A composite brazing filler metal suitable for low-melting brazing of titanium alloy thin-walled structural parts, a preparation method and application thereof

Abstract

The application relates to a composite filler suitable for low-melting and low-erosion brazing of a titanium alloy thin-wall structural member, a preparation method and application of the composite filler. In order to solve the contradiction between low erosion and high strength, the composite filler suitable for low-melting and low-erosion brazing of the titanium alloy thin-wall structural member is composed of two layers of TiZrHfCuNiCo amorphous high-entropy foils and one layer of Ti foil, the one layer of Ti foil is arranged in the middle of the two layers of TiZrHfCuNiCo amorphous high-entropy foils, and the TiZrHfCuNiCo amorphous high-entropy foils and the Ti foil are compounded together through a bonding agent or resistance spot welding method. The composite filler can improve the brazing joint performance while effectively reducing the erosion of the base material and improving the joint strength. The main product form of the composite filler is a foil, the composition is uniform, assembly is convenient, the brazing seam width can be well controlled, the composite filler is an ideal filler material, is more suitable for actual production, and can greatly improve the joint strength under the condition of low erosion of the base material.

Description

TECHNICAL FIELD

[0001] The present application relates to an amorphous high-entropy composite filler metal and a preparation method and application thereof. BACKGROUND

[0002] TC4 titanium alloy has been widely used as a structural material due to its excellent specific strength and corrosion resistance. With the continuous development of manufacturing industry, higher requirements are put forward for the welding process of TC4 titanium alloy. However, the traditional titanium-based filler metal is prone to produce dissolution defects when brazing thin-walled structural parts such as honeycomb plates and heat exchangers of TC4 titanium alloy. When there is serious dissolution in the brazed joint of thin-walled structure of TC4, the strength and fatigue resistance of the joint will be seriously deteriorated, and it is extremely easy to fail under high temperature and high pressure and corrosion conditions.

[0003] The main reason for the dissolution of the traditional titanium-based filler metal is that Ni, Cu and other elements are often added to the filler metal to reduce the melting point of the filler metal. However, during brazing, Cu and Ni elements will diffuse to the TC4 base material, causing the surface of the base material to be alloyed, the melting point to be reduced, and then dissolution defects are produced. Although the use of low-dissolution amorphous high-entropy foil can inhibit the diffusion of elements in the TC4 base material to the filler metal, thereby achieving the purpose of reducing the dissolution of the base material, at the same time, due to the low dissolution of the base material, the diffusion of Ti elements in the base material to the filler metal is less. At this time, the filler metal does not fully react with the Ti elements in the base material, resulting in a large amount of residual filler metal in the joint, which seriously restricts the improvement of the joint strength. SUMMARY

[0004] In order to solve the contradiction between low dissolution and high strength of TC4 titanium alloy brazed joint, the present application provides a composite filler metal suitable for low-melting brazing of titanium alloy thin-walled structural parts and a preparation method and application thereof.

[0005] The composite filler metal suitable for low-melting brazing of titanium alloy thin-walled structural parts of the present application is composed of two layers of TiZrHfCuNiCo amorphous high-entropy foil and one layer of Ti foil. The Ti foil is arranged in the middle of the two layers of TiZrHfCuNiCo amorphous high-entropy foil, and the TiZrHfCuNiCo amorphous high-entropy foil and the Ti foil are composed together by means of adhesive or resistance spot welding.

[0006] Ti in the TiZrHfCuNiCo amorphous high-entropy foil in the application can make the high-entropy brazing filler metal have good wettability and flowability on the surface of the base material. Zr and Hf are same group elements with Ti, can be infinitely soluble, improve the wettability of the brazing filler metal and the base material, and can significantly reduce the melting point of the brazing filler metal, and improve the degree of confusion of the alloy, increase the entropy value of the alloy. The effects of Cu, Ni and Co are similar and can be infinitely soluble with each other, so that the melting point of the brazing filler metal is further reduced, and the degree of confusion of the alloy is improved, and the entropy value of the alloy is increased. The Ti foil is set in the composite brazing filler metal because pure Ti will undergo polymorphic transformation when heated to 882 DEG C, and the crystal structure of Ti is changed from alpha-Ti of close-packed hexagonal structure to beta-Ti of body-centered cubic structure; and the base material TC4 contains a large amount of Al element, and the Al element is an alpha-Ti stabilizer, which can increase the phase transition temperature of alpha-Ti to about 985-995 DEG C, when the brazing temperature is between 882 DEG C and 985 DEG C, the base material has not been transformed, still contains a large amount of alpha-Ti, while the pure Ti foil in the composite brazing filler metal has been completely transformed into beta-Ti, and because the diffusion coefficient and solubility of Cu, Ni, Co and other melting reducing elements in beta-Ti are much higher than those in alpha-Ti, Cu, Ni and Co will enter the pure Ti foil first during brazing, and the pure Ti foil will be eroded, so that Ti element and the brazing filler metal can fully react, reduce the residual brazing filler metal in the brazing seam, and improve the joint strength.

[0007] The application is suitable for the preparation method of the composite brazing filler metal for low-erosion brazing of titanium alloy thin-walled structural parts, which is carried out according to the following steps:

[0008] Step one: the raw materials of the TiZrHfCuNiCo amorphous high-entropy foil are weighed according to the atomic percentage;

[0009] The TiZrHfCuNiCo amorphous high-entropy foil is composed of 12-30% of Ti, 12-30% of Zr, 12-30% of Hf, 12-30% of Cu, 12-30% of Ni and 12-30% of Co according to the atomic percentage;

[0010] Step two: the raw materials weighed in step one are melted to obtain a brazing filler metal ingot;

[0011] Step three: the brazing filler metal ingot obtained in step two is prepared into a TiZrHfCuNiCo amorphous high-entropy foil by a single-roll spinning method;

[0012] Step four: the Ti foil is placed between two layers of TiZrHfCuNiCo amorphous high-entropy foils, and is compounded together by using an adhesive or resistance spot welding method to prepare a low-erosion high-strength amorphous high-entropy composite brazing filler metal for TC4 titanium alloy brazing;

[0013] The thickness ratio of the TiZrHfCuNiCo amorphous high-entropy foil to the Ti foil is 0.8-3:1.

[0014] The method for brazing TC4 titanium alloy by using the composite filler metal suitable for low-melting brazing of thin-walled titanium alloy structure is carried out according to the following steps:

[0015] Step one: polish the surface to be welded of the TC4 alloy with fine sandpaper, remove the surface dirt and oxides, and then put the polished TC4 alloy and the low-erosion high-strength amorphous high-entropy composite filler metal for brazing of TC4 titanium alloy into anhydrous ethanol for ultrasonic cleaning;

[0016] Step two: assemble according to the form from top to bottom of TC4 alloy, low-erosion high-strength amorphous high-entropy composite filler metal for brazing of TC4 titanium alloy, and TC4 alloy, and finally put into a vacuum brazing furnace for brazing, i.e., complete;

[0017] The brazing process is: start heating at a speed of 10℃ / min to 940-960℃ and keep for 10min, then reduce the temperature to 150-200℃ at a speed of 10-15℃ / min, and then cool down to room temperature with the furnace, and complete the brazing of the TC4 alloy.

[0018] The technical effect of the present application is:

[0019] 1、The TiZrHfCuNiCo amorphous high-entropy foil in the low-erosion high-strength amorphous high-entropy composite filler metal for brazing of TC4 titanium alloy has good wettability with the base material, and has multiple component types, high content, close component content, and disordered atomic arrangement, so the mixing entropy of the atomic arrangement is high, and the generation of intermetallic compounds can be inhibited.

[0020] 3、The pure Ti foil in the composite filler metal can be transformed into beta-Ti during brazing, improves the diffusion coefficient and solubility of the melting elements such as Cu, Ni and Co in the pure Ti foil, melts the pure Ti foil before the TC4 base material, makes the Ti element fully react with the filler metal, and improves the joint strength.

[0021] 4、The main product form of the composite brazing filler material is foil, which is uniform in composition, convenient to assemble, and can better control the brazing seam width, is an ideal brazing filler material, is more suitable for actual production, and can greatly improve the joint strength under the condition of low erosion of the base material. BRIEF DESCRIPTION OF DRAWINGS

[0022] Figure 1 Figure is the interface microstructure diagram of the TC4 / TiZrHfCuNiCo / pure Ti / TiZrHfCuNiCo / TC4 brazed joint obtained under the brazing condition of 940℃ / 10min in Example 1.

[0023] Figure 2 Figure is the interface microstructure diagram of the TC4 / TiZrHfCuNiCo / TC4 brazed joint obtained under the brazing condition of 940℃ / 10min in the comparative example. DETAILED DESCRIPTION

[0024] The technical scheme of the present application is not limited to the following specific embodiments, and also includes any reasonable combination between the specific embodiments.

[0025] Specific embodiment one: the composite brazing filler material suitable for low-erosion brazing of titanium alloy thin-walled structural parts in this embodiment is composed of two layers of TiZrHfCuNiCo amorphous high-entropy foils and one layer of Ti foil, the Ti foil is arranged in the middle of the two layers of TiZrHfCuNiCo amorphous high-entropy foils, and the TiZrHfCuNiCo amorphous high-entropy foils and the Ti foil are composed together by means of adhesive or resistance spot welding.

[0026] This embodiment has the following beneficial effects:

[0027] 1、The TiZrHfCuNiCo amorphous high-entropy foil in the low-erosion high-strength amorphous high-entropy composite brazing filler material for TC4 titanium alloy brazing in this embodiment has good wettability with the base material, and has a large number of components with high content and close content, and the atomic arrangement is disordered, so the mixing entropy of the atomic arrangement is high, and the generation of intermetallic compounds can be inhibited. At the same time, the atomic sizes of various elements in the high-entropy alloy are quite different, especially when the mixing entropy of the alloy is high, the cooperative diffusion between the main elements of the alloy will become difficult, and due to the differences in atomic size, bond type and lattice potential between each main element, the crystal structure of the high-entropy alloy is distorted, which hinders the movement of atoms, making diffusion difficult in the high-entropy alloy, thereby inhibiting the diffusion rate of atoms, which can improve the performance of the brazed joint while effectively reducing the erosion of the base material.

[0028] 3. In this embodiment, the pure Ti foil in the composite brazing filler metal can undergo a phase transformation to β-Ti during brazing, which increases the diffusion coefficient and solubility of Cu, Ni, Co and other demelting elements in the pure Ti foil. This allows the pure Ti foil to melt before the TC4 base material, enabling the Ti element to fully react with the brazing filler metal and improving the joint strength.

[0029] 4. The main product form of the composite brazing filler metal in this embodiment is foil. It has uniform composition, is easy to assemble, and can better control the brazing gap width. It is an ideal brazing filler metal material, more suitable for actual production, and can significantly improve the joint strength under the condition of low corrosion of the base material.

[0030] Specific Implementation Method Two: This implementation method differs from Specific Implementation Method One in that the purity of the Ti foil is 99.9 wt.%.

[0031] Specific Implementation Method 3: This implementation method differs from Specific Implementation Method 1 or 2 in that the TiZrHfCuNiCo amorphous high-entropy foil is composed of 12-30% Ti, 12-30% Zr, 12-30% Hf, 12-30% Cu, 12-30% Ni and 12-30% Co by atomic percentage.

[0032] Specific Implementation Method Four: This implementation method applies to the preparation of composite brazing filler metal for low-erosion brazing of thin-walled titanium alloy structural parts, and is carried out according to the following steps:

[0033] Step 1: Weigh the raw materials for the TiZrHfCuNiCo amorphous high-entropy foil according to atomic percentage;

[0034] The TiZrHfCuNiCo amorphous high-entropy foil is composed of 12-30% Ti, 12-30% Zr, 12-30% Hf, 12-30% Cu, 12-30% Ni and 12-30% Co by atomic percentage.

[0035] Step 2: Melt the raw materials weighed in Step 1 to obtain brazing filler metal ingots;

[0036] Step 3: The brazing filler ingot obtained in Step 2 is used to prepare TiZrHfCuNiCo amorphous high-entropy foil by single-roll spin quenching.

[0037] Step 4: Place the Ti foil between two layers of TiZrHfCuNiCo amorphous high-entropy foils and bond them together using an adhesive or resistance spot welding method to prepare a low-alkalinity, high-strength amorphous high-entropy composite brazing filler metal for brazing TC4 titanium alloy.

[0038] The thickness ratio of the TiZrHfCuNiCo amorphous high-entropy foil to the Ti foil is 0.8 to 3:1.

[0039] Embodiment five: different from embodiment four, the melting in step two is carried out in an arc melting furnace or an induction melting furnace.

[0040] Embodiment six: different from embodiment four or five, the atmosphere for the melting in step two is vacuum or inert gas protection atmosphere.

[0041] Embodiment seven: different from one of embodiments four to six, the thickness of the TiZrHfCuNiCo amorphous high-entropy foil in step three is 30-100 μm.

[0042] Embodiment eight: different from one of embodiments four to seven, the binder in step four is a water solution of carboxymethyl cellulose with a mass fraction of 20-50%.

[0043] Embodiment nine: the method for brazing TC4 titanium alloy by using a composite filler suitable for low-melting and low-erosion brazing of thin-walled structure of titanium alloy is carried out according to the following steps:

[0044] Step one: polish the surface of TC4 alloy to be welded by using fine sandpaper, remove surface dirt and oxides, then put the polished TC4 alloy and low-erosion high-strength amorphous high-entropy composite filler for brazing of TC4 titanium alloy into anhydrous ethanol for ultrasonic cleaning;

[0045] Step two: assemble according to the form from top to bottom of TC4 alloy, low-erosion high-strength amorphous high-entropy composite filler for brazing of TC4 titanium alloy, TC4 alloy, and finally put into a vacuum brazing furnace for brazing, i.e. complete;

[0046] The brazing process is: start heating at a speed of 10℃ / min to 940-960℃ and keep for 10 min, then cool down at a speed of 10-15℃ / min to 150-200℃, then cool down in the furnace to room temperature, and complete the brazing of TC4 alloy.

[0047] 1. In this embodiment, the TiZrHfCuNiCo amorphous high-entropy composite brazing alloy for brazing TC4 titanium alloys exhibits good wettability with the base material. Furthermore, it contains a variety of components in high concentrations, with relatively similar component contents and a somewhat disordered atomic arrangement, resulting in a high mixing entropy. This effectively suppresses the formation of intermetallic compounds. Simultaneously, the significant differences in atomic sizes among the various elements in the high-entropy alloy, particularly when the alloy's mixing entropy is high, hinders cooperative diffusion between the alloy's principal elements. Moreover, the differences in atomic size, bond type, and lattice potential energy among the principal elements distort the crystal structure of the high-entropy alloy, further impeding atomic movement and making diffusion difficult. This suppresses the atomic diffusion rate, improving brazing joint performance while effectively reducing base material corrosion.

[0048] 3. In this embodiment, the pure Ti foil in the composite brazing filler metal can undergo a phase transformation to β-Ti during brazing, which increases the diffusion coefficient and solubility of Cu, Ni, Co and other demelting elements in the pure Ti foil. This allows the pure Ti foil to melt before the TC4 base material, enabling the Ti element to fully react with the brazing filler metal and improving the joint strength.

[0049] 4. The main product form of the composite brazing filler metal in this embodiment is foil. It has uniform composition, is easy to assemble, and can better control the brazing gap width. It is an ideal brazing filler metal material, more suitable for actual production, and can significantly improve the joint strength under the condition of low corrosion of the base material.

[0050] Specific Implementation Method 10: This implementation method differs from Specific Implementation Method 9 in that the brazing process is as follows: the temperature is initially raised to 940°C at a rate of 10°C / min and held for 10 minutes, then cooled to 200°C at a rate of 10°C / min, and then cooled to room temperature with the furnace to complete the brazing of TC4 alloy.

[0051] Example 1:

[0052] This embodiment is applicable to the low-erosion brazing of thin-walled titanium alloy structural parts. The composite brazing filler metal is composed of two layers of TiZrHfCuNiCo amorphous high-entropy foil and one layer of Ti foil. The Ti foil is placed between the two layers of TiZrHfCuNiCo amorphous high-entropy foil. The TiZrHfCuNiCo amorphous high-entropy foil and Ti foil are combined together by adhesive or resistance spot welding.

[0053] The TiZrHfCuNiCo amorphous high-entropy foil is composed of 25 at.% Ti, 25 at.% Zr, 25 at.% Hf, 8 at.% Cu, 8 at.% Ni and 9 at.% Co by atomic percentage.

[0054] The purity of the Ti foil is 99.9 wt.%.

[0055] The preparation method of the composite filler suitable for low melting and corrosion brazing of titanium alloy thin-walled structural parts is carried out according to the following steps:

[0056] Step one: the raw materials of the TiZrHfCuNiCo amorphous high-entropy foil are weighed according to the atomic percentage;

[0057] Step two: the raw materials weighed in step one are subjected to melting to obtain filler ingots;

[0058] The melting is carried out in an arc melting furnace or an induction melting furnace;

[0059] The atmosphere of the melting is vacuum or inert gas protection atmosphere;

[0060] Step three: the filler ingots obtained in step two are prepared into TiZrHfCuNiCo amorphous high-entropy foils by a single-roll spinning method;

[0061] The thickness of the TiZrHfCuNiCo amorphous high-entropy foil is 50 μm;

[0062] Step four: the Ti foil is placed between two layers of TiZrHfCuNiCo amorphous high-entropy foils, and the method of adhesive or resistance spot welding is used to composite them together to prepare a low corrosion high-strength amorphous high-entropy composite filler for TC4 titanium alloy brazing;

[0063] The thickness ratio of the TiZrHfCuNiCo amorphous high-entropy foil to the Ti foil is 2:1;

[0064] The adhesive is a carboxymethyl cellulose aqueous solution with a mass fraction of 35%;

[0065] The method for brazing TC4 titanium alloy by using the composite filler suitable for low melting and corrosion brazing of titanium alloy thin-walled structural parts is carried out according to the following steps:

[0066] Step one: the surface to be welded of the TC4 alloy is polished with fine sandpaper to remove surface dirt and oxides, and then the polished TC4 alloy and the low corrosion high-strength amorphous high-entropy composite filler for TC4 titanium alloy brazing are ultrasonically cleaned in anhydrous ethanol;

[0067] Step two: the assembly is carried out in the form of TC4 alloy, low corrosion high-strength amorphous high-entropy composite filler for TC4 titanium alloy brazing, and TC4 alloy from top to bottom, and finally placed in a vacuum brazing furnace for brazing, i.e. completed;

[0068] The brazing process is as follows: start heating at a speed of 10 ℃ / min to 940 ℃ and keep for 10 min, then cool down to 200 ℃ at a speed of 10 ℃ / min, and then cool down to room temperature with the furnace, to complete the brazing of the TC4 alloy.

[0069] Comparative Example 1:

[0070] The method for brazing TC4 titanium alloy by using TiZrHfCuNiCo amorphous high-entropy foil is carried out according to the following steps:

[0071] Step one: polish the surface to be welded of TC4 alloy with fine sandpaper, remove surface dirt and oxides, then put the polished TC4 alloy and TiZrHfCuNiCo amorphous high-entropy foil into anhydrous ethanol for ultrasonic cleaning;

[0072] The preparation method of the TiZrHfCuNiCo amorphous high-entropy foil is carried out according to the following steps: the raw materials of the TiZrHfCuNiCo amorphous high-entropy foil are weighed according to atomic percentage; the TiZrHfCuNiCo amorphous high-entropy foil is composed of 25 at.% of Ti, 25 at.% of Zr, 25 at.% of Hf, 8 at.% of Cu, 8 at.% of Ni and 9 at.% of Co according to atomic percentage; the weighed raw materials are melted to obtain a filler metal ingot; the melting is carried out in an arc melting furnace or an induction melting furnace; the atmosphere of the melting is vacuum or inert gas protective atmosphere; the filler metal ingot is prepared into a TiZrHfCuNiCo amorphous high-entropy foil by a single-roll spinning method; the thickness of the TiZrHfCuNiCo amorphous high-entropy foil is 50 μm;

[0073] Step two: assemble according to the form from top to bottom of TC4 alloy, TiZrHfCuNiCo amorphous high-entropy foil and TC4 alloy, and finally put into a vacuum brazing furnace for brazing, that is, completed;

[0074] The brazing process is as follows: start heating at a speed of 10 ℃ / min to 940 ℃ and keep for 10 min, then cool down to 200 ℃ at a speed of 10 ℃ / min, and then cool down to room temperature in the furnace, to complete the brazing of TC4 alloy.

[0075] Figure 1 The interface microstructure diagram of the TC4 / TiZrHfCuNiCo / pure Ti / TiZrHfCuNiCo / TC4 brazed joint obtained under the brazing condition of 940 ℃ / 10 min in Example 1; Figure 2 The interface microstructure diagram of the TC4 / TiZrHfCuNiCo / TC4 brazed joint obtained under the brazing condition of 940 ℃ / 10 min in Comparative Example 1. By Figure 1 and Figure 2It can be seen that, under the same process parameters, the brazed joint obtained by using the composite filler material in Example 1 has no residual filler material layer, and the weld after welding has no obvious widening, while the single TiZrHfCuNiCo high-entropy filler material used in the comparative example produces a residual filler material layer in the brazed joint, and the weld after welding increases by about 40 μm. The joint strength of Example 1 is 248 MPa, while that of the comparative example is only 79 MPa.

[0076] Example 2

[0077] The composite filler material suitable for low melting and etching brazing of titanium alloy thin-walled structural parts in this embodiment is composed of two layers of TiZrHfCuNiCo amorphous high-entropy foil and one layer of Ti foil, and one layer of Ti foil is arranged between the two layers of TiZrHfCuNiCo amorphous high-entropy foil. The TiZrHfCuNiCo amorphous high-entropy foil and the Ti foil are compounded together by means of adhesive or resistance spot welding.

[0078] The TiZrHfCuNiCo amorphous high-entropy foil is composed of 22 at.% of Ti, 22 at.% of Zr, 22 at.% of Hf, 11 at.% of Cu, 11 at.% of Ni and 12 at.% of Co in terms of atomic percentage;

[0079] The purity of the Ti foil is 99.9 wt.%;

[0080] The preparation method of the above-mentioned composite filler material suitable for low melting and etching brazing of titanium alloy thin-walled structural parts is carried out according to the following steps:

[0081] Step one: weigh the raw materials of the TiZrHfCuNiCo amorphous high-entropy foil according to atomic percentage;

[0082] Step two: melt the raw materials weighed in step one to obtain filler material ingots;

[0083] The melting is carried out in an electric arc melting furnace or an induction melting furnace;

[0084] The atmosphere of the melting is vacuum or inert gas protective atmosphere;

[0085] Step three: prepare the TiZrHfCuNiCo amorphous high-entropy foil from the filler material ingots obtained in step two by single-roll spinning method;

[0086] The thickness of the TiZrHfCuNiCo amorphous high-entropy foil is 50 μm;

[0087] Step four: place the Ti foil between the two layers of TiZrHfCuNiCo amorphous high-entropy foil and compound them together by using adhesive or resistance spot welding to prepare a low-etching high-strength amorphous high-entropy composite filler material for TC4 titanium alloy brazing;

[0088] The thickness ratio of the TiZrHfCuNiCo amorphous high-entropy foil to the Ti foil is 2:1;

[0089] The binder is a water solution of carboxymethyl cellulose with a mass fraction of 35%;

[0090] The method for brazing TC4 titanium alloy by using the composite filler metal suitable for low-melting brazing of titanium alloy thin-walled structural parts is performed according to the following steps:

[0091] Step one: polish the surface to be welded of the TC4 alloy with fine sandpaper to remove surface dirt and oxides, and then ultrasonically clean the polished TC4 alloy and the low-erosion high-strength amorphous high-entropy composite filler metal for TC4 titanium alloy brazing in anhydrous ethanol;

[0092] Step two: assemble in the order of TC4 alloy, low-erosion high-strength amorphous high-entropy composite filler metal for TC4 titanium alloy brazing, and TC4 alloy from top to bottom, and finally put into a vacuum brazing furnace for brazing, i.e., complete;

[0093] The brazing process is: start heating at a speed of 10℃ / min to 950℃ and keep for 10min, then cool down to 200℃ at a speed of 10℃ / min, and then cool down to room temperature with the furnace, to complete the brazing of the TC4 alloy.

[0094] Comparative Example 2:

[0095] The method for brazing TC4 titanium alloy by using the TiZrHfCuNiCo amorphous high-entropy foil is performed according to the following steps:

[0096] Step one: polish the surface to be welded of the TC4 alloy with fine sandpaper to remove surface dirt and oxides, and then ultrasonically clean the polished TC4 alloy and the TiZrHfCuNiCo amorphous high-entropy foil in anhydrous ethanol;

[0097] The preparation method of the TiZrHfCuNiCo amorphous high-entropy foil is performed according to the following steps: weigh the raw materials of the TiZrHfCuNiCo amorphous high-entropy foil according to the atomic percentage; the TiZrHfCuNiCo amorphous high-entropy foil is composed of 22at.% of Ti, 22at.% of Zr, 22at.% of Hf, 11at.% of Cu, 11at.% of Ni, and 12at.% of Co; melt the weighed raw materials to obtain a filler metal ingot; the melting is performed in an arc melting furnace or an induction melting furnace; the atmosphere of the melting is vacuum or inert gas protection atmosphere; the filler metal ingot is prepared into a TiZrHfCuNiCo amorphous high-entropy foil by a single-roll spinning method; the thickness of the TiZrHfCuNiCo amorphous high-entropy foil is 50μm;

[0098] Step two: assemble in the form of TC4 alloy, TiZrHfCuNiCo amorphous high-entropy foil, TC4 alloy from top to bottom, and finally put into a vacuum brazing furnace for brazing, i.e. completed;

[0099] The brazing process is as follows: start heating at a speed of 10℃ / min to 950℃ and keep for 10 min, then cool down to 200℃ at a speed of 10℃ / min, and then cool down to room temperature in the furnace, to complete the brazing of TC4 alloy.

[0100] The joint strength in Example 2 is 233 MPa, and the joint strength in Comparative Example 2 is only 68 MPa.

[0101] Example 3:

[0102] The composite filler suitable for low-melting brazing of titanium alloy thin-walled structural parts in this embodiment is composed of two layers of TiZrHfCuNiCo amorphous high-entropy foil and one layer of Ti foil, and the TiZrHfCuNiCo amorphous high-entropy foil and the Ti foil are compounded together by means of adhesive or resistance spot welding;

[0103] The TiZrHfCuNiCo amorphous high-entropy foil is composed of 20 at.% of Ti, 20 at.% of Zr, 20 at.% of Hf, 13 at.% of Cu, 13 at.% of Ni and 14 at.% of Co;

[0104] The purity of the Ti foil is 99.9 wt.%;

[0105] The preparation method of the above-mentioned composite filler suitable for low-melting brazing of titanium alloy thin-walled structural parts is carried out according to the following steps:

[0106] Step one: weigh the raw materials of TiZrHfCuNiCo amorphous high-entropy foil according to atomic percentage;

[0107] Step two: melt the raw materials weighed in step one to obtain filler ingot;

[0108] The melting is carried out in an electric arc melting furnace or an induction melting furnace;

[0109] The atmosphere of the melting is vacuum or inert gas protection atmosphere;

[0110] Step three: prepare the TiZrHfCuNiCo amorphous high-entropy foil from the filler ingot obtained in step two by single-roll spinning method;

[0111] The thickness of the TiZrHfCuNiCo amorphous high-entropy foil is 50 μm;

[0112] Step four: place the Ti foil between two layers of TiZrHfCuNiCo amorphous high-entropy foil, and use adhesive or resistance spot welding method to composite together, to prepare a low-erosion high-strength amorphous high-entropy composite filler for TC4 titanium alloy brazing;

[0113] The thickness ratio of the TiZrHfCuNiCo amorphous high-entropy foil to the Ti foil is 2:1;

[0114] The adhesive is a 35% carboxymethyl cellulose aqueous solution by mass fraction;

[0115] The method for brazing TC4 titanium alloy using the above-mentioned composite filler suitable for low-erosion brazing of titanium alloy thin-walled structural parts is carried out according to the following steps:

[0116] Step one: polish the surface to be welded of the TC4 alloy with fine sandpaper to remove surface dirt and oxides, and then ultrasonically clean the polished TC4 alloy and the low-erosion high-strength amorphous high-entropy composite filler for TC4 titanium alloy brazing in anhydrous ethanol;

[0117] Step two: assemble according to the order from top to bottom of TC4 alloy, low-erosion high-strength amorphous high-entropy composite filler for TC4 titanium alloy brazing, and TC4 alloy, and finally put into a vacuum brazing furnace for brazing, i.e. complete;

[0118] The brazing process is: start heating at a rate of 10℃ / min to 960℃ and hold for 10 min, then cool down to 200℃ at a rate of 10℃ / min, and then cool down to room temperature with the furnace, to complete the brazing of the TC4 alloy.

[0119] Comparative Example 3:

[0120] The method for brazing TC4 titanium alloy using TiZrHfCuNiCo amorphous high-entropy foil is carried out according to the following steps:

[0121] Step one: polish the surface to be welded of the TC4 alloy with fine sandpaper to remove surface dirt and oxides, and then ultrasonically clean the polished TC4 alloy and the TiZrHfCuNiCo amorphous high-entropy foil in anhydrous ethanol;

[0122] The preparation method of the TiZrHfCuNiCo amorphous high-entropy foil is performed according to the following steps: raw materials of the TiZrHfCuNiCo amorphous high-entropy foil are weighed according to atomic percentage; the TiZrHfCuNiCo amorphous high-entropy foil is composed of 22 at.% of Ti, 22 at.% of Zr, 22 at.% of Hf, 11 at.% of Cu, 11 at.% of Ni and 12 at.% of Co according to atomic percentage; the weighed raw materials are subjected to smelting to obtain a filler metal ingot; the smelting is performed in an electric arc smelting furnace or an induction smelting furnace; the atmosphere of the smelting is vacuum or inert gas protection atmosphere; the filler metal ingot is prepared into the TiZrHfCuNiCo amorphous high-entropy foil by a single-roller spinning method; and the thickness of the TiZrHfCuNiCo amorphous high-entropy foil is 50 μm.

[0123] Step two: the TC4 alloy, the TiZrHfCuNiCo amorphous high-entropy foil and the TC4 alloy are assembled in the form of from top to bottom, and finally placed into a vacuum brazing furnace for brazing, that is, completed.

[0124] The brazing process is as follows: heating to 960 ℃ at a speed of 10 ℃ / min and keeping for 10 min, then cooling to 200 ℃ at a speed of 10 ℃ / min, and then furnace cooling to room temperature, to complete the brazing of the TC4 alloy. The joint strength in Example 3 is 198 MPa. The joint strength in Comparative Example 3 is only 53 MPa.

Claims

1. A composite filler material suitable for low melt erosion brazing of thin walled titanium alloy structures, characterized in that: The composite filler suitable for low-melting and low-erosion brazing of titanium alloy thin-walled structural parts is composed of two layers of TiZrHfCuNiCo amorphous high-entropy foils and one layer of Ti foil, one layer of Ti foil is arranged between the two layers of TiZrHfCuNiCo amorphous high-entropy foils, and the TiZrHfCuNiCo amorphous high-entropy foils and the Ti foil are combined together by means of adhesive or resistance spot welding. The TiZrHfCuNiCo amorphous high-entropy foil is composed of 12-30% of Ti, 12-30% of Zr, 12-30% of Hf, 12-30% of Cu, 12-30% of Ni and 12-30% of Co in terms of atomic percentage.

2. The composite filler material suitable for low melt brazing of titanium alloy thin walled structures of claim 1, wherein: The purity of the Ti foil is 99.9 wt.%.

3. The method for preparing the composite brazing filler metal for low-erosion brazing of thin-walled titanium alloy structural parts as described in claim 1, characterized in that: The method is performed according to the following steps: Step one: weigh the raw materials of the TiZrHfCuNiCo amorphous high-entropy foil according to atomic percentage; The TiZrHfCuNiCo amorphous high-entropy foil is composed of 12-30% of Ti, 12-30% of Zr, 12-30% of Hf, 12-30% of Cu, 12-30% of Ni and 12-30% of Co in terms of atomic percentage; Step two: melt the raw materials weighed in step one to obtain filler ingot; Step three: prepare the TiZrHfCuNiCo amorphous high-entropy foil from the filler ingot obtained in step two by single-roller spinning method; Step four: place the Ti foil between the two layers of TiZrHfCuNiCo amorphous high-entropy foils and combine them together by means of adhesive or resistance spot welding to prepare the low-erosion high-strength amorphous high-entropy composite filler for TC4 titanium alloy brazing; The thickness ratio of the TiZrHfCuNiCo amorphous high-entropy foil to the Ti foil is 0.8-3:

1.

4. The method for preparing the composite filler suitable for low-fusion brazing of titanium alloy thin-walled structure according to claim 3, characterized in that: The melting in step two is performed in an electric arc melting furnace or an induction melting furnace.

5. The method of claim 3, wherein the composite filler material is prepared by the following steps: (1) mixing the filler metal powder with the fluxing agent to form a mixture; (2) heating the mixture to a temperature of 600-800°C for 1-2 hours; (3) cooling the mixture to room temperature; and (4) mixing the mixture with the titanium alloy powder to form the composite filler material. The atmosphere of the melting in step two is vacuum or inert gas protection atmosphere.

6. The method of claim 3, wherein the composite filler material is prepared by the following steps: (1) mixing the filler metal powder with the fluxing agent to form a mixture; (2) heating the mixture to a temperature of 600-800°C for 1-2 hours; (3) cooling the mixture to room temperature; and (4) mixing the mixture with the titanium alloy powder to form the composite filler material. The thickness of the TiZrHfCuNiCo amorphous high-entropy foil in step three is 30-100 μm.

7. The method according to claim 3, characterized in that: The adhesive in step four is a carboxymethyl cellulose aqueous solution with a mass fraction of 20-50%.

8. The method for brazing TC4 titanium alloy by using the composite filler metal suitable for low-melting brazing of titanium alloy thin-walled structure as claimed in claim 1, characterized in that: The method is performed according to the following steps: Step one: polish the surface to be welded of the TC4 alloy with fine sandpaper to remove surface dirt and oxides, then ultrasonically clean the polished TC4 alloy and the low-erosion high-strength amorphous high-entropy composite filler for TC4 titanium alloy brazing in anhydrous ethanol; Step two: assemble according to the form from top to bottom of TC4 alloy, low-erosion high-strength amorphous high-entropy composite filler for TC4 titanium alloy brazing, TC4 alloy, and finally put into a vacuum brazing furnace for brazing, i.e. complete; The brazing process is as follows: start heating at a speed of 10 ℃ / min to 940-960 ℃ and keep for 10 min, then cool down at a speed of 10-15 ℃ / min to 150-200 ℃, and then cool down to room temperature with the furnace, thus completing the brazing of the TC4 alloy.

9. The method of brazing TC4 titanium alloy of claim 8, characterized in that: The brazing process is as follows: heating to 940 ℃ at a rate of 10 ℃ / min and holding for 10 min, then cooling to 200 ℃ at a rate of 10 ℃ / min, and then furnace cooling to room temperature, to complete the brazing of the TC4 alloy.

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