A rare earth-doped copper-aluminum temperature-controlled alloy and its preparation method and application

Abstract

The present invention belongs to the field of alloy technology, specifically a rare earth-doped copper-aluminum temperature-calibration alloy and its preparation method and application. The rare earth-doped copper-aluminum temperature-calibration alloy, calculated by mass percentage, includes: Al 0-20wt%, RE 0.005-1.5wt%, and the balance is Cu and unavoidable impurity elements, and its melting point range is 1020-1084.6℃. A plurality of rare earth-doped copper-aluminum temperature-calibration alloys with different melting points and a container are combined to form an alloy temperature-calibration device, and the alloy temperature-calibration device is placed at a position where calibration or temperature measurement is required. After the process is completed, the actual temperature of the position where the alloy temperature-calibration device is located is judged based on whether the shape of the temperature-calibration alloy changes, thereby realizing industrial furnace temperature calibration and temperature measurement. The present invention has the characteristics of fast detection, convenient and flexible operation, in-situ, and no need for wiring. The melting point of the temperature-calibration alloy is not easily affected by a small amount of oxygen in the atmosphere, nor is it affected by particle radiation, electromagnetic interference, or pressure changes. It is suitable for temperature calibration and measurement of industrial furnaces with various atmosphere pressures, ensuring the accuracy of temperature in scientific research and production processes.

Description

Technical Field

[0001] The present invention belongs to the technical field of alloys, and in particular relates to a rare earth-doped copper-aluminum temperature-controlled alloy and a preparation method and application thereof. Background Art

[0002] Temperature is a physical quantity that indicates the degree of hotness or coldness of an object. It reflects the intensity of the thermal motion of molecules within an object at the microscopic level. Temperature measurement is widely used, for example, to measure the temperature of various gases, liquids, and solids. Temperature measurement and control are crucial in industrial furnaces, such as those used to sinter magnetic materials, carbide, and ceramic materials. Temperature measurement and control are directly related to process success, product quality, and energy efficiency.

[0003] Industrial furnaces typically use thermocouples, RTDs, optical pyrometers, and other devices for temperature measurement and control. The most widely used industrial temperature measurement and control systems primarily consist of thermocouples, compensation wires, and instrumentation. Numerous factors affect the accuracy of these systems, including errors inherent in thermocouples, compensation wires, and instrumentation. In particular, thermocouples inevitably deteriorate over time due to high-temperature volatilization of the thermocouple wire, oxidation, corrosion and contamination, and changes in grain structure. This gradually alters the thermoelectric properties of the thermocouple, leading to significant errors in the temperature measurement and control system. Thermocouples and instrumentation are also susceptible to interference from external factors such as neutron radiation and electromagnetic interference, which can affect temperature measurement accuracy.

[0004] Pure metals (single element metals) and some alloys have definite melting points. If a series of pure metals or alloys with different melting points are placed in a container, such as ceramic or glass, and then placed in an industrial furnace, if the ambient temperature of the container exceeds the melting point of certain pure metals or alloys, they will melt and undergo a noticeable change in shape after becoming liquid. This shape change occurs within a few seconds, and they will retain their molten shape after cooling to room temperature. If the ambient temperature is below the melting point of certain pure metals or alloys, these metals or alloys will not melt or change shape significantly. By directly observing the shape change of these pure metals or alloys in a transparent container at high temperatures or after cooling to room temperature, it can be determined whether they have melted and the actual temperature of the furnace where these containers are located can be easily determined. For example, prior art has found that the temperature inside a dry quenching furnace can reach over 1000°C. Conventional temperature measurement methods are difficult to accurately measure the operating temperature of the corbel bricks. This, coupled with the inability to correctly select the materials for the corbel bricks in different locations, can lead to stress accumulation within the corbel bricks, ultimately manifesting as cracks on the brick surface. To address the above-mentioned issues, a temperature measurement device and method for accurately measuring the three-dimensional temperature field of a corbel brick has been proposed. The method involves placing multiple metal or alloy blocks with melting points arranged in an arithmetic progression within a refractory box divided into multiple compartments. The refractory box is then positioned at the corbel brick location. Based on whether the metal or alloy melts and changes shape, the true temperature at that location can be determined. This true temperature lies between the melting points of the highest melting point of the melted metal blocks and the lowest melting point of the unmelted metal blocks. For example, if a metal block with a melting point of 1045°C melts in a refractory box, but a metal block with a melting point of 1048°C does not, the temperature at that location can be accurately determined to be between 1045°C and 1048°C. Such metals are considered temperature-sensitive metals. The above technical solution does not address the specific atmosphere surrounding the corbel brick and the effect of any oxygen in the atmosphere on the melting point of the temperature-sensitive metal.

[0005] High-radiation environments, such as reactor cores, or extreme environments, such as neutron irradiation experiments, require more precise temperature monitoring methods. Under the harsh conditions of intense neutron irradiation, conventional temperature measurement methods, such as thermocouples, cannot accurately measure or assess the ambient temperature. Because the melting point of metals is not easily affected by high-energy radiation and high-dose neutron irradiation, a series of temperature-measuring alloys and application methods have been developed. These alloys, such as silver-lithium alloys, antimony-containing alloys, and lead-bismuth alloys, utilize the alloys' shape changes and flow properties after melting to effectively address this issue, enabling temperature measurement in environments ranging from 180°C to 1200°C under intense neutron irradiation. These metals, known as temperature-measuring alloys, typically contain relatively active elements that react easily with oxygen in the environment, reducing their temperature measurement accuracy or even rendering the alloy completely ineffective. To avoid problems such as oxidation, the temperature measuring alloy needs to be sealed with a quartz tube or a corrosion-resistant metal tube, and filled with inert gas or evacuated to form a temperature measuring device. After use, the temperature measurement value is obtained by measuring the change in the center of gravity of the temperature measuring device or by dissecting the device to check the state of the temperature measuring alloy and the dripping situation. This method of using quartz tubes or metal tubes to completely seal the temperature measuring metal and completely isolate the influence of oxygen in the external environment on the melting point of the alloy has limitations. When the furnace changes from high temperature and high pressure to high temperature and high vacuum atmosphere, the pressure difference between the inside and outside of the temperature measuring device is too large, which may cause the device to collapse or burst, posing a risk of failure.

[0006] Industrial furnaces typically use temperature measurement and control systems to achieve automatic heating. However, as temperature sensors and other temperature measurement and control system components age, system errors gradually increase, causing the temperature displayed and controlled by the system to deviate increasingly from the actual temperature. Without timely temperature calibration and compensation, the actual temperature of various industrial furnaces will increasingly deviate from the target value (the temperature required by the process), leading to fluctuations in product quality and performance. Therefore, to ensure the measurement accuracy and reliable temperature values ​​of industrial furnace temperature measurement and control systems, regular or irregular temperature calibration is required for operating furnaces. Existing temperature measurement systems often cannot detect the actual temperature of the processed materials because their probes are located far away from the location of the processed materials in the furnace. Therefore, the development of methods that can detect the actual temperature of the materials is urgently needed.

[0007] Compared to traditional permanent magnets, rare earth permanent magnets currently possess the highest coercivity and largest magnetic energy product. When manufacturing rare earth permanent magnets, to minimize the degradation of material performance due to primary phase grain growth, the sintering temperature of neodymium iron boron (Nd-Fe-B) permanent magnets is typically controlled between 1020°C and 1080°C. The goal is to obtain a nearly dense, uniformly sized permanent magnet sintered body with a grain size range of 5-15μm. The temperature control accuracy of the sintering process has a decisive influence on the quality of the permanent magnet material. Even slight differences in sintering temperature can significantly affect the performance of the alloy. Furthermore, if the actual temperature differences at different locations in the sintering furnace are too large (i.e., the sintering furnace has poor temperature uniformity), the performance of products from the same furnace will vary significantly, affecting the performance consistency of batches of Nd-Fe-B materials. In industrial production, many heat treatment and sintering processes are carried out in furnaces with temperatures of 950-1100°C. How to simply and accurately calibrate the temperature of these furnaces and how to accurately measure the actual temperature of processed materials and workpieces in situ have become issues that concern technicians and need to be urgently addressed.

[0008] Currently, Nd-Fe-B magnet manufacturers typically use a nine-point thermocouple temperature calibration method to calibrate the sintering furnace temperature. This method involves the following steps: prepare the calibration equipment and confirm that the measurement errors of the nine calibration thermocouples at the same temperature are within the allowable range; clear the effective space in the sintering furnace and set up a rectangular bracket inside the furnace; install a total of nine calibration thermocouples horizontally and diagonally on the bracket in three layers: upper, middle, and lower. These nine thermocouples are then connected to calibration instruments outside the furnace using wires; the furnace door is then closed, and without any product loaded, a sintering process is started in a similar, dry-burning manner to the normal production process. During this process, the furnace temperature and uniformity are calibrated on-site. This furnace temperature calibration method is complex and requires interrupting normal production, clearing the sintering furnace, installing brackets and temperature calibration equipment, and performing a dry-burning operation during calibration, which wastes a lot of energy. This temperature calibration operation is labor-intensive and costly, and the resulting temperature is not the actual temperature of the processed material or workpiece. Summary of the Invention

[0009] In order to solve the problems existing in the prior art, the present invention provides a rare earth-doped copper-aluminum temperature-controlled alloy and its preparation method and application.

[0010] n pure metals and alloys with non-spherical shapes and increasing melting points (e.g., the melting point difference between adjacent alloys is about 2-20°C) are grouped together. These melting points will cover a certain range, denoted as {T a(1) 、T a(2) ,…,T a(n)}, where T a(1) ℃ represents the melting point of alloy a(1) with the lowest melting point in this group of metals, T a(n) ℃ represents the melting point of the alloy a(n) with the highest melting point in this group of metals, Ta(1) <T a(2) <T a(3) <…<T a(n-2) <T a(n-1) <T a(n) These alloys were placed in small containers and combined to form a device, labeled {T a（1） ~T a（n）}, place this device in a furnace where the real temperature needs to be detected. When the real furnace temperature is within the range covered by the melting points of these alloys, after these alloys placed in small containers have undergone the furnace heat process, the metals with a melting point lower than the real furnace temperature will melt and undergo obvious shape changes, such as alloys numbered 1, 2, ..., n-3 have undergone obvious shape changes and are spherical after melting; metals with a melting point higher than the real furnace temperature will not melt and their shapes will not change significantly, such as alloys numbered n-2, n-1, and n have not undergone obvious shape changes and are still non-spherical. Therefore, the real furnace temperature can be determined based on whether the shape of the alloy has changed significantly after use, that is, the real furnace temperature is [T a(n-3) ,T a(n-2) ]℃, this range depends on the difference in melting point temperature of adjacent alloys, and can be preferably controlled within 2-5℃, thus achieving accurate temperature measurement. The device is called an alloy temperature measuring device, and these alloys are called temperature measuring alloys. The alloy temperature measuring device is placed together with the materials and workpieces to be processed. The temperature measurement does not affect the normal production of the furnace. The actual temperature measurement of the materials and workpieces is achieved during the process or after the process is completed. This temperature measurement method is called in-situ temperature measurement, and the alloy temperature measuring device can easily achieve in-situ temperature measurement. The actual furnace temperature obtained by the above method is recorded as T z ℃, in the present invention, it is defined as T z =(T a(n-3) +T a(n-2) ) / 2. The above phenomenon can also be achieved by assembling the alloy temperature measuring device in descending order of alloy melting points without affecting the final effect.

[0011] If the furnace itself is equipped with a temperature measurement and control system, the maximum process temperature in the temperature control system is set to T s ℃, which is the process target temperature; during operation, the corresponding temperature measurement system will measure a maximum measurement temperature, recorded as T c ℃, under normal circumstances, these two values ​​should be very close, so it can be considered that T s =T c The actual furnace temperature value T obtained using the alloy temperature measuring device z and T s 、T c There is a difference, T z -T s =T z -T c= ΔT, where ΔT°C is the temperature the system needs to compensate for. This achieves furnace temperature calibration. A device capable of this function is called an alloy temperature calibration device, and the alloy is called a temperature calibration alloy. The method of using an alloy temperature calibration device to calibrate furnace temperature is called an alloy temperature calibration method. Placing the alloy temperature calibration device and the material to be processed together allows for temperature calibration without affecting normal furnace production. This method achieves true material temperature calibration during or after the process is complete. This temperature calibration method is called in-situ temperature calibration, and the alloy temperature calibration method of the present invention can achieve in-situ temperature calibration.

[0012] The temperature calibration alloy in the present invention can measure ambient temperature and is primarily used in alloy temperature calibration devices to achieve in-situ temperature calibration. When the temperature calibration alloy is used for temperature calibration, temperature measurement is also performed. Therefore, the concepts of "temperature measuring alloy" and "temperature calibration alloy" are considered synonymous in the present invention and can be used interchangeably. Similarly, in this application, "temperature calibration" and "temperature measurement" are generally interchangeable, and "alloy temperature measuring device" and "alloy temperature calibration device" are also interchangeable.

[0013] For copper-aluminum alloys, the mass percentage of copper (Cu) is about 100-80% and the mass percentage of aluminum (Al) is 0-20%, which can form a uniform solid solution alloy. The alloy with a composition in this range has a specific melting point, which ranges from 1084.6°C to about 1020°C. When the inventors used copper-aluminum alloys to calibrate industrial furnaces with operating temperatures of 1020-1084.6°C, they found that in some cases, abnormal conditions such as low temperature calibration accuracy occurred. Even when the actual temperature of the furnace exceeded 1085°C, the copper-aluminum temperature calibration alloy did not undergo obvious shape changes, indicating that the copper-aluminum temperature calibration alloy had failed. After careful inspection, it was found that when the oxygen content in the atmosphere inside the furnace was high, the copper-aluminum temperature calibration alloy was prone to failure. The reason is that the oxygen in the atmosphere inside the furnace preferentially reacts with the more active aluminum element in the copper-aluminum alloy, forming a dense and strong aluminum oxide film on the surface of the alloy. Because the melting point of aluminum oxide exceeds 2000°C, even if the center of the alloy melts, the shape of the alloy will not change significantly due to the presence of the surface aluminum oxide film, which makes the temperature calibration alloy prone to failure.

[0014] Aluminum alloys, widely used in industry and daily life, take full advantage of the fact that oxygen and aluminum readily react to form a strong film: the aluminum in the alloy reacts rapidly with oxygen in air, forming a thin film of aluminum oxide on its surface. This film has a very dense structure, tightly covering the surface of the aluminum alloy. It has high chemical stability and can exist on the surface of the aluminum alloy for a long time, isolating the aluminum alloy from external oxygen. Oxygen cannot penetrate this film to continue reacting with the aluminum inside, thus preventing the reaction from continuing and protecting the aluminum metal inside the component from oxidation during service.

[0015] Professionals involved in heat treatment, sintering, and other processes generally know that trace amounts of oxygen are always present in the atmosphere within industrial furnaces. The main reasons are as follows: air consists of 78.08 vol% nitrogen, 20.95 vol% oxygen, 0.93 vol% argon, 0.038 vol% carbon dioxide, and 0.002 vol% of other gases. During the loading and unloading process, air enters the furnace chamber. Purging or vacuuming cannot completely remove this air, leaving a certain amount of air. Furthermore, workpieces, refractory materials, and insulation materials absorb oxygen from the air, which is released during heating. Industrial gases such as nitrogen, argon, and hydrogen can retain and mix with small amounts of air during production, storage, and transportation, leading to trace amounts of oxygen entering the furnace atmosphere. Over time, the sealing performance of industrial furnaces deteriorates and the wear of vacuum systems increases, which can also lead to a gradual increase in oxygen levels within the furnace atmosphere.

[0016] Therefore, when the atmosphere inside an industrial furnace is in a vacuum, inert, or reducing atmosphere, it contains a certain amount of oxygen. In other words, oxygen is ubiquitous; the only difference is the oxygen content, or the oxygen partial pressure. The inventors discovered that during use, temperature-calibration alloys tend to absorb impurities such as oxygen from the furnace atmosphere. These impurities enter the alloy's crystal lattice, becoming interstitial or replacement atoms (which can be considered as absorbed and dissolved oxygen in the lattice), changing the alloy's melting point. For example, if pure copper absorbs 0.008% oxygen by mass, its melting point drops from 1084.6°C to 1066°C (see "Binary Alloy Phase Diagram and Interphase Crystal Structure," published by Central South University Press in 2009, ISBN: 9787811058314). Therefore, the presence of oxygen in the atmosphere can severely affect the alloy's temperature calibration accuracy. In more serious cases, aluminum reacts with atmospheric oxygen, forming a solid oxide film on its surface, causing the temperature-calibration alloy to completely fail.

[0017] The amount of dissolved oxygen that can be absorbed into the alloy lattice for a specific alloy composition depends on a variety of factors, including the temperature of the environment in which the alloy is located, the oxygen partial pressure, the alloy surface condition, the type and content of alloying elements, and the reaction time. This is a very complex process and is not explored in depth in this invention. For details on the results and mechanisms of the interaction between specific alloy systems and atmospheric oxygen, please refer to the relevant published literature.

[0018] After extensive research and temperature calibration practices, the inventors discovered that using the alloy temperature calibration method to accurately calibrate furnace temperature requires solving the following key issues: (1) the effect of trace oxygen in the furnace atmosphere on the melting point of the temperature calibration alloy; (2) the method used to determine whether the temperature calibration alloy has melted; and (3) the effect of changes in the atmosphere pressure in the industrial furnace on the temperature measuring device. Only by solving the above problems can the alloy temperature calibration method ensure temperature calibration accuracy and be widely used in the field of industrial furnace temperature calibration. The above three issues are mutually influential. When designing an alloy temperature calibration solution, the above three issues should be considered and solved as a whole to make the alloy temperature calibration technology solution more optimal and have wide applicability.

[0019] To overcome the effect of atmospheric oxygen on the melting point of the temperature-calibration alloy, existing technologies typically seal the alloy in a vacuum or protective gas-filled container to isolate it from the furnace atmosphere. This approach results in complex, bulky, and costly temperature-measuring devices, making them suitable only for specific furnaces with small pressure fluctuations. If the pressure in a high-temperature furnace fluctuates significantly during processing, the sealed temperature-measuring device can collapse or crack at high temperatures due to the large pressure fluctuations. For example, if a glass container containing the temperature-calibration alloy is evacuated and sealed before being placed in the furnace, the sealed glass container may collapse if the furnace temperature exceeds 1000°C and the pressure exceeds 10 atmospheres, rendering the temperature calibration ineffective.

[0020] If the temperature measuring device is not sealed, the oxygen in the atmosphere outside the device can fully contact the temperature calibration alloy, and more oxygen will enter the matrix lattice of the temperature calibration alloy, which will greatly affect the melting point of the temperature calibration alloy, thereby resulting in low temperature calibration and measurement accuracy. Professional and technical personnel in this field are not fully aware that trace oxygen in the atmosphere inside the furnace will greatly affect the melting point of the temperature calibration alloy and affect the temperature calibration accuracy.

[0021] After extensive research, the inventors discovered that when oxygen in the atmosphere comes into contact with the surface of the temperature-controlled alloy, if no rare earth elements are added to the copper-aluminum temperature-controlled alloy, the oxygen will preferentially react with the surface aluminum to form an aluminum oxide film. This is because the enthalpy change of the reaction between oxygen and aluminum is greater than the enthalpy change of the reaction between oxygen and copper (see Table 1). A larger reaction enthalpy change indicates that the reaction is easier to proceed. Because the radius of aluminum atoms is relatively small (118 pm), the diffusion rate is fast and they are oxygen-friendly. The oxygen potential on the surface is higher than that in the alloy matrix. The aluminum atoms in the matrix will diffuse to the surface, causing the surface aluminum oxide film to thicken. If the oxygen content in the atmosphere is relatively high, or the temperature-controlled alloy is exposed to high temperatures for a long time, the surface aluminum oxide film will grow to a sufficient thickness and density, which is similar to the common aluminum alloy protective film in life. This dense and strong surface aluminum oxide film will prevent the temperature-controlled alloy from changing shape even if the center of the temperature-controlled alloy matrix melts.

[0022] Enthalpy of formation of metal oxides ΔH fIt is a physical quantity that reflects the stability of its oxide. The lower its value, the more stable it is. It also indicates that the metal element is more active and more likely to react with oxygen. Traditional (structural) steel usually uses active elements such as Mn, Si, and Al to remove oxygen from the steel liquid during smelting. For example, the oxygen content of silicon-deoxidized steel can reach 30×10 -6 The oxygen content of aluminum-deoxidized killed steel can reach 20×10 -6 Below; in order to further deoxidize, more active rare earth elements need to be added, such as cerium (Ce), lanthanum (La), yttrium (Y), etc. The deoxidation performance of these rare earth elements is much higher than that of aluminum.

[0023] Based on the above factors, the inventors found that adding rare earth elements (RE), which are more active than aluminum, to the copper-aluminum alloy can effectively reduce and control the adverse effect of oxygen in the atmosphere on the melting point of the temperature-calibrated alloy during temperature calibration.

[0024] The inventors have found through research that if a small amount of rare earth metal elements are added to the copper-aluminum temperature-controlled alloy, the rare earth can form intermetallic compounds with copper and aluminum, and mainly precipitate at the grain boundaries to form a dispersed and fine second phase. m O n More stable than Al2O3 (see Table 1), that is, rare earth metal elements are more active and more oxygen-friendly than aluminum elements. Oxygen will react preferentially with rare earth elements because the atomic radius of rare earth elements is relatively large (144-204pm). The solid solubility and diffusion rate of rare earth elements in the copper-aluminum matrix are very low. At the same time, the atomic radius of oxygen is relatively small (66pm), and oxygen can easily diffuse into the interior of the alloy matrix. The rare earth at the grain boundary will capture the oxygen diffused from the atmosphere into the alloy, and generate fine rare earth oxide particles at the grain boundary in the copper-aluminum alloy matrix, which plays a role in purifying the matrix. Oxygen reacts with rare earth elements without reducing the aluminum content in the copper-aluminum matrix, and will not affect the melting point of the copper-aluminum matrix; rare earths are very active and can reduce the free oxygen in the alloy matrix to below 5ppm, eliminating the influence of oxygen in the lattice on the melting point of the alloy, and stabilizing the melting point of the temperature-controlled alloy; fine rare earth oxides are mainly dispersed at the grain boundaries and will not form a dense and strong surface film, and the melting point of rare earth oxides is above 2200℃, which is stable at high temperatures and will not dissolve or decompose in the alloy matrix, will not change the melting point of the matrix, will not affect the surface tension of the alloy when it melts and the wettability with the container, and thus will not affect the shape change of the alloy after melting.

[0025] Based on the above mechanism, adding rare earth elements to copper-aluminum alloy can better solve the influence of oxygen in the atmosphere on the melting point of the temperature-controlled alloy.

[0026] Table 1 Formation enthalpy ΔH of solid oxides of RE, Cu, and Al metal elements f (0.5 mol of oxygen is consumed)

[0027]

[0028] The data in Table 1 are quoted from the literature: DTA and Heat-flux DSC Measurements of Alloy Melting and Freezing: NIST Recommended Practice Guide, Special Publication 960-15. National Institute of Standards and Technology, Washington, DC, USA 2006.

[0029] The present invention discovered that when a rare earth alloy with a mass percentage of 2% is added to the alloy, the alloy will strongly adhere to the container wall when used for temperature calibration, regardless of whether the alloy is melted. This is because the container holding the rare earth-doped copper-aluminum temperature calibration alloy is itself made of oxides, such as zirconium oxide and aluminum oxide. RE is very active. The higher concentration of RE in the temperature calibration alloy will react violently with the container at high temperatures, seizing some of the oxygen in the container material to form complex oxides, causing the container to change color, reduce strength, a large amount of container material elements entering the temperature calibration alloy to change its melting point, and the temperature calibration alloy to strongly adhere to the container. Although temperature calibration and measurement can be achieved using a temperature calibration alloy with a rare earth content higher than 2% when low temperature calibration and measurement accuracy is required, the preferred rare earth content in the temperature calibration alloy should not exceed 2% by mass.

[0030] Rare earth metals rarely form interstitial or substitutional solid solutions with the copper and aluminum matrix, resulting in low solid solubility. However, rare earth elements can form low-melting-point eutectic alloys with copper and aluminum. For example, the eutectic temperature of 12.6% by mass of rare earth Y with copper is 880°C (at this temperature, the solid solubility of Y in solid copper is less than 0.05%), while the eutectic temperature of 9% by mass of rare earth Y with aluminum is 639°C. Therefore, adding large amounts of rare earth metals significantly alters the melting point of the copper and aluminum matrix, reducing temperature calibration accuracy. Research conducted in this paper has found that controlling the rare earth metal addition to 1.5% by mass can achieve ideal temperature calibration accuracy.

[0031] In addition, the RE content in the alloy cannot be too low. For example, if the mass percentage is lower than 0.005%, during use, the rare earth in the temperature-calibrating alloy will be quickly consumed by oxygen, and the oxygen in the atmosphere will react with the active element aluminum in the copper-aluminum alloy, resulting in reduced temperature-calibrating accuracy and even the formation of a dense and stable alumina shell structure on the surface of the alloy sample, causing the copper-aluminum temperature-calibrating alloy to completely fail.

[0032] After extensive research and practical experience in alloy temperature calibration, the inventors found that the optimal rare earth incorporation mass percentage in the temperature calibration alloy is 0.005-1.50%, the suboptimal rare earth incorporation mass percentage is 0.08-1.00%, the optimal rare earth incorporation mass percentage is 0.09-0.60%, and the optimal rare earth incorporation mass percentage is 0.10-0.35%.

[0033] During the development of this invention, it was discovered that the initial shape of a metal or alloy sample before temperature calibration can vary greatly. From a processing perspective, the sample shape primarily depends on the metal or alloy material and the sample preparation method. However, regardless of the significant difference in initial shape, the shape after melting and solidification is not necessarily related to the initial sample shape. The key factors determining the shape of the temperature-calibrated alloy sample after melting and solidification are the container material, container shape and size, and the amount of temperature-calibrated alloy sample used.

[0034] By selecting an appropriate container material, designing the container shape and size, and controlling the amount of alloy sample used, the final shape of the temperature-calibrated alloy sample after the melting-solidification process can be controlled, achieving a variety of shapes from simple to complex. The shape after temperature calibration can also be used to determine whether the alloy has melted, thereby obtaining the temperature information that needs to be calibrated. Among these feasible solutions, the inventors believe that designing a solution that controls the final shape of the temperature-calibrated alloy sample after melting and solidification to be spherical or quasi-spherical is a preferred solution, possibly the best solution. In this case: the amount of temperature-calibrated alloy sample used is small; the sample will eventually become spherical or quasi-spherical after melting, making it easier for technicians to determine whether the alloy has melted; the alloy will hardly stick to the container after melting, and the container can be reused after simple cleaning.

[0035] Based on the above principles of the present invention, after extensive experiments and optimized designs, the inventors have invented a better alloy temperature control device. The alloy temperature control device consists of a small container, a small container cover, a large container, a large container cover, and a temperature control alloy.

[0036] The material of the small container is selected based on the fact that no reaction occurs between the temperature-correcting alloy and the small container at high temperatures, or the reaction is very slight and does not affect the inherent melting point of the temperature-correcting alloy and the change in its morphology after melting. Therefore, the preferred container material is a high-temperature resistant oxide.

[0037] Furthermore, the small container can be shaped in any form that is easily processed and readily available, with a preferred shape being a cylindrical crucible with a lid. The large container should be shaped and sized to prevent multiple small containers from tipping over when stacked within it, and the large container should include a lid. The large container should be made of a high-temperature-resistant oxide ceramic or metal.

[0038] The shape of the temperature calibration alloy can be various non-spherical shapes that are easy to process and crush. Furthermore, the preferred shape is a short filament or thin sheet with any dimension less than 6 mm, which is convenient for distinguishing from the spherical shape that the alloy will become after melting due to the action of surface tension. This allows the operator to determine the temperature of the test position without the need for professional tools and professional knowledge, thereby achieving accurate temperature calibration.

[0039] Throughout the entire process of processing workpieces and products in industrial furnaces, the same process may require complex and variable atmospheres, such as low temperature, high temperature, and low temperature, as well as vacuum, low pressure, normal pressure, and high pressure. While using sealed vacuum or gas-filled protective seals on the temperature-calibrating alloy can protect it from trace oxygen in the external atmosphere, they cannot adapt to such complex pressure and temperature variations. For example, if the temperature measuring device is sealed and vacuumed at low temperatures, it may collapse and crack under high temperatures and high pressures, causing it to fail. If the temperature measuring device is sealed and gas-filled at low temperatures, it may expand and crack when the furnace is in a vacuum at high temperatures, causing it to fail. The alloy temperature calibration device of the present invention, during the processes of heating, cooling, pressurizing, etc., when there is a pressure difference between the small container and the large container, and between the large container and the external environment, the atmosphere can be exchanged between the two through the gap driven by the pressure difference, that is, the gas can enter and exit the container through the gap between the container and the cover, thereby achieving pressure balance between the atmosphere inside the container and the external atmosphere, avoiding damage to the alloy temperature calibration device of the present invention caused by changes in the pressure of the atmosphere inside the furnace, and solving the problem that the temperature calibration device is complicated and has narrow adaptability due to complete sealing, so that the alloy temperature calibration device of the present invention can achieve accurate temperature calibration and temperature measurement under various pressure conditions from negative pressure to positive pressure in a low-oxygen atmosphere, and can be widely used in the temperature calibration and temperature measurement of industrial furnaces.

[0040] For example, in a process, when the oxygen partial pressure is ≤400Pa, the absolute vacuum pressure is sometimes less than 0.001Pa, and the pressurized pressure sometimes exceeds 2500bar. Because the alloy temperature calibration device adopts the solution of the present invention, precise temperature calibration and temperature measurement can be achieved. If a completely sealed solution is adopted, it is difficult to find a suitable sealing material that can withstand the extreme changes in external high temperature and pressure without failure.

[0041] To ensure the lifespan of temperature sensors installed in industrial furnaces, facilitate material loading and unloading, and ensure sensor cleanliness, these sensors are typically located far from the materials and workpieces being processed. Furthermore, it is difficult to penetrate deep into the materials and workpieces. As a result, the temperatures measured by these sensors often deviate from the true temperatures of the materials and workpieces, with significant errors. The alloy temperature calibration device developed in this invention can be placed alongside, or even within, the materials and workpieces being processed. After the heating process is complete, the shape change of the calibration alloy can be used to determine the true temperature of the materials and workpieces in situ.

[0042] The above-mentioned alloy temperature calibration device and method are based on the use of an appropriate amount of temperature calibration alloy and a suitable container shape design, so that the alloy melts and becomes spherical under the action of surface tension, thereby achieving temperature calibration and temperature measurement functions. If the amount of temperature calibration alloy used is large and the volume of the small container is small, the amount of liquid after the temperature calibration alloy melts exceeds the amount required to fill the entire bottom of the small container. In this case, the shape of the temperature calibration alloy after melting and solidification depends on the shape of the bottom of the small container. In this case, based on the state of filling the bottom of the container after solidification, it can also be determined whether the temperature calibration alloy is melted, thereby achieving the temperature calibration and temperature measurement purposes solved by the present invention.

[0043] Based on the above principles, the present invention has the following beneficial effects:

[0044] (1) A small amount of active rare earth metal elements is added to the copper-aluminum temperature-calibration alloy to solve the problem that the melting point is easily affected by oxygen in the atmosphere. The temperature-calibration accuracy is high and the adaptability is wide.

[0045] (2) The amount of temperature calibration alloy used is small; after the alloy is melted, it does not wet the container but spheroidizes. It is convenient to judge whether the alloy is melted based on whether the alloy is spheroidized, and no other detection means are needed.

[0046] (3) The alloy temperature calibration device formed by assembling the temperature calibration alloy and large and small containers with lids does not require vacuum or inert gas packaging. The pressure inside the container and the pressure inside the furnace can be freely balanced, and the speed at which oxygen in the external environment atmosphere diffuses into the alloy temperature calibration device is controlled, making it suitable for industrial furnace temperature calibration and temperature measurement under various pressure conditions with oxygen partial pressure ≤400Pa.

[0047] (4) The alloy temperature calibration device is small and not affected by other factors, and can realize in-situ temperature calibration and temperature measurement. BRIEF DESCRIPTION OF THE DRAWINGS

[0048] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on the structures shown in these drawings without paying any creative work.

[0049] Figure 1 This is a schematic diagram of the cross-sectional structure of an alloy temperature calibration device provided by the present invention.

[0050] Figure 2 This is a partial enlarged view of the cross-sectional structural diagram of an alloy temperature calibration device provided by the present invention.

[0051] Figure 3 This is a schematic diagram of the cross-sectional structure of an alloy temperature calibration device provided by the present invention after use.

[0052] Figure 4 This is the SEM of the original ECA-04 alloy sample in Example 1 of the present invention that has not undergone atmosphere sensitivity evaluation.

[0053] Figure 5 This is the energy spectrum analysis result of the original ECA-04 alloy sample in Example 1 of the present invention that has not undergone atmosphere sensitivity evaluation.

[0054] Figure 6 This is the surface SEM of the ECA-04 alloy sample after the P1032.0-10-40 atmosphere sensitivity evaluation in Example 1 of the present invention.

[0055] Figure 7 Surface energy spectrum analysis results of the ECA-04 alloy sample subjected to P1032.0-10-40 atmosphere sensitivity evaluation in Example 1 of the present invention.

[0056] Figure 8 This is the SEM of the original ECA-05 alloy sample in Example 1 of the present invention that has not undergone atmosphere sensitivity evaluation.

[0057] Figure 9 This is the energy spectrum analysis result of the original ECA-05 alloy sample in Example 1 of the present invention that has not undergone atmosphere sensitivity evaluation.

[0058] Figure 10 This is the surface SEM of the ECA-05 alloy sample after the P1032.0-10-40 atmosphere sensitivity evaluation in Example 1 of the present invention.

[0059] Figure 11 Surface energy spectrum analysis results of the ECA-05 alloy sample subjected to P1032.0-10-40 atmosphere sensitivity evaluation in Example 1 of the present invention.

[0060] Figure 12 This is a schematic diagram of the arrangement of the rare earth-doped copper-aluminum temperature-calibrating alloy device in the Y-18# NdFeB sintering furnace in Example 4 of the present invention.

[0061] In the figure, 1-small container, 2-small container cover, 3-large container, 4-large container cover, 5-temperature calibration alloy, 6-alloy temperature calibration device, 7-space one, 8-space two, 9-exterior of alloy temperature calibration device, 10-gap structure one, 11-gap structure two, 21-front furnace door, 22-rear furnace door, 101-temperature measuring point one, 102-temperature measuring point two, 103-temperature measuring point three, 104-temperature measuring point four, 105-temperature measuring point five, 106-temperature measuring point six, 107-temperature measuring point seven, 108-temperature measuring point eight, 109-temperature measuring point nine.

[0062] The purpose, features and advantages of the present invention will be further described with reference to the accompanying drawings and in conjunction with the embodiments. DETAILED DESCRIPTION

[0063] The following will be a clear and complete description of the technical solutions in the embodiments. Obviously, the embodiments described are only part of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making any creative efforts are within the scope of protection of the present invention.

[0064] According to the above principles of the present invention, after a lot of experiments and optimization design, the inventors invented a better alloy temperature control device, such as Figure 1 shown. Figure 1 This is a schematic diagram of the cross-sectional structure of this preferred alloy temperature calibration device. The alloy temperature calibration device 6 consists of a small container 1, a small container cover 2, a large container 3, a large container cover 4, and a temperature calibration alloy 5. Figure 1 The cross-sectional structural diagram of the alloy temperature-regulating device shown is only an example of the alloy temperature-regulating device structure proposed in the present invention. Its purpose is only to intuitively demonstrate the components of the alloy temperature-regulating device of the present invention. The actual alloy temperature-regulating device structure can be optimized according to the principles of the present invention.

[0065] The material of the small container is selected based on the fact that no reaction occurs between the temperature-correcting alloy 5 and the small container 1 at high temperatures, or the reaction is very slight and does not affect the inherent melting point of the temperature-correcting alloy and the change in its morphology after melting. Therefore, the preferred container material is a high-temperature resistant oxide, such as silicon oxide, aluminum oxide, zirconium oxide, yttrium oxide, cerium oxide, lanthanum oxide, etc.; at the same time, the molten liquid of the temperature-correcting alloy sample and the container should not be completely wetted, that is, the contact angle is greater than 60°, preferably greater than 90°, and most preferably greater than 110°, to ensure that it becomes spherical or quasi-spherical under the action of surface tension after melting.

[0066] Furthermore, the small container 1 can be shaped in any form that is easily machined and readily available. A preferred shape is a cylindrical crucible with a lid. Furthermore, the size of the small container 1 can be minimized while still meeting the requirements of its intended use. A preferred volume is 50-250 μL. After the temperature calibration alloy 5 is placed, the total volume of space 7 (space 7 being the remaining space after the small container and lid are added, minus the volume of the contained temperature calibration alloy) is small, thereby minimizing the amount of oxygen in space 7. This allows the total gas volume contained in the small container 1 to be less than 200 μL. During the temperature calibration process, the rare earth metals in the temperature calibration alloy consume oxygen from the atmosphere, creating a localized, nearly oxygen-free environment within the small container 1.

[0067] The shape and size of the large container 3 should ensure that multiple small containers 1 stacked therein do not tip over, and the large container 3 also requires a large container lid 4. Furthermore, the large container 3 can be shaped in a variety of easily machined and readily available forms, with a preferred shape being a cylindrical crucible with a lid. Furthermore, the preferred dimensions of the large container 3 are: its inner diameter is 1-6 mm larger than the outer diameter of the small containers 1. This creates a relatively small space 8 (space 8 is the internal space formed by the large container with the lid added, minus the total volume of all small containers with lids contained therein) and facilitates stacking and removal of small containers 1 within the large container 3. The large container 3 should be made of a high-temperature-resistant oxide ceramic or metal.

[0068] The shape of the temperature calibration alloy 5 can be various non-spherical shapes that are easy to process and crush. Furthermore, the preferred shape is a short filament or thin sheet with any dimension less than 6 mm, which is convenient for distinguishing from the spherical shape that the alloy will become under the action of surface tension after melting. This allows the operator to determine the temperature of the test position without professional tools and professional knowledge, thereby achieving accurate temperature calibration.

[0069] Furthermore, the volume of the rare earth-doped copper-gallium temperature-calibration alloy placed in the small container 1 should be 1 / 20-1 / 2 of the volume of the small container 1, ensuring that the temperature-calibration alloy 5 placed in the small container 1 will not occupy the entire bottom of the small container 1 after melting, so that the temperature-calibration alloy 5 forms a spherical or quasi-spherical shape under the action of surface tension after melting. In the subsequent process, this shape will be maintained, especially after cooling down, it can still maintain the spherical or quasi-spherical shape.

[0070] Adding active rare earth metals to the temperature-calibrating alloy can control the amount of oxygen absorbed from the external atmosphere and dissolved in the alloy matrix lattice, thus unaffecting the alloy matrix's melting point. However, there is an upper limit to the amount of rare earth metals permitted in the alloy matrix. Over time, the rare earth metals in the alloy can be completely consumed by the atmospheric oxygen. Furthermore, if the oxygen content in the space 7 in contact with the alloy can be reduced relative to the ambient atmosphere outside the entire alloy temperature-calibrating device 9, the amount of oxygen entering the alloy matrix lattice from this atmosphere can be reduced, achieving a similar function to that of rare earth metal doping, or equivalently, adding more rare earth metals to the alloy matrix. Furthermore, if the oxygen content (oxygen partial pressure) in the space 7 in contact with the alloy can be reduced to an extremely low level, the alloy matrix will no longer absorb dissolved oxygen from the atmosphere, effectively eliminating any effect of atmospheric oxygen on the alloy matrix's melting point.

[0071] right Figure 1 The partial structure in the cross-sectional structural diagram of the alloy temperature calibration device provided by the present invention is partially enlarged, and the partial structure enlarged diagram is as follows: Figure 2As shown, the gap structure 10 is formed by the small container 1 and the small container cover 2; the gap structure 2 11 is formed by the large container 3 and the large container cover 4. Figure 2 From the gap structure 10, it can be seen that after the small container 1 is covered with the small container cover 2, there is still a slight gap between the two; Figure 2 From the gap structure 11, it can be seen that after the large container 3 is covered with the large container cover 4, there is also a slight gap between the two.

[0072] In such Figure 1 In the illustrated alloy temperature-calibration device 6, after the temperature-calibration alloy 5 is placed, the volume of space 1 (7) is small. The active rare earth elements in the temperature-calibration alloy absorb trace oxygen in the atmosphere of space 1 (7) to form rare earth oxides, resulting in an extremely low oxygen content in the atmosphere of space 1 (7). The oxygen concentration in the ambient atmosphere 9 outside the alloy temperature-calibration device is relatively high, while the oxygen concentration in space 2 (8) is relatively low, and the oxygen concentration in space 7 is the lowest. This oxygen concentration gradient exists between the two. The higher concentration of oxygen in the ambient atmosphere outside the alloy temperature-calibration device 9 must first diffuse through gap structure 2 (11) into space 2 (8), then through gap structure 1 (10) before slowly diffusing into the interior of small container 1, ultimately having a chance to enter the temperature-calibration alloy matrix. Compared to direct contact between the alloy and the external ambient atmosphere, this oxygen diffusion process takes longer due to high resistance. Even if some oxygen does enter the temperature-calibration alloy matrix, the rare earth metal elements in the temperature-calibration alloy react with oxygen in the crystal lattice to form a stable high-melting-point oxide precipitate. This ensures that the melting point of the temperature-calibration alloy is not affected by trace oxygen in the furnace atmosphere for a long period of time during use, thus ensuring temperature calibration accuracy.

[0073] Throughout the entire process of processing workpieces and products in industrial furnaces, the same process may require complex and variable atmospheres, such as low temperature, high temperature, and low temperature, as well as vacuum, low pressure, normal pressure, and high pressure. While using sealed vacuum or gas-filled protective seals on the temperature-calibrating alloy can protect it from trace oxygen in the external atmosphere, they cannot adapt to such complex pressure and temperature variations. For example, if the temperature measuring device is sealed and vacuumed at low temperatures, it may collapse and crack under high temperatures and high pressures, causing it to fail. If the temperature measuring device is sealed and gas-filled at low temperatures, it may expand and crack when the furnace is in a vacuum at high temperatures, causing it to fail. The temperature measuring device of the present invention has gap structure 10 and gap structure 2 11. During the processes of heating, cooling, pressurizing, etc., when there is a pressure difference between the small container and the large container, and between the large container and the external environment, the atmosphere can be exchanged through the gap driven by the pressure difference, that is, the gas can enter and exit the container through the gap between the container and the cover, thereby achieving pressure balance between the internal atmosphere of the container and the external atmosphere, avoiding damage to the alloy temperature calibration device of the present invention caused by changes in the internal atmosphere pressure of the furnace, and solving the problem that the temperature measuring device is complicated and has narrow adaptability due to complete sealing, so that the alloy temperature calibration device 6 of the present invention can achieve accurate temperature calibration and temperature measurement under various pressure conditions from negative pressure to positive pressure in a low-oxygen atmosphere, and can be widely used in the temperature calibration and temperature measurement of industrial furnaces.

[0074] For example, in a process, when the oxygen partial pressure is ≤400Pa, the absolute vacuum pressure is sometimes less than 0.001Pa, and the pressurized pressure sometimes exceeds 2500bar. Because the alloy temperature calibration device adopts the solution of the present invention, precise temperature calibration and temperature measurement can be achieved. If a completely sealed solution is adopted, it is difficult to find a suitable sealing material that can withstand the extreme changes in external high temperature and pressure without failure.

[0075] To ensure the lifespan of temperature sensors installed in industrial furnaces, facilitate material loading and unloading, and ensure sensor cleanliness, these sensors are typically located far from the materials and workpieces being processed. Furthermore, it's difficult to penetrate deep into the materials and workpieces. Consequently, the temperatures measured by these sensors often deviate from the true temperatures of the materials and workpieces, with significant errors. The temperature calibration device developed in this invention can be placed alongside, or even within, the materials and workpieces being processed. After the heating process is complete, the true temperature of the materials and workpieces can be measured in situ based on the shape changes of the calibration alloy.

[0076] The alloy temperature calibration device and method described above utilizes an appropriate amount of temperature calibration alloy and an appropriate container shape, allowing the alloy to melt and become spherical under the action of surface tension, thereby achieving temperature measurement. If a large amount of temperature calibration alloy is used and the small container is small, the amount of liquid from the melted temperature calibration alloy exceeds the amount required to fill the entire bottom of the small container. In this case, the shape of the melted and solidified temperature calibration alloy will depend on the shape of the bottom of the small container. In this case, the melted or solidified temperature calibration alloy can be used to determine whether the sample has melted based on how well it fills the bottom of the container, thereby achieving the temperature calibration and measurement objectives addressed by the present invention.

[0077] Based on the above principles, the detailed implementation process of the present invention is summarized as follows:

[0078] According to the first aspect of the present invention, the present invention provides the following technical solutions:

[0079] A rare earth-doped copper-aluminum temperature-controlled alloy comprises, by mass percentage, 0-20wt% of Al, 0.005-1.5wt% of RE, and the balance being Cu and unavoidable impurity elements.

[0080] Specifically, the mass percentage of Al in the rare earth doped copper-aluminum temperature-controlled alloy can be any one of 0wt%, 0.05wt%, 0.1wt%, 0.2wt%, 0.5wt%, 1wt%, 2wt%, 3wt%, 4wt%, 5wt%, 6wt%, 7wt%, 8wt%, 9wt%, 10wt%, 11wt%, 12wt%, 13wt%, 14wt%, 15wt%, 16wt%, 17wt%, 18wt%, 19wt%, 20wt% or the range between any two of them; The mass percentage of RE in the copper-aluminum temperature-controlled alloy can be any one of 0.005wt%, 0.01wt%, 0.02wt%, 0.03wt%, 0.04wt%, 0.05wt%, 0.1wt%, 0.2wt%, 0.3wt%, 0.4wt%, 0.5wt%, 0.6wt%, 0.7wt%, 0.8wt%, 0.9wt%, 1wt%, 1.1wt%, 1.2wt%, 1.3wt%, 1.4wt%, 1.5wt%, or the range between any two of them.

[0081] As a preferred embodiment of the rare earth-doped copper-aluminum temperature-regulating alloy described in the present invention, the rare earth-doped copper-aluminum temperature-regulating alloy has a precise melting point (i.e., the melting point of the rare earth-doped copper-aluminum temperature-regulating alloy with a fixed composition is fixed, and its melting point is determined by the composition of the alloy), and its melting point range is 1020-1084.6°C.

[0082] As a preferred embodiment of the rare earth-doped copper-aluminum temperature-controlled alloy described in the present invention, RE is one or any combination of at least two of lanthanum, cerium, praseodymium, neodymium, promethium, samarium, europium, gadolinium, terbium, dysprosium, holmium, erbium, thulium, ytterbium, lutetium, scandium, and yttrium.

[0083] As a preferred embodiment of the rare earth-doped copper-aluminum temperature-calibrating alloy described in the present invention, the rare earth in the rare earth-doped copper-aluminum temperature-calibrating alloy can react with oxygen in the alloy lattice to generate a stable high-melting-point oxide precipitate, thereby ensuring that the melting point of the temperature-calibrating alloy is not affected by trace oxygen in the atmosphere inside the furnace during use, thereby ensuring the temperature calibration accuracy.

[0084] According to the second aspect of the present invention, the present invention provides the following technical solutions:

[0085] A method for preparing the above-mentioned rare earth-doped copper-aluminum temperature-controlled alloy comprises:

[0086] Step 0: Based on the target melting point, formulate a rare earth-doped copper-aluminum temperature-calibrated alloy formula, and record the formula number as x.

[0087] Step 1: According to the requirements of Recipe X, weigh the required amounts of copper, aluminum, and rare earth raw materials by mass percentage. The purity of the copper and aluminum raw materials must be above 99.99%. The shapes are not limited; preferred shapes for convenient smelting include granules, blocks, and flakes. The purity of the rare earth raw materials must be above 99.5%. Preferred shapes for convenient smelting include the corresponding rare earth granules, rare earth-copper master alloys, or rare earth-aluminum master alloys.

[0088] Step 2: Place the copper and aluminum raw materials into the cleaned crucible of the vacuum induction melting furnace. Wrap the rare earth raw materials with copper foil (the weight of the copper foil is included in the total copper content of the calibration alloy) and place them in the charging device of the vacuum induction melting furnace. Turn on the power control cabinet switch, turn on the cooling circulating water pump switch, cover the vacuum induction melting furnace, close the furnace door lock ring, close the air inlet valve and vent valve, and operate the vacuum induction melting furnace control panel to evacuate the furnace. When the vacuum reaches below 10Pa, turn off the vacuum pump and valves, and fill with argon gas with a purity of 5N or above to an absolute pressure of 10 kPa, and then evacuate the vacuum again until the vacuum degree reaches below 10Pa. Slowly increase the power to heat the copper and aluminum raw materials in the melting crucible until the copper and aluminum raw materials in the melting crucible melt and become liquid. Use the rocker to feed the rare earth raw materials in the feeding device into the melting crucible. After the rare earth raw materials roll evenly with the liquid copper-aluminum alloy, slightly reduce the power until the liquid copper-aluminum alloy rolls less violently. Turn the rotating rod inward to quickly cast the liquid alloy in the melting crucible into the mold at one time. Then reduce the power to 0, turn off the switches of the power control cabinet in sequence, keep the circulating water pump on, and take out the ingot from the mold to obtain a rare earth-doped copper-aluminum alloy ingot a(x).

[0089] Melting methods are not limited to the vacuum induction furnace method mentioned above. Other methods, such as suspension melting and arc melting, can also be used to melt the alloy. The goal of melting is to melt copper, aluminum, and rare earth elements at high temperatures to form a uniform alloy. The melting atmosphere must be carefully controlled to minimize impurities such as oxygen and nitrogen. High-purity raw materials must be used to minimize rare earth element loss during melting and reduce impurity content in the final alloy.

[0090] It is generally known to those skilled in the art of smelting that, during the copper alloy smelting process, the addition of a certain amount of RE can purify and remove low-melting-point impurities in the alloy, such as sulfur (melting point 95°C), phosphorus (melting point 44°C), selenium (melting point 220°C), tin (melting point 232°C), bismuth (melting point 271°C), lead (melting point 327°C), and arsenic (melting point 818°C). The principle is that these low-melting-point elements react with rare earth metals to form high-melting-point compounds. When smelting the rare earth-doped copper-aluminum temperature-controlled alloy of the present invention, the added rare earth has a similar effect, purifying and reducing the impurity elements oxygen, phosphorus, sulfur, arsenic, antimony, lead, bismuth, etc. in the alloy, thereby making the alloy's melting point more stable.

[0091] Step 3: Annealing the smelted alloy ingot a(x) in a vacuum atmosphere, an inert atmosphere, or a hydrogen atmosphere to further homogenize the alloy. The maximum holding temperature during the annealing process can be 20-400°C below the melting point of the ingot a(x), and the holding time is not limited. The annealing temperature is typically controlled at 30-200°C below the melting point, preferably 30-150°C below, and optimally 50-100°C below. The holding time is typically 2-48 hours, preferably 4-24 hours, and optimally 6-12 hours.

[0092] Step 4: Using machining equipment to remove the surface layer of the alloy ingot a(x) after annealing and homogenization treatment, which is thicker than 1 mm and contains a lot of impurities and is easily dirty, to obtain a pure and uniform alloy ingot a(x).

[0093] Step 5: Process the pure and uniform alloy ingot a(x) into a wire or sheet, and use a shearing tool or equipment to break the wire or sheet alloy into short wires or thin sheets with any dimension less than 6 mm to obtain a usable rare earth-doped copper-aluminum temperature-controlled alloy a(x).

[0094] In steps 4 and 5, coolant and other media are not used during machining to avoid introducing impurities that could contaminate the alloy. The machining speed must be controlled to prevent the alloy from overheating and causing severe oxidation. When shearing tools or equipment are used to break the alloy, care must also be taken to avoid contamination from other foreign impurities.

[0095] Step 6: Measure the melting point of the rare earth-doped copper-aluminum temperature-calibrated alloy a(x). The melting point of the alloy a(x) is determined using methods well known to those skilled in the art, such as using a DSC thermal analyzer. The specific method is as follows:

[0096] Melting points of the calibration alloys were measured using a Netzsch DSC 449 F5 thermal analyzer. The shielding and carrier gases used were 99.999% pure argon. After passing through a gas purification system, the oxygen content in the argon was maintained below 1 ppm. A trace oxygen analyzer monitored the oxygen content in the gas system in real time. The argon flow rate was 30 mL / min. To further reduce the oxygen content in the thermal analyzer atmosphere and improve melting point accuracy, a zirconium ring was placed on the DSC stand. The heating rate was 10 K / min. The crucible was made of high-purity alumina and calcined at 1400°C in clean air for 3 hours before use. The thermal analyzer was first calibrated using pure silver and copper with a purity of at least 99.999% according to ASTM E967. According to the ITS-90 International Temperature Scale, the melting points of high-purity silver, gold, and copper are 961.78°C, 1064.18°C, and 1084.62°C, respectively. After the DSC thermal analyzer was calibrated, the melting point of pure gold (purity of 99.999%) was measured five times, and the melting point of pure gold was found to be 1064.1-1064.5°C. Therefore, it can be roughly assumed that the accuracy of the thermal analyzer in measuring the melting point is ±0.2°C.

[0097] When measuring the melting point of rare earth-doped copper-aluminum temperature-calibrated alloy a(x), take 15-20 mg of alloy sample each time, measure 3 times according to ASTM E794 standard, take the average value as the melting point of the measured alloy, and use T a(x) Indicated in ℃.

[0098] Step 7: Use the "temperature-calibration alloy atmosphere sensitivity evaluation program" developed by the present invention to evaluate the sensitivity of the melting point of the rare earth-doped copper-aluminum temperature-calibration alloy a(x) to oxygen in the atmosphere. The specific evaluation method is as follows:

[0099] The sensitivity of the temperature-calibrated alloy to the atmosphere was evaluated using a Netzsch DSC 449 F5 thermal analyzer. During the measurement, the shielding gas and carrier gas sources were argon. After passing through a gas purification system or an oxygenation system, the oxygen content in the argon gas can be adjusted in the range of less than 1ppm to 500ppm. A trace oxygen analyzer was provided in the gas system to monitor the oxygen content in the gas in real time. During the measurement, the ASTM E794 standard was followed, and a 15-20mg alloy sample was taken. The sample was loaded in an uncovered high-purity alumina crucible and calcined at 1400℃ in clean air for 3 hours before use. The argon flow rate was 30mL / min, and the oxygen content in the argon gas was controlled at E ppm. The temperature was raised from room temperature to T at a rate of 30℃ / min. h °C, at T h℃ for a certain time S min, so that the alloy sample and the oxygen in the argon atmosphere can fully react at a temperature close to the melting point of the alloy, in order to evaluate the sensitivity of the alloy melting point to oxygen; then the temperature is raised to (T h +80)℃, measure the melting point of the alloy; at (T h +80)℃ for 5 minutes, then cool directly to 50℃, end the measurement, remove the crucible and sample from the thermal analyzer, and observe whether the sample is spherical, as well as the surface color and other conditions. The above evaluation method is marked as PT h -ES, such as P1054.5-5-20, where 1054.5 means the holding temperature is 1054.5°C, 5 means the oxygen content in the argon is 5 ppm, and 20 means the holding time is 20 min.

[0100] The melting point of alloy a(x) measured under the above conditions is recorded as T a(x) [PT h -ES]℃. When evaluating the atmosphere sensitivity of a specific alloy, such as alloy a(x), (T h +30)℃ is usually equal to or close to the melting point of the alloy T a(x) ℃; E represents the oxygen content in argon gas. 0, 5, 20 ppm and other values ​​can be selected during detection. The larger the value, the greater the oxygen content in the atmosphere. "0" means that the oxygen content in the atmosphere is zero during measurement (strictly speaking, the oxygen content should be extremely low), that is, the oxygen content of the purified argon gas before entering the thermal analyzer is less than 0.5 ppm. Usually, the display value of the trace oxygen analyzer is 0.2-0.5 ppm (close to the lower limit of measurement of the instrument). In order to further control and reduce the oxygen content in the atmosphere of the thermal analyzer, a zirconium ring is placed on the DSC bracket to absorb oxygen during measurement; S represents the oxygen content in the atmosphere at T h ℃ holding time, usually 20, 40 minutes, etc., the larger the value, the longer the temperature-controlled alloy reacts with oxygen in the atmosphere when it is close to the melting point but not melted.

[0101] Before the formal measurement, the DSC thermal analyzer temperature was calibrated using metallic silver and copper with a purity of more than 99.999% in accordance with ASTM E967 standards to ensure the accuracy of melting point measurements.

[0102] Measure three times under the same conditions and take the average value as the melting point of the alloy under the above conditions, which is recorded as T a(x) [PT h -ES]℃, and the normal melting point of the alloy T a(x) ℃, compare the deviation values, and evaluate the sensitivity of the alloy to oxygen in the atmosphere.

[0103] After the alloy specimens have undergone the above-mentioned atmosphere sensitivity evaluation measurement, if necessary, especially when obvious oxidation phenomena are observed on the specimen surface, a scanning electron microscope (SEM) can be used to confirm the microscopic state of the specimen surface, and an energy dispersive X-ray spectroscopy (EDS) can be used to analyze the surface composition.

[0104] According to the third aspect of the present invention, the present invention provides the following technical solutions:

[0105] A temperature calibration and temperature measurement method using the rare earth-doped copper-aluminum temperature calibration alloy comprises the following steps:

[0106] Step 1: Estimate the ambient temperature range of the location where the temperature needs to be calibrated and measured, and determine the lower limit of the temperature range as T min ℃, the upper limit temperature is T max ℃, if it is estimated that the ambient temperature range of the temperature measurement location where temperature calibration is required may be 1055-1076℃, then T min =1055、T max =1076.

[0107] Step 2: According to the temperature calibration and temperature measurement accuracy requirements, select n rare earth-doped copper-aluminum temperature calibration alloys with increasing melting points, and the lowest melting point temperature is T a(1) ℃, the highest melting point is T a(n) ℃, T a(1) <T a(2) <T a(3) <…<T a(n-2) <T a(n-1) <T a(n) , T a(1) <T min 、T a(n) >T max The alloys can also be arranged in descending order of melting point without affecting the final temperature calibration and measurement results.

[0108] Step 3: Take appropriate amounts of n temperature-calibrating alloys with different melting points selected in step 2 and place them in n small containers. Each small container is covered with a container lid. Then, the small containers (containing alloys) are stacked in a large container in the order of increasing or decreasing melting point temperature of the alloys. The large container is covered with a container lid to assemble an alloy temperature-calibrating device. a(1) ~T a(n)},like Figure 1 shown.

[0109] Step 4: Place the single or multiple alloy temperature calibration devices {T a(1) ~T a(n) Placed at the point in the equipment where temperature calibration and measurement are required. The alloy temperature calibration device can be placed together with the material to be processed, or if necessary, placed inside the material for in-situ temperature calibration.

[0110] Step 5: Set the heating program according to the normal production process requirements and start the equipment to enter the operating state. If the equipment has its own temperature measurement and control system, set the maximum process temperature T s ℃, the highest temperature measured is T c ℃.

[0111] Step 6: After the equipment cools down to room temperature, take out the alloy temperature calibration device, observe the state of the temperature calibration alloy, and determine the actual temperature T where the alloy temperature calibration device is located. z ℃, such as Figure 3 As shown. The actual temperature T z ℃ is determined by:

[0112] If it is observed that the alloy temperature calibration device {T a(1) ~T a(n) Alloys numbered 1, 2, ..., n-3 melt into spheres, while alloys n-2, n-1, and n remain unmelted and in their original flake form. Determine the true temperature T at this location. z ℃ in [T a(n-3) ,T a(n-2) ]℃, in the present invention, it is considered that T z =(T a(n-3) +T a(n-2) ) / 2.

[0113] For example, 6 temperature-calibrating alloys with increasing melting points are placed in a small container and stacked in a large container according to their melting points from low to high. Figure 1 As shown, the alloy temperature calibration device {T a(1) ~T a(6) The device is placed in the furnace where temperature calibration and temperature measurement are required. After the heat process, the alloy temperature calibration device is taken out to determine the melting state of the alloy in the small container. The cross-sectional structure diagram of the alloy temperature calibration device after use is shown in the figure below. Figure 3 As shown, from Figure 3 It can be found that three alloys a(1), a(2), and a(3) melted and spheroidized, while three alloys a(4), a(5), and a(6) did not melt and their shapes did not change significantly. Therefore, when determining the true temperature value T z =(T a(3) +T a(4) ) / 2.

[0114] Step 7: The highest temperature T is measured by the temperature measurement system of the device according to Steps 5 and 6. c ℃ and the actual temperature T where the alloy temperature calibration device is located z ℃, we can get a temperature difference ΔT = T z -T c, ΔT℃ is the temperature that the equipment needs to compensate for. The equipment temperature is adjusted according to ΔT, such as setting process temperature compensation or performing maintenance on the furnace.

[0115] After use, if the alloy temperature calibration device and the container cover are not damaged, they can be reused after cleaning.

[0116] As a preferred solution for temperature calibration and temperature measurement using rare earth-doped copper-aluminum temperature calibration alloy described in the present invention, the rare earth-doped copper-aluminum temperature calibration alloy can be used for temperature calibration and temperature measurement in a low oxygen atmosphere with an oxygen partial pressure of ≤400Pa.

[0117] As a preferred embodiment of the present invention for using a rare earth-doped copper-aluminum temperature calibration alloy for temperature calibration and measurement, the low-oxygen atmosphere includes a vacuum atmosphere, an inert gas atmosphere, and a reducing atmosphere. Preferably, the low-oxygen atmosphere includes a vacuum atmosphere, an inert gas atmosphere (inert gas refers to Group 0 elements on the periodic table, including helium, neon, argon, krypton, xenon, and radon), and a reducing atmosphere (such as hydrogen). Further preferably, the low-oxygen atmosphere refers to an atmosphere with an oxygen partial pressure of ≤200 Pa. The atmosphere pressure can range from negative to positive, such as an absolute pressure of less than 0.001 Pa in a vacuum furnace and exceeding 2000 bar in a hot isostatic pressing furnace.

[0118] Compared with the prior art, the temperature calibration and temperature measurement method using the rare earth-doped copper-aluminum temperature calibration alloy of the present invention has the following characteristics:

[0119] (1) The comprehensive cost of temperature calibration and temperature measurement is low: the alloy temperature calibration device does not require vacuum or protective gas sealing. After use, the small and large containers in the alloy temperature calibration device can be reused many times after cleaning, and the temperature calibration and temperature measurement process does not require interruption of normal production work of the equipment.

[0120] (2) Temperature calibration and measurement are simple: The temperature measuring device has a simple structure. The temperature calibration and measurement process does not require loading and unloading thermocouples, installing temperature measuring devices, or other complicated operations. The temperature calibration and measurement data can be obtained by visually observing whether the temperature calibration alloy is melted and spheroidized. The temperature calibration and measurement process can be carried out together with normal production to achieve in-situ temperature calibration and measurement.

[0121] (3) Wide applicability of temperature calibration and temperature measurement: The rare earth in the rare earth-doped copper-aluminum temperature calibration alloy can absorb oxygen in the atmosphere of the alloy temperature calibration device, so that the oxygen content in the atmosphere of the small container of the alloy temperature calibration device is lower than that of the external environment. At the same time, the small container with a lid and the large container with a lid slow down the diffusion of oxygen from the environment into the small container, so that the temperature calibration alloy in the alloy temperature calibration device is not easily affected by oxygen in the atmosphere, so that the alloy temperature calibration device can be used for temperature calibration and temperature measurement of various industrial furnaces under low oxygen atmosphere (including vacuum atmosphere, inert gas atmosphere, reducing atmosphere) with an oxygen partial pressure of ≤400Pa. In addition, the alloy temperature calibration device can exchange atmosphere with the external environment through a small gap between the container and the container cover to achieve pressure balance, and can control the speed at which oxygen in the atmosphere enters the interior, so as to achieve temperature calibration and temperature measurement under various pressure conditions from negative pressure to positive pressure of the low oxygen atmosphere, thereby avoiding damage to the temperature measuring device caused by changes in the pressure of the atmosphere inside the furnace, so that the temperature calibration and temperature measurement method of the present invention can be widely applied in temperature calibration and temperature measurement of industrial furnaces.

[0122] The technical solution of the present invention is further described below with reference to specific embodiments.

[0123] Example 1

[0124] This example determines the optimal rare earth addition amount by evaluating the sensitivity of copper-aluminum alloys with different rare earth addition amounts to oxygen in the atmosphere.

[0125] According to the preparation process of rare earth-doped copper-aluminum temperature-corrected alloy of the present invention, three kinds of copper ingots with rare earth Y mass percentage contents of 0.00%, 0.15%, and 0.50% were prepared using a vacuum induction melting furnace. Similarly, a vacuum induction melting furnace was used to prepare five kinds of copper-aluminum alloy ingots with rare earth Y mass percentage contents of 0.00%, 0.02%, 0.15%, 0.50%, and 2.00%, respectively. Machining equipment and shearing tools or equipment were used to process and shear these three kinds of copper ingots and five kinds of copper-aluminum alloy ingots into short wire-shaped samples of any dimension not exceeding 6 mm, which were convenient for various tests. The melting points of the above eight kinds of samples were determined according to the alloy melting point measurement method of the present invention. The specific composition of the alloys and the corresponding melting points are shown in Table 2.

[0126] Table 2 Melting points of copper and copper-aluminum alloys with different rare earth Y contents

[0127]

[0128] By comparing the melting points of ECA-01, ECA-02, and ECA-03 (see Table 2), it can be seen that adding a small amount of rare earth Y (0.15% by mass) to copper has no effect on its melting point, while increasing the amount of rare earth Y added to copper (0.50% by mass) will slightly reduce the melting point of copper. Furthermore, by comparing the melting points of ECA-04, ECA-05, ECA-06, ECA-07, and ECA-08 (see Table 2), it can be seen that adding a very small amount of rare earth Y (0.02% by mass) to the Cu-Al alloy has almost no effect on its melting point, that is, the melting points of alloys ECA-05 and ECA-04 are almost the same (the melting point difference is 0.1°C, which is within the allowable error range of the melting point). Similarly, adding a small amount of rare earth Y (0.15% by mass) to the Cu-Al alloy has almost no effect on its melting point, that is, the melting point of alloy ECA-05 and ECA-04 is almost the same (the melting point difference is 0.1°C, which is within the allowable error range of the melting point). The melting points of A-06 and ECA-04 are almost the same (the difference in melting points is 0.2°C, which is within the allowable error range of the melting points). When the amount of rare earth Y added to the Cu-Al alloy increases (mass percentage content 0.50%), the melting point of the Cu-Al alloy will be slightly reduced, that is, the melting point of alloy ECA-07 is slightly lower than that of ECA-04. When the content of rare earth Y added to the Cu-Al alloy is too high (mass percentage content 2.00%), the melting point of the Cu-Al alloy will be significantly reduced, that is, the melting point of alloy ECA-08 is significantly lower than that of ECA-04 (see Table 2).

[0129] The sensitivity of ECA-01, ECA-02, and ECA-03 alloys to oxygen in the atmosphere was evaluated according to the "Atmosphere Sensitivity Evaluation Procedure for Temperature-Calibrated Alloys" described in the present invention. The evaluation results are shown in Table 3.

[0130] Table 3 Evaluation data of sensitivity of prepared copper with different rare earth Y contents to oxygen in the atmosphere

[0131]

[0132] Note: The more “+” in the column of sensitivity evaluation to oxygen in the atmosphere, the greater the influence of oxygen in the atmosphere.

[0133] As can be seen from Table 3, when the atmosphere sensitivity evaluation condition is set to P1054.5-0-40, that is, the first-step holding temperature is set to 1054.5°C (the second-step holding temperature is 1134.5°C), the oxygen content in the atmosphere is 0 ppm (strictly speaking, the oxygen content should be extremely low), and the first-step holding time is 40 min (the second-step holding time is 5 min), when the oxygen content in the atmosphere is extremely low, the ECA-01, ECA-02, and ECA-03 alloys are considered to be unaffected by the oxygen in the atmosphere, taking into account the instrument measurement error. They show a melting endothermic peak and become spherical, and their sensitivity to oxygen in the atmosphere is evaluated as "+".

[0134] When the atmosphere sensitivity evaluation condition is set to P1054.5-10-40, that is, the first step holding temperature is set to 1054.5℃ (the second step holding temperature is set to 1134.5℃), the oxygen content in the atmosphere is 10 ppm, and the first step holding time is 40 min (the second step holding time is 5 min), the T of the ECA-01 alloy without rare earth Y addition is a(x) [PT h -ES] than T a(x) The T of ECA-02 alloy with a small amount of rare earth Y added (0.15% by mass) decreased by 5.4℃, indicating that the melting temperature of ECA-01 alloy without rare earth Y addition will be significantly affected when the oxygen content in the atmosphere is high. a(x) [PT h -ES] than T a(x) The temperature of ECA-03 alloy with a large amount of rare earth Y added (0.50% by mass) decreased by only 0.2℃. This is because the small amount of active rare earth Y added to ECA-02 alloy will react with oxygen in the atmosphere first, thus protecting the ECA-02 alloy matrix. a(x) [PT h -ES] than T a(x) The temperature of the alloy increased by 0.5℃. At the same time, it was observed that the ECA-03 alloy had a slight sticking crucible phenomenon after the evaluation test. This is because the rare earth Y is more active than aluminum. The relatively large amount of Y in the ECA-03 alloy will react with the alumina crucible, resulting in a slight sticking crucible. Comprehensive analysis of T under the conditions of P1054.5-0-40 a(x) [PT h -ES] and test results show that when the oxygen content in the atmosphere is high, the melting temperature of ECA-01 alloy will be significantly affected, there is a melting endothermic peak, and the alloy becomes spherical, and its sensitivity to oxygen in the atmosphere is evaluated as "+++"; when the oxygen content in the atmosphere is high, the melting temperature of ECA-02 alloy is not affected by the oxygen in the atmosphere, there is a melting endothermic peak, and the alloy becomes spherical, and its sensitivity to oxygen in the atmosphere is evaluated as "+"; when the oxygen content in the atmosphere is high, the melting temperature of ECA-03 alloy is less affected by the oxygen in the atmosphere, there is a melting endothermic peak, and the alloy becomes spherical, but it is observed that the ECA-03 alloy after the evaluation test has a slight crucible sticking phenomenon, and its sensitivity to oxygen in the atmosphere is evaluated as "++".

[0135] This shows that when the mass percentage of rare earth addition in the rare earth-doped copper temperature-controlled alloy is 0.15%, its melting temperature and melting state are only slightly affected by oxygen in the atmosphere, that is, its gas sensitivity resistance is the best.

[0136] The sensitivity of ECA-04, ECA-05, ECA-06, ECA-07, and ECA-08 alloys to oxygen in the atmosphere was further evaluated according to the evaluation method of the "temperature-calibrated alloy atmosphere sensitivity evaluation procedure" described in the present invention. The evaluation results are shown in Table 4.

[0137] Table 4 Evaluation data of sensitivity of prepared copper-aluminum alloys with different rare earth Y contents to oxygen in the atmosphere

[0138]

[0139] Note: “ / ” in the table indicates no exact value. The more “+” in the column of sensitivity evaluation to oxygen in the atmosphere, the greater the influence of oxygen in the atmosphere.

[0140] As can be seen from Table 4, when the atmosphere sensitivity evaluation condition is set to P1032.0-0-40, that is, the first step holding temperature is set to 1032℃, the holding time is 40 min, the second step holding temperature is set to 1112℃, the holding time is 5 min, and the oxygen content in the atmosphere is 0 ppm (strictly speaking, the oxygen content should be extremely low), the melting temperatures of ECA-04, ECA-05, and ECA-06 alloys are not affected by, or only slightly affected by, the oxygen in the atmosphere. There is a melting endothermic peak and it becomes spherical. The sensitivity to oxygen in the atmosphere is evaluated as "+". ECA-07 has a slight crucible sticking phenomenon and its sensitivity to oxygen in the atmosphere is evaluated as "++". The T value of ECA-08 alloy cannot be determined. a(x) [PT h -ES], and after the evaluation test, it strongly adhered to the crucible and became hemispherical. This is because the ECA-08 alloy contains relatively more rare earth Y, which is more active than Al. After reacting with the alumina crucible at high temperature, it showed strong adhesion to the crucible wall and prevented it from forming a spherical shape. The sensitivity to oxygen in the atmosphere was evaluated as "++++".

[0141] When the evaluation conditions are set to P1032.0-10-40, that is, the oxygen content in the atmosphere is 10 ppm, the T a(x) [PT h -ES] than T a(x) The temperature of the original ECA-04 alloy ( Figure 4 、 Figure 5 ) and ECA-04 alloy ( Figure 6 、 Figure 7 ) SEM and EDS energy spectrum analysis were performed to Figure 4 and Figure 5 It can be seen that the original ECA-04 is a homogeneous alloy composed of Cu and Al after smelting. Figure 6and Figure 7 The surface energy spectrum of the ECA-04 alloy sample subjected to the P1032.0-10-40 atmospheric sensitivity evaluation shows only O and Al, with no traces of the main matrix element, copper. This indicates that Al diffuses and accumulates from within the matrix, forming a dense, solid, pure aluminum oxide layer on the surface. This prevents the matrix alloy from deforming after melting, maintaining its original thin strip shape. Its sensitivity to atmospheric oxygen is evaluated as "++++." The ECA-05 alloy, which contains a trace amount of rare earth Y (0.02% by mass), exhibits similar behavior to the ECA-04 alloy. This is due to the low rare earth content in the ECA-05 alloy. After the rare earth element is completely consumed by oxygen, the oxygen continues to react with aluminum that has diffused to the alloy surface, forming a dense, solid aluminum oxide layer on the surface. This also prevents deformation and maintains its original thin strip shape. Its sensitivity to atmospheric oxygen is evaluated as "++++."

[0142] Under this condition, the ECA-08 alloy with excessive rare earth Y (mass percentage content 2.00%) cannot be judged. a(x) [PT h -ES] is mainly due to the presence of relatively more rare earth Y in the ECA-08 alloy, which is more active than Al. When kept at a high temperature of 1032°C for a long time, the rare earth Y reacts with the alumina crucible, showing strong adhesion to the crucible wall and preventing it from forming a spherical shape. The sensitivity to oxygen in the atmosphere is evaluated as "++++".

[0143] The same evaluation was conducted on ECA-06 alloy with a small amount of rare earth Y added (mass percentage 0.15%). a(x) [PT h -ES] than T a(x) The melting point was lowered by 0.2℃ (within the tolerance of melting point), and spheroidization occurred. Figure 8 、 Figure 9 ) and ECA-06 alloy ( Figure 10 、 Figure 11 ) SEM and EDS energy spectrum analysis were performed to Figure 8 and Figure 9 It can be seen that the original ECA-06 is a homogeneous alloy composed of Cu, Al and Y; Figure 10 and Figure 11It can be seen that the main components of the surface of the ECA-06 alloy sample evaluated by the P1032.0-10-40 atmosphere sensitivity are Al, Y, and O, and a weak peak of the matrix element Cu is also observed. This proves that when the oxygen content in the furnace atmosphere is high, oxygen will react with the rare earth Y and Al on the sample surface to form oxides, but the surface layer of rare earth Y and Al oxides formed is discontinuous; most of the oxygen that enters the alloy matrix will diffuse into the matrix and react with the rare earth Y inside the matrix to form rare earth oxide precipitation; compared with the ECA-04 alloy, due to the presence of more active rare earth Y in the matrix, the Al in the ECA-06 alloy matrix has a weak tendency to diffuse to the surface, so a weak peak of the matrix element Cu can still be observed on the surface of the ECA-06 alloy sample (see Figure 11 ), and the resulting rare earth Y and Al oxide surface layers are discontinuous, non-dense, and weak, which does not affect its melting state and is rated "+" for atmosphere sensitivity. ECA-07 alloy (Y content 0.50% by mass) exhibits slight adhesion to the crucible, with a slight shift in melting point and a "+++" sensitivity to atmospheric oxygen.

[0144] This further illustrates that when 0.15% by mass of rare earth is added to the rare earth-doped copper-aluminum temperature-controlled alloy, its melting temperature and melting state are almost unaffected by oxygen in the atmosphere, that is, its gas sensitivity resistance is the best.

[0145] Example 2

[0146] This embodiment provides a series of rare earth-doped copper-aluminum temperature-controlled alloys with gradient melting point temperatures.

[0147] According to the method for preparing rare earth-doped copper-aluminum temperature-controlled alloys of the present invention, a series of rare earth-doped copper-aluminum temperature-controlled alloys with different melting points were prepared by varying the aluminum content in the alloy using a vacuum induction melting furnace and shearing tools or equipment. The rare earth content was 0.15% by weight, and the rare earth metals added were Y, La, Ce, and Lu, respectively.

[0148] According to the alloy melting point measurement method of the present invention, the melting points of this series of alloys were measured using a Netzsch DSC 449 F5 thermal analyzer. The specific results are shown in Table 5:

[0149] Table 5 A series of rare earth-doped copper-aluminum temperature-controlled alloys with different melting points

[0150]

[0151] Example 3

[0152] The rare earth-doped copper-aluminum alloy temperature calibration and temperature measurement method of the present invention is used to calibrate the actual temperature at the center of the NdFeB sintering furnace.

[0153] Take the short filamentary alloys numbered CA-11, CA-10, CA-09, CA-08, CA-07, CA-06, CA-05, and CA-04 prepared in Example 2, and assemble them into a similar alloy temperature measuring device {1042.0~1067.7} according to the alloy temperature calibration device described in the specification of the present invention. The alloy temperature calibration device {1042.0~1067.7} is placed in the center of the NdFeB sintering furnace numbered Y-10#, and the NdFeB compacts to be sintered are placed in other positions. According to the requirements of the NdFeB material sintering process, the maximum sintering temperature is set to 1045.0℃, that is, T c Temperature, keep at this temperature for 120 minutes, and the sintering atmosphere is vacuum. After the furnace temperature drops below 50℃, take out the NdFeB products and the temperature calibration device together, and observe the shape changes of these alloys. It was found that the shapes of CA-06, CA-05, and CA-04 alloys did not change significantly, and they were still long strips; the shapes of CA-11, CA-10, CA-09, CA-08, and CA-07 alloys changed significantly and became spherical. The melting points of CA-07 and CA-06 alloys are 1053.4℃ and 1057.3℃ respectively. According to the shape changes, it is determined that the highest true temperature at the center of the Y-10# sintering furnace is between 1053.4-1057.3℃. Taking the middle value, the highest true sintering temperature at the center is 1055.4±2℃, that is, T z Temperature, get T z ℃-T c ℃ = ΔT℃ is 10.4℃. When sintering the product next time, by setting the maximum sintering temperature of the Y-10# furnace to 1034.6℃ in the control software, the required actual sintering temperature of 1045.0℃ can be achieved.

[0154] This method allows for in-situ calibration of the true temperature at the center of the Y-10# NdFeB sintering furnace without disrupting normal production. The desired sintering temperature can then be achieved by simply changing the temperature setting in the control software. Regularly performing this temperature calibration and adjustment ensures consistent, long-term sintering temperatures in the Y-10# sintering furnace, enabling the furnace to consistently produce high-quality products.

[0155] Typically, multiple sintering furnaces are installed on a single production line. Using the alloy temperature calibration technology described in this invention, all sintering furnaces on the line are uniformly calibrated using the aforementioned method. Temperature compensation is then applied to each sintering furnace based on the calibration results, ensuring that all sintering furnaces on the same line maintain the same actual sintering temperature. This approach to quality management reduces fluctuations in product performance indicators across the production line, helping companies achieve their quality goals.

[0156] Example 4

[0157] The application of rare earth-doped copper-aluminum temperature correction alloy can truly reflect the actual temperature field distribution of the NdFeB sintering furnace, and can guide the temperature correction of points that deviate from the target temperature.

[0158] Take the long strips of alloys numbered CA-08, CA-07, CA-06, CA-05, CA-04, CA-03, and CA-02 prepared in Example 2, each weighing 0.02-0.10 grams, and assemble them into a similar alloy temperature measuring device {1050.1~1080.9} according to the alloy temperature calibration device described in the specification of the present invention. Place 9 sets of alloy temperature calibration devices {1050.1~1080.9} in a NdFeB sintering furnace numbered Y-18#. Figure 12 There are nine temperature measuring points shown, namely, temperature measuring point 1 101, temperature measuring point 2 102, temperature measuring point 3 103, temperature measuring point 4 104, temperature measuring point 5 105, temperature measuring point 6 106, temperature measuring point 7 107, temperature measuring point 8 108, and temperature measuring point 9 109. In the figure, the front furnace door 21 and the rear furnace door 22 are used to illustrate the furnace structure and the arrangement of the nine temperature measuring points in the furnace body. The NdFeB compacts to be sintered are placed in other locations. According to the requirements of the NdFeB material sintering process, the maximum sintering holding temperature is set to 1070°C, that is, T c Temperature, kept at this temperature for 120 minutes, sintering atmosphere is vacuum. After the furnace temperature drops below 50℃, the NdFeB products and temperature calibration device are taken out together, and the shape changes of these alloys are observed. The results are shown in Table 6.

[0159] Table 6 Actual temperature data of each point in the furnace of the Y-18# NdFeB sintering furnace with the holding temperature set at 1070℃

[0160]

[0161] According to the data in Table 6, the temperature ΔT that needs to be compensated at each point of the Y-18# NdFeB sintering furnace can be obtained as shown in Table 7.

[0162] Table 7 ΔT at each point in the furnace of the Y-18# NdFeB sintering furnace with a holding temperature of 1070℃

[0163]

[0164] Therefore, by placing rare earth copper-aluminum temperature calibration alloy devices at different positions of the NdFeB sintering furnace for temperature calibration, the actual temperature field distribution of the NdFeB sintering furnace can be truly reflected, and the points that deviate from the target temperature can be guided to perform temperature correction. On the one hand, the real temperature can be obtained by the rare earth copper-aluminum temperature calibration alloy device to grasp the quality of the NdFeB materials sintered in the same furnace and distinguish unqualified products. On the other hand, the heating element or furnace compensation coefficient can be adjusted according to the temperature ΔT that needs to be compensated to achieve uniformity of the overall temperature field of the NdFeB sintering furnace, thereby improving the performance and quality consistency of the products sintered in the same furnace.

[0165] The above description is only a preferred embodiment of the present invention and does not limit the patent scope of the present invention. All equivalent structural transformations made by using the contents of the present invention specification under the inventive concept of the present invention, or direct / indirect application in other related technical fields are included in the patent protection scope of the present invention.

Claims

1. An application of rare earth-doped copper-aluminum alloy in the field of temperature control, characterized in that: The rare earth-doped copper-aluminum alloy comprises, by mass percentage, 0-20wt% Al, 0.005-1.5wt% RE, and the remainder being Cu and unavoidable impurity elements; the melting point range of the rare earth-doped copper-aluminum alloy is 1020-1084.6°C.

2. The application of the rare earth-doped copper-aluminum alloy in the field of temperature control according to claim 1, characterized in that: RE is one or any combination of at least two of lanthanum, cerium, praseodymium, neodymium, promethium, samarium, europium, gadolinium, terbium, dysprosium, holmium, erbium, thulium, ytterbium, lutetium, scandium, and yttrium.

3. The use of the rare earth-doped copper-aluminum alloy according to any one of claims 1-2 in the field of temperature control, characterized in that: The preparation method of the rare earth-doped copper-aluminum alloy comprises the following steps: Step 0: Formulate alloy formula according to target melting point; Step 1: according to the formula requirements, weigh the required mass of copper, aluminum and rare earth raw materials according to mass percentage; Step 2: Smelting copper, aluminum and rare earth raw materials to alloy and homogenize the materials to obtain a rare earth-doped copper-aluminum alloy ingot; Step 3, processing the rare earth-doped copper-aluminum alloy ingot, crushing it into a non-spherical shape, and preparing a rare earth-doped copper-aluminum alloy to be used; Step 4, measuring the melting point T°C of the rare earth-doped copper-aluminum alloy; Step 5: Evaluate the sensitivity of the rare earth-doped copper-aluminum alloy to oxygen in the atmosphere.

4. A temperature calibration and temperature measurement method, using the rare earth-doped copper-aluminum alloy according to any one of claims 1-2 in the application of the rare earth-doped copper-aluminum alloy in the field of temperature calibration, characterized in that: The steps include: Step 1: Estimate the ambient temperature range of the location where the temperature needs to be calibrated and measured, and determine the lower limit of the temperature range as T min ℃, the upper limit temperature is T max ℃; Step 2: According to the temperature calibration and temperature measurement accuracy requirements, select n rare earth-doped copper-aluminum alloys with increasing melting points. The lowest melting point of these alloys is T a(1) ℃, the highest melting point is T a(n) ℃, T a(1) <T a(2) <T a(3) <…<T a(n-2) <T a(n-1) <T a(n) , T a(1) <T min 、T a(n) >T max ; Step 3, assembling the n rare earth-doped copper-aluminum alloys with increasing melting points and a container into an alloy temperature calibration device; Step 4: Place one or more alloy temperature calibration devices described in step 3 at the location where temperature calibration or measurement is required; Step 5: Set the heating program according to the normal production process requirements, start the equipment and enter the running state. The equipment has its own temperature measurement system, and the highest temperature measured is T c ℃; Step 6: After the equipment has finished running and cooled to room temperature, take out the alloy temperature calibration device, observe the state of the alloy in the container, and determine the actual temperature T of the environment where the alloy temperature calibration device is located. z ℃, thus achieving temperature measurement; Step 7, T z -T c =ΔT, ΔT℃ is the temperature that the device needs to compensate for. The device temperature is adjusted according to ΔT, thus achieving temperature calibration.

5. The temperature calibration and measurement method according to claim 4, characterized in that: The alloy temperature calibration device in step 3 includes: N rare earth-doped copper-aluminum alloys with different melting points are placed in n small containers, each small container is covered with a container cover and placed in a large container, and the large container is covered with a container cover.

6. The temperature calibration and measurement method according to claim 5, characterized in that: The alloy does not wet the small container; the volume of the rare earth-doped copper-aluminum alloy placed in the small container is 1 / 20-1 / 2 of the volume of the small container.

7. The temperature calibration and measurement method according to claim 4, characterized in that: The temperature calibration and measurement process is carried out together with normal production. The alloy temperature calibration device is placed together with the workpiece to be processed, which does not affect normal production work and realizes in-situ temperature calibration and measurement.

8. The temperature calibration and measurement method according to claim 4, characterized in that: The actual temperature T in step 6 z ℃ is determined by: It was observed that the alloys numbered 1, 2, ..., n-3 in the alloy temperature calibration device melted into spherical shapes, while the alloys numbered n-2, n-1, and n remained unmelted and kept their original shapes. The actual temperature at the temperature calibration and measurement location is [T a(n-3) ,T a(n-2) ]℃, it is considered that T z =(T a(n-3) +T a(n-2) ) / 2.

9. The temperature calibration and measurement method according to claim 4, characterized in that: The alloy temperature calibration device can be used for temperature calibration and temperature measurement of various industrial furnaces in low oxygen atmosphere; the alloy temperature calibration device does not require vacuum or protective gas sealing and can also protect the melting point of the internal alloy from being affected by oxygen in the external environment.

10. The temperature calibration and measurement method according to claim 9, characterized in that: The alloy temperature calibration device can realize the temperature calibration and temperature measurement of industrial furnaces under various pressure conditions from negative pressure to positive pressure in the low oxygen atmosphere; the low oxygen atmosphere is an atmosphere with an oxygen partial pressure of ≤400Pa, and the low oxygen atmosphere includes a vacuum atmosphere, an inert gas atmosphere, and a reducing atmosphere.

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