to be connected is formed by sequentially stacking a titanium aluminum carbide base material, a middle layer and a niobium base material from top to bottom, the middle layer is made of high-entropy alloy, and the high-entropy alloy is composed of Ti, Zr, Hf, V, Nb and Ta according to the molar ratio of 1: 1: 1: 1: 1: 1; and S2, the to-be-connected assembly is subjected to spark plasma sintering under preset air pressure, and the connection joint is obtained. By the adoption of the method, joint cracking can be inhibited, generation of brittle intermetallic compounds can be avoided, the interface bonding strength can be improved, and therefore the strength of the connecting joint is improved.

Description

Technical Field

[0001] The present invention relates to the field of welding technology, and in particular to a method for connecting titanium aluminum carbide and niobium using a high entropy alloy intermediate layer and a connection joint. Background Art

[0002] As the core of an aircraft, the thrust-to-weight ratio of an aircraft engine directly determines its performance. To improve the thrust-to-weight ratio, weight reduction becomes the key, and the use of lightweight, high-strength, and high-temperature resistant materials is the path to achieve this. Nb is widely used in aircraft engines due to its excellent high-temperature strength, but its high density (8.6g / cm 3 ) has limited performance improvement. Titanium aluminum carbide (Ti3AlC2) is a MAX phase material that combines the advantages of metal and ceramics. It has a low density (4.2g / cm 3 ) has good oxidation resistance and is considered an ideal candidate for the next generation of hot end components. However, its brittleness limits its engineering applications.

[0003] Connecting titanium carbide aluminum and niobium can combine the advantages of both and is the key to achieving high-performance integrated components. However, this connection technology faces the following problems: (1) The metallurgical compatibility between the two is poor, and brittle Nb-Al intermetallic compounds are easily generated, resulting in low strength of the joint; (2) The thermal expansion mismatch between the two leads to large residual stress in the joint, which easily causes cracking of the joint. Summary of the Invention

[0004] The problem to be solved by the present invention is that the following problems exist during the connection process between titanium carbide aluminum ceramics and niobium: (1) the metallurgical compatibility between the two is poor, and brittle Nb-Al intermetallic compounds are easily generated, resulting in low strength of the joint; (2) the thermal expansion mismatch between the two leads to large residual stress in the joint, which easily causes cracking of the joint.

[0005] To solve the above problems, the present invention provides a method for connecting titanium aluminum carbide and niobium using a high entropy alloy intermediate layer, comprising:

[0006] Step S1, preparing a component to be connected; the component to be connected is formed by stacking a titanium carbide aluminum base material, an intermediate layer, and a niobium base material in sequence from top to bottom, wherein the intermediate layer is made of a high entropy alloy, and the high entropy alloy is composed of Ti, Zr, Hf, V, Nb, and Ta in a molar ratio of 1:1:1:1:1:1;

[0007] Step S2: performing spark plasma sintering on the components to be connected under a preset pressure to obtain a connection joint.

[0008] Optionally, in step S2, the spark plasma sintering is performed at a temperature of 900° C. to 1300° C., a pressure of 10 MPa to 40 MPa, and a time of 5 min to 30 min.

[0009] Optionally, in step S2, the preset air pressure is lower than 0.001 Pa.

[0010] Optionally, the spark plasma sintering is performed at a temperature of 1200° C., a pressure of 20 MPa, and a time of 20 min.

[0011] Optionally, in step S1 , the thickness of the intermediate layer is 100 μm to 300 μm.

[0012] Optionally, in step S1, the thickness of the titanium carbide aluminum base material is 2 mm to 4 mm.

[0013] Optionally, in step S1, the thickness of the niobium base material is 2 mm to 4 mm.

[0014] Optionally, in step S1, the niobium base material is made of pure niobium.

[0015] Optionally, in step S2, the spark plasma sintering is performed in a spark plasma sintering furnace.

[0016] The present invention also provides a connecting joint, which is made by the above-mentioned method of connecting titanium carbide aluminum and niobium using a high entropy alloy intermediate layer.

[0017] Compared with the related art, the present invention utilizes a Ti-Zr-Hf-V-Nb-Ta high entropy alloy intermediate layer to connect titanium aluminum carbide and niobium. The high entropy effect of the Ti-Zr-Hf-V-Nb-Ta high entropy alloy helps to form a solid solution or refine the eutectic structure, avoiding the formation of brittle intermetallic compounds (such as Nb3Al, Nb2Al), so that the connection joint has higher strength; due to the delayed diffusion effect, the atomic diffusion rate in the high entropy alloy is reduced, which can inhibit the non-uniform diffusion inside the weld and reduce the precipitation of brittle phases, so that the connection joint has higher strength. In addition, the lattice distortion effect and the cocktail effect also give the connection joint high strength and high temperature resistance, so that the connection joint has better high temperature mechanical properties and oxidation resistance. In addition, the present invention adopts a spark plasma sintering method to achieve the connection of the components to be connected. During the connection process, the discharge plasma is excited by a pulse current to reduce the atomic diffusion free energy, increase the diffusion rate, and realize a short, low-temperature welding process. Since the current is concentrated at the welding interface, the welding area can be locally heated, avoiding deformation and residual stress caused by large-area heating of the parent material, and suppressing joint cracking. In addition, the electromigration effect in the spark plasma sintering process accelerates the diffusion of interface atoms, which is beneficial to improving the welding quality, thereby forming a connection joint with higher strength. In summary, the method of the present invention can not only suppress joint cracking, but also avoid the formation of brittle intermetallic compounds, help to improve the interface bonding strength, thereby improving the strength of the connection joint. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 Schematic diagram of a method for connecting titanium carbide aluminum and niobium using a high entropy alloy intermediate layer in an embodiment of the present invention;

[0019] Figure 2 This is one of the scanning electron microscope images of the connection joint prepared in Example 1;

[0020] Figure 3 This is the second scanning electron microscope image of the connection joint prepared in Example 1;

[0021] Figure 4 This is a scanning electron microscope image of the connection joint prepared in Comparative Example 1;

[0022] Figure 5 This is a scanning electron microscope image of the connection joint prepared in Comparative Example 2. DETAILED DESCRIPTION

[0023] To make the above-mentioned objects, features, and advantages of the present invention more clearly understood, specific embodiments of the present invention are described in detail below with reference to the accompanying drawings. Although certain embodiments of the present invention are shown in the accompanying drawings, it should be understood that the present invention can be implemented in various forms and should not be construed as being limited to the embodiments described herein. Instead, these embodiments are provided to provide a more thorough and complete understanding of the present invention. It should be understood that the drawings and embodiments of the present invention are for illustrative purposes only and are not intended to limit the scope of protection of the present invention.

[0024] Unless otherwise defined, all technical and scientific terms used in the present invention have the same meaning as those commonly understood by those skilled in the art of the present invention. The terms used in the specification are only for the purpose of describing specific embodiments and are not intended to limit the present invention.

[0025] The term "including" and its variations used in this document are open inclusions, that is, "including but not limited to"; the term "based on" means "at least partially based on"; the term "one embodiment" means "at least one embodiment"; the term "another embodiment" means "at least one other embodiment"; the term "some embodiments" means "at least some embodiments"; the term "optionally" means "optional embodiments". The relevant definitions of other terms will be given in the following description. It should be noted that the concepts of "first" and "second" mentioned in the present invention are used to distinguish different objects, rather than to describe a specific order or a primary and secondary relationship. In addition, the terms "first" and "second" are used for descriptive purposes only and cannot be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Therefore, the features defined as "first" and "second" may explicitly or implicitly include one or more of the features. In the description of the present invention, unless otherwise specified, "multiple" means two or more.

[0026] like Figure 1 As shown, an embodiment of the present invention provides a method for connecting titanium aluminum carbide and niobium using a high entropy alloy intermediate layer, comprising:

[0027] Step S1, preparing a component to be connected; the component to be connected is formed by stacking a titanium carbide aluminum base material, an intermediate layer, and a niobium base material in sequence from top to bottom, wherein the intermediate layer is made of a high entropy alloy, and the high entropy alloy is composed of Ti, Zr, Hf, V, Nb, and Ta in a molar ratio of 1:1:1:1:1:1;

[0028] Step S2: performing spark plasma sintering on the components to be connected under a preset pressure to obtain a connection joint.

[0029] The embodiment of the present invention utilizes a Ti-Zr-Hf-V-Nb-Ta high-entropy alloy intermediate layer to connect titanium carbide and niobium. The high entropy effect of the Ti-Zr-Hf-V-Nb-Ta high-entropy alloy helps to form a solid solution or refine the eutectic structure, avoiding the formation of brittle intermetallic compounds (such as Nb3Al and Nb2Al), resulting in a higher strength joint. Due to the delayed diffusion effect, the atomic diffusion rate in the high-entropy alloy is reduced, which can inhibit the non-uniform diffusion within the weld and reduce the precipitation of brittle phases, resulting in a higher strength joint. In addition, the lattice distortion effect and the cocktail effect also give the joint high strength and high temperature resistance, so that the joint has excellent high-temperature mechanical properties and oxidation resistance. In addition, the present invention uses spark plasma sintering to achieve the connection of the components to be connected. During the connection process, a pulsed current is used to excite the discharge plasma, reducing the atomic diffusion free energy, increasing the diffusion rate, and achieving a short, low-temperature welding process. Because the current is concentrated at the welding interface, the welding area can be locally heated, avoiding deformation and residual stress caused by large-area heating of the parent material, and can inhibit joint cracking. In addition, the electromigration effect during spark plasma sintering accelerates interfacial atomic diffusion, which helps improve welding quality and thus form a stronger joint. In summary, the method of the embodiment of the present invention can not only suppress joint cracking, but also avoid the formation of brittle intermetallic compounds, which helps to improve the interfacial bonding strength, thereby improving the strength of the joint.

[0030] In some embodiments of the present invention, in step S2, the spark plasma sintering is performed at a temperature of 900°C to 1300°C, a pressure of 10 MPa to 40 MPa, and a time of 5 to 30 minutes; and the preset gas pressure is lower than 0.001 Pa. Preferably, the spark plasma sintering is performed at a temperature of 1200°C, a pressure of 20 MPa, and a time of 20 minutes.

[0031] In some embodiments of the present invention, in step S1, the thickness of the intermediate layer is 100 μm to 300 μm, the thickness of the titanium aluminum carbide parent material is 2 mm to 4 mm, the thickness of the niobium parent material is 2 mm to 4 mm, and the niobium parent material is made of pure niobium.

[0032] In some embodiments of the present invention, in step S2, the spark plasma sintering is performed in a spark plasma sintering furnace.

[0033] An embodiment of the present invention further provides a connecting joint, which is manufactured by the above-mentioned method of connecting titanium carbide aluminum and niobium using a high entropy alloy intermediate layer.

[0034] The present invention is further described below with reference to specific embodiments.

[0035] Example 1

[0036] A1. Prepare the components to be connected; the components to be connected are composed of a titanium carbide aluminum base material, an intermediate layer, and a niobium base material stacked in sequence from top to bottom, the intermediate layer is made of a high-entropy alloy, and the high-entropy alloy is composed of Ti, Zr, Hf, V, Nb, and Ta in a molar ratio of 1:1:1:1:1:1; the thickness of the intermediate layer is 200 μm, the thickness of the titanium carbide aluminum base material is 3 mm, the thickness of the niobium base material is 3 mm, and the niobium base material is made of pure niobium.

[0037] A2. Spark plasma sintering the components to be connected under a preset gas pressure to obtain a connection joint; wherein the preset gas pressure is 0.0005 Pa, the spark plasma sintering temperature is 1200° C., the pressure is 20 MPa, and the time is 20 min.

[0038] Example 2

[0039] A1. Prepare the components to be connected; the components to be connected are composed of a titanium carbide aluminum base material, an intermediate layer, and a niobium base material stacked in sequence from top to bottom, the intermediate layer is made of a high-entropy alloy, and the high-entropy alloy is composed of Ti, Zr, Hf, V, Nb, and Ta in a molar ratio of 1:1:1:1:1:1; the thickness of the intermediate layer is 100 μm, the thickness of the titanium carbide aluminum base material is 2 mm, the thickness of the niobium base material is 2 mm, and the niobium base material is made of pure niobium.

[0040] A2. Perform spark plasma sintering on the components to be connected under a preset gas pressure to obtain a connection joint; wherein the preset gas pressure is 0.0005 Pa, the spark plasma sintering temperature is 900° C., the pressure is 40 MPa, and the time is 30 min.

[0041] Example 3

[0042] A1. Prepare the components to be connected; the components to be connected are composed of a titanium carbide aluminum base material, an intermediate layer, and a niobium base material stacked in sequence from top to bottom, the intermediate layer is made of a high-entropy alloy, and the high-entropy alloy is composed of Ti, Zr, Hf, V, Nb, and Ta in a molar ratio of 1:1:1:1:1:1; the thickness of the intermediate layer is 300 μm, the thickness of the titanium carbide aluminum base material is 4 mm, the thickness of the niobium base material is 4 mm, and the niobium base material is made of pure niobium.

[0043] A2. Spark plasma sintering the components to be connected under a preset gas pressure to obtain a connection joint; wherein the preset gas pressure is 0.0005 Pa, the spark plasma sintering temperature is 1300° C., the pressure is 10 MPa, and the time is 5 min.

[0044] Comparative Example 1

[0045] The difference from Example 1 is that step A2 is: in an ordinary heating diffusion furnace, the components to be connected are subjected to high-temperature diffusion welding under a preset air pressure to obtain a connecting joint; the preset air pressure is 0.006 Pa, the temperature of the high-temperature diffusion welding is 1200°C, the pressure is 20 MPa, and the time is 20 minutes.

[0046] Comparative Example 2

[0047] The difference from Example 1 is that in step A1, the material of the intermediate layer is Nb.

[0048] Experimental example

[0049] The connection joints prepared in Example 1 and Comparative Examples 1 to 2 were analyzed by scanning electron microscopy. Figures 2 to 5 ,from Figure 2 and Figure 3 It can be seen that a joint with good metallurgical bonding is obtained in Example 1 without cracks. The connection joint prepared in Example 1 contains only high entropy carbides and high entropy alloys, and has good high temperature mechanical properties and oxidation resistance. Figure 4 It can be seen that no joint with good metallurgical bonding was obtained in Comparative Example 1. Cracks existed between the high entropy intermediate layer and the Ti3AlC2 ceramic and Nb metal in the joint prepared in Comparative Example 1. Figure 5 It can be seen that a joint with good metallurgical bonding was not obtained in Comparative Example 2, and obvious cracks were present in the joint. The room temperature shear strength and high temperature shear strength (at 1000°C) test results of the joints prepared in Examples 1 to 3 and Comparative Examples 1 to 2 are shown in Table 1. As can be seen from Table 1, compared with Comparative Examples 1 to 3, the joints prepared in Examples 1 to 3 have higher room temperature shear strength and higher high temperature shear strength.

[0050] Table 1

[0051]

[0052]

[0053] It should be noted that obvious cracks existed in the connection joints prepared in Comparative Examples 1 and 2, resulting in low strength of the connection joints and failure to perform testing. In Table 1, the connection joints marked with a "-" have low strength and cannot be measured.

[0054] Although the present invention is disclosed as above, the protection scope of the present invention is not limited thereto. Those skilled in the art may make various changes and modifications without departing from the spirit and scope of the present invention, and these changes and modifications will fall within the protection scope of the present invention.

Claims

1. A method for connecting titanium aluminum carbide and niobium using a high entropy alloy intermediate layer, characterized in that: include: Step S1, preparing a component to be connected; the component to be connected is formed by stacking a titanium carbide aluminum base material, an intermediate layer, and a niobium base material in sequence from top to bottom, wherein the intermediate layer is made of a high entropy alloy, and the high entropy alloy is composed of Ti, Zr, Hf, V, Nb, and Ta in a molar ratio of 1:1:1:1:1:1; Step S2: performing spark plasma sintering on the components to be connected under a preset pressure to obtain a connection joint.

2. The method for connecting titanium carbide and niobium using a high entropy alloy intermediate layer according to claim 1, characterized in that: In step S2, the spark plasma sintering is performed at a temperature of 900° C. to 1300° C., a pressure of 10 MPa to 40 MPa, and a time of 5 min to 30 min.

3. The method for connecting titanium aluminum carbide and niobium using a high entropy alloy intermediate layer according to claim 1, characterized in that: In step S2, the preset air pressure is lower than 0.001 Pa.

4. The method for connecting titanium aluminum carbide and niobium using a high entropy alloy intermediate layer according to claim 2, characterized in that: The spark plasma sintering temperature is 1200° C., the pressure is 20 MPa, and the time is 20 min.

5. The method for connecting titanium aluminum carbide and niobium using a high entropy alloy intermediate layer according to claim 1, characterized in that: In the step S1 , the thickness of the intermediate layer is 100 μm to 300 μm.

6. The method for connecting titanium aluminum carbide and niobium using a high entropy alloy intermediate layer according to claim 1, characterized in that: In the step S1, the thickness of the titanium carbide aluminum base material is 2 mm to 4 mm.

7. The method for connecting titanium aluminum carbide and niobium using a high entropy alloy intermediate layer according to claim 1, characterized in that: In the step S1, the thickness of the niobium base material is 2 mm to 4 mm.

8. The method for connecting titanium aluminum carbide and niobium using a high entropy alloy intermediate layer according to claim 1, characterized in that: In the step S1, the niobium base material is made of pure niobium.

9. The method for connecting titanium aluminum carbide and niobium using a high entropy alloy intermediate layer according to claim 1, characterized in that: In the step S2, the spark plasma sintering is performed in a spark plasma sintering furnace.

10. A connecting joint, characterized in that: The method of connecting titanium carbide, aluminum carbide and niobium using a high entropy alloy intermediate layer as described in any one of claims 1 to 9 is adopted.

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