Ag-free high-temperature active alloy brazing filler metal and preparation method and application thereof

Abstract

The invention discloses Ag-free high-temperature active alloy brazing filler metal and a preparation method and application thereof. The brazing filler metal alloy comprises 9.5-12.5 wt% of Ge, 9-11 wt% of Ti, 0.1-1.5 wt% of Ni and the balance Cu, the melting point of the brazing filler metal alloy ranges from 960 DEG C to 975 DEG C, and the recommended brazing temperature ranges from 1000 DEG C to 1100 DEG C. The product forms comprise foil strips, wires and powder paste. The preparation method comprises the steps of vacuum alloying, spherical gas atomization powder preparation, centrifugal ball milling powder mixing, spark plasma sintering, homogenizing heat treatment, isothermal rolling, isothermal rotary swaging and precise drawing. The alloy brazing filler metal is suitable for ceramic high-temperature direct packaging, diamond material device high-temperature brazing, refractory metal vacuum brazing and the like, high-strength weld joints can be obtained, the service temperature is high, the cost is low, and the problem that Ag element steam pollutes devices can be effectively solved.

Description

Technical Field

[0001] The present invention relates to an Ag-free high-temperature active alloy solder and a preparation method, in particular to a Cu-based active solder, which is mainly used for high-temperature direct encapsulation of ceramics, vacuum high-temperature brazing of diamond-material devices, vacuum brazing of refractory metals, etc., and belongs to the field of welding materials. Background Art

[0002] Metal-based composite ceramics have higher high-temperature performance than metal-based and polymer-based composite materials, and also have excellent properties such as high strength, high hardness, corrosion resistance, wear resistance and good insulation performance of ceramics. They even have fracture toughness and thermal vibration resistance that are superior to traditional ceramic materials. They show great potential in demanding application environments and are the best materials for the selection of third-generation semiconductors. They have been widely used in many fields such as aerospace, radar electronics, rail transportation, 5G communications, quantum mechanics, etc. However, due to the inherent hardness and brittleness of ceramics, they are difficult to process and manufacture. Many advanced application fields require the use of stable and reliable brazing technology to achieve connection with metals, and then achieve complementary performance with metals, in order to obtain ceramic-metal composite components that have both excellent properties of ceramics and metals, and better play the superior performance of ceramics as structural materials and electrical insulation materials. Through a lot of practice, it is found that there are two difficulties in ceramic welding: one is that the surface of ceramics is not easily wetted by general brazing filler metals; the other is that the thermal expansion coefficients of ceramics and metals are too different, and the welded parts crack due to the large difference in expansion coefficients. Traditional ceramic brazing methods require pre-metallization of the ceramic surface using Mo-Mn, PVD, CVD and other methods. These treatment processes are complicated, long-term, and costly, which are not conducive to modern and diversified production needs. Therefore, it is imperative to develop highly reliable active brazing materials for direct brazing of ceramic connections, and alloy brazing materials that meet the different brazing temperature requirements of complex combination devices, to effectively solve the problem of direct welding of ceramic-ceramic and ceramic-metal materials.

[0003] The technology to realize the direct connection of metal-based composite ceramics is the active brazing connection technology, which utilizes the metallurgical combination of active elements (such as Ti, Zr, Nb, V, Hf) in the active brazing filler metal and the ceramic interface to realize the connection of metal-based composite ceramics. At present, the industry research is mainly centered on AgCuTi active brazing filler metal. This alloy brazing filler metal is based on the Ag-28Cu eutectic brazing filler metal and adds 1-8% Ti elements to obtain a melting temperature range of 780-850°C. It has a good metallurgical reaction to ceramics and is widely used. There are also studies on adding melting-reducing elements (such as In, Sn, etc.) to the AgCuTi alloy to obtain an active brazing filler metal with a melting temperature below 750°C. There are also studies on Au-based, Ni-based and other active brazing fillers, which have higher melting temperatures but are expensive and are mainly formed in an amorphous state. The research direction of Cu-based active solder is mainly concentrated in CuTi and CuSnTi. The Ti content in CuTi alloy reaches 23%, and there is a eutectic point near 880℃, but a large amount of TiCu intermetallic compounds in the alloy basically cannot be formed; by adjusting the addition ratio of Sn and Ti elements in CuSnTi alloy, a multi-group alloy with a melting point between 820 and 920℃ can be obtained, but the metallurgical effect on metal-based composite ceramics is worse than that of AgCuTi. There is no research report on Cu-based active solder between 950 and 1000℃. Secondly, CuSnTi has poor high-temperature service performance, low joint strength, and easy cracking of welded joints at high temperatures, which also restricts the application of Cu-based active solder in high-temperature service environments.

[0004] In addition, most metal-based composite ceramic devices need to be used for a long time at high temperature (over 500°C) in a vacuum environment. The Ag element in the Ag-based active solder can easily generate metal vapor, which pollutes the ceramic device and therefore cannot be used. Multilayer ceramic structure devices often require multiple brazing gradients to achieve complex structure packaging. Conventional active solders are basically between 750 and 900°C, and there is no choice for the upper level solder. Therefore, the design melting temperature is between 950 and 1000°C, and the brazing temperature is within 1100°C. High-strength, high-temperature fatigue-resistant Cu-based active solder has important practical application value. Summary of the invention

[0005] In view of the problems existing in the prior art, the present invention provides a CuGeTiNi quaternary near-eutectic high-temperature active solder, which has a melting point of 960-975°C, a recommended brazing temperature of 1000-1100°C, and a product form including foil strip, wire, and powder paste. It is an Ag-free high-temperature active alloy solder with high-temperature brazing, high-temperature service, and high strength. The alloy solder is suitable for high-temperature direct encapsulation of metal-based composite ceramics, high-temperature brazing of diamond-material devices, and vacuum brazing of refractory metals. It can obtain high-strength welds, has a high service temperature, and is low in cost, and can effectively avoid the problem of Ag element vapor contamination of devices.

[0006] To achieve the above object, the present invention adopts the following technical solutions:

[0007] A Ag-free high-temperature active alloy solder comprises: Ge 9.5-12.5wt%, Ti 9-11wt%, Ni 0.1-1.5wt%, and Cu as the balance.

[0008] The Ag-free high temperature active alloy solder as described above preferably has the following composition: Ge 10.2-11.2wt%, Ti 9.2-10.2wt%, Ni 0.3-0.5wt%, and Cu as the balance.

[0009] On the other hand, the present invention provides a method for preparing the Ag-free high temperature active alloy solder as described above, the method comprising the following steps:

[0010] I. Raw material selection: prepare Cu, Ge, Ti and Ni with purity greater than 5N as raw materials, among which Cu and Ti are 5N spherical powders;

[0011] II. The metals in step I are vacuum melted to prepare Cu~40Ge and Cu-10Ni master alloys respectively;

[0012] III. Spherical vacuum gas atomization: The master alloys Cu-40Ge and Cu-10Ni obtained in step II were vacuum gas atomized and pulverized, and ultrasonic screening was selected to obtain spherical alloy powders with a particle size range of 25 to 75 μm;

[0013] IV. Centrifugal ball milling: The Cu-40Ge, Cu-10Ni master alloy powder obtained in step III, the Cu powder and the Ti powder in step I are weighed according to the composition ratio, placed in a stainless steel grinding tank, and centrifuged;

[0014] V. Spark plasma sintering: the uniformly mixed powder obtained in step IV is placed in a graphite mold and spark plasma sintered to obtain an alloy ingot with uniform composition;

[0015] VI. Homogenization heat treatment: The alloy ingot obtained in step V is subjected to high vacuum heat treatment, with a vacuum degree of ≤2.0×10 -2 Pa, heat treatment temperature: 750-850°C, heat treatment holding time: 6-12h;

[0016] VII. Solder Forming

[0017] A. Wire preparation: The alloy ingot obtained after the heat treatment in step VI is processed by isothermal rotary forging; after pickling and peeling, it is processed by cold drawing to obtain a finished product, and an alloy welding wire with a diameter range of 0.5 to 1.0 mm can be obtained;

[0018] B. Preparation of foil strip: The alloy ingot obtained after the heat treatment in step VI is processed by isothermal hot rolling to a thickness of 0.6-1.0 mm; after pickling and peeling, it is processed by precision cold rolling to a finished product, and an alloy welding sheet with a thickness of ≥0.03 mm can be obtained.

[0019] C. Preparation of powder paste: The alloy ingot obtained after the heat treatment in step VI is powdered by vacuum arc melting, and sieving to obtain alloy spherical powder with a particle size range of 10 to 25 μm; a nitrate-cotton-based binder is added, and the powder and the binder are in a mass percentage of (94 to 96) %: (4 to 6) % to obtain an alloy paste.

[0020] In the preparation method described above, preferably, in step III, the intermediate alloys Cu-40Ge and Cu-10Ni are respectively powdered by vacuum gas atomization, and the vacuum degree is ≤5.0×10 -3 Pa, atomization temperature 1080 ~ 1120 ℃, atomization gas pressure: 8 ~ 10MPa, atomization gas medium is high purity nitrogen, ultrasonic screening is selected to obtain spherical alloy powder with a particle size range of 25 ~ 75μm.

[0021] In the preparation method as described above, preferably, centrifugal ball milling is used in step IV, the ball milling speed is 400-600 rpm, and the ball milling time is 2-4 h.

[0022] In the preparation method as described above, preferably, spark plasma sintering is adopted in step V, with the sintering temperature of the first stage being 620-680°C, the sintering pressure of the first stage being 30-40MPa, and the sintering time of the first stage being 20-50min; the sintering temperature of the second stage being 800-850°C, the sintering pressure of the second stage being 40-60MPa, and the sintering time of the second stage being 30-90min, to obtain an alloy ingot with uniform composition.

[0023] According to the preparation method as described above, preferably, in step A, the alloy ingot is processed by isothermal rotary forging to a diameter of 2.4-3.2 mm, the rotary forging temperature is 580-620°C, and the deformation per pass is 10-15%; after pickling and peeling, it is cold drawn to the finished product, the deformation rate per annealing pass is 15-30%, the intermediate online annealing temperature is 650-750°C, the speed is 0.05-0.12m / min, and the inert atmosphere is protected, so that the alloy welding wire with a diameter range of 0.5-1.0mm can be obtained.

[0024] According to the preparation method described in the method, preferably, in the step B, the alloy ingot is processed by isothermal hot rolling to 0.6-1.0 mm, the hot rolling temperature is 430-470°C, the deformation per pass is 5-15%, and after pickling and peeling, it is processed into a finished product by precision cold rolling, the deformation rate per annealing pass is 30-50%, the vacuum annealing temperature is 650-750°C, and the holding time is 2-3h, so that an alloy welding sheet with a thickness ≥0.03 mm can be obtained.

[0025] In the preparation method described in the method, preferably, in the step C, the alloy ingot is melted by vacuum arc melting, and the powder making vacuum degree is ≤3.0×10 -3 Pa, melt temperature: 1100-1150℃, atomizing pressure of 3-6MPa, atomizing guide tube diameter of 3-5mm, atomizing medium of high-purity argon, after screening, alloy spherical powder with a particle size range of 10-25μm is obtained; with nitrate-cotton-based binder, the powder and agent are in a mass ratio of 95:5 to obtain alloy paste.

[0026] In another aspect, the present invention provides the use of the Ag-free high-temperature active alloy solder as described above as a solder for direct high-temperature encapsulation of ceramics, vacuum high-temperature brazing of diamond-based devices, or vacuum brazing of refractory metals.

[0027] The present invention designs an Ag-free high-temperature active alloy solder and a preparation method. The main design idea is to adjust the respective price adjustment ratios based on the research of CuGe, CuTi, and CuNi alloys, focusing on the ceramic active metallurgical reaction mechanism, combining the physical and chemical properties of the three elements, and obtaining a quaternary near-eutectic high-temperature active solder. The design test process found that the solid solubility of Ge element in Cu is relatively high (800°C, 13%), and an alloy with a lower melting point than the Cu element can be obtained. At the same time, the Ge element improves the wetting fluidity of the alloy, reduces the liquid surface tension of the alloy, and improves the strength of the alloy. However, if the addition exceeds 12.5%, a large amount of ξ-phase intermetallic compounds will be produced, which are extremely brittle and make processing difficult. Moreover, the more the addition amount is, the lower the melting point of the ε phase will be precipitated. Ti is an active element. First, it participates in the metallurgical bonding of ceramics. Secondly, Ti has a good solid solubility in Cu at high temperatures. When the Ti content is 9% to 11%, the melting point of the alloy is basically around 980°C. Secondly, the experiment found that when the Ti content is lower than 8%, the wetting effect on ceramics is extremely poor. Once the Ti content increases, CuTi multiphase intermetallic compounds appear in the alloy, resulting in a sharp drop in the plasticity of the alloy. The addition of Ni further optimizes the melting point of the alloy, making it tend to the eutectic melting point, and can improve the fluidity of the alloy and its wetting ability on the metal end. At the same time, the Ni element is distributed in the Cu element, which can increase the solubility and speed of the Ti element enriched on the ceramic side during the brazing process.

[0028] The beneficial effects of the present invention are as follows:

[0029] 1. The Ag-free high-temperature active alloy solder (CuGeTiNi alloy) of the present invention has a melting temperature of 960-975°C, and after further optimization, the melting temperature is 965-969°C, which is basically a quaternary eutectic solder. The brazing temperature is between 1000-1100°C, filling the gap of active solder in this temperature range.

[0030] 2. The Ag-free high-temperature active alloy solder of the present invention can directly solder ceramics, diamonds, and refractory metals under vacuum and high temperature. The strength of the joint after welding is greater than 200 MPa, which is much higher than that of common active solders.

[0031] 3. Since there are no high vapor pressure elements in the alloy solder, especially no Ag, there is no problem of Ag vapor contamination during high temperature service after welding.

[0032] 4. The Ag-free high-temperature active alloy solder disclosed in the present invention has low cost and can meet the long-term service requirements of vacuum devices at a high temperature of 800°C.

[0033] 5. The CuGeTiNi active solder of the present invention can be used as the highest level of brazing in a multi-level gradient solder.

[0034] 6. The preparation method disclosed in the present invention includes vacuum alloying, spherical gas atomization powder making, centrifugal ball milling powder mixing, spark plasma sintering, homogenization heat treatment, isothermal rolling, isothermal rotary forging, and precision drawing. The method realizes the full-process processing of Cu-based active solder foil, wire, powder paste and other products. The method can quickly realize the preparation of active solder, with a short process and high yield rate, and the obtained product alloy has uniform composition, no micro-segregation of Ti element distribution, and fine structure, solving the problems encountered in the forming of active solder. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] Figure 1 This is a photograph of the solid-liquid phase melting point curve of the Ag-free high-temperature active alloy solder (CuGeTiNi alloy) obtained in Example 1. DETAILED DESCRIPTION

[0036] The Ag-free high temperature active alloy solder and the preparation method thereof will be further described below in conjunction with an example of specific ingredient calculation.

[0037] Table 1 Ratio of each element in the alloy in Examples 1 to 5

[0038]

[0039] Table 2 Weight of each element and master alloy in Examples 1 to 5

[0040]

[0041] Example 1

[0042] I. Raw material selection: prepare high-purity Cu, Ge, Ti and Ni as raw materials according to the composition ratio of Ag-free high-temperature active alloy solder in Table 1, wherein Cu and Ti are 5N spherical powders;

[0043] II. The metals in step I were melted in vacuum to prepare Cu-40Ge and Cu-10Ni master alloys;

[0044] III. Spherical vacuum gas atomization: The master alloys Cu-40Ge and Cu-10Ni obtained in step II are respectively vacuum gas atomized to produce powders, and the vacuum degree is ≤5.0×10 -3 Pa, atomization temperature 1100℃, atomization gas pressure: 8MPa, atomization gas medium is high-purity nitrogen, ultrasonic screening is selected to obtain spherical alloy powder with a particle size range of 25-75μm;

[0045] IV. Centrifugal ball milling: The Cu-40Ge and Cu-10Ni master alloy powders obtained in step III, the Cu powder and the Ti powder in step I are weighed according to the composition ratio in Table 2 and placed in a stainless steel grinding tank. The centrifugal ball mill is used at a ball milling speed of 500 rpm and a ball milling time of 3 h.

[0046] V Spark plasma sintering: The uniformly mixed powder obtained in step IV is placed in a graphite mold, the first stage sintering temperature is 650°C, the first stage sintering pressure is 35MPa, and the first stage sintering time is 30min; the second stage sintering temperature is 800°C, the second stage sintering pressure is 50MPa, and the second stage sintering time is 60min, to obtain an alloy ingot with uniform composition.

[0047] VI. Homogenization heat treatment: The alloy ingot obtained in step V is subjected to high vacuum heat treatment, with a vacuum degree of ≤2.0×10* 2 Pa, heat treatment temperature: 800℃, heat treatment holding time: 12h.

[0048] VII. Solder Forming

[0049] A. Wire preparation: The alloy ingot obtained after heat treatment in step VI is subjected to isothermal rotary forging to a diameter of 3.0 mm, the rotary forging temperature is 600°C, and the deformation rate per pass is 15%; after pickling and peeling, it is subjected to cold drawing to obtain a finished product, the deformation rate per annealing pass is 20%, the intermediate online annealing temperature is 700°C, the speed is 0.1m / min, and the inert atmosphere is protected, and an alloy welding wire with a diameter range of 0.5mm can be obtained;

[0050] B. Preparation of foil strip: The alloy ingot obtained after the heat treatment in step VI is processed by isothermal hot rolling to 0.8 mm, the hot rolling temperature is 450°C, and the deformation is 10% per pass. After pickling and peeling, it is processed into a finished product by precision cold rolling, the deformation rate of each annealing pass is 30%, the vacuum annealing temperature is 700°C, and the holding time is 3h. An alloy welding sheet with a thickness of 0.03 mm can be obtained.

[0051] C. Preparation of powder paste: The alloy ingot obtained after heat treatment in step VI is melted by vacuum arc melting, and the powder making vacuum degree is ≤3.0×10 -3 Pa, melt temperature: 1100℃, atomization pressure of 5MPa, atomization guide tube diameter of 4mm, atomization medium of high-purity argon, after screening, alloy spherical powder with a particle size range of 10-25μm was obtained; with nitrate-cotton-based binder, the mass ratio of powder to agent was 95:5 to obtain alloy paste.

[0052] Example 2

[0053] I. Raw material selection: prepare high-purity Cu, Ge, Ti and Ni as raw materials according to the composition ratio of Ag-free high-temperature active alloy solder in Table 1, wherein Cu and Ti are 5N spherical powders;

[0054] II. The metals in step I were melted in vacuum to prepare Cu-40Ge and Cu-10Ni master alloys;

[0055] III. Spherical vacuum gas atomization: The master alloys Cu-40Ge and Cu-10Ni obtained in step II are respectively vacuum gas atomized to produce powders, and the vacuum degree is ≤5.0×10 -3 Pa, atomization temperature 1100℃, atomization gas pressure: 9MPa, atomization gas medium is high-purity nitrogen, ultrasonic screening is selected to obtain spherical alloy powder with a particle size range of 25-75μm;

[0056] IV. Centrifugal ball milling: The Cu-40Ge and Cu-10Ni master alloy powders obtained in step III, the Cu powder and the Ti powder in step I are weighed according to the composition ratio in Table 2 and placed in a stainless steel grinding tank. The centrifugal ball mill is used at a ball milling speed of 400 rpm and a ball milling time of 4 h.

[0057] V Spark plasma sintering: The uniformly mixed powder obtained in step IV is placed in a graphite mold. The first stage sintering temperature is 650°C, the first stage sintering pressure is 40MPa, and the first stage sintering time is 20min. The second stage sintering temperature is 830°C, the second stage sintering pressure is 50MPa, and the second stage sintering time is 30min to obtain an alloy ingot with uniform composition.

[0058] VI. Homogenization heat treatment: The alloy ingot obtained in step V is subjected to high vacuum heat treatment, with a vacuum degree of ≤2.0×10 -2 Pa, heat treatment temperature: 750℃, heat treatment holding time: 12h;

[0059] VII. Solder Forming

[0060] A. Wire preparation: The alloy ingot obtained after heat treatment in step VI is subjected to isothermal rotary forging to a diameter of 3.0 mm, the rotary forging temperature is 600°C, and the deformation per pass is 10%; after pickling and peeling, it is subjected to cold drawing to obtain a finished product, the deformation rate per annealing pass is 15%, the intermediate online annealing temperature is 650°C, the speed is 0.05m / min, and the inert atmosphere is protected, and an alloy welding wire with a diameter range of 1.0 mm can be obtained;

[0061] B. Preparation of foil strip: The alloy ingot obtained after the heat treatment in step VI is processed by isothermal hot rolling to 0.8 mm, the hot rolling temperature is 450°C, and the deformation rate is 5% per pass. After pickling and peeling, it is processed into a finished product by precision cold rolling, the deformation rate of each annealing pass is 30%, the vacuum annealing temperature is 650°C, and the holding time is 3h. An alloy welding sheet with a thickness of 0.05 mm can be obtained.

[0062] C. Preparation of powder paste: The alloy ingot obtained after heat treatment in step VI is melted by vacuum arc melting, and the powder making vacuum degree is ≤3.0×10 -3 Pa, melt temperature: 1100℃, atomization pressure of 6MPa, atomization guide tube diameter of 3mm, atomization medium of high-purity argon, after screening, alloy spherical powder with a particle size range of 10-25μm was obtained; with nitrate-cotton-based binder, the mass ratio of powder to agent was 95.5:4.5 to obtain alloy paste.

[0063] Example 3

[0064] 1. Raw material selection: prepare high-purity Cu, Ge, Ti and Ni as raw materials according to the composition ratio of Ag-free high-temperature active alloy solder in Table 1, where Cu and Ti are 5N spherical powders;

[0065] II. The metals in step I were melted in vacuum to prepare Cu-40Ge and Cu-10Ni master alloys;

[0066] III. Spherical vacuum gas atomization: The master alloys Cu-40Ge and Cu-10Ni obtained in step II are respectively vacuum gas atomized to produce powders, and the vacuum degree is ≤5.0×10 -3 pa, atomization temperature 1100℃, atomization gas pressure: 8.5MPa, atomization gas medium is high-purity nitrogen, ultrasonic screening is selected to obtain spherical alloy powder with a particle size range of 25-75μm;

[0067] IV. Centrifugal ball milling: The Cu-40Ge and Cu-10Ni master alloy powders obtained in step III, the Cu powder and the Ti powder in step I are weighed according to the composition ratio of the Ag-free high-temperature active alloy solder in Table 1, and are placed in a stainless steel grinding tank and centrifuged at a ball milling speed of 600 rpm for 2 h.

[0068] V Spark plasma sintering: The uniformly mixed powder obtained in step IV is placed in a graphite mold. The first stage sintering temperature is 650°C, the first stage sintering pressure is 35MPa, and the first stage sintering time is 50min. The second stage sintering temperature is 850°C, the second stage sintering pressure is 50MPa, and the second stage sintering time is 90min to obtain an alloy ingot with uniform composition.

[0069] VI. Homogenization heat treatment: The alloy ingot obtained in step V is subjected to high vacuum heat treatment, with a vacuum degree of ≤2.0×10 -2 Pa, heat treatment temperature: 850°C, heat treatment holding time: 6h;

[0070] VII. Solder Forming

[0071] A. Wire preparation: The alloy ingot obtained after heat treatment in step VI is subjected to isothermal rotary forging to a diameter of 3.0 mm, the rotary forging temperature is 600°C, and the deformation per pass is 15%; after pickling and peeling, it is subjected to cold drawing to obtain a finished product, the deformation rate per annealing pass is 30%, the intermediate online annealing temperature is 750°C, the speed is 0.12m / min, and the inert atmosphere is protected, and an alloy welding wire with a diameter range of 0.8mm can be obtained;

[0072] B. Preparation of foil strip: The alloy ingot obtained after the heat treatment in step VI is processed by isothermal hot rolling to 0.8 mm, the hot rolling temperature is 450°C, and the deformation rate is 15% per pass. After pickling and peeling, it is processed into a finished product by precision cold rolling, the deformation rate of each annealing pass is 50%, the vacuum annealing temperature is 750°C, and the holding time is 2h. An alloy welding sheet with a thickness of 0.03 mm can be obtained.

[0073] C. Preparation of powder paste: The alloy ingot obtained after heat treatment in step VI is melted by vacuum arc melting, and the powder making vacuum degree is ≤3.0×10 -3 Pa, melt temperature: 1150℃, atomization pressure of 3MPa, atomization guide tube diameter of 5mm, atomization medium of high-purity argon, after screening, alloy spherical powder with a particle size range of 10-25μm was obtained; with nitrate-cotton-based binder, the mass ratio of powder to agent was 95:5 to obtain alloy paste.

[0074] Example 4

[0075] 1. Raw material selection: prepare high-purity Cu, Ge, Ti and Ni as raw materials according to the composition ratio of Ag-free high-temperature active alloy solder in Table 1, where Cu and Ti are 5N spherical powders;

[0076] 2. II. The metals in step I are vacuum melted to prepare Cu-40Ge and Cu-10Ni master alloys respectively;

[0077] III. Spherical vacuum gas atomization: The master alloys Cu-40Ge and Cu-10Ni obtained in step II are respectively vacuum gas atomized to produce powders, and the vacuum degree is ≤5.0×10 -3 Pa, atomization temperature 1120℃, atomization gas pressure: 8MPa, atomization gas medium is high-purity nitrogen, ultrasonic screening is selected to obtain spherical alloy powder with a particle size range of 25-75μm;

[0078] IV. Centrifugal ball milling: The Cu-40Ge and Cu-10Ni master alloy powders obtained in step III, the Cu powder and the Ti powder in step I are weighed according to the composition ratio in Table 2 and placed in a stainless steel grinding tank. The centrifugal ball mill is used at a ball milling speed of 400 rpm and a ball milling time of 2 h.

[0079] V Spark plasma sintering: The uniformly mixed powder obtained in step IV is placed into a graphite mold. The first stage sintering temperature is 680°C, the first stage sintering pressure is 40MPa, and the first stage sintering time is 20min. The second stage sintering temperature is 850°C, the second stage sintering pressure is 40MPa, and the second stage sintering time is 90min to obtain an alloy ingot with uniform composition.

[0080] VI. Homogenization heat treatment: The alloy ingot obtained in step V is subjected to high vacuum heat treatment, with a vacuum degree of ≤2.0×10 -2 Pa, heat treatment temperature: 750℃, heat treatment holding time: 6h;

[0081] VII. Solder Forming

[0082] A. Wire preparation: The alloy ingot obtained after heat treatment in step VI is subjected to isothermal rotary forging to a diameter of 3.2 mm, the rotary forging temperature is 600°C, and the deformation per pass is 10%; after pickling and peeling, it is subjected to cold drawing to obtain a finished product, the deformation rate per annealing pass is 15%, the intermediate online annealing temperature is 650°C, the speed is 0.08m / min, and the inert atmosphere is protected, and an alloy welding wire with a diameter range of 1.0mm can be obtained;

[0083] B. Preparation of foil strip: The alloy ingot obtained after the heat treatment in step VI is processed by isothermal hot rolling to 1.0 mm, the hot rolling temperature is 450°C, and the deformation rate is 10% per pass. After pickling and peeling, it is processed into a finished product by precision cold rolling, the deformation rate of each annealing pass is 30%, the vacuum annealing temperature is 650°C, and the holding time is 2h. An alloy welding sheet with a thickness of 0.12 mm can be obtained.

[0084] C. Preparation of powder paste: The alloy ingot obtained after heat treatment in step VI is melted by vacuum arc melting, and the powder making vacuum degree is ≤3.0×10 -3 Pa, melt temperature: 1100℃, atomization pressure of 5MPa, atomization guide tube diameter of 3mm, atomization medium of high-purity argon, after screening, alloy spherical powder with a particle size range of 10-25μm was obtained; with nitrate-cotton-based binder, the mass ratio of powder to agent was 96:4 to obtain alloy paste.

[0085] Example 5

[0086] 1. Raw material selection: prepare high-purity Cu, Ge, Ti and Ni as raw materials according to the composition ratio of Ag-free high-temperature active alloy solder in Table 1, where Cu and Ti are 5N spherical powders;

[0087] II. The metals in step I were melted in vacuum to prepare Cu-40Ge and Cu-10Ni master alloys;

[0088] III. Spherical vacuum gas atomization: The master alloys Cu-40Ge and Cu-10Ni obtained in step II are respectively vacuum gas atomized to produce powders, and the vacuum degree is ≤5.0×10 -3 Pa, atomization temperature 1080℃, atomization gas pressure: 9MPa, atomization gas medium is high-purity nitrogen, ultrasonic screening is selected to obtain spherical alloy powder with a particle size range of 25-75μm;

[0089] IV. Centrifugal ball milling: The Cu-40Ge and Cu-10Ni master alloy powders obtained in step III, the Cu powder and the Ti powder in step I are weighed according to the composition ratio in Table 2, and are placed in a stainless steel grinding jar and centrifuged at a ball milling speed of 600 rpm for 4 h.

[0090] V Spark plasma sintering: The uniformly mixed powder obtained in step IV is placed in a graphite mold. The first stage sintering temperature is 620°C, the first stage sintering pressure is 40MPa, and the first stage sintering time is 30min. The second stage sintering temperature is 850°C, the second stage sintering pressure is 60MPa, and the second stage sintering time is 30min to obtain an alloy ingot with uniform composition.

[0091] VI. Homogenization heat treatment: The alloy ingot obtained in step V is subjected to high vacuum heat treatment, with a vacuum degree of ≤2.0×10 -2 Pa, heat treatment temperature: 850°C, heat treatment holding time: 12h;

[0092] VII. Solder Forming

[0093] A. Wire preparation: The alloy ingot obtained after heat treatment in step VI is subjected to isothermal rotary forging to a diameter of 2.8 mm, the rotary forging temperature is 600°C, and the deformation per pass is 15%; after pickling and peeling, it is subjected to cold drawing to obtain a finished product, the deformation rate per annealing pass is 30%, the intermediate online annealing temperature is 750°C, the speed is 0.12m / min, and the inert atmosphere is protected, and an alloy welding wire with a diameter range of 0.5mm can be obtained;

[0094] B. Preparation of foil strip: The alloy ingot obtained after the heat treatment in step VI is processed by isothermal hot rolling to 0.6 mm, the hot rolling temperature is 450°C, and the deformation rate is 15% per pass. After pickling and peeling, it is processed into a finished product by precision cold rolling, the deformation rate of each annealing pass is 50%, the vacuum annealing temperature is 650°C, and the holding time is 3h. An alloy welding sheet with a thickness of 0.03 mm can be obtained.

[0095] C. Preparation of powder paste: The alloy ingot obtained after heat treatment in step VI is melted by vacuum arc melting, and the powder making vacuum degree is ≤3.0×10 -3 Pa, melt temperature: 1150℃, atomization pressure of 6MPa, atomization guide tube diameter of 3mm, atomization medium of high-purity argon, after screening, alloy spherical powder with a particle size range of 10-25μm was obtained; with nitrate-cotton-based binder, the mass ratio of powder to agent was 94:6 to obtain alloy paste.

[0096] Example 6

[0097] The Ag-free high temperature active alloy solders prepared in Examples 1-5 were tested for melting point, wettability (BeO), tensile strength (BeO / Kovar), etc. The test data obtained are shown in Table 3.

[0098] Table 3 Performance of high elongation SnPbSbInAu alloy solders of Examples 1 to 6

[0099] Example Melting temperature Melting Range Brazing temperature Spread coefficient tensile strength 1 965.16～968.51℃ 3.35℃ 1020℃ 94.7％ 243MPa 2 965.36～969.03℃ 3.67℃ 1020℃ 94.2％ 238MPa 3 964.12～967.78℃ 3.66℃ 1020℃ 94.5％ 240MPa 4 970.61～974.89℃ 4.28℃ 1020℃ 93.1％ 225MPa 5 965.86～970.24℃ 4.38℃ 1020℃ 93.2％ 227MPa

[0100] like Figure 1As shown, it is a differential thermal curve of Ag-free high-temperature active alloy solder prepared in Example 1. It can be seen from the figure that the CuGeTiNi active solder temperature obtained by adopting the alloy proportion and preparation method designed in the present invention is 965.16-968.51°C, the melting range is 3.35°C, the exothermic peak curve is smooth and obvious, there is no low-melting point phase precipitation and phase change, considering the equipment testing accuracy, the alloy melting point can be regarded as 967°C eutectic temperature, which meets the patent design requirements.

[0101] The above embodiments only cite some embodiments of the Ag-free high-temperature active alloy solder and the preparation method thereof of the present invention. In the above technical scheme of the present invention: the alloy composition, key parameters in the preparation process, etc. can be freely selected within the prescribed range and are no longer listed here one by one. Therefore, the technical scheme contained in the above description should be regarded as illustrative rather than used to limit the scope of protection of the patent application of the present invention.

Claims

1. An Ag-free high temperature active alloy solder, characterized in that: The composition thereof is: Ge 9.5-12.5wt%, Ti 9-11wt%, Ni 0.1-1.5wt%, and Cu as the balance.

2. The Ag-free high temperature active alloy solder according to claim 1, characterized in that: The composition thereof is: Ge 10.2-11.2wt%, Ti 9.2-10.2wt%, Ni 0.3-0.5wt%, and Cu as the balance.

3. The method for preparing the Ag-free high temperature active alloy solder according to claim 1 or 2, characterized in that: The method comprises the following steps: I. Raw material selection: prepare Cu, Ge, Ti and Ni with purity greater than 5N as raw materials, among which Cu and Ti are 5N spherical powders; II. The metals in step I were melted in vacuum to prepare Cu-40Ge and Cu-10Ni master alloys; III. Spherical vacuum gas atomization: The master alloys Cu-40Ge and Cu-10Ni obtained in step II were vacuum gas atomized and pulverized, and ultrasonic screening was selected to obtain spherical alloy powders with a particle size range of 25 to 75 μm; IV. Centrifugal ball milling: The Cu-40Ge, Cu-10Ni master alloy powder obtained in step III, the Cu powder and the Ti powder in step I are weighed according to the composition ratio, placed in a stainless steel grinding tank, and centrifuged; V. Spark plasma sintering: the uniformly mixed powder obtained in step IV is placed in a graphite mold and spark plasma sintered to obtain an alloy ingot with uniform composition; VI. Homogenization heat treatment: The alloy ingot obtained in step V is subjected to high vacuum heat treatment, with a vacuum degree of ≤2.0×10 - 2 Pa, heat treatment temperature: 750-850°C, heat treatment holding time: 6-12h; VII. Solder Forming A. Wire preparation: The alloy ingot obtained after the heat treatment in step VI is processed by isothermal rotary forging; after pickling and peeling, it is processed by cold drawing to obtain a finished product, and an alloy welding wire with a diameter range of 0.5 to 1.0 mm can be obtained; B. Preparation of foil strip: The alloy ingot obtained after the heat treatment in step VI is processed by isothermal hot rolling to a thickness of 0.6-1.0 mm; after pickling and peeling, it is processed by precision cold rolling to a finished product, and an alloy welding sheet with a thickness of ≥0.03 mm can be obtained. C. Preparation of powder paste: The alloy ingot obtained after the heat treatment in step VI is powdered by vacuum arc melting, and sieving to obtain alloy spherical powder with a particle size range of 10 to 25 μm; The alloy paste is prepared by mixing a nitrate-cotton-based binder with the powder and the binder in a mass percentage of (94-96) %: (4-6) %.

4. The preparation method according to claim 3, characterized in that: In step III, the master alloys Cu-40Ge and Cu-10Ni are respectively powdered by vacuum gas atomization, and the vacuum degree is ≤5.0×10 -3 Pa, atomization temperature 1080 ~ 1120 ℃, atomization gas pressure: 8 ~ 10MPa, atomization gas medium is high purity nitrogen, ultrasonic screening is selected to obtain spherical alloy powder with a particle size range of 25 ~ 75μm.

5. The preparation method according to claim 3, characterized in that: In step IV, centrifugal ball milling is used, the ball milling speed is 400-600 rpm, and the ball milling time is 2-4 hours.

6. The preparation method according to claim 3, characterized in that: In step V, spark plasma sintering is adopted, the first stage sintering temperature is 620-680° C., the first stage sintering pressure is 30-40 MPa, and the first stage sintering time is 20-50 min; The second stage sintering temperature is 800-850°C, the second stage sintering pressure is 40-60MPa, and the second stage sintering time is 30-90min to obtain an alloy ingot with uniform composition.

7. The preparation method according to claim 3, characterized in that: In step A, the alloy ingot is processed by isothermal rotary forging to a diameter of 2.4-3.2 mm, the rotary forging temperature is 580-620° C., and the deformation per pass is 10-15%; after pickling and peeling, it is processed by cold drawing to a finished product, the deformation rate per annealing pass is 15-30%, the intermediate online annealing temperature is 650-750° C., the speed is 0.05-0.12 m / min, and the inert atmosphere is protected, so that the alloy welding wire with a diameter range of 0.5-1.0 mm can be obtained.

8. The preparation method according to claim 3, characterized in that: In the step B, the alloy ingot is processed to 0.6-1.0 mm by isothermal hot rolling, the hot rolling temperature is 430-470°C, the deformation is 5N15% per pass, and after pickling and peeling, it is processed to a finished product by precision cold rolling, the deformation rate per annealing pass is 30-50%, the vacuum annealing temperature is 650-750°C, and the holding time is 2-3h, so that an alloy welding sheet with a thickness of ≥0.03 mm can be obtained.

9. The preparation method according to claim 3, characterized in that: In step C, the alloy ingot is melted by vacuum arc melting, and the powder making vacuum degree is ≤3.0×10 -3 Pa, melt temperature: 1100-1150℃, atomizing pressure of 3-6MPa, atomizing guide tube diameter of 3-5mm, atomizing medium of high-purity argon, after screening, alloy spherical powder with a particle size range of 10-25μm is obtained; with nitrate-cotton-based binder, the powder and agent are in a mass ratio of 95:5 to obtain alloy paste.

10. Application of the Ag-free high temperature active alloy solder as claimed in claim 1 or 2 as solder for direct high temperature encapsulation of ceramics, vacuum high temperature brazing of diamond material devices or vacuum brazing of refractory metals.

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