Braze alloy

Abstract

The present invention relates to a brazing alloy composition comprising, in wt%: 80 to 97.98% of Cu; 2.0 < = Ge < = 9.5; the volume is 0.02 lt; b < = 1.25; and incidental impurities. The brazing alloy composition includes no more than 0.4% Sn.

Description

Technical Field

[0001] This invention relates to brazing alloys and components thereof for high-temperature hermetic housings, including brazed joints; and a process for producing brazed joints using said brazing alloys. Background Technology

[0002] A high-pressure vacuum tube consists of an anode and a cathode, which are positioned opposite each other within a vacuum interior space. The vacuum interior space is typically surrounded by a cylindrical metal casing, and the anode and / or cathode are electrically insulated by a ring-shaped insulator.

[0003] A high-voltage vacuum tube is a device that controls the flow of current in a high vacuum between electrodes. The filament (heater) and electron bombardment of the anode generate a large amount of heat. High-voltage applications of vacuum tubes include X-ray tubes, magnetrons, traveling wave tubes, exciton tubes, and klystrons.

[0004] High-voltage vacuum tubes typically use ceramic insulators to isolate high-voltage and low-voltage regions. For example, the anode under high voltage can be isolated from the vacuum tube body via a ceramic insulator. The vacuum tube body is typically attached to the ceramic insulator. A metal sealing ring can be brazed to the outer surface of the ceramic insulator, thereby connecting the body to the ceramic insulator. This connection forms a three-phase junction between the ceramic insulator, the sealing ring, and the surrounding medium. The electric field at this three-phase junction can be relatively high, generating electrons that can potentially become sources of arcing and / or perforation. US Patent 4126803 discloses a high-voltage structure in which the insulator is part of the vacuum chamber.

[0005] X-ray tubes used for various applications are known to apply a high-voltage direct current or alternating current between the anode and cathode, with the applied voltage reaching hundreds of kilovolts depending on the required radiation intensity. In such X-ray tubes, the necessary insulation path is primarily arranged along the axial direction.

[0006] As described in US Patent US20210134553, the bonding of iron-nickel-cobalt or iron-nickel alloys with niobium may require brazing alloys with a liquidus temperature above approximately 900°C to achieve the desired wettability and brazing fluidity. The choice of brazing material can be adjusted according to the desired wettability and brazing fluidity, for example, a 50 / 50 Au / Cu mixture, an 81.5 / 16.5 Au / Cu mixture (Nicoro... TM -80) and 82 / 18 Au / Cu mixture (Nioro TM ).

[0007] Gold-copper brazing materials belong to the broader family of high-temperature brazing materials, which are based on precious metals (palladium, platinum, gold, and silver) with the addition of nickel and copper. They exhibit good mechanical properties and oxidation resistance at high temperatures. In vacuum brazing applications, Cu-Ge based alloys are often used as alternatives to precious metal brazing alloys (such as Au-Cu and Cu-Ag based alloys).

[0008] Non-precious metal alloys, such as Cu-Ge alloys (trade name Gemco) TM Alloys with a nominal composition of 87.75% Cu, 12% Ge, and 0.25% Ni have been used for vacuum brazing of copper, steel, and nickel-based metals. However, the wide range between the solidus and liquidus temperatures of these alloys, known as the solidification temperature range (STR), can lead to liquefaction problems in brazing applications. Liquefaction in brazing refers to the phenomenon where the lower-melting-point components of the brazing alloy separate from and flow away from the higher-melting-point components during heating. Liquefaction occurs when an alloy is slowly heated to its melting point range (e.g., in furnace brazing), manifesting as unmelted alloy lumps remaining at the brazing alloy coating. This typically leads to reduced joint strength due to the presence of brittle intermetallic compound phases in the brazed joint. Liquefaction is usually more pronounced in alloys with a large STR. Brazing operations performed in furnaces with large temperature fluctuations are also prone to liquefaction, especially when the brazing alloy has a large STR.

[0009] Another problem with brazing alloys with high STR (Stretch Strength) is that they cannot be used for step brazing when using cryogenic alloys for step brazing complex joints. During step brazing, the liquidus temperature of the cryogenic filler metal approaches the solidus temperature of the high-temperature filler metal (due to the latter's high STR), which can lead to changes in component dimensions.

[0010] SU564128 discloses a brazing alloy composition with good wettability at 1000℃, comprising: 9.5-11 wt% Ge; 0.8-1.3 wt% Sn; 0.03-0.15 wt% B, Co, and Fe group elements; with the balance being Cu. By increasing the Ge content and decreasing the B content, this alloy composition overcomes the shortcomings of the SU255015 brazing alloy composition. Although suitable for brazing temperatures of 1000-1040℃, it suffers from poor formability; cracks begin to appear when the initial billet is rolled to a reduction rate of only 14%. Its composition range is: 6.5 to 9 wt% Ge; 0.1 to 2.5 wt% Ni; 0.5 to 1.5 wt% Sn; 0.05 to 0.25 wt% Co; 0.05 to 0.25 wt% B; with the balance being Cu.

[0011] While these brazing alloy compositions partially address the demand for alternatives to brazing alloys containing significant amounts of precious metals, there remains a market demand for brazing alloys, brazing components, and devices comprising parts made from alternative brazing materials that are sufficiently ductile, can be fabricated into wires, foils, and preforms, and do not rely on large amounts of precious metals. Furthermore, these brazing alloys should have sufficiently low STRs compared to traditional non-precious metal brazing alloys to avoid or reduce the risk of liquefaction. Summary of the Invention

[0012] A first aspect of the present invention provides a brazing alloy composition comprising, by weight percent:

[0013] Cu from 80 to 97.98;

[0014] 2.0 ≤ Ge ≤ 9.5;

[0015] 0.02 < B ≤ 1.25; and

[0016] Impurities

[0017] The brazing alloy composition includes no more than 0.4 wt% Sn.

[0018] The copper content in the brazing alloy can be greater than 85 wt%, or greater than 87 wt%, or greater than 89 wt%, or greater than 91 wt%, or greater than 93 wt% (as a percentage of the total weight). Alternatively, the copper content in the brazing alloy can not exceed 96 wt%, or not exceed 94 wt%, or not exceed 92 wt% (as a percentage of the total weight).

[0019] In one embodiment, the brazing alloy composition may further include balancing additives other than Cu, Ge, and B. In another embodiment, the brazing alloy composition may further include 0 to 10 wt% (or 0 to 5 wt%) of additives excluding Cu, Ge, and B. In some embodiments, the additives are selected from one or more elements selected from the group consisting of rare earth metals and transition metals, but excluding Cu. In some embodiments, the content of Sn is no more than 0.2 wt%, or it is present as an incidental impurity. In other embodiments, Sn is present as an optional additive.

[0020] In some embodiments, additives constitute the remainder of the brazing alloy composition, in addition to copper, germanium, boron, and tin. The content of the additives may exceed 0.1 wt% of the total weight of the brazing alloy composition.

[0021] The composition of brazing alloys is typically crystalline. However, in some embodiments, it can be at least partially amorphous.

[0022] On the other hand, the brazing alloy composition, expressed as a percentage by weight, includes:

[0023] 2.0 ≤ Ge ≤ 9.5 and 0 ≤ Al ≤ 2.0; 0 ≤ Si ≤ 1.0; 0 ≤ In ≤ 2.0;

[0024] 0.02 < B ≤ 1.25;

[0025] Additives ranging from 0 to 5.0;

[0026] Containing impurities; and

[0027] The rest is Cu.

[0028] The tin content in the additives and impurities does not exceed 0.4 wt% of the total weight of the brazing alloy components.

[0029] The additives may include or be composed of one or more additives (i.e. elements) selected from the group consisting of transition metals and rare earth metals.

[0030] The brazing alloy composition is preferably suitable for vacuum tubes and possesses the required properties, including low vapor pressure and low magnetism. The requirement for low magnetism limits the amounts of Ni, Co, and Fe. In some embodiments, the total content of Ni, Co, and Fe does not exceed 4.0 wt%, or 3.0 wt%, or 2.0 wt%, or 1.0 wt%.

[0031] The brazing alloy composition of this invention is suitable for high-temperature brazing, particularly brazing under vacuum conditions, providing an alternative with non-precious metal or low-precious metal content. The applicant has identified a narrow composition range that yields a brazing alloy with an ideal liquidus temperature, solidification temperature range (STR), and good formability, capable of forming an hermetically tight seal under low pressure.

[0032] For the purposes of this invention, good formability means that the brazing alloy has a formability of at least 38% (determined according to the formability test described herein), and / or the brazing alloy can be drawn into wires with diameters as small as 0.030 inches (0.76 mm), preferably as small as at least 0.015 inches (0.38 mm). Typically, wires with a maximum diameter of 0.10 inches can be used, but larger diameter wires can also be manufactured as needed.

[0033] It should be understood that, in various embodiments, the brazing alloy composition may include the components described above in weight percentages. Therefore, the first aspect of the invention may also relate to a brazing alloy composition comprising the following weight percentages:

[0034] 2.0 ≤ Ge ≤ 9.5, and 0 ≤ Al ≤ 2.0; 0 ≤ Si ≤ 1.0; and 0 ≤ In ≤ 2.0;

[0035] 0.02 < B ≤ 1.25;

[0036] The additives are 0 to 5.0, preferably selected from the group consisting of transition metals and rare earth metals;

[0037] Containing impurities; and

[0038] The rest is Cu.

[0039] The tin content in the additives and impurities shall not exceed 0.4 wt% of the total weight of the brazing alloy components.

[0040] In one embodiment, the brazing alloy composition, by weight percent, includes:

[0041] 2.5 ≤ Ge ≤ 7.4, and 0 ≤ Al ≤ 2.0; 0 ≤ Si ≤ 1.0; and 0 ≤ In ≤ 2.0;

[0042] 0.25 < B ≤ 0.75;

[0043] The additives are 0 to 3.0, preferably selected from the group consisting of transition metals and rare earth metals;

[0044] Containing impurities; and

[0045] The rest is Cu.

[0046] The tin content in the additives and impurities shall not exceed 0.4 wt% of the total weight of the brazing alloy components.

[0047] In another embodiment, the brazing alloy composition, by weight percent, includes:

[0048] 3.0 ≤ Ge ≤ 6.2, and 0 ≤ Al ≤ 2.0; 0 ≤ Si ≤ 1.0; and 0 ≤ In ≤ 2.0;

[0049] 0.3 < B ≤ 0.70;

[0050] The additives are 0 to 2.0, preferably selected from the group consisting of transition metals and rare earth metals;

[0051] Containing impurities; and

[0052] The rest is Cu.

[0053] The tin content in the additives and impurities shall not exceed 0.4 wt% of the total weight of the brazing alloy components.

[0054] In another embodiment, the brazing alloy composition, by weight percent, includes:

[0055] 2.0 ≤ Ge ≤ 6.3, and 0 ≤ Al ≤ 2.0; 0 ≤ Si ≤ 1.0; and 0 ≤ In ≤ 2.0;

[0056] 0.02 < B ≤ 1.25;

[0057] Additives ranging from 0 to 5.0;

[0058] Containing impurities; and

[0059] The rest is Cu.

[0060] The tin content in the additives and impurities shall not exceed 0.4 wt% of the total weight of the brazing alloy components.

[0061] In another embodiment, the brazing alloy composition, by weight percent, includes:

[0062] 2.0 ≤ Ge ≤ 9.5, and 0 ≤ Al ≤ 2.0; 0 ≤ Si ≤ 1.0; and 0 ≤ In ≤ 2.0;

[0063] 0.27 < B ≤ 1.25;

[0064] Additives ranging from 0 to 5.0;

[0065] Containing impurities; and

[0066] The rest is Cu.

[0067] The tin content in the additives and impurities shall not exceed 0.4 wt% of the total weight of the brazing alloy components.

[0068] It should be understood that, in some embodiments, the brazing alloy composition may include the weight percentages of each component specified in the specification.

[0069] Brazing alloys within this composition range have lower STR values ​​and higher liquidus temperatures, making them suitable for joining substrates containing at least copper.

[0070] In some embodiments, the sum of Ge+B+Cu is greater than 85.0 wt%, or greater than 90.0 wt%, or greater than 95.0 wt%, or greater than 96.0 wt%, or greater than 97.0 wt%, or greater than 98.0 wt%, or greater than 99.0 wt%, or greater than 99.5 wt%, or greater than 99.7 wt% of the total weight of the brazing alloy components.

[0071] It is important to note that if the content of a certain element, compound, or other component is described as a numerical range including 0 or a numerical range without a lower limit, then the content of that element, compound, or other component can be zero. In other words, that element, compound, or other component may be absent and is therefore optional.

[0072] germanium content

[0073] A germanium content below 2.0 wt% results in an excessively high liquidus temperature in the brazing alloy, making it unsuitable for brazing copper or copper-based alloys. In some embodiments, the germanium content of the brazing alloy is at least 2.2 wt%, or at least 2.5 wt%, or at least 2.7 wt%, or at least 2.9 wt%, or at least 3.1 wt%, or at least 3.3 wt%, or at least 3.5 wt%, or at least 3.7 wt%, or at least 3.9 wt%, or at least 4.1 wt%, or at least 4.3 wt%, or at least 4.5 wt%, or at least 4.7 wt%. When the germanium content is above 10 wt%, the liquidus temperature of the brazing alloy composition is low.

[0074] When the germanium content is higher than 9.5 wt%, its solidification temperature range (STR) is high, which is not ideal for brazing applications, especially stepped brazing. Studies have found that when the Ge content is lower than 10 wt%, the STR value is acceptable in many applications. Although the liquidus temperature is increased, it is still within the target liquidus temperature range for brazing, such as brazing copper (or copper alloys) to substrates such as stainless steel (e.g., 900 to 1050 °C).

[0075] In some embodiments, the germanium content is no more than 9.3 wt%, or no more than 9.0 wt%, or no more than 8.5 wt%, or no more than 8.0 wt%, or no more than 7.5 wt%, or no more than 7.2 wt%, or no more than 7.0 wt%, or no more than 6.5 wt%, or no more than 6.4 wt%, or no more than 6.3 wt%, or no more than 6.2 wt%, or no more than 6.1 wt%, or no more than 6.0 wt%, or no more than 5.8 wt%, or no more than 5.5 wt%, or no more than 5.2 wt%, or no more than 5.0 wt%.

[0076] In one embodiment, the germanium content is 2.5 wt% to 7.4 wt%, or 3.0 wt% to 6.5 wt%, or 3.5 wt% to 6.3 wt%, or 3.8 wt% to 6.0 wt%, or 4.0 wt% to 5.8 wt%. Studies have found that germanium content within these composition ranges can achieve both a low STR value and relatively good formability for a given boron content.

[0077] Optional liquidus temperature inhibitors

[0078] As described in the first aspect of the invention, the amount of optional liquidus temperature inhibitors of aluminum, indium and silicon helps to reduce the liquidus temperature of the brazing alloy while maintaining a relatively small solidification temperature range (STR).

[0079] Studies have found that aluminum, indium, and silicon require relatively smaller amounts to lower the liquidus temperature of brazing alloy compositions compared to germanium. Generally, it is believed that, on a weight percentage basis, more germanium is needed to lower the liquidus temperature than any combination of aluminum, indium, and silicon (e.g., 2.5 wt% germanium has the same ability to lower the liquidus temperature as 1.0 wt% aluminum, indium, and silicon). For example, instead of using 7.25 wt% germanium, consider using 3.0 wt% germanium and 1.7 wt% indium, or 5.5 wt% germanium and 0.7 wt% indium.

[0080] As those skilled in the art understand, the exact amount of reduction in equivalent liquidus temperature can vary depending on the specific liquidus temperature inhibitor used and the overall composition of the brazing alloy. Furthermore, studies have found that relatively small amounts of aluminum, indium, and silicon, compared to germanium, can adversely affect the STR or liquidus temperature of the brazing alloy composition. Therefore, in the total amount of liquidus temperature inhibitors (germanium, indium, silicon, and aluminum), germanium preferably comprises at least 50 wt%, or at least 60 wt%, or at least 70 wt%, or at least 80 wt%, or at least 90 wt%, or at least 95 wt%.

[0081] Boron content

[0082] Adding elemental boron (e.g., boron content > 0.02 wt% or > 0.05 wt% or > 0.10 wt%) has been shown to reduce STR values, while boron content exceeding 1.25 wt% results in insufficient brazing alloy formability, making it impossible to process the brazing alloy into the desired shape (e.g., wire or sheet / foil).

[0083] In some embodiments, the boron content is greater than 0.05 wt%, or greater than 0.10 wt%, or greater than 0.12 wt%, or greater than 0.15 wt%, or greater than 0.20 wt%, or greater than 0.23 wt%, or greater than 0.25 wt%, or greater than 0.27 wt%, or greater than 0.28 wt%, or greater than 0.29 wt%, or greater than 0.30 wt%, or greater than 0.31 wt%, or greater than 0.32 wt%, or greater than 0.33 wt%, or greater than 0.34 wt%, or greater than 0.35 wt%, or greater than 0.37 wt%, or greater than 0.39 wt%. In some embodiments, the boron content is no more than 1.2 wt%, or no more than 1.1 wt%, or no more than 1.0 wt%, or no more than 0.90 wt%, or no more than 0.80 wt%, or no more than 0.75 wt%, or no more than 0.70 wt%, or no more than 0.65 wt%, or no more than 0.60 wt%, or no more than 0.55 wt%, or no more than 0.50 wt%.

[0084] In a preferred embodiment, the boron content is in the range of greater than 0.27 wt% and not exceeding 0.80 wt%. Within this range, the brazing alloy exhibits both good formability and a low STR value.

[0085] additive

[0086] A range of elemental additives (preferably metallic additives) can be added to the alloy composition to improve wettability and flowability during brazing, and / or increase the mechanical strength of the resulting brazed joint. Appropriate additives should be selected so as not to have a significant adverse effect on the brazing alloy's STR, liquidus temperature, formability and / or vapor pressure, or the mechanical integrity or hermeticity of the resulting joint.

[0087] It will be apparent to those skilled in the art that small amounts of additives can be added to brazing alloy compositions to enhance, or at least not impair, the functionality of the brazing alloy composition in a particular system or application. The type and amount of additives should be within the capabilities of those skilled in the art, without requiring excessive experimentation. The scope of this disclosure covers the addition of such additives.

[0088] In some embodiments, the additive includes one or both of transition metals and rare earth metals. The additive may include one or more elements from the group consisting of transition metals. The additive may include one or more elements from the group consisting of rare earth metals.

[0089] In some embodiments, the additive content is greater than 0.0 wt% (>0.0 wt%), therefore the alloy composition must contain a certain amount of additives. For example, in some embodiments, the composition includes >0 to 5.0 wt% of additives selected from the group consisting of transition metals and rare earth metals (excluding copper). The upper limit of the total amount of additives and individual components will be limited by their ability to maintain the functional properties of the brazing alloy, while the lower limit will be limited by the amount required to provide functional advantages to the brazing alloy.

[0090] In some embodiments, the additive contains 0 or >0 to 5 wt% of a transition metal.

[0091] Transition metals and rare earth metals may include scandium, titanium, vanadium, chromium, manganese, iron, cobalt, nickel, zinc, yttrium, zirconium, niobium, molybdenum, technetium, ruthenium, rhodium, silver, cadmium, lanthanum, hafnium, tantalum, tungsten, rhenium, osmium, iridium, mercury, actinium, and so on. , , , , 、鿏、 , , , cerium, praseodymium, neodymium, promethium, samarium, europium, gadolinium, terbium, dysprosium, holmium, erbium, thulium, ytterbium and lutetium.

[0092] In some embodiments, the additive may include a wetting additive selected from niobium, nickel, molybdenum, tungsten, cobalt, and iron.

[0093] In some embodiments, the brazing alloy composition may include one or more liquidus temperature inhibitors, with concentration ranges as follows:

[0094] >0 to 2.0 wt%; or >0 to 1.5 wt%; or >0 to 1.0 wt%; or >0 to 0.5 wt% Al;

[0095] >0 to 1.0 wt%; or >0 to 0.5 wt% Si;

[0096] >0 to 2.0 wt%; or >0 to 1.5 wt%; or >0 to 1.0 wt%; or >0 to 0.5 wt% of In.

[0097] The greater the amount of these elements, the more likely it is to cause a deterioration in the ductility and / or STR of the brazing alloy composition.

[0098] In some embodiments, the additive may include Ag or Zn to further improve the machinability of the brazing alloy.

[0099] Ti, V and / or Zr can also be added to help the brazing alloy bond to the ceramic surface.

[0100] Other transition metals, including precious and / or rare metals, may also be added to improve functional performance. In some embodiments, the proportion of precious metals (either in combination or as an additive of any element) is less than 4.0 wt%, or less than 3.0 wt%, or less than 2.0 wt%, or less than 1.0 wt%, or less than 0.5 wt%. While small proportions of precious metals may provide some functional benefits, their addition is optional.

[0101] In one embodiment, the additive includes one or more of Nb, Ni, Mo, W, Co, Cr, Fe, Ti, V, Zr, Au, Ag, Zn, Pt, and Pd.

[0102] In some embodiments, the additive comprises 0 or >0 to 3 wt% of rare earth metals. The amount of rare earth metals may not exceed 2.0 wt%, or not exceed 1.0 wt%, or not exceed 0.5 wt%, or not exceed 0.3 wt%, or not exceed 0.1 wt%.

[0103] Rare earth metals, such as Nd, Y, Yb and Ce, can be added to further improve strength and / or airtightness through grain refinement.

[0104] In one embodiment, the additive includes one or more of Nb, Ni, Mo, W, Co, Cr, Fe, Ti, V, Zr, Au, Ag, Zn, Pt, Pd, Y, Yb, Nd, and Ce.

[0105] In another embodiment, the additive includes one or more of Ni, Co, Cr, Fe, Zr, Au, Ag, Zn, Y, and Nd.

[0106] In a preferred embodiment, the additive includes Ni. In a preferred embodiment, the additive is selected from the group consisting of Ni, Co, Fe, Au, and Ag. In a preferred embodiment, the brazing alloy composition contains up to 4.8 wt% of the additive.

[0107] In a preferred embodiment, the brazing alloy composition contains up to 1.0 wt% of the additive. In a preferred embodiment, the brazing alloy composition contains at least 0.2 wt% of the additive.

[0108] It has been found that the addition of Sn has an adverse effect on the STR and formability of brazing alloys. Therefore, the addition of Sn should be avoided, and if present, the amount added (additives + incidental impurities) should not exceed 0.4 wt%, or 0.3 wt%, or 0.25 wt%, or 0.2 wt%, or 0.15 wt%, or 0.1 wt% of the total weight of the brazing alloy composition. In some embodiments, the Sn content in the brazing alloy composition is 0.05 wt% or less, more preferably 0.01 wt% or less.

[0109] The additives preferably include metals with a liquidus temperature greater than 500°C, or at least 800°C, or at least 900°C, or at least 1000°C. High liquidus temperature additives are preferred due to the need for low vapor pressure and high-temperature performance.

[0110] In some embodiments, additives are present in amounts of ≤4.0 wt%, ≤3.0 wt%, ≤2.0 wt%, ≤1.0 wt%, or ≤0.5 wt%. In other embodiments, when present, the additive content may be ≥0.05 wt%, ≥0.10 wt%, ≥0.15 wt%, or ≥0.20 wt%. Additive levels below these amounts may be insufficient to provide the desired functional effects, such as improved wettability or improved brazed joint strength. In some embodiments, the additives include or consist of metal wetting additives, which, when present, can be selected to improve the wettability of the brazing alloy on the substrate surface to be joined (e.g., Nb, Ni, Co, and / or Fe). The wettability of the brazing alloy to the substrate is critical for ensuring robust mechanical and hermetic joints. Because brazing alloys require low vapor pressures in some applications, additives such as Cd and Zn are preferably not used.

[0111] In one embodiment, the vapor pressure of each additive at 700°C does not exceed 1.0 x 10⁻⁶. 7 mm Hg (1.33 x 10) -5 Pa), preferably not exceeding 5 x 10⁻⁵ at 700°C. 8 mm Hg (6.65 x 10) -6 Pa), or not exceeding 1.0 x 10⁻⁶ at 700°C. 8 mm Hg (1.33 x 10) -6 In another embodiment, the addition of additives (including wetting additives) does not cause the vapor pressure to exceed 1.0 x 10⁻⁶ at 700°C. 7 mm Hg (1.33 x 10) -5 Pa), or more than 5 x 10⁻⁵ at 700°C. 8mm Hg (6.65 x 10) -6 Pa) or more than 1.0 x 10⁻ 8 mm Hg (1.33 x 10) -6 These undesirable synthetic vapor pressures are typically higher than the vapor pressure of brazing alloys without additives. Brazing alloys preferably contain no more than 0.5 wt%, or no more than 0.4 wt%, or no more than 0.3 wt%, or no more than 0.2 wt%, or no more than 0.1 wt%, or no more than 0.05 wt% of additives that do not meet this requirement.

[0112] It should be understood that the composition of a brazed joint can be derived from the composition of the brazing alloy and the composition of the substrate to be joined (including its coating). At least some (if not all) of the additives in the brazed joint composition can be derived from the diffusion of components in the substrate to which the brazed joint is joined.

[0113] Impurities

[0114] The incidental impurities used in this article refer to unavoidable elemental traces (including their oxidized or reduced forms) during the production of brazing alloys.

[0115] Unless otherwise specified, contaminants may include any elements or compounds not yet specified in the brazing alloy composition (e.g., excluding Ge, Cu, B, Al, In, Si, Sn, and additives). Contaminants may include elements (and their derivatives) from Groups 1, 2, 3A (excluding B), 4A (excluding Sn and Ge), 5A, 6A, 7A, and 8A of the periodic table.

[0116] Group 1 elements include H, Li, Na, K, Rb, Cs, and Fr.

[0117] Group 2 elements include Be, Mg, Ca, Sr, Ba, and Ra.

[0118] Group 3A elements include Ga and Ti.

[0119] Group 4A elements include C and Pb.

[0120] Group 5A elements include N, P, As, Sb, and Bi.

[0121] Group 6A elements include O, S, Se, Te, and Po.

[0122] Group 7A elements include F, Cl, Br, I, and At.

[0123] Group 8A elements include He, Ne, Ar, Kr, Xe, and Rd.

[0124] In a preferred embodiment, the brazing alloy composition contains less than 1.0 wt% or at most 0.5 wt% of incidental impurities, preferably at most 0.3 wt% of incidental impurities, and most preferably at most 0.15 wt% of incidental impurities. These small amounts of elements generally do not affect or alter the practical use and / or performance of the brazing alloy.

[0125] In one embodiment, the brazing alloy composition, preferably excluding oxygen, contains no more than 0.2 wt%, or no more than 0.15 wt%, or no more than 0.1 wt%, or no more than 0.05 wt% of any single incidental impurity element.

[0126] While incidental impurities (also known as unavoidable impurities) may vary depending on the purity of the raw materials used, typical incidental impurities are less than 0.8 wt%, or less than 0.5 wt%, or less than 0.2 wt%, or less than 0.1 wt%, or less than 0.05 wt% of the total weight of the brazing alloy composition. Oxygen (O) may be present as an incidental impurity due to oxidation reactions, at most 1.0 wt%, or at most 0.8 wt%, or at most 0.5 wt% of the total weight of the brazing alloy composition. Some applications require more stringent limits. For example, the limit for each of Zn, Cd, Pb, and C may be less than 0.1 wt%, or less than 0.05 wt%, or less than 0.01 wt%, or less than 0.005 wt% or less than 0.01 wt% of the total weight of the brazing alloy composition. In one embodiment, Zn and Cd have limits of less than 0.002 wt%, or less than 0.001 wt%. The contents of Pb and P can be limited to less than 0.01 wt% or less than 0.002 wt%. The content of C can be limited to less than 0.05 wt% or less than 0.01 wt% of the total weight of the brazing alloy components. The vapor pressure at 500°C is higher than 10. -7 mm Hg (1.33 x 10) -5 All other elemental impurities (including metallic impurities) of Pa are preferably limited to 0.1 wt% or less than 0.01 wt%; or less than 0.005 wt% or less than 0.002 wt% or less. The vapor pressure at 500°C is less than 10. -7 The elemental impurities in mm Hg are preferably limited to no more than 0.2 wt% or 0.1 wt% or 0.075 wt% of the total weight of the brazing alloy composition.

[0127] The list of incidental impurities typically tested includes Al, P, Pb, Cd, and Zn. For the repeat analysis of Example 8 (Table 1), the measurements of all incidental impurities were below the detection limits (%wt), i.e., Al < 0.001; P < 0.002; Pb < 0.001; Cd < 0.001; and Zn < 0.001. Although Cd and Zn are transition metals, for brazing alloy applications (such as X-ray tubes), both Cd and Zn are considered incidental impurities for this particular end use. Any use of the ultrapure feedstock used in Example 8 does not reflect typical incidental impurity levels that might be used.

[0128] Brazing alloy form

[0129] Brazing alloys preferably have sufficient ductility for standard alloy processing. They have sufficient machinability, meaning they can be easily deformed into the required size and shape via standard metal forming processes such as rolling, wire forming, drawing, and stamping.

[0130] In one embodiment, the brazing alloy can be fabricated into wires with diameters as low as 0.030 inches (760 µm), 0.015 inches (380 µm), or 200 µm. The wire diameter typically does not exceed 5.0 mm or 2.54 mm. In another embodiment, the brazing alloy can be fabricated into foils with thicknesses as low as at least 0.002 inches (50 µm) or less. Typically, the foil thickness can range from 0.001 inches (25 µm) to 0.010 inches (250 µm) or more than 0.020 inches (500 µm).

[0131] application

[0132] Brazing alloys can be used to form brazing components in aero-engines (OEM and repair), aerospace fuel line assemblies, semiconductor process chamber assemblies, vacuum tubes (including high-pressure vacuum tubes such as X-ray tubes), waveguide and klystron assemblies, power surge arresters, and automotive parts.

[0133] In a second aspect of the invention, a housing comprising a first component and a second component is provided, wherein a brazed joint (preferably airtight) connects the first component and the second component together, the housing comprising a brazing alloy composition of the first aspect of the invention or a brazing assembly of the fourth aspect of the invention.

[0134] It should be understood that in other embodiments, the brazing alloy composition may consist of the components described above in weight percentages.

[0135] It should be understood that, in the context of this specification and claims, the housing refers to a high-temperature, hermetically tight housing capable of operating at at least 500°C or at least 800°C, and capable of operating under a vacuum or containing gas, such that the brazed joint therein prevents gas from leaking into or out of the housing. Preferably, the hermetically tightness allows the brazed joint to pass through a hermetically tightness of 1x10 -6 Leakage test atm.cc / s or lower (ASTM F2391 using helium).

[0136] "Shell" refers to a container, tube, or shell that defines an enclosed space in which enclosed components, fluids, vacuum, or gases can reside. The shell separates or isolates the enclosed space from the space outside the shell.

[0137] As used herein, “airtight” and its variations refer to a sealed, airtight, and liquidtight brazed joint, container, tube, or housing relative to environmental conditions typically experienced by the enclosure or shell as described herein. Airtightness generally means that the brazed joint is able to isolate the external environment of the device from the interior of the same device. The enclosure can be part of an assembly, such as a high-pressure vacuum tube or a semiconductor process chamber assembly, in whole or in part.

[0138] Depending on their nature, housings typically include at least one brazed joint, one of which must be formed as a blind joint. That is, the joint, formed by drawing molten brazing alloy into the gap between two parts to be joined (e.g., 5µm to 500µm or 200µm) (e.g., via capillary action), is usually formed after the sub-assembly components within the housing are in place. Therefore, the properties of the brazing alloy are crucial for first forming the brazed joint of the required size, which will be placed directly near the parts to be joined. Second, the brazed joint should have sufficient wettability and flowability to form a high-quality connection between the parts via capillary action (e.g., without liquefaction). Third, the brazed joint needs sufficient hermetical tightness, corrosion resistance, high-temperature resistance, and strength to ensure the long-term functional integrity of the housing. At least some brazed joints within the housing (or other brazed assemblies) should be blind-jointed.

[0139] Furthermore, many designs cannot be inspected after manufacturing. This is particularly important because brazed joints require a finite gap for proper brazing. If manufacturing tolerances are inconsistent, problems will arise regarding the required gap, as the final brazed gap will be unknown and too large. Therefore, it is essential to maintain the stress-bearing capacity, inspectability, and production consistency of brazed joints.

[0140] The average thickness of brazed joints typically ranges from 5µm to 500µm, or 8µm to 200µm, or 8µm to 100µm. The depth of brazed joints can range from 5µm to 50 mm, or 30µm to 10 mm, or 40µm to 5.0 mm. The flowability of the brazing filler metal is particularly important when forming blind joints, especially when the molten filler alloy needs to flow a greater distance to cover the required depth of the brazed joint.

[0141] Such components typically require operation at high temperatures and / or high precision, where highly conductive components such as copper are indispensable for their effective thermal management system. In vacuum tubes, the housing may also include a heat source enclosed therein, such as the cathode filament of an X-ray vacuum tube or the lamp head in a rapid thermal processing assembly within a semiconductor processing chamber. The heat source is preferably capable of heating at least a portion of the contents within the housing to at least 800°C, at least 900°C, or at least 1000°C. The maximum operating temperature of the housing is determined by the softening temperature and liquidus temperature of the materials used. At least a portion of the brazed joint is exposed on the inside of the housing (e.g., the inside of the vacuum tube), which may be affected by high temperatures and high vacuum.

[0142] In one embodiment, an X-ray tube is provided, comprising:

[0143] X-ray tube housing, including the interior;

[0144] The anode assembly, which is disposed inside the X-ray tube housing; and

[0145] The cathode assembly, located inside the X-ray tube housing, emits an electrode beam to strike the target surface of the anode assembly and generate X-rays.

[0146] The X-ray tube includes a brazing assembly comprising a first component and a second component connected together by a first brazing joint, the first brazing joint comprising a component configured to include a solidification temperature range not exceeding 90°C and a liquidus temperature range of 950°C to 1060°C; the brazing joint comprises the component as described in the first aspect of this disclosure, wherein at least a portion of the brazing joint is exposed inside the X-ray tube housing, and wherein at least one of the first component and the second component forms part of one or more of the X-ray tube housing, the anode assembly, and the cathode assembly.

[0147] In one embodiment, an apparatus is provided comprising a heat source and a housing, the housing including a first component and a second component, wherein a brazing joint connects the first component and the second component together, the brazing joint comprising a brazing alloy component comprising, by weight percent:

[0148] 2.0 ≤ Ge ≤ 9.5 and 0 ≤ Al ≤ 2.0; 0 ≤ Si ≤ 1.0; and 0 ≤ In ≤ 2.0;

[0149] 0.02 < B ≤ 1.25;

[0150] Additives ranging from 0 to 5.0;

[0151] Less than 1.0 wt% of incidental impurities; and

[0152] The rest is Cu.

[0153] Wherein, the additives and impurities do not contain Sn exceeding 0.4 wt% of the total weight of the brazing alloy components; and wherein, the outer shell is airtight.

[0154] In another embodiment, the brazed joint includes:

[0155] Cu from 80 to 97.98;

[0156] 2.0 ≤ Ge ≤ 9.5 and 0 ≤ Al ≤ 2.0; 0 ≤ Si ≤ 1.0; and 0 ≤ In ≤ 2.0;

[0157] 0.02 < B ≤ 1.25;

[0158] Sn ≤0.4; and

[0159] Impurities are present.

[0160] In another embodiment, an apparatus is provided comprising a housing and a heat source, the housing comprising a brazing assembly, the brazing assembly comprising a first component and a second component connected together by a first brazing joint, wherein the brazing joint comprises a solidification temperature range not exceeding 90°C, the brazing joint comprises a liquidus temperature range of 950°C to 1060°C, and a precious metal content of less than 4.0 wt% relative to the total weight of the brazing joint.

[0161] The heat source can be located inside the enclosure or form part of the enclosure.

[0162] The first or second component may include copper or a copper alloy having excellent electrical conductivity. The first or second component may also include other metals, including but not limited to stainless steel, copper alloys, or other metals or metal alloys with a melting temperature greater than 1050°C or 1080°C. The housing may also include a cooling system to remove heat from the system. The housing may be under vacuum, such as in a vacuum tube, or may include process gases (e.g., in a semiconductor processing chamber).

[0163] The first or second component may also include ceramic or metallized ceramic (i.e., ceramic including a metallized coating).

[0164] In embodiments where the housing forms part of a vacuum tube, the housing may include an anode and a cathode disposed opposite to each other within the vacuum interior space. The vacuum interior space may be surrounded by a cylindrical metal housing, and the anode and / or cathode are electrically insulated by an annular insulator (e.g., a ceramic or metallized ceramic component). A brazed joint may form a seal between the cylindrical metal housing and the annular insulator.

[0165] The brazing joint may include a ceramic (or metal-coated ceramic) component and a metal component, wherein the brazing joint joins the ceramic / metal-coated ceramic and the metal component together. In one embodiment, the brazing joint includes a brazing alloy component comprising, by weight percent:

[0166] 2.0 ≤ Ge ≤ 9.5 and 0 ≤ Al ≤ 2.0; 0 ≤ Si ≤ 1.0; 0 ≤ In ≤ 2.0;

[0167] 0.02 < B ≤ 1.25;

[0168] Additives ranging from 0 to 5.0, preferably selected from the group consisting of transition metals and rare earth metals;

[0169] Containing impurities; and

[0170] The rest is Cu.

[0171] The additives and impurities do not contain Sn exceeding 0.4 wt% of the total weight of the brazing alloy components.

[0172] It should be understood that, in the embodiments, the brazing alloy composition may be the components described above in weight percentages.

[0173] The brazed joint may also include a variation in the composition of the brazing alloy according to any embodiment of the first aspect of the invention.

[0174] Ceramic components may include metallization coatings, such as molybdenum-manganese coatings or nickel plating.

[0175] In a third aspect of the invention, a vacuum tube assembly or semiconductor process chamber, such as a rapid thermal processing assembly, is provided, comprising the housing of the second aspect of the invention. In some embodiments, the vacuum tube assembly or rapid thermal processing assembly operates at temperatures up to 800°C or higher, or 900°C or higher, or 1000°C or higher.

[0176] When available, wetting / bonding additives may be selected to improve the wettability and / or bonding of the alloy on the first and / or second components.

[0177] The vacuum tube of the present invention may include a brazed joint formed of a high-copper-content brazing alloy, the brazed joint having specific amounts of trace components that can be varied to adjust the desired solidus temperature while maintaining a relatively narrow liquidus-solidus temperature range. Furthermore, the brazed joint typically exhibits excellent wettability and flowability on a range of substrates, including copper, nickel and their alloys, stainless steel, nickel-cobalt-iron alloys, and molybdenum-manganese metallized substrates. These brazing alloy properties enable the formation of a wide variety of vacuum tubes using various brazing techniques and conditions.

[0178] Brazing alloy

[0179] Brazing alloys typically possess excellent wettability and flowability, enabling reliable hermetic seals at high temperatures. They are particularly well-suited for applications in high-temperature environments, including vacuum tubes (such as X-ray tubes, waveguides, and klystron assemblies); aerospace applications (such as engine components and maintenance, fuel line assemblies); gas turbine assemblies; semiconductor process chamber components, such as power supplies for rapid thermal processing units; power surge arresters; and automotive parts.

[0180] Brazing alloys require melting before operation. The melting behavior is determined by the solidus and liquidus temperatures, with the melting initiation temperature (solidus) and the melting range (the difference between the two points) being the most important for brazing. The solidus temperature of the brazing alloy should be higher than its highest operating temperature but lower than the solidus temperature of the lowest melting point base material.

[0181] The liquidus temperature of the brazing alloy composition is typically below about 1060°C, or typically below 1055°C, or below 1050°C, or below 1045°C. The liquidus temperature is typically at least 890°C, or at least 900°C, or at least 910°C, or at least 920°C, or at least 925°C, or at least 950°C. Therefore, the brazing alloy is particularly suitable for brazing copper or copper alloy substrates. In one embodiment, the liquidus temperature of the brazing alloy is in the range of 950°C to 1060°C, or in the range of 970°C to 1050°C. The brazing alloy composition is preferably configured to obtain the above-mentioned liquidus temperature or range thereof.

[0182] Some brazing alloys have narrow melting ranges, while others have wider ones. The melting range is typically related to the flow rate, which can influence the choice, as well as the required heating rate. Brazing alloys with narrow melting ranges (smaller temperature range between the solidus and liquidus) can be used at rapid (e.g., greater than 30°C / min or 40°C / min from the solidus to the liquidus) or slow heating rates (e.g., in the range of 5°C / min or 10°C / min to 30°C / min from the solidus to the liquidus). For brazing alloys with wide melting ranges, slow heating rates, such as in-furnace brazing, can cause the solid and liquid phases to reach equilibrium and coexist for extended periods. This leads to liquefaction, where the initially formed liquid (with a specific composition different from the bulk) flows into the joint gap and physically separates from the solid residue. The resulting chemical inhomogeneity can be detrimental to the strength of the joint and is often aesthetically unappealing.

[0183] In some brazing applications, the filler metal (i.e., brazing alloy) may need to flow to enter the joint gap, but even with pre-placement, flow characteristics remain important for ensuring all joint gaps are filled. Alloys with better flowability can penetrate smaller capillary gaps, but if the alloy flows too freely in larger gaps, it may not remain in the joint, leading to porosity and reduced strength. The flow of an alloy is primarily determined by the relative amounts of solids and liquids present at the brazing temperature. If an alloy melts at a single point (e.g., a eutectic composition or a pure metal), it will be completely liquid at the brazing temperature and flow easily. Alloys brazed within their melting range will contain a certain amount of solids and liquids; if it is mostly molten, it will flow well; if the solids fraction is large, the flow will be slower.

[0184] substrate

[0185] The brazing alloy of the present invention is applicable to a range of brazing applications, including but not limited to components having a substrate, the substrate comprising copper or copper alloys, Kovar... TM (Ni-Co-Fe alloys), metallized ceramic components (e.g., molybdenum-manganese metallization or nickel or copper plating); steel, including stainless steel; nickel and nickel alloys (including nickel superalloys); and other refractory metals (e.g., molybdenum and its alloys) whose melting temperature is preferably at least 20°C or at least 50°C higher than the liquidus temperature of the brazing alloy.

[0186] Solidification temperature range

[0187] To avoid liquefaction and promote good brazing coverage on the joint, the brazing alloy preferably has a narrow temperature difference (i.e., a low STR value) between its solidus and liquidus temperatures. In some embodiments, the boron and / or germanium content of the brazing composition is configured to obtain a temperature difference between the solidus and liquidus temperatures of the brazing alloy that does not exceed 90°C, or 88°C, or 85°C, or 82°C, or 80°C, or 75°C, or 70°C, or 65°C, or 60°C, or 55°C, or 50°C, or 45°C, or 40°C, or 35°C, or 30°C, or 25°C, or 20°C. The above-mentioned STR range is considered a low STR value.

[0188] In a fourth aspect of the invention, a brazing assembly is provided, comprising a first joint and a second joint, wherein at least one joint comprises a brazing alloy composition according to a first aspect of the invention. Alternatively, the brazing assembly is part of a device comprising a housing and a heat source, the housing comprising the brazing assembly, the brazing assembly comprising a first component and a second component joined together by a first brazed joint, wherein the solidification temperature of the first brazed joint is not greater than 90°C, the first brazed joint comprises a liquidus temperature in the range of 950°C to 1060°C, and a precious metal content of less than 4.0 wt% relative to the total weight of the first brazed joint.

[0189] In one embodiment, the component includes two joints, each joint comprising a brazing alloy composition according to a first aspect of the invention. Each brazing alloy may be different. The first joint may include a brazing alloy whose liquidus temperature is lower than the solidus temperature of the second brazing alloy.

[0190] In one embodiment, the first and second brazing alloys comprise brazing alloy components according to the first aspect of the invention. Preferably, the difference between the solidus temperature of the first joint and the liquidus temperature of the second joint is at least +15°C or at least +20°C. The first joint may contain brazing alloy components with a solidus temperature of at least 950°C or at least 990°C, and the liquidus temperature of the second joint is no more than 1017°C, no more than 1000°C, or no more than 980°C.

[0191] This type of component is well-suited for stepped brazing processes, in which a higher-temperature brazed joint is assembled and cooled before assembling a second brazed joint at a lower temperature. Since the solidus temperature of the first brazed joint is higher than the liquidus temperature of the second brazed joint, the integrity of the first brazed joint should not be compromised if the brazing temperature of the second brazed joint remains below the solidus temperature of the brazing alloy of the first brazed joint.

[0192] While the present invention includes stepped brazing using two brazing alloy compositions, the present invention also includes additional stepped brazing in which only one brazed joint comprises a brazing alloy according to the first aspect of the present invention.

[0193] In some embodiments, the brazing process may cause boron to migrate from the brazed joint. The reduction in boron content in the first brazed joint compared to the original brazing alloy composition may result in an increase in both the solidus and liquidus temperatures, allowing the same brazing alloy composition to be used for stepped brazing operations. The increased liquidus temperature allows the same original brazing alloy to be subsequently used for brazing adjacent components (second brazed joints) at temperatures lower than the solidus temperature of the first brazed joint.

[0194] In some embodiments, the brazed joint may be derived from the brazing alloy composition of the first aspect of the invention. The derived brazed joint may have a lower boron content compared to the brazing alloy composition of the brazed joint derived therefrom. The adjacent materials / components of the brazed joint may also have an assessed boron level relative to the material / component before the brazed joint is formed.

[0195] As used herein, brazing refers to the joining process of two (or more) materials together using a brazing alloy, which mixes with the materials to be joined upon melting. The melting temperature of the brazing alloy is lower than that of the materials to be joined. The liquefied / molten brazing alloy interacts with the materials to be joined and forms a brazed joint during cooling. The interaction between the brazing alloy and the materials to be joined can be described by the diffusion and formation processes of intermetallic phases and other compounds. Brazing can be performed in a vacuum, reducing, or protective environment (e.g., a mixture of hydrogen and nitrogen). Flux can be used during brazing to remove oxides from the brazing surfaces of the materials to be joined and to prevent oxide formation during brazing, thus allowing the liquefied / molten brazing alloy to thoroughly wet the surfaces of the materials to be joined. However, fluxless brazing is preferred.

[0196] A high-voltage vacuum tube consists of an anode and a cathode, which are positioned opposite each other within a vacuum interior space. This vacuum interior space is typically surrounded by a cylindrical metal casing, and the anode and / or cathode are electrically insulated by a ring-shaped insulator. High-voltage vacuum tubes can operate at temperatures exceeding 800°C, 900°C, 950°C, or 1000°C.

[0197] In some embodiments, the anode is a rotating anode. The rotating anode applies additional stress to the brazed joints contained therein, thus making the strength of these brazed joints particularly important compared to brazed joints within a vacuum tube with a static anode.

[0198] In a fifth aspect of the invention, a method is provided for producing a brazed joint between a first component and a second component using a brazing alloy composition according to a first aspect of the invention.

[0199] The brazing process may include:

[0200] a. Optionally, the brazing alloy composition may be held at a temperature between 10°C and 400°C below the liquidus temperature of the brazing alloy composition for at least 10 minutes.

[0201] b. Heating the brazing alloy composition to a brazing temperature higher than the liquidus temperature of the brazing alloy composition; and

[0202] c. Cool the brazing alloy composition to below the solidus temperature of the brazing alloy composition to produce a brazed joint.

[0203] The process may include raising the brazing temperature between the solidus and liquidus temperatures at a rate of 1°C / min to 30°C / min between the solidus and liquidus temperatures of the brazing alloy. The rate of temperature rise may be less than 28°C / min, or less than 26°C / min, or less than 24°C / min, or less than 22°C / min, or less than 20°C / min, or less than 18°C / min, or less than 16°C / min, or less than 14°C / min, or less than 12°C / min. Compared to brazing alloys with high STR, the brazing alloy of the present invention can be brazed at a lower heating rate without incurring the same risk of liquefaction, thus avoiding poor joint performance. Using a lower heating rate also avoids other disadvantages associated with faster heating rates, such as component deformation, spalling, and excessive outgassing. This allows the brazing alloy to be used effectively in a wider range of brazing environments, including the brazing of components with low electrical conductivity (e.g., ceramics) and / or large thermal mass, making rapid heating rates difficult to achieve.

[0204] In some embodiments, the brazing cycle further includes holding the brazed joint and associated substrate at a temperature between 10°C and 400°C below the solidus temperature for 10 to 30 minutes before brazing the brazed joint at the brazing temperature, typically 15°C to 60°C above the liquidus temperature of the brazing alloy.

[0205] In other embodiments, double brazing is used, wherein the brazed joint is cooled by about 100°C (to below the solidus temperature) between brazing cycles.

[0206] Brazed joints can be formed in brazing furnaces that include vacuum, reduction (e.g., H2), or protective (e.g., N2 or argon) furnaces. Blind joints are particularly well-suited for brazing in furnaces or ovens because the temperature and atmospheric conditions can be reliably controlled. Vacuum furnaces can achieve vacuum levels less than 8 x 10⁻⁶. -4 mm Hg (1.17 x 10) -3 Pa), preferably less than 5 x 10 -4mm Hg (6.65 x 10) -2 Pa). The required levels of temperature and environmental control may also be achieved using laser brazing in controlled environments.

[0207] In some embodiments, a two-step stepped brazing process is employed, comprising heating a first brazing alloy component to a first brazing temperature and allowing cooling to form a first brazed joint, and then cooling a second brazing alloy component to a second brazing temperature and allowing cooling to form a second brazed joint, wherein the solidus temperature of the first brazed joint is higher than the liquidus temperature of the second brazed joint, and wherein the second brazing temperature is maintained below the solidus temperature of the first brazed joint.

[0208] In one embodiment, a brazed joint is formed by placing brazing alloy components in the form of wire, powder, slurry, or foil near the two components to be joined, heating the brazing components above their liquidus temperature, and allowing the molten brazing alloy to flow between the two components via capillary action.

[0209] In a sixth aspect of the invention, a brazed joint produced or obtainable by the method according to a fifth aspect of the invention is provided. The process of preparing the brazed joint ensures that the brazing alloy composition has a sufficiently low liquidus temperature and sufficient fluidity and wettability to form a blind joint by drawing the brazing alloy between the substrates to be joined through capillary action. The boron content of the cooled brazed joint may be reduced compared to the original brazing alloy composition. Therefore, without the brazing process of the present invention, it would be impossible to obtain the brazed joint composition because the liquidus temperature of the brazed joint composition would be much higher.

[0210] Brazed joint performance

[0211] The brazing alloy and derived joint of the present invention are preferably airtight, and have good mechanical strength and low vapor pressure.

[0212] The brazed joint of the present invention preferably has airtightness, and the maximum permissible leakage rate of the sealed vacuum assembly is 1x10⁻⁶. -6 atm.cc / s or lower, 1x10 -7 atm.cc / s / or lower, or 1x10 -8 atm. cc / s or lower (ASTM F2391 for helium). In some applications, such as RTP assemblies, lower seal integrity may be sufficient, although the integrity of the brazed joint should ensure that the process gas is contained within the process chamber and does not leak through the brazed joint.

[0213] The brazed joints of the present invention preferably have a tensile strength of at least 900 MPa, or at least 950 MPa, or at least 1000 MPa. The brazed joints of the present invention preferably have a shear strength of at least 5.0 or at least 7.0 MPa. Tensile and shear strengths are measured according to the AWS C.3.2M / C3.2:2019 standard method for evaluating the strength of brazed joints. The reference substrate used for testing is 304 stainless steel bonded to 100% copper.

[0214] The brazing alloy of the present invention preferably has a content of less than 1 x 10⁻⁶ at 500°C. -11 mm Hg (1.33 x 10) -9 A vapor pressure of Pa, or having a vapor pressure of less than 1 x 10 at 500°C. -12 mm Hg (1.33 x 10) -10 A vapor pressure of Pa, or having a vapor pressure of less than 1 x 10 at 500°C. -13 mm Hg (1.33 x 10) -11 A vapor pressure of Pa, or having a vapor pressure of less than 1 x 10 at 500°C. -14 mm Hg (1.33x10 -12 A vapor pressure of Pa, or having a vapor pressure of less than 1 x 10 at 500°C. -15 mm Hg (1.33 x 10) -13 The vapor pressure (Pa) of the brazing alloy is preferably less than 1 x 10⁻⁶ at 700°C. -8 mm Hg (1.33 x 10) -6 Pa), or less than 1 x 10 -9 mmHg (1.33 x 10) -7 Pa), or less than 5 x 10 -10 mm Hg (1.33 x 10) -8 Pa), or less than 1 x 10 -11 mm Hg (1.33 x 10) -9 Pa).

[0215] In this invention, vacuum tubes include power tubes, X-ray tubes, magnetrons, traveling wave tubes, exciton tubes, and klystrons.

[0216] The solidus temperature is the highest temperature of a metal, or the temperature at which an alloy becomes completely solid. The liquidus temperature is the lowest temperature at which a metal or alloy becomes completely liquid.

[0217] For the purposes of this invention, high voltage means a voltage of at least 1 kV, at least 10 kV, or at least 100 kV. The benefits of the brazing alloy of this invention can also be determined by applications with a sufficiently high voltage / distance (V / d) ratio, such as at least 0.5 kV / mm, at least 1 kV / mm, or at least 10 kV / mm.

[0218] Vacuum brazing is typically performed at a pressure of approximately 1 x 10⁻⁵ mm Hg (1.33 x 10⁻³ Pa).

[0219] The statement “the remainder is Cu” indicates that copper accounts for the remaining portion of the brazing alloy composition, up to 100.00 wt% (i.e., the weight % of copper = 100.00 wt% - the weight % of all other components in the brazing alloy).

[0220] The sum of all components in the brazing alloy composition must not exceed 100 wt%. The theoretical sum of component combinations exceeding 100 wt% should be disregarded.

[0221] Unless otherwise stated, references to %wt are based on the total weight of the brazing alloy composition.

[0222] Additives do not include elements already defined within the brazing alloy composition range (e.g., Cu, Ge, Sn, Al, Si, In, and B).

[0223] For the purposes of this invention, precious metals refer to gold, silver, palladium, and platinum.

[0224] When boron, copper, germanium, and additives are mentioned, they refer to components in the form of these elements (i.e., oxidation number = 0). Concurrent impurities can be in any permissible oxidation state, but preferably have an oxidation number of zero.

[0225] For the purposes of this invention, a brazed joint composition derived from a brazing alloy composition refers to a brazed joint that, while being formed from the brazing alloy composition, may also include components from the associated substrate forming the joint, which may have diffused into the joint during the brazing process. Similarly, at least a portion of some components of the original brazing alloy composition may have diffused into the adjacent substrate (e.g., boron from the brazing alloy composition may have at least partially diffused into the adjacent substrate). Attached Figure Description

[0226] The invention will now be described with reference to the accompanying drawings, which illustrate particularly preferred embodiments of the invention, wherein:

[0227] Figure 1 This is a schematic diagram of an X-ray tube within the scope of this invention.

[0228] Figure 2 It is a differential scanning calorimetry (DSC) scan of sample 4.

[0229] Figure 3 This relates to the effect of boron content in brazing alloys on the solidification temperature range.

[0230] Figure 4 This is a photograph of the brazing fluidity test results between a copper and a 304 stainless steel substrate, which are bonded together by the brazing alloy composition of sample 14, in a hydrogen environment.

[0231] Figure 5 yes Figure 4 Microscopic image of the cross-section of the brazed joint.

[0232] Figures 6A to 6F These are photographs illustrating the formability of samples 8 to 12; C-6, respectively.

[0233] Figure 7 A is a photograph of two adjacent components before the brazing alloy wire of the present invention is used for brazing with the brazing alloy of sample 13.

[0234] Figure 7 B and 7C are respectively Figure 7 Photographs and SEM images of brazed joint A after brazing.

[0235] Figure 8 A is a photograph of two adjacent components before brazing with commercially available brazing alloy wire using GEMCO™ brazing alloy.

[0236] Figure 8 B and 8C are respectively Figure 8 Photographs and SEM images of brazed joint A after brazing. Detailed Implementation

[0237] Brazing alloys need to exhibit deformability (the alloy's ability to undergo plastic deformation without fracturing), particularly ductility (under tensile stress), and be manufactured in various forms such as wire and foil. The production of brazing alloys begins with mixing all the elements in appropriate amounts, melting the mixture to a sufficiently high temperature, and then casting it into a solid ingot or billet. The alloy's state can be changed from as-cast to forged by cold working or hot working (such as rolling, drawing, and stamping).

[0238] Rapid solidification methods (i.e., at extremely high cooling rates), such as melt spinning, can produce brazing alloys in the form of thin foils. Casting, ingot casting, or any other form of grinding or atomization techniques for brazing alloys can be used to produce alloys in powder form. Preformed brazing alloys are prepared by precisely cutting shaped and cold-forged wire into rings, or by stamping alloy strips or foils. Preforms provide precise volume for specific areas of a particular brazing joint. The preform is placed in the joining area and melts during brazing, then cools and solidifies to join with the substrate. In some embodiments, brazing is performed in a vacuum, hydrogen, or inert gas environment, and the brazing temperature is typically at least 20°C higher than the liquidus temperature of the brazing alloy.

[0239] Reference Figure 1 The diagram illustrates a bipolar rotating X-ray tube 10, which, in addition to serving as an intermediate component connecting the cathode 30 and the anode 40, includes a hermetically sealed housing 20 to maintain a high vacuum. For high-pressure vacuum tubes (e.g., 150 kV), the housing is typically made of stainless steel, heat-resistant steel, carbon structural steel, non-magnetic stainless steel, copper, or a nickel-copper alloy. The housing may include one or more welded seals W that provide a hermetically sealed seal.

[0240] Electrons are generated by heating the cathode filament 50. Under the influence of the accelerating electric field between the cathode 30 and the anode, the electrons bombard the target surface 60 at high speed, thereby generating X-rays. The target surface is a rotating disk made of tungsten, capable of withstanding the high temperatures generated by the impacting electrons. The induction motor 70 includes bearings 80 and a rotor rod 90, which is typically made of molybdenum. Its relatively low conductivity provides the motor with a degree of thermal insulation from the target surface 60. The stator (not shown) includes a series of magnets that can drive the rotation of the rotor 90 from outside the housing 20.

[0241] Electron bombardment on the target surface releases an X-ray stream, which can be selectively transmitted to the outside of the housing via emission window 100. High-voltage lines 110 and 120 are supplied to the cathode 30 and anode 40 via feedthroughs 130 and 140, respectively. The feedthroughs include conductors 110 and 120, which are insulated from the housing by metallized ceramic seals 150 and 160.

[0242] In this configuration, a brazing alloy capable of connecting various metal and / or ceramic components is required. For example, brazed joint B1 needs to hermetically seal the housing to the anode feed 140 and the conductor 120 within the ceramic seal 160. A similar arrangement is required at the cathode feed with brazed joint B2. Brazed joint B3 is also needed to hermetically seal the X-ray emission window 100 to the housing 20. Brazed joint B4 may also be needed to connect components of the rotating anode 40 or cathode (30).

[0243] Since only 1% of the total energy is used to generate X-rays, and the remaining 99% is converted into heat, X-ray vacuum tubes need to be composed of hermetically sealed components with different electrical conductivity and mechanical strength. These components must maintain good dimensional stability under extreme temperature changes during startup.

[0244] The housing assembly (not shown) may also include a cooling fluid (e.g., oil) that helps remove heat from the housing and maintain the temperature within the target operating range, typically up to 800°C, 900°C, 1000°C, or higher. Due to the high electrical conductivity of copper, many metal components of the vacuum tube and housing contain copper; therefore, using copper-based brazing alloys offers the advantage of similar coefficients of thermal expansion and allows operation at the required temperatures within the vacuum tube. Consequently, the brazing alloys of the present invention are advantageously used for brazing joints of B1, B2, B3, and B4 to join metals to metals, metals to metallized ceramics, and / or metals to ceramics.

[0245] The complexity of the device clearly demonstrates the critical importance of the brazing alloy's ability to be positioned and flow into a compact space to achieve the necessary mechanical and hermetic integrity for the brazed joint. Compared to brazing alloys with high STR values, the brazing process can employ a relatively lower temperature rise because the brazed joint of this invention is less prone to liquefaction.

[0246] While the brazing alloys and joints of the present invention are particularly suitable for high-temperature vacuum tube applications, the brazing alloys are not limited to these applications.

[0247] For example, brazing alloys can be used for brazing joints within semiconductor process chamber components, such as rapid thermal processing (RTP) chamber components. RTP is used in many high-temperature industrial processes, including processes that heat to temperatures exceeding 1000°C in no more than a few seconds. During cooling, the wafer temperature must be reduced slowly to prevent misalignment and wafer breakage due to thermal shock. This rapid heating rate is typically achieved using high-intensity lamps or lasers. Like high-temperature vacuum tube components, RTP components need to withstand high temperatures and include highly conductive metals for system thermal management. Therefore, copper components are typically used, often brazed to other metal components, such as stainless steel components. RTP chambers typically include lamp heads as heat sources, and the chamber contains process gas flows, such as inert gases like nitrogen, to facilitate the thermal processing. Due to the criticality of purity in wafer fabrication, the chamber needs to be hermetically sealed during operation. Examples of RTP components and processes are provided in US8698049 and US0210348302.

[0248] Example

[0249] A brazing alloy sample containing copper, germanium, and boron, as well as various components listed in Table 1, with 0.25 wt.% nickel was prepared by heating a mixture of elemental components to approximately 1080 °C to form a homogeneous melt. The molten alloy was then cast into ingots, followed by cold working and annealing to produce alloys in the form of wire and / or foil.

[0250] Methodology

[0251] Solid-liquid phase temperature

[0252] Differential scanning calorimetry (DSC) was used to characterize the melting behavior of these alloys. Liquidus and solidus temperatures were measured by DSC using small samples of approximately 20 mg mass placed in a covered alumina crucible. After loading the samples, the chamber was evacuated and backfilled with argon. Melting was performed at 20 K mins in the temperature range of 298 K to 1373 K. -1 The heating rate is analyzed. The output of the analysis is a curve showing the change in heat flux with temperature.

[0253] refer to Figure 2 DSC measures the physical and chemical changes within a material in response to temperature. It provides information about endothermic (absorbing heat), exothermic (releasing heat), and changes in heat capacity.

[0254] The DSC experiment (measured using a Netzch DSC instrument, model Jupiter STA 449 F3) consisted of two phases: heating and cooling, followed by a second identical cycle (a second heating and cooling cycle). Figure 2 These are the DSC curves for the second heating-cooling cycle of Sample 4. For better visibility, the (continuous) DSC curves are separated, with the bottom curve representing the heating curve (from left to right) and the top curve representing the cooling curve (from right to left). The solidus temperature of 1032.4 °C was determined at the point on the heating curve before the heat flux increases, indicating the beginning of liquid phase formation. The liquidus temperature of 1039.3 °C was determined at the point on the cooling curve before the heat flux decreases, indicating the beginning of solid phase formation. The interpretation of the DSC data is based on Special Publication 960-15 of the National Institute of Standards and Technology (NIST), entitled “DTA and Heat-flux Measurements of Alloy Melting and Freezing,” by WJ Boettinger, UR Kattner, KW Moon, and JH Perepezko (November 2006).

[0255] Formability

[0256] The alloy composition was prepared by melting 5 ± 1 grams (0.25 inches high) of the alloy in a water-cooled copper furnace under argon atmosphere using tungsten electrodes to produce hemispherical alloy ingots (cast ingots). Ingots of different compositions were cold-rolled using a twin-roll mill to test their ability to plastically deform into sheet-like shapes.

[0257] The formability of each component was determined by measuring the deformation (visually observed) required to cause fracture when passing through rolls at room temperature. In each step, the roll gap was adjusted to correspond to a 10% reduction in ingot thickness. Alloys capable of withstanding cold rolling to 0.002-inch (approximately 50 µm) thick sheets were considered to have formability close to ductility. Formability testing defined a reduction from 0.25 inches to 0.002 inches as 100% formability and a reduction to 0.125 inches as 50% formability.

[0258] If early fracture occurs before reaching the target thickness of approximately 50 µm, these components are considered to be somewhat brittle in nature. This methodology is used to evaluate the ability of various components of this alloy to manufacture braze filler wires or preforms. Early fracture is defined as a visible fracture appearance in the sample, as shown in Figures 6d (60% formability), 6e (38% formability), and 6f (20% formability). Compared to Figures 6a-6c, when the samples are machined to a thickness of 50 µm (100% formability), Figures 6a-6c show no obvious signs of fracture.

[0259] A formability percentage of at least 38% is considered suitable for manufacturing brazing alloy preforms, although at least 45%, or at least 50%, or at least 60%, or at least 70%, or at least 80%, or at least 90%, or 100% formability is preferred. Therefore, the boron content of the brazing alloy composition can be configured to obtain the aforementioned formability values ​​or ranges.

[0260] Experimental results

[0261] A series of experiments were conducted to evaluate the properties of the brazing alloy in terms of solidus and liquidus temperatures and formability.

[0262] The vapor pressure of the brazing alloy of the present invention was found to be less than 1 x 10⁻⁶ in Table 1. -11 mm Hg (1.33 x 10) -9 The vapor pressure of each alloy was estimated using the individual vapor pressure contribution of each element: Pa.

[0263] (Formula 1)

[0264] in, It is activity. It is the equilibrium vapor pressure at the liquidus temperature +50°C.

[0265] The preferential evaporation of different alloying elements is a function of the element's volatility and its activity in the alloy. The partial contribution of each alloying element to the total equilibrium vapor pressure is a function of the equilibrium vapor pressure of the pure element and its activity in the alloy, as described in Equation (1).

[0266] We refer to Figure 3 The effect of boron on brazing alloys containing 2.5 wt% germanium (Line A) and 4.8 wt% germanium (Line B) indicates that each alloy has an optimal boron content that produces the minimum STR value. For 2.5 wt% germanium content (samples 1, 2, 3, C-1), 4.2 wt% (sample 4), and 4.8 wt% (samples C-2, C-3, 5, 6, 7), the optimal boron content ranges from approximately 0.5 to 1.25 wt% boron. Although a similar decrease in STR was observed at germanium contents of 7.2 wt% (the minimum STR recorded at 0.55 wt% boron) and 10 wt% (the minimum STR recorded at 0.80 wt% boron), the absolute minimum STR values ​​are not low compared to brazing alloys with lower germanium contents.

[0267] However, the limitation of low Ge content lies in their elevated liquidus temperature, which can be detrimental to applications involving brazing copper or copper alloy components. The brazing alloys of the present invention, with a Ge content of about 4.2 wt% to 4.8 wt%, have been found to possess an excellent combination of low STR values; liquidus temperatures within the target range for brazing copper / copper alloy components; and good formability. The brazing alloy compositions of the present invention provide a wide range of liquidus temperatures, favorable STR ranges, and acceptable formability to meet the functional requirements of many end-use applications, all without requiring the use of any significant amounts of precious metals.

[0268] For example, the melting curve of sample 4 is similar to that of the noble metal brazing alloy 35Au-65Cu (WESGO). TM Similar to the latter, which has a liquidus temperature of 1010 °C and an STR of 20 °C (Table 2). While other samples may have higher STRs than noble metal brazing alloy alternatives, they still offer better performance compared to existing non-noble metal alternatives. For example, 50Au-50Cu (WESGO) TM The liquidus temperature of sample 15 is 970℃, and the STR is 15℃ (Table 2). Samples 15 and 16 have similar liquidus temperatures, but their STRs are 68-69℃. This is for non-precious metal brazing alloys (WESGO). TM GEMCO TM This represents a significant improvement, with the liquidus temperature of the alloy being 975°C, while that of STR is 95°C (Table 2).

[0269] While brazing alloys with higher Ge content (e.g., 7.2 wt% or more) may have relatively higher STR levels and lower liquidus temperatures (compared to brazing alloys with lower Ge content), these brazing alloy properties are still acceptable in some applications.

[0270] As shown in Table 1, the formability of the brazing alloy tends to decrease with increasing boron content. When the boron content increases to above 1.0 wt%, the formability decreases significantly. The Ge content seems to have a smaller effect on formability. At a constant boron content of 1.25 wt%, as the Ge content increases from 2.5 wt% to 4.8 wt% to 7.2 wt%, the formability decreases from 43 to 40 to 38.

[0271] Figures 6A to 6F The foils formed in samples 8 to 12 are shown; samples 11, 12 and C-6 show obvious signs of breakage as formability decreases.

[0272] Table 1

[0273]

[0274] Effects of Additives

[0275] Most examples contain 0.25 wt% Ni, which is added as a wetting aid to help the brazing alloy wet the stainless steel substrate. The brazing alloy composition tolerates Ni levels up to 4.8 wt% while still maintaining acceptable STR values, but additive levels above 5.0 wt% are expected to have adverse effects on STR or liquidus temperature, as shown in Comparative Example 10 (C-10) containing 5.25 wt% additive. Higher levels of Ni and Ag (C-9, C-11) further confirm this negative trend.

[0276] The effect of adding Sn was investigated by adding 1.0 wt% Sn to the composition of Example 5, which had a low STR of 12°C. The resulting composition (C-6) showed a deterioration in STR value to 173°C. Other Sn-containing compositions, C-7 and C-8, also exhibited high STR values ​​of 116°C and 185°C, respectively. The effect of Sn also significantly worsened the formability (100% formability) of Example 5, with the addition of 1.0 wt% Sn causing a sharp drop in formability to 20% (Figure 6f). Similarly, after adding 1.0 wt% Sn, the formability of Sample 17 decreased from 100% to 30% (Sample C-7).

[0277] Brazed joint performance

[0278] refer to Figure 4 and Figure 5It was found that the brazing components (sample 13) could flow between copper 410, 510 and 304 stainless steel 420, 520 blind joints 430, 530. Figure 4 The arrows in the image indicate the flow direction. (See cross-sectional images of the microstructure.) Figure 5 As shown in the diagram, copper 510 and 304 stainless steel substrate 520 are joined together by brazed joints 530 with an average thickness of approximately 10µm. Figure 5 As shown, the brazed joint provides a continuous and clean interface between the substrates. No significant liquefaction was observed. Testing confirmed that the brazed joint meets the 1x10 standard requirements for high-vacuum components. -8 The maximum permissible leakage rate of a closed vacuum assembly is atm.cc / s or lower.

[0279] Similar performance was obtained when 304 stainless steel strip was brazed onto copper strip in a “T” configuration (not shown) using a brazing alloy, and no liquefaction was observed.

[0280] Figure 7 A shows a copper plate 700 on a 304 stainless steel substrate 710, with brazed alloy wire (0.030 inches in diameter) 720 close to the two substrates. Figure 7 B shows that after brazing (1048°C, 15 minutes under vacuum), the brazing alloy formed visible brazing fillets 730 on all four edges of the square blind joint specimen, indicating good brazing fluidity. Combined with EDS analysis of a portion of the brazed joint at (x30) magnification, the brazed joint 730 adjacent to the near end 740 and far end 750 of the copper plate 700 has a uniform and smooth appearance (i.e., no signs of liquefaction). EDS spectroscopy confirmed the uniform concentration of brazing elements, and the EDS spectrum also confirmed the presence of 304 stainless steel 760.

[0281] Table 2

[0282]

[0283] Figure 8 A shows a copper plate 800 on a 304 stainless steel substrate 810, using the commercial brazing alloy GEMCO. TM The wire (0.030 inch in diameter) 820 is adjacent to two substrates. Figure 8 B shows that after brazing (1000℃, vacuum for 15 minutes), the brazing alloy forms a visible brazing fillet at the edge where the brazed wire is placed, indicating limited brazing fluidity. Figure 7Compared to the brazed joint of type B, this is a lower quality blind joint. Furthermore, combined with EDS analysis of a portion of brazed joint 830 at magnification (x30), it is shown that in portions of brazed joint 840 and 850 of the copper plate 800, the portion farther from the copper plate 850 exhibits a rough appearance (i.e., evidence of liquefaction), and the EDS spectrum also confirms the variation in the elemental concentration of the brazing element in this portion. Due to the variation in the brazed joint composition, the function of the brazed joint is expected to be impaired.

[0284] It should be understood that modifications and variations may be made without departing from the spirit and scope of the novel concept of this invention.

Claims

1. A brazing alloy composition, comprising, by weight percent: Cu from 80 to 97.98; 2.0 ≤ Ge ≤ 9.5; 0≤ Al ≤ 2.0； 0 ≤ Si ≤ 1.0; 0 ≤ In ≤ 2.0; 0.02 < B ≤ 1.25； as well as Impurities The brazing alloy composition includes no more than 0.4% Sn.

2. The brazing alloy composition according to claim 1, further comprising balanced additives, but excluding Cu, Ge, Sn, Al, Si, In and B.

3. The brazing alloy composition according to claim 1, comprising 0 to 5.0 wt% additives.

4. The brazing alloy composition according to claim 1, wherein, The additive comprises one or more elements selected from the group consisting of transition metals and rare earth metals, but excluding Cu.

5. The brazing alloy composition according to claim 1, wherein, The additive content is less than 1.0 wt%.

6. The brazing alloy composition according to claim 1, wherein, The content of the additives and impurities Sn does not exceed 0.25 wt% of the total weight of the brazing alloy components.

7. The brazing alloy composition according to claim 1, comprising a solidification temperature range not exceeding 90°C.

8. The brazing alloy composition according to claim 1, comprising a liquidus temperature in the range of 950°C to 1060°C.

9. The brazing alloy composition according to claim 1, wherein the formability of the brazing alloy composition comprises at least 38% of the brazing alloy composition, wherein, The formability test method is as follows: 5 ± 1 grams of brazing alloy components are melted and made into an ingot about 0.25 inches high. Then, the ingot is passed through a twin-roll mill at room temperature. The gap between the rolls is adjusted to reduce the ingot height by about 10%. The ingot is repeatedly passed through the mill until the thickness reaches 0.002 inches. At this point, the formability is considered to be 100%. Alternatively, the formability test method is to observe the percentage of the ingot thickness to the initial height when fracture occurs.

10. The brazing alloy composition according to claim 1, wherein, The addition of the additive will not cause the vapor pressure to rise above 1.0 × 10⁻⁶ at 700°C. -8 mmHg (1.33×10) -6 Pa).

11. The brazing alloy composition according to claim 1, wherein the vapor pressure at 500°C is less than 1 × 10⁻⁶. -11 mmHg (1.33×10) -9 Pa).

12. The brazing alloy composition according to claim 1, wherein, The amount of any single impurity element in the accompanying impurities does not exceed 0.2 wt%.

13. The brazing alloy composition according to claim 1, wherein, The brazing alloy composition can be in the form of wire, powder, preform, slurry, or foil.

14. The brazing alloy composition according to claim 13, wherein, The diameter of the wire ranges from 0.2 mm to 5.0 mm, or from 0.38 mm to 2.54 mm.

15. The brazing alloy composition according to claim 13, wherein, The thickness of the foil is in the range of 25µm to 500µm.

16. A brazing alloy composition, comprising, by weight percent: 2.0 ≤ Ge ≤ 9.5; 0≤ Al ≤ 2.0； 0 ≤ Si ≤ 1.0; 0 ≤ In ≤ 2.0; 0.02 < B ≤ 1.25； Additives ranging from 0 to 5.0; 0 ≤ Sn ≤ 0.4; Impurities less than 1.0; as well as The rest is Cu. The additive is composed of one or more elements selected from the group consisting of rare earth metals and transition metals, but excluding Cu.

17. The brazing alloy composition according to claim 16, comprising at most 0.50 wt%, preferably at most 0.30 wt%, more preferably at most 0.15 wt% of incidental impurities.

18. The brazing alloy composition according to claim 16, wherein, The accompanying impurities consist of any element other than Ge, B, Cu, Al, Si, In, Sn, and additives.

19. The brazing alloy composition according to claim 16, wherein, The accompanying impurities, excluding oxygen, include a content of 0.2 wt% or less for any single impurity element in the brazing alloy composition, preferably 0.10 wt% or less.

20. The brazing alloy composition according to claim 16, comprising, by weight percent: 0.27 ≤ B ≤ 1.25。 21. The brazing alloy composition according to claim 16, wherein, The additive is composed of one or more elements selected from Nb, Ni, Mo, W, Co, Cr, Fe, Ti, V, Zr, Au, Ag, Zn, Pt, Pd, Y, Yb, Nd and Ce.

22. The brazing alloy composition according to claim 16, comprising a solidification temperature range not exceeding 90°C.

23. The brazing alloy composition according to claim 16, comprising a liquidus temperature in the range of 950°C to 1060°C.

24. The brazing alloy composition according to claim 16, wherein, The additive includes or consists of one or more elements selected from transition metals and rare earth metals.

25. The brazing alloy composition according to claim 16, wherein, The brazing alloy composition can be in the form of wire, powder, preform, slurry, or foil.

26. The brazing alloy composition according to claim 16, wherein, The diameter of the wire ranges from 0.2 mm to 5.0 mm, or from 0.38 mm to 2.54 mm.

27. The brazing alloy composition according to claim 16, wherein, The thickness of the foil is in the range of 25µm to 500µm.

28. A brazing assembly comprising a first component and a second component connected together by a brazing joint, the brazing joint comprising or derived from the brazing alloy composition of claim 1.

29. The brazing assembly according to claim 28, wherein, The brazed joint is airtight.

30. The brazing assembly according to claim 28, wherein, The brazed joint passed the leakage test, and its airtightness was 1×10⁻⁶. -6 atm.cc / s or lower (ASTM F2391 using helium).

31. A brazing assembly comprising a first component and a second component connected together by a first brazing joint and a second brazing joint, wherein, At least one of the first brazed joint and the second brazed joint includes the brazing alloy composition according to claim 1 or is derived from the brazing alloy composition according to claim 1.

32. The brazing assembly according to claim 31, wherein, The first brazed joint and the second brazed joint comprise the brazing alloy composition according to claim 1 or derived from the brazing alloy composition according to claim 1.

33. The brazing assembly according to claim 31, wherein, The difference between the solidus temperature of the first brazed joint and the liquidus temperature of the second brazed joint is at least +15°C.

34. The brazing assembly according to claim 31, wherein, The first brazed joint includes a brazing alloy component configured to achieve a solidus temperature of at least 950°C, and the second brazed joint includes a brazing alloy component configured to achieve a liquidus temperature not exceeding 1017°C.

35. An apparatus comprising a heat source and a housing, the housing comprising the brazing assembly according to claim 28.

36. The apparatus according to claim 35, wherein, The heat source is enclosed within the housing or forms part of the housing.

37. The apparatus according to claim 35, wherein, The heat source is capable of heating at least a portion of the contents of the outer shell to a temperature greater than 800°C.

38. The apparatus according to claim 35, wherein, The first or second component includes copper.

39. The apparatus according to claim 35, wherein, The first or second component comprises ceramic or metallized ceramic.

40. The apparatus according to claim 35, wherein, The first or second component may be made of stainless steel, copper, copper alloy, nickel alloy or Ni-Co-Fe alloy.

41. The apparatus according to claim 35, wherein, The outer shell is under vacuum.

42. A vacuum tube assembly comprising the device according to claim 35.

43. A rapid heat treatment assembly, comprising the apparatus of claim 35.

44. A method for producing a brazed joint between a first component and a second component using the brazing alloy composition according to claim 1, wherein, The brazing alloy composition is as follows: a. Optionally, maintain at a temperature between 10°C and 400°C below the liquidus temperature of the brazing alloy composition for at least 10 minutes; b. A brazing temperature higher than the liquidus temperature of the brazing alloy composition; and c. Cool to below the solidus temperature of the brazing alloy composition.

45. The method of claim 44, comprising increasing the brazing temperature between the solidus and liquidus temperatures at a rate of 1°C / min to 30°C / min between the solidus and liquidus temperatures of the brazing alloy.

46. ​​The method of claim 44, wherein, The brazed joint is heated inside a brazing furnace.

47. The method of claim 44, further comprising heating a first brazing alloy component to a first brazing temperature and allowing cooling to form a first brazed joint, and then heating a second brazing alloy component to a second brazing temperature and allowing cooling to form a second brazed joint, wherein, The first brazing alloy composition and the second brazing alloy composition are configured such that the solidus temperature of the first brazed joint is higher than the liquidus temperature of the second brazed joint, wherein the second brazing temperature is maintained below the solidus temperature of the first brazed joint.

48. The method according to claim 44, wherein, The brazing joint is formed by placing the brazing alloy component in the form of wire, powder, slurry, or foil near the first and second components to be joined, heating the brazing alloy component to above its liquidus temperature, and allowing the molten brazing alloy to flow between the first and second components via capillary action.

49. The method according to claim 44, wherein, The brazed joints are produced in a vacuum, reducing, or protective environment.

50. A brazed joint, which is produced or obtained by the method according to any one of claims 44 to 49.

51. The brazed joint according to claim 50, wherein, One or both of the first and second components include copper.

52. The brazed joint according to claim 50, wherein, The brazed joint is a blind joint.

53. The brazed joint according to claim 50, wherein, Compared to the brazing alloy composition, the brazed joint contains a lower proportion of boron, and one or both of the first and second components include a detectable amount of boron derived from the brazing alloy composition.

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