A method for diffusion bonding of dissimilar titanium alloys based on a high-entropy alloy interlayer

Abstract

The present invention provides a method for diffusion bonding heterogeneous titanium alloys based on a high-entropy alloy interlayer, which relates to the technical field of heterogeneous titanium alloy bonding. The method comprises the following steps: Step 1: subjecting a high-entropy alloy ingot to rolling and machining treatments to obtain high-entropy alloy foils; wherein, the high-entropy alloy ingot is composed of elements with the following atomic percentages: Ti-15Co-15Fe-15Mo-10Cr-10Ni-15Zr-5Y; Step 2: stacking a Ti150 alloy base material, a high-entropy alloy foil and a Ti180 alloy base material in sequence, with the high-entropy alloy foil positioned between the Ti150 alloy base material and the Ti180 alloy base material, to obtain a heterogeneous alloy combination; Step 3: subjecting the heterogeneous alloy combination to vacuum diffusion welding treatment to obtain a heterogeneous alloy diffusion welded joint. The present invention realizes the strengthening and toughening of the heterogeneous titanium alloy diffusion welded joint by using a self-designed Ti-based high-entropy alloy interlayer, and connects the heterogeneous titanium alloys by using the Ti-based high-entropy alloy interlayer, thereby obtaining a diffusion welded joint with high strength and toughness.

Description

Technical Field

[0001] The present invention relates to the technical field of dissimilar titanium alloy joining, and particularly relates to a method for diffusion bonding dissimilar titanium alloys based on a high-entropy alloy interlayer. Background Art

[0002] As a material for aeroengines, it must possess excellent high-temperature properties. Titanium alloy is a lightweight material with low density, high strength, and high temperature resistance. Therefore, titanium alloy has become the preferred material for aeroengines, which can effectively reduce the self-weight of aeroengines and thus improve the thrust-to-weight ratio. With the evolution of aero power systems towards higher thrust-to-weight ratios, the engineering application of the integral blisk technology has put forward multi-dimensional performance requirements for the titanium alloy material system. Research shows that under the coupled working conditions of high temperature and high stress, the degradation of the mechanical properties of traditional titanium alloys has become a key factor restricting the service reliability of compressor components. The new generation of blisk components not only need to have excellent thermal strength matching, but also require the material to maintain stable creep resistance and oxidation resistance within a wide temperature range. The Ti150 alloy exhibits significantly better comprehensive high-temperature performance than traditional titanium alloys through multi-component alloying design. Its strengthening mechanism stems from: 1) the substructure strengthening network formed by β-phase stabilizing elements; 2) the interface strengthening effect generated by the interaction between nano-precipitates and dislocations; 3) the improvement of environmental resistance brought by the self-healing characteristics of the surface oxide layer. Microstructural characterization shows that the gradient microstructure formed during the thermal exposure process of this alloy can effectively coordinate the stress distribution under thermo-mechanical loads. It is worth noting that the Ti150 alloy components prepared based on additive manufacturing technology exhibit typical epitaxial growth columnar crystal characteristics, and this anisotropic tissue configuration significantly improves the thermal shock resistance of blisk components. With the continuous optimization of thermo-mechanical processing technology, the application potential of this material system in the hot-end components of advanced aeroengines is gradually being verified by engineering. Currently, the joining methods for dissimilar titanium alloys mainly include welding methods such as inert gas welding, electron beam welding, and friction welding. However, for traditional fusion welding methods, defects such as cracks, oxidation, and non-uniform microstructure will be generated during the welding process. Using diffusion welding can effectively reduce the thermal stress of the joint and has little influence on the joint microstructure.

[0003] In current reports on heterogeneous titanium alloys, some researchers have carried out electron beam welding on TiAl / TC4 heterogeneous titanium alloys, but the generation of Al-phase structure during welding results in joint fracture along the fusion line. There are also researchers who have studied the diffusion bonding of Ti-43Al-9V / TC4. Although good joints can be obtained under the conditions of 920 °C / 45 MPa / 2 h, brittle α-Ti3Al phase is generated during the diffusion process of the two alloys. In the diffusion welding of heterogeneous titanium alloys, the use of traditional metal interlayers, such as pure copper, pure nickel, and aluminum-based alloys, is prone to the formation of intermetallic compounds. These products will lead to a decrease in the toughness of the joint and become the path for crack initiation and propagation. At the same time, it may also cause element segregation, further leading to weakening of the interface bonding. Summary of the Invention

[0004] Aiming at the problem of the easy formation of intermetallic compounds when using traditional metal interlayers in the diffusion welding of heterogeneous titanium alloys mentioned in the above background technology, the present invention proposes a method for diffusion bonding heterogeneous titanium alloys based on a high-entropy alloy interlayer. By using a high-entropy alloy interlayer to connect heterogeneous titanium alloys, a diffusion welded joint with high strength and toughness is obtained.

[0005] To achieve the above object, the present invention adopts the following technical solutions:

[0006] The present invention provides a method for diffusion bonding heterogeneous titanium alloys based on a high-entropy alloy interlayer, including the following steps:

[0007] Step 1: Rolling and machining a high-entropy alloy ingot to obtain a high-entropy alloy foil; wherein, the high-entropy alloy ingot is composed of elements with the following atomic percentages: Ti-15Co-15Fe-15Mo-10Cr-10Ni-15Zr-5Y;

[0008] Step 2: Stacking a Ti150 alloy (the Ti150 alloy is composed of elements with the following atomic percentages: 85.36Ti-5.62Al-3.8Sn-3.6Zr-0.7Nb-0.49Mo-0.37Si-0.06C) base material, the high-entropy alloy foil, and a Ti180 alloy (the Ti180 alloy is composed of elements with the following atomic percentages: 81.77Ti-6.09Al-2.05Sn-3.94Zr-6.15Mo) base material in sequence, so that the high-entropy alloy foil is located between the Ti150 alloy base material and the Ti180 alloy base material to obtain a heterogeneous alloy combination;

[0009] Step 3: Performing vacuum diffusion welding treatment on the heterogeneous alloy combination to obtain a heterogeneous alloy diffusion welded joint.

[0010] As a further illustration of the present invention, the high-entropy alloy ingot is prepared by arc melting.

[0011] As a further illustration of the present invention, in Step 1, before rolling the high-entropy alloy ingot, the high-entropy alloy ingot needs to be cut and surface-treated.

[0012] As a further illustration of the present invention, in Step 1, the rolling treatment of the high-entropy alloy ingot is specifically as follows: the high-entropy alloy ingot is subjected to multiple cold rolling treatments to obtain a foil with a thickness of 0.1 mm - 0.2 mm.

[0013] As a further illustration of the present invention, in Step 1, the machining treatment is specifically as follows: the rolled foil is cut into segments and ground to a thickness of 100 μm - 130 μm, and then the foil is polished, cleaned, and dried in sequence to obtain a high-entropy alloy foil.

[0014] As a further illustration of the present invention, before Step 2, the method further includes cutting, grinding and polishing, cleaning, and drying the Ti150 alloy base material and the Ti180 alloy base material in sequence.

[0015] As a further illustration of the present invention, in Step 3, the vacuum diffusion welding treatment is carried out in a vacuum diffusion furnace.

[0016] As a further illustration of the present invention, in Step 3, the welding process conditions of the vacuum diffusion welding treatment are specifically as follows: the first stage: heating from room temperature to 300 °C at a heating rate of 10 °C / min and holding at 300 °C for 10 min; the second stage: heating from 300 °C to 600 °C at a heating rate of 10 °C / min and holding at 600 °C for 10 min; the third stage: heating from 600 °C to 800 °C at a heating rate of 10 °C / min and holding at 800 °C for 10 min; the fourth stage: heating from 800 °C to the welding target temperature of 820 °C - 910 °C at a heating rate of 10 °C / min, and the heating ends; the fifth stage: holding at the welding target temperature for 1 h while applying a pressure of 5 MPa - 10 MPa; after the holding ends, the sample is cooled to room temperature with the furnace and the pressure returns to zero, and the welding is completed.

[0017] Compared with the prior art, the present invention has the following beneficial technical effects:

[0018] The present invention realizes the strengthening and toughening of the dissimilar titanium alloy diffusion welded joint by using a self-designed Ti-based high-entropy alloy interlayer. The dissimilar titanium alloys are connected by using the Ti-based high-entropy alloy interlayer, thereby obtaining a diffusion welded joint with high strength and toughness.

[0019] The present invention adopts a diffusion welding connection method, and successfully connects heterogeneous titanium alloys by using a high-entropy intermediate layer. Moreover, the obtained weld seam is defect-free, realizing high-quality diffusion connection of heterogeneous titanium alloys.

[0020] Other features and advantages of this technical solution will be described in the subsequent specification. Moreover, some of them will become obvious from the specification, or be understood by implementing this technical solution. The objectives and other advantages of this technical solution can be achieved and obtained through the structures specifically pointed out in the written specification and the drawings.

[0021] The following further describes the technical solution of this technical solution in detail through the drawings and embodiments. Description of the Drawings

[0022] The drawings are used to provide a further understanding of this technical solution, and constitute a part of the specification. Together with the embodiments of this technical solution, they are used to explain this technical solution and do not constitute a limitation to this technical solution. In the drawings:

[0023] Figure 1 is the scanning electron microscope morphology diagram of the Ti150-high-entropy alloy intermediate layer-Ti180 diffusion welding joint obtained in Embodiment 1 of the present invention.

[0024] Figure 2 is the scanning electron microscope morphology diagram of the Ti150-conventional high-entropy alloy intermediate layer-Ti180 diffusion welding joint obtained in Comparative Example 1 of the present invention.

[0025] Figure 3 is the scanning electron microscope morphology diagram of the Ti150-conventional high-entropy alloy intermediate layer-Ti180 diffusion welding joint obtained in Comparative Example 2 of the present invention.

[0026] Figure 4 is the fracture morphology diagram of the Ti150-high-entropy alloy intermediate layer-Ti180 diffusion welding joint obtained in Embodiment 1 of the present invention. Detailed Embodiments

[0027] The following describes the preferred embodiments of this technical solution in conjunction with the drawings. It should be understood that the preferred embodiments described herein are only used to illustrate and explain this technical solution and are not used to limit this technical solution.

[0028] The present invention provides a method for diffusion connecting heterogeneous titanium alloys based on a high-entropy alloy intermediate layer, including the following steps:

[0029] Step 1: Roll and mechanically process a high-entropy alloy ingot to obtain a high-entropy alloy foil; wherein, the high-entropy alloy ingot is composed of elements with the following atomic percentages: Ti-15Co-15Fe-15Mo-10Cr-10Ni-15Zr-5Y.

[0030] The element design principles of the high-entropy alloy interlayer in the present invention are as follows: To solve the defects such as cracks, oxidation, and non-uniform microstructure caused by existing welding technologies. The present invention designs the high-entropy alloy elements and their specific atomic percentages as above, and realizes the high reaction energy release characteristics of the material through the synergistic effect of highly active components. The single-phase solid solution structure characteristics and weak metal bonding characteristics of the above high-entropy alloy system enable the lattice atoms to easily undergo de-embedding movement during high-speed impact, quickly releasing energy. Specifically, since Ti is the main element of the base material, the high-entropy alloy designed in the present invention is a Ti-based high-entropy alloy, and the Ti element therein can ensure the crystal structure compatibility between the interlayer and the base material, reducing the interfacial lattice misfit. Ti atoms preferentially migrate along the grain boundaries of the base material during high-temperature diffusion welding to form a defect-free transition layer; the strong β-stabilizing elements Mo, Cr, Fe, Co, and Ni in the high-entropy alloy form a dynamic balance with the α-stabilizing elements such as Al, Sn, and Zr in the base material, and their mutual diffusion with Ti preferentially occupies the β-Ti lattice sites; the introduction of Mo and Cr in the high-entropy alloy further reduces the eutectoid transformation temperature of the β phase. At the same time, Mo is an element with a high melting point, and its slow diffusion characteristics combined with the "hysteresis effect" of the high-entropy alloy significantly reduce the interfacial segregation rate of light elements such as Al and Sn, thereby improving the plastic deformation ability of the joint. Zr in the high-entropy alloy forms a continuous solid solution with the corresponding elements in the base material, reducing the grain boundary energy and inhibiting element segregation. The unique lattice distortion effect of the high-entropy alloy, through the elastic strain field introduced by elements with large atomic radii such as Mo, and the solid solution strengthening of Zr, synergistically improve the strength while maintaining good coordinated deformation ability. This "high strength - moderate toughness" matching characteristic effectively inhibits crack initiation. Fe and Co in the high-entropy alloy promote the decomposition of dislocations into partial dislocations with higher mobility by reducing the stacking fault energy of the matrix, delaying strain localization; while the solid solution atoms of Mo and Cr, as strong pinning points, hinder the long-range slip of dislocations, forming a dynamic strong and tough balance. Y in the high-entropy alloy can segregate at the grain boundaries to refine the grains, increasing the grain boundary ratio to absorb deformation energy.

[0031] Specifically, the above high-entropy alloy ingot is prepared by arc melting.

[0032] Specifically, in Step 1, before rolling the high-entropy alloy ingot, the high-entropy alloy ingot needs to be cut and surface-treated. For example, the obtained high-entropy alloy ingot is processed to the target size by a wire electrical discharge machine, and then the cut high-entropy alloy ingot is surface-treated.

[0033] Specifically, in Step 1, the rolling treatment of the high-entropy alloy ingot is: The high-entropy alloy ingot is subjected to multiple cold rolling treatments to obtain a foil; specifically, the thickness of the foil obtained by cold rolling is preferably 0.1 mm - 0.2 mm.

[0034] Specifically, in Step 1, the machining process is as follows: The rolled foil is cut into segments and polished to a thickness of 100 μm - 130 μm, and then the foil is polished, cleaned, and dried in sequence to obtain a high-entropy alloy foil. For example, the cold-rolled foil is cut into segments, and then the foil is polished using 400#, 800#, 1500#, and 2000# sandpapers in sequence to a thickness of 100 - 130 μm. After that, the polished foil is polished using a SiO2-H2O2 polishing agent, and finally, the foil is ultrasonically cleaned with alcohol for 10 min and then dried to obtain a high-entropy alloy foil.

[0035] Step 2: Stack the Ti150 alloy base material, the high-entropy alloy foil, and the Ti180 alloy base material in sequence, with the high-entropy alloy foil positioned between the Ti150 alloy base material and the Ti180 alloy base material to obtain a heterogeneous alloy combination.

[0036] Specifically, before Step 2, the method further includes cutting, grinding and polishing, cleaning, and drying the Ti150 alloy base material and the Ti180 alloy base material in sequence. For example, the Ti150 alloy base material and the Ti180 alloy base material are processed into a cuboid structure using a wire electrical discharge machine; the surfaces of the titanium alloy cuboids are polished using 400#, 800#, 1500#, and 2000# sandpapers in sequence, then polished using a SiO2-H2O2 polishing agent, and finally, the treated titanium alloy cuboids are ultrasonically cleaned with alcohol for 10 min and then dried.

[0037] Step 3: Perform vacuum diffusion welding on the heterogeneous alloy combination to obtain a heterogeneous alloy diffusion welded joint.

[0038] Specifically, in Step 3, the vacuum diffusion welding is carried out in a vacuum diffusion furnace, and the welding process conditions for the vacuum diffusion welding are specifically as follows: The first stage: Heat from room temperature to 300 °C at a heating rate of 10 °C / min and hold at 300 °C for 10 min; the second stage: Heat from 300 °C to 600 °C at a heating rate of 10 °C / min and hold at 600 °C for 10 min; the third stage: Heat from 600 °C to 800 °C at a heating rate of 10 °C / min and hold at 800 °C for 10 min; the fourth stage: Heat from 800 °C to the welding target temperature of 820 °C - 910 °C at a heating rate of 10 °C / min, and the heating is completed; the fifth stage: Hold at the welding target temperature for 1 h while applying a pressure of 5 MPa - 10 MPa; after the holding is completed, the sample is cooled to room temperature with the furnace and the pressure returns to zero, and the welding is completed.

[0039] The following is illustrated with specific examples:

[0040] Example 1

[0041] A method for diffusion bonding heterogeneous titanium alloys based on a high-entropy alloy intermediate layer is achieved through the following steps:

[0042] Step 1: Prepare a high-entropy alloy ingot by arc melting; the prepared high-entropy alloy ingot is composed of elements with the following atomic percentages: Ti-15Co-15Fe-15Mo-10Cr-10Ni-15Zr-5Y, and the element purity is greater than 99.9 wt%.

[0043] Step 2: Use a wire electrical discharge machine to process the high-entropy alloy ingot obtained in Step 1 into a cuboid with dimensions of 25 mm × 25 mm × 5 mm; perform surface treatment on the cut high-entropy alloy ingot; subject the surface-treated high-entropy alloy ingot to multiple cold rolling operations to obtain a foil with a thickness of 0.15 mm; cut the cold-rolled foil into segments, then successively polish the foil with 400#, 800#, 1500#, and 2000# sandpapers until the thickness reaches 100 μm, and then polish the polished foil with a SiO2-H2O2 polishing agent. Finally, ultrasonically clean the foil with alcohol for 10 min and then dry it to obtain a high-entropy alloy foil.

[0044] Step 3: Use a wire electrical discharge machine to process both the Ti150 alloy base material and the Ti180 alloy base material into cuboids with dimensions of 15 mm × 10 mm × 5 mm; successively polish the surfaces of the titanium alloy cuboids with 400#, 800#, 1500#, and 2000# sandpapers, then polish them with a SiO2-H2O2 polishing agent, and finally ultrasonically clean the treated titanium alloy cuboids with alcohol for 10 min and then dry them.

[0045] Step 4: Stack the Ti150 alloy cuboid obtained in Step 3, the high-entropy alloy foil obtained in Step 2, and the Ti180 alloy cuboid obtained in Step 3 in sequence, with the high-entropy alloy foil positioned between the Ti150 alloy cuboid and the Ti180 alloy cuboid to obtain a heterogeneous alloy combination.

[0046] Step 5: Place the heterogeneous alloy assembly obtained in Step 4 into a vacuum diffusion furnace for diffusion welding. The specific welding process conditions are as follows: The first stage: Heat from room temperature to 300 °C at a heating rate of 10 °C / min and hold at 300 °C for 10 min; The second stage: Heat from 300 °C to 600 °C at a heating rate of 10 °C / min and hold at 600 °C for 10 min; The third stage: Heat from 600 °C to 800 °C at a heating rate of 10 °C / min and hold at 800 °C for 10 min; The fourth stage: Heat from 800 °C to the welding target temperature of 820 °C at a heating rate of 10 °C / min, and the heating is completed; The fifth stage: Hold at 820 °C for 1 h while applying a pressure of 5 MPa; After the holding is completed, the sample is cooled to room temperature in the furnace and the pressure returns to zero, and the welding is completed.

[0047] In this embodiment, the tensile strength of the Ti150-high entropy alloy interlayer-Ti180 joint reaches 938 MPa.

[0048] Example 2

[0049] In Step 2, a foil with a thickness of 0.1 mm is obtained by cold rolling. After the cold-rolled foil is segmented and cut, the thickness is not polished anymore, and it is directly polished with a SiO2-H2O2 polishing agent; The welding target temperature in Step 5 is 870 °C, and the rest is the same as in Example 1. In this embodiment, the tensile strength of the Ti150-high entropy alloy interlayer-Ti180 joint reaches 857 MPa.

[0050] Example 3

[0051] In Step 2, a foil with a thickness of 0.2 mm is obtained by cold rolling. The cold-rolled foil is segmented and cut, and then the foil is polished with 400#, 800#, 1500#, and 2000# sandpapers in sequence until the thickness is 130 μm; The welding target temperature in Step 5 is 910 °C, and the rest is the same as in Example 1. In this embodiment, the tensile strength of the Ti150-high entropy alloy interlayer-Ti180 joint reaches 820 MPa.

[0052] Example 4

[0053] The welding target temperature in Step 5 is 870 °C, and the pressure is 10 MPa, and the rest is the same as in Example 1. In this embodiment, the tensile strength of the Ti150-high entropy alloy interlayer-Ti180 joint reaches 895 MPa.

[0054] Example 5

[0055] The welding temperature in Step 5 is 910 °C and the pressure is 10 MPa, and the rest is the same as in Example 1. The tensile strength of the Ti150 - high - entropy alloy interlayer - Ti180 joint obtained in this example reaches 836 MPa.

[0056] Comparative Example 1

[0057] In Step 1, an arc melting method is used to prepare a high - entropy alloy ingot; the prepared high - entropy alloy ingot is composed of elements with the following atomic percentages: Ti - 30Fe - 20Ni - 10Cr - 10Y; the rest is the same as in Example 1.

[0058] In this comparative example, the high - entropy alloy interlayer composition used does not contain Co, Mo, and Zr elements. By comparison Figure 1 、 Figure 2 it can be seen that brittle intermetallic compound phases are significantly formed in the welded joints using the traditional high - entropy alloy interlayer, accompanied by micro - porosity and crack defects. However, no brittle phases appear in the welded joints using the high - entropy alloy interlayer of the present invention. Through tensile tests, it can be obtained that the tensile strength of the Ti150 - traditional high - entropy alloy interlayer - Ti180 diffusion - welded joint obtained using the traditional high - entropy alloy interlayer is only 596 MPa; the tensile strength of the Ti150 - high - entropy alloy interlayer - Ti180 diffusion - welded joint obtained using the high - entropy alloy interlayer of the present invention reaches a maximum of 938 MPa. Figure 4 Figure 15 is the fracture morphology diagram of the Ti150 - high - entropy alloy interlayer - Ti180 diffusion - welded joint obtained in Example 1. After observing the fracture surface, it is found that the fracture mechanism is ductile fracture. Therefore, by using the high - entropy alloy interlayer of the present invention to inhibit the formation of brittle phases and reduce the defect density, the mechanical properties of the welded joint are effectively optimized and improved.

[0059] Comparative Example 2

[0060] In Step 1, an arc melting method is used to prepare a high - entropy alloy ingot; the prepared high - entropy alloy ingot is composed of elements with the following atomic percentages: Ti - 30Nb - 20Ta - 10Hf - 10Al; the rest is the same as in Example 1.

[0061] In this comparative example, a traditional high - entropy alloy interlayer is used. The composition of the high - entropy alloy interlayer used in this comparative example is quite different from that in Example 1. By Figure 3 it can be seen that there are no obvious defects in the diffusion - welded joints obtained in this comparative example. However, through tensile tests, it is obtained that the tensile strength of the Ti150 - traditional high - entropy alloy interlayer - Ti180 diffusion - welded joint obtained using the traditional high - entropy alloy interlayer in this comparative example is only 517 MPa, and the joint performance drops significantly.

[0062] Obviously, those skilled in the art can make various changes and modifications to this technical solution without departing from the spirit and scope of this technical solution. Thus, if these modifications and variations of this technical solution fall within the scope of the claims of this technical solution and its equivalent technologies, then this technical solution is also intended to include these changes and modifications.

Claims

1. A method for diffusion bonding heterogeneous titanium alloys based on a high entropy alloy intermediate layer, characterized in that: The steps include: Step 1: rolling and machining a high entropy alloy ingot to obtain a high entropy alloy foil; wherein the high entropy alloy ingot is composed of the following elements in atomic percentage: Ti-15Co-15Fe-15Mo-10Cr-10Ni-15Zr-5Y; Step 2: stacking the Ti150 alloy base material, the high entropy alloy foil and the Ti180 alloy base material in sequence, so that the high entropy alloy foil is located between the Ti150 alloy base material and the Ti180 alloy base material, to obtain a heterogeneous alloy assembly; Step three: subjecting the heterogeneous alloy assembly to vacuum diffusion welding to obtain a heterogeneous alloy diffusion welding joint.

2. The method for diffusion bonding heterogeneous titanium alloys based on a high entropy alloy intermediate layer according to claim 1, characterized in that: The high entropy alloy ingot is prepared by arc melting.

3. The method for diffusion bonding heterogeneous titanium alloys based on a high entropy alloy intermediate layer according to claim 1, characterized in that: In step one, the high entropy alloy ingot needs to be cut and surface treated before rolling.

4. The method for diffusion bonding heterogeneous titanium alloys based on a high entropy alloy intermediate layer according to claim 1, characterized in that: In step 1, the rolling process of the high entropy alloy ingot is specifically as follows: the high entropy alloy ingot is subjected to multiple cold rolling processes to obtain a foil with a thickness of 0.1 mm to 0.2 mm.

5. The method for diffusion bonding heterogeneous titanium alloys based on a high entropy alloy intermediate layer according to claim 1, characterized in that: In step one, the mechanical processing is specifically as follows: the rolled foil is cut into sections and polished to a thickness of 100 μm-130 μm, and then the foil is polished, cleaned and dried in sequence to obtain a high entropy alloy foil.

6. The method for diffusion bonding heterogeneous titanium alloys based on a high entropy alloy intermediate layer according to claim 1, characterized in that: Before step 2, the method further comprises cutting, grinding, polishing, cleaning and drying the Ti150 alloy base material and the Ti180 alloy base material in sequence.

7. The method for diffusion bonding heterogeneous titanium alloys based on a high entropy alloy intermediate layer according to claim 1, characterized in that: In step three, the vacuum diffusion welding process is performed in a vacuum diffusion furnace.

8. The method for diffusion bonding heterogeneous titanium alloys based on a high entropy alloy intermediate layer as claimed in claim 1, characterized in that: In step 3, the welding process conditions of the vacuum diffusion welding treatment are specifically as follows: first stage: heating from room temperature to 300°C at a heating rate of 10°C / min, and keeping at 300°C for 10 minutes; The second stage: heating from 300°C to 600°C at a heating rate of 10°C / min, and keeping at 600°C for 10 minutes; The third stage: heating from 600 ℃ to 800 ℃ at a heating rate of 10 ℃ / min, and keeping at 800 ℃ for 10 minutes; the fourth stage: heating from 800 ℃ to the welding target temperature of 820 ℃~910 ℃ at a heating rate of 10 ℃ / min, and the heating is completed; the fifth stage: keeping at the welding target temperature for 1 hour while applying 5MPa~10MPa pressure; after the insulation is completed, the sample is cooled to room temperature with the furnace and the pressure returns to zero, and the welding is completed.

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