CN114058798B - Flash annealing process and device for La-Fe-Si alloy - Google Patents
Flash annealing process and device for La-Fe-Si alloy Download PDFInfo
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- CN114058798B CN114058798B CN202111425084.XA CN202111425084A CN114058798B CN 114058798 B CN114058798 B CN 114058798B CN 202111425084 A CN202111425084 A CN 202111425084A CN 114058798 B CN114058798 B CN 114058798B
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- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
- C21D1/00—General methods or devices for heat treatment, e.g. annealing, hardening, quenching or tempering
- C21D1/26—Methods of annealing
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- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
- C21D1/00—General methods or devices for heat treatment, e.g. annealing, hardening, quenching or tempering
- C21D1/34—Methods of heating
- C21D1/40—Direct resistance heating
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- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
- C21D6/00—Heat treatment of ferrous alloys
- C21D6/008—Heat treatment of ferrous alloys containing Si
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- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
- C21D9/00—Heat treatment, e.g. annealing, hardening, quenching or tempering, adapted for particular articles; Furnaces therefor
- C21D9/0081—Heat treatment, e.g. annealing, hardening, quenching or tempering, adapted for particular articles; Furnaces therefor for slabs; for billets
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- C21D9/00—Heat treatment, e.g. annealing, hardening, quenching or tempering, adapted for particular articles; Furnaces therefor
- C21D9/46—Heat treatment, e.g. annealing, hardening, quenching or tempering, adapted for particular articles; Furnaces therefor for sheet metals
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- H01F—MAGNETS; INDUCTANCES; TRANSFORMERS; SELECTION OF MATERIALS FOR THEIR MAGNETIC PROPERTIES
- H01F41/00—Apparatus or processes specially adapted for manufacturing or assembling magnets, inductances or transformers; Apparatus or processes specially adapted for manufacturing materials characterised by their magnetic properties
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01F—MAGNETS; INDUCTANCES; TRANSFORMERS; SELECTION OF MATERIALS FOR THEIR MAGNETIC PROPERTIES
- H01F1/00—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties
- H01F1/01—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties of inorganic materials
- H01F1/012—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties of inorganic materials adapted for magnetic entropy change by magnetocaloric effect, e.g. used as magnetic refrigerating material
- H01F1/015—Metals or alloys
Abstract
The invention discloses a flash annealing process and device of La-Fe-Si alloy, belonging to the technical field of alloy heat treatment. The process comprises the following steps: 1. heating the alloy plate to 1150 ℃ at a heating rate of 5-10 ℃/s, and preserving heat for 5-15 s; 2. heating the alloy plate to 1185-1225 ℃ by applying pulse current, then cooling to 1150-1165 ℃, and circularly heating and cooling at the stage for 5-15 s; in this phase, the pulse current parameters are: pulse width is 0.5-2 ms, peak current is 1000-2000A, frequency is 5-100 Hz; 3. cooling to 300 ℃ at a cooling rate of 50-100 ℃/s, and cooling to room temperature. The device is a heat treatment device designed by matching with the process. The invention can greatly reduce the heat treatment time of La-Fe-Si alloy, reduce the heat treatment energy consumption and improve the stability of the heat treatment effect of La-Fe-Si alloy.
Description
Technical Field
The invention belongs to the technical field of alloy heat treatment, and particularly relates to a flash annealing process and device of La-Fe-Si alloy.
Background
The magnetic refrigeration technology is a mode for realizing refrigeration by utilizing the magnetocaloric effect of the solid magnetic refrigeration function alloy, and has the advantages of low energy consumption, no pollution, high efficiency and the like compared with the traditional gas compression refrigeration mode. The light rare earth iron-based alloy La-Fe-Si is considered as one of the room temperature magnetic refrigeration functional alloys with the most commercial application prospect due to the excellent cost performance. However, the conventional casting method cannot directly prepare a magnetic refrigeration functional phase (La (Fe, si)) having a large volume fraction and a giant magnetocaloric effect 13 Phase) must be subjected to a subsequent treatment using a high temperature heat treatment process.
At present, the commercial application of the system alloy is severely restricted aiming at the problems of long heat treatment time (60-100 h), high-temperature energy consumption (heat treatment temperature is more than 1000 ℃) and the like in the heat treatment annealing process of La-Fe-Si system alloy. Therefore, how to formulate a scientific heat treatment process to shorten the heat treatment time and reduce the consumption of energy and resources in the heat treatment process becomes one of the key bottlenecks of the large-scale application of La-Fe-Si alloy.
The conventional heat treatment temperature range for La-Fe-Si alloy is generally between 1000 and 1150 ℃, and if the temperature is continuously raised to more than 1150 ℃, remelting of part phases can occur, and the alloy can be subjected to the risk of large-area melting. However, it is difficult to reduce the heat treatment time while ensuring the heat treatment effect by heat-treating the La-Fe-Si alloy in a temperature range of 1000 to 1150 ℃.
For example, the Chinese patent application number is: CN201811113587.1, publication date: patent literature of 2019, 1 and 25 days discloses a La-Fe-Si-Cu magnetic refrigeration material with excellent magnetic thermal performance and short preparation period and a preparation method thereof, wherein the chemical general formula of the La-Fe-Si-Cu magnetic refrigeration material is (La) y Fe 13-z Si z ) 100-x Cu x ，0<x is less than or equal to 50, y is less than or equal to 1 and less than or equal to 2, and z is less than or equal to 0 and less than or equal to 10. The preparation method comprises the following steps: (1) Mixing La, fe, si and Cu according to the mass percentage of each element in the general formula; (2) Under the protection of high-purity argon, repeatedly smelting, cooling and turning the prepared raw materials in a vacuum arc furnace for four times; (3) Will castThe ingot is quenched in cold water after high temperature heat treatment under high purity argon atmosphere.
Compared with the traditional method, the invention shortens the preparation period of La-Fe-Si magnetic refrigeration material, but the La-Fe-Si-Cu alloy with more La (Fe, si) content can be obtained only by carrying out back flushing of 0.01-0.03 MPa high-purity argon protection under the vacuum condition and isothermal annealing for 6 days at 1050 DEG C 13 And the energy consumption in the heat treatment process is still relatively large.
For another example, chinese patent application No.: CN201210239559.0, publication date: patent literature of 2013, 4 and 17 discloses La (Fe, si) prepared from high Ce industrial pure mixed rare earth 13 The base magnetic refrigeration material has a chemical formula as follows: la (La) 1-x (Ce,Pr,Nd) x (Fe 1-p-q Co p Mn q ) 13-y Si y Having NaZn 13 A shaped structure. The preparation method comprises the following steps: la is prepared by smelting and annealing high Ce industrial pure mixed rare earth serving as raw material 1-x (Ce,Pr,Nd) x (Fe 1-p-q Co p Mn q ) 13-y Si y Magnetic refrigeration material.
The invention reduces the preparation cost of the material, but the heat treatment annealing process used by the invention is as follows: the melted alloy ingot is heated at 1000 ℃ and the vacuum degree is less than 10 -3 Annealing for 60 days under Pa, then quenching in liquid nitrogen, so that the whole heat treatment process is long in period and high in cost.
The flash heat treatment annealing is a heat treatment process for heating alloy to a certain temperature in a very short time and rapidly cooling after short-time heat preservation, and the process greatly reduces the heat treatment time while ensuring the heat treatment effect, thereby saving energy consumption. However, the prior art does not have a technology of applying the flash heat treatment annealing to the La-Fe-Si alloy specifically, so that the actual process steps and the corresponding parameters are difficult to determine, and the flash heat treatment annealing of the La-Fe-Si alloy is difficult to be realized well by the existing device.
Meanwhile, the applicant has found that, in the course of studying the heat treatment process of La-Fe-Si based alloy, la-Fe-Si based alloy is alloyed by the flash heat treatment processThe heating temperature of the gold is increased to 1185-1225 ℃, and the temperature is rapidly reduced to 1150-1165 ℃ after short-time heat preservation, so that the alloy can be prevented from being melted in a large area. However, when the La-Fe-Si alloy is heat treated by this method, if the holding time is too short, it becomes difficult to prepare a magnetic refrigeration functional phase (La (Fe, si)) having a large volume fraction 13 Phase) and if the holding time is too long, the alloy may also undergo large area melting. And the optimal heat preservation time is changed due to different shapes, sizes and heating modes of the alloy, so that the optimal heat preservation time of the La-Fe-Si alloy in heat treatment is difficult to scientifically formulate, and the heat treatment effect is unstable.
Disclosure of Invention
1. Problems to be solved
Aiming at the problems that the conventional La-Fe-Si alloy has imperfect heat treatment process and unsatisfactory heat treatment effect, the invention provides a flash annealing process of La-Fe-Si alloy, which can greatly reduce the heat treatment time of La-Fe-Si alloy, reduce heat treatment energy consumption and improve the stability of the heat treatment effect of La-Fe-Si alloy.
The invention also provides a flash annealing device of the La-Fe-Si alloy, which can be used in the process to heat treat the La-Fe-Si alloy and improve the performance of the La-Fe-Si alloy.
2. Technical proposal
In order to solve the problems, the invention adopts the following technical scheme.
A flash annealing process of La-Fe-Si alloy comprises the following steps:
1. preheating stage
Heating the alloy plate to 1150 ℃ at a heating rate of 5-10 ℃/s, and preserving heat for 5-15 s;
2. flash heating stage
Heating the alloy plate to 1185-1225 ℃ by applying pulse current, then cooling to 1150-1165 ℃, and circularly heating and cooling at the stage for 5-15 s; in this phase, the pulse current parameters are: pulse width is 0.5-2 ms, peak current is 1000-2000A, frequency is 5-100 Hz;
3. cooling stage
Cooling to 300 ℃ at a cooling rate of 50-100 ℃/s, and cooling to room temperature.
As a further improvement of the technical scheme, in the second step, the average heating rate is 7000-37500 ℃/s, and the average cooling rate is 100-5000 ℃/s.
As a further improvement of the technical scheme, the first step adopts a direct current heating mode, keeps the power of a direct current power supply constant after the heat preservation is finished, and enters the second step.
As a further improvement of the technical scheme, in the third step, the alloy plate is cooled by spraying cooling inert gas.
As a further improvement of the technical scheme, the method further comprises the following step four: and (3) carrying out phase content statistics and standard magnetic performance test on the alloy plate processed in the step (III).
As a further improvement of the technical scheme, the alloy plate is La-Fe-Si alloy plate with the thickness of 0.5-2 mm.
As a further improvement of the technical scheme, the alloy plate is La-Fe-Si-X alloy plate, and X is one or more of RE, B, C, co and H.
A flash annealing device of La-Fe-Si alloy is used for the flash annealing process and comprises a vacuum cavity, a current heating mechanism, a graphite groove, a cooling mechanism and a pulse heating mechanism; the current heating mechanism is arranged in the vacuum cavity and is used for electrifying and heating the graphite groove, and a space for placing the alloy plate is arranged in the graphite groove; the cooling mechanism is used for cooling the alloy plate in the graphite groove; the coil of the pulse heating mechanism is wound on the surface of the alloy plate.
As a further improvement of the technical scheme, the cooling mechanism comprises an inert gas cylinder and a blowing nozzle, wherein the blowing nozzle is arranged above the graphite tank, and an inlet of the blowing nozzle is connected with the inert gas cylinder through a pipeline.
As a further improvement of the technical scheme, tungsten wires or molybdenum wires are adopted as the material of the coil.
3. Advantageous effects
Compared with the prior art, the invention has the beneficial effects that:
(1) Compared with the conventional quartz tube packaging or vacuum indoor constant temperature annealing treatment process, the flash annealing process of the La-Fe-Si alloy greatly shortens the heat treatment time, can be completed in a few minutes, obviously reduces the energy consumption in the heat treatment process, has higher practical value, particularly realizes the cyclic flash heating and cooling of the alloy plate through pulse magnetic induction heating, can realize the local discontinuous flash melting, flash high temperature synthesis and flash solidification in the alloy plate on the premise of ensuring that the alloy plate does not melt in a whole large area, and solves the problem that the conventional constant temperature heat treatment process cannot heat the La-Fe-Si alloy plate to a temperature near 1200 ℃ so as to rapidly obtain a large proportion of La (Fe, si) 13 The phase is difficult, the problem that the optimal heat preservation time of the La-Fe-Si alloy plate in the flash heat treatment process is difficult to scientifically formulate is solved, the stability of the heat treatment effect of the La-Fe-Si alloy is improved, and the prepared La-Fe-Si alloy plate is excellent in magnetic refrigeration performance;
(2) According to the flash annealing device for the La-Fe-Si alloy, disclosed by the invention, the flash annealing process can be well realized by carrying out unique design on the device structure, and the La-Fe-Si alloy with excellent performance can be prepared.
Drawings
FIG. 1 is a schematic structural view of a flash annealing device for La-Fe-Si alloy according to the present invention;
FIG. 2 is a graph showing the pulse current input function of the flash annealing process of La-Fe-Si based alloy of the present invention;
FIG. 3 is a schematic view of a flash annealing process of La-Fe-Si based alloy according to the present invention;
FIG. 4 is a photograph of a tissue of a scanning electron microscope of a heat-treated sample of example 1 of the present invention;
FIG. 5 is a schematic diagram showing isothermal magnetization-demagnetization curves of a heat treated sample according to example 1 of the present invention;
FIG. 6 is a schematic diagram of isothermal magnetic entropy change of a heat treated sample according to example 1 of the present invention;
FIG. 7 is a photograph of a tissue of a scanning electron microscope of a heat-treated sample of example 2 of the present invention;
FIG. 8 is a schematic diagram showing isothermal magnetization-demagnetization curves of a heat treated sample according to example 2 of the present invention;
FIG. 9 is a schematic diagram showing isothermal magnetic entropy change of a heat treated sample according to example 2 of the present invention;
FIG. 10 is a photograph of a tissue of a scanning electron microscope of a heat-treated sample of example 3 of the present invention;
FIG. 11 is a schematic diagram showing isothermal magnetization-demagnetization curves of a heat treated sample according to example 3 of the present invention;
FIG. 12 is a schematic diagram showing isothermal magnetic entropy change of a heat treated sample according to example 3 of the present invention;
in the figure: 1. a vacuum chamber; 2. a current heating mechanism; 3. a graphite tank; 4. a cooling mechanism; 5. a pulse heating mechanism; 6. alloy sheet material.
Detailed Description
The invention is further described below in connection with specific embodiments and the accompanying drawings.
A flash annealing process of La-Fe-Si alloy is used for carrying out high-temperature heat treatment on La-Fe-Si alloy to prepare La-Fe-Si alloy with excellent performance, but the flash annealing process of the invention is difficult to perfectly realize by adopting the existing heat treatment device, and the invention is matched with the flash annealing device of La-Fe-Si alloy to solve the problem.
As shown in fig. 1, the apparatus includes a vacuum chamber 1, a current heating mechanism 2, a graphite tank 3, a cooling mechanism 4, and a pulse heating mechanism 5. The electric current heating mechanism 2 is arranged in the vacuum cavity 1 and is used for heating the graphite tank 3 in an electrified manner, and a space for placing the alloy plate 6 is arranged in the graphite tank 4. The cooling mechanism 4 is used for cooling the alloy plate 6 in the graphite tank 4, and the coil of the pulse heating mechanism 5 is wound on the surface of the alloy plate 6.
Specifically, the current heating mechanism 2 adopts a water-cooled copper electrode externally connected with a power supply, the graphite tank 3 is fixedly arranged between the water-cooled copper electrodes, two ends of the graphite tank are fixedly connected with the copper electrodes, and the graphite tank 3 can be heated after the power supply connected with the water-cooled copper electrodes is started. The graphite tank 3 may adopt the following arrangement: the graphite tank 3 is provided with through holes penetrating through two opposite side surfaces along the width direction, and before the heat treatment work is started, the alloy plate 6 is inserted into the through holes, and then the graphite tank 3 is placed between the water-cooled copper electrodes for fixation. The cooling mechanism 4 comprises an inert gas cylinder and a blowing nozzle, the blowing nozzle is fixedly arranged at the top end of the vacuum cavity 1 above the graphite groove 3, the inlet of the blowing nozzle is connected with the inert gas cylinder through a pipeline, and the inert gas adopts common inert gases such as nitrogen, argon and the like. The pulse heating mechanism 5 is pulse magnetic induction heating, the coil material adopts tungsten filament or molybdenum filament, and before heating, the outer surface of the alloy sheet 6 is wound with tungsten filament or molybdenum filament and then is placed into the graphite tank 3.
It should be noted that, in order to timely feed back the heating temperature, so as to control the current heating mechanism 2 to adjust the heating temperature of the graphite tank according to the feedback temperature, a hole groove is formed in the central area of the bottom of the graphite tank 3, a thermocouple is inserted into the hole groove, and the thermocouple is externally connected with a temperature display device.
When the flash annealing device is adopted, the flash annealing process comprises the following steps of firstly preparing a part, placing a La-Fe-Si alloy plate with the thickness of 0.5-2 mm, the outer surface of which is wrapped with tungsten wires or molybdenum wires, in a graphite tank 3, fixedly connecting two ends of the graphite tank 3 with a current heating mechanism 2, inserting thermocouples in a bottom hole groove of the graphite tank 3, and then entering a heat treatment part, wherein the method comprises the following specific steps:
1. preheating stage
The current heating mechanism 2 is connected with a direct current power supply to heat the graphite tank 3, the alloy plate 6 is heated to 1150 ℃ from the heating rate of 5-10 ℃/s, then the temperature is kept for 5-15 s, and then the power of the direct current power supply is kept constant, and the next stage is started.
2. Flash heating stage
The tungsten wire or the molybdenum wire surrounding the alloy plate 6 is connected with a pulse magnetic induction power supply, so that the alloy plate is quickly heated to 1185-1225 ℃, then quickly cooled to 1150-1165 ℃, and the temperature is circularly raised and lowered at the stage for 5-15 s. The high frequency pulse current in the tungsten wire or the molybdenum wire can generate a pulse skin-seeking heating effect on the surface of the alloy plate 6. The pulse magnetic induction heating power supply has three input ends, namely pulse width, peak current and pulse frequency, and parameters of the input ends are set in the supply equipment of the pulse heating power supply before heating begins, so that a certain current input function can be generated, and a pulse current waveform shown in figure 2 is generated. In this phase, the pulse current parameters are: pulse width is 0.5-2 ms, peak current is 1000-2000A, and frequency is 5-100 Hz.
As shown in fig. 2, t p For pulse width, i.e. duration of arrival of pulse current in one pulse period T, at T p And (3) the pulse current enables the alloy plate to generate a pulse skin-approaching heating effect, and the alloy plate is subjected to heat treatment. f is the pulse frequency, pulse period T=1/f, T-T p For a pulse current of 0 in a pulse period T, namely a cooling stage in the flash heat treatment process, by adjusting f and T p The minimum temperature during the flash heat treatment can be controlled. I p For peak current, the peak-to-valley ratio of the current is 1:0.5 by regulating peak current I p The maximum temperature of the flash heat treatment can be controlled.
When a pulse current arrives, the temperature will rise, so the highest heating temperature is controlled by the peak current and the pulse width, after the pulse current, i.e. when the pulse current is 0, the temperature will drop, so the lowest temperature is controlled by the pulse width and the pulse period (pulse frequency), the longer the pulse period, the longer the cooling time, and the lower the lowest temperature.
Since the pulse current is not uniformly changed in the heating process, the specific temperature rise and fall rate is not constant in the flash heating stage, and the control is difficult, so that the method controls the highest temperature and the lowest temperature which can be achieved in one pulse period. For the convenience of understanding, the temperature rise and fall rate can be represented by an average value, and in this stage, the average temperature rise rate can be calculated to be 7000-37500 ℃/s from the pulse width and the highest temperature, and the average temperature fall rate can be calculated to be 100-5000 ℃/s from the pulse period and the lowest temperature.
The alloy plate is processed by the pulse magnetic induction heating mode of flash circulation heating and cooling, the duration is not strictly limited, and the situation that the optimal heat preservation time is difficult to control is unlike the conventional flash heat treatment heating. This is because the pulse magnetic induction heating duration is prolonged, the number of times of heat treatment is increased, and the single heat treatment process does not stay at the highest temperature for too long, so that each heat treatment process is safe, even if the duration is increased, the number of times of heat treatment is only increased, the whole process is safe, the condition of whole melting of alloy does not occur, and the heat treatment effect is good. Whereas conventional flash heat treatment is continued at the highest temperature and is slightly prolonged, resulting in the overall melting of the alloy.
In this stage, the pulse power supply device can be realized by adopting the common devices on the market, and the specific structure thereof is not described in detail.
3. Cooling stage
And (3) turning off a pulse magnetic induction power supply, turning on a cooling inert gas injection alloy plate 6, cooling to 300 ℃ at a cooling rate of 50-100 ℃/s, and cooling to room temperature in a furnace. Staged cooling is used here because cooling to room temperature with a constant cooling rate results in a waste of cooling gas and therefore furnace cooling to room temperature after cooling to 300 ℃.
4. And (3) carrying out phase content statistics and standard magnetic performance test on the alloy plate processed in the step (III).
Compared with the conventional quartz tube packaging or vacuum indoor constant temperature annealing treatment process, the process greatly shortens the heat treatment time, can be completed in a few minutes, remarkably reduces the energy consumption in the heat treatment process, has higher practical value, particularly, realizes the cyclic flash temperature rise and temperature reduction of the alloy plate through pulse magnetic induction heating, can realize the local discontinuous flash melting, flash high-temperature synthesis and flash solidification in the alloy plate on the premise of ensuring that the alloy plate does not melt in a whole large area, and solves the problem that the conventional heat treatment process cannot heat the La-Fe-Si alloy plate to a temperature near 1200 ℃ so as to rapidly obtain a large proportion of La (Fe, si) 13 Phase difficulty, and meanwhile, the flash heat treatment process of La-Fe-Si alloy plate is solvedThe optimal heat preservation time is difficult to scientifically formulate, the stability of the heat treatment effect on the La-Fe-Si alloy is improved, and the prepared La-Fe-Si alloy plate has excellent magnetic refrigeration performance.
Specific examples are given below.
Example 1
LaFe is selected from heat-treated samples 11.6 Si 1.4 The thickness of the alloy plate is 0.5mm, and the specific process is as follows:
firstly, laFe with the thickness of 0.5mm and wrapped with tungsten wires or molybdenum wires on the outer surface 11.6 Si 1.4 Alloy sheet 6 is arranged in graphite tank 3, graphite tank 3 both ends and copper electrode fixed connection to with graphite tank 3 both ends and electric current heating mechanism 2 fixed connection, and insert the thermocouple in the bottom hole groove of graphite tank 3, then get into the heat treatment part, specifically as follows:
1. preheating stage
The current heating mechanism 2 is connected with a direct current power supply to heat the graphite tank 3, the alloy plate 6 is heated to 1150 ℃ from the room temperature at the heating rate of 5 ℃/s, then the temperature is kept for 10 seconds, and then the power of the direct current power supply is kept constant, and the next stage is started.
2. Flash heating stage
The tungsten wire or molybdenum wire surrounding the alloy plate 6 is connected with a pulse magnetic induction power supply, so that the alloy plate is quickly heated to 1185 ℃ and then quickly cooled to 1150 ℃, and the temperature is circularly raised and lowered for 5 seconds at the stage. In this phase, the pulse current parameters are: pulse width 0.5ms, peak current 1000A, frequency 5Hz. The highest temperature which can be reached in the flash circulation heating process of the alloy plate is 1185 ℃, and the lowest temperature of flash circulation cooling is 1150 ℃.
3. Cooling stage
And (3) turning off the pulse magnetic induction power supply, turning on the cooling inert gas to blow the alloy plate 6, cooling to 300 ℃ at a cooling rate of 50 ℃/s, and cooling to room temperature in the furnace.
4. And (3) carrying out phase content statistics and standard magnetic performance test on the alloy plate processed in the step (III).
The results of the test are shown below, and FIG. 4 shows the scanning of the heat-treated sample of the present exampleAs can be seen from the tissue photograph of the electron microscope, the heat-treated sample forms La (Fe, si) with a large volume fraction 13 The image processing software ipp is adopted to carry out phase inversion on the La (Fe, si) of the magnetic refrigeration function phase 13 Counting the phase content of the phase to obtain La (Fe, si) 13 The volume fraction of the phase is more than 95%, then the test is carried out on the sample, the test results are respectively shown in fig. 5 and 6,3T, the maximum magnetic entropy change of the sample under the magnetic field reaches 27J/(kg.K), and the corresponding effective refrigerating capacity reaches 227.10J/kg.
Example 2
LaFe is selected from heat-treated samples 11.6 Si 1.4 B 0.06 The alloy plate has the thickness of 1mm and comprises the following specific heat treatment steps:
firstly, 1mm thick LaFe with tungsten wire or molybdenum wire wound on the outer surface 11.6 Si 1.4 B 0.06 Alloy sheet 6 is arranged in graphite tank 3, graphite tank 3 both ends and copper electrode fixed connection to with graphite tank 3 both ends and electric current heating mechanism 2 fixed connection, and insert the thermocouple in the bottom hole groove of graphite tank 3, then get into the heat treatment part, specifically as follows:
1. preheating stage
The current heating mechanism 2 is connected with a direct current power supply to heat the graphite tank 3, the alloy plate 6 is heated to 1150 ℃ from the room temperature at the heating rate of 7 ℃/s, then the temperature is kept for 10 seconds, and then the power of the direct current power supply is kept constant, and the next stage is started.
2. Flash heating stage
The tungsten wire or the molybdenum wire surrounding the alloy plate 6 is connected with a pulse magnetic induction power supply, so that the alloy plate is quickly heated to 1200 ℃, then quickly cooled to 1160 ℃, and the temperature is circularly raised and lowered at the stage for 10 seconds. In this phase, the pulse current parameters are: pulse width 1ms, peak current 1500A, frequency 25Hz. The highest temperature which can be reached in the flash circulation heating process of the alloy plate is 1200 ℃, and the lowest temperature of flash circulation cooling is 1160 ℃.
3. Cooling stage
And (3) turning off the pulse magnetic induction power supply, turning on the cooling inert gas to blow the alloy plate 6, cooling to 300 ℃ at a cooling rate of 70 ℃/s, and cooling to room temperature in the furnace.
4. And (3) carrying out phase content statistics and standard magnetic performance test on the alloy plate processed in the step (III).
As shown in FIG. 7, which shows a scanning electron microscope photograph of a heat-treated sample of the present example, la (Fe, si) was formed in a large volume fraction 13 The image processing software ipp is adopted to carry out phase inversion on the La (Fe, si) of the magnetic refrigeration function phase 13 Counting the phase content of the phase to obtain La (Fe, si) 13 The volume fraction of the phase is more than 94%, then the test is carried out on the sample, the test results are respectively shown in fig. 8 and 9,3T, the maximum magnetic entropy change of the sample under the magnetic field reaches 21J/(kg.K), and the corresponding effective refrigerating capacity reaches 243.10J/kg.
Example 3
LaFe is selected from heat-treated samples 11.6 Si 1.4 C 0.06 The alloy plate has the thickness of 2mm and comprises the following specific heat treatment steps:
firstly, winding a tungsten wire or a molybdenum wire on the outer surface of the LaFe with the thickness of 2mm 11.6 Si 1.4 C 0.06 Alloy sheet 6 is arranged in graphite tank 3, graphite tank 3 both ends and copper electrode fixed connection to with graphite tank 3 both ends and electric current heating mechanism 2 fixed connection, and insert the thermocouple in the bottom hole groove of graphite tank 3, then get into the heat treatment part, specifically as follows:
1. preheating stage
The current heating mechanism 2 is connected with a direct current power supply to heat the graphite tank 3, the alloy plate 6 is heated to 1150 ℃ from room temperature at the heating rate of 10 ℃/s, then the temperature is kept for 10s, and then the power of the direct current power supply is kept constant, and the next stage is started.
2. Flash heating stage
The tungsten wire or molybdenum wire surrounding the alloy plate 6 is connected with a pulse magnetic induction power supply, so that the alloy plate is quickly heated to 1225 ℃, then quickly cooled to 1165 ℃, and the temperature is circularly raised and lowered at the stage for 15 seconds. In this phase, the pulse current parameters are: pulse width 2ms, peak current 2000A, frequency 50Hz. The highest temperature which can be reached in the flash circulation heating process of the alloy plate is 1225 ℃, and the lowest temperature of flash circulation cooling is 1165 ℃.
3. Cooling stage
And (3) turning off the pulse magnetic induction power supply, turning on the cooling inert gas to blow the alloy plate 6, cooling to 300 ℃ at a cooling rate of 100 ℃/s, and cooling to room temperature in the furnace.
4. And (3) carrying out phase content statistics and standard magnetic performance test on the alloy plate processed in the step (III).
As shown in FIG. 10, which shows a scanning electron microscope photograph of a heat-treated sample of the present example, la (Fe, si) was formed in a large volume fraction 13 The image processing software ipp is adopted to carry out phase inversion on the La (Fe, si) of the magnetic refrigeration function phase 13 Counting the phase content of the phase to obtain La (Fe, si) 13 The volume fraction of the phase is more than 95%, then the test is carried out on the sample, the test results are respectively shown in fig. 11 and 12,3T, the maximum magnetic entropy change of the sample under the magnetic field reaches 22.5J/(kg.K), and the corresponding effective refrigerating capacity reaches 257.10J/kg.
The examples of the present invention are merely for describing the preferred embodiments of the present invention, and are not intended to limit the spirit and scope of the present invention, and those skilled in the art should make various changes and modifications to the technical solution of the present invention without departing from the spirit of the present invention.
Claims (7)
1. A flash annealing process of La-Fe-Si alloy comprises the following steps:
1. preheating stage
Heating the alloy plate to 1150 ℃ at a heating rate of 5-10 ℃/s, and preserving heat for 5-15 s;
2. flash heating stage
Heating the alloy plate to 1185-1225 ℃ by applying pulse current, then cooling to 1150-1165 ℃, and circularly heating and cooling at the stage for 5-15 s; in this phase, the pulse current parameters are: pulse width is 0.5-2 ms, peak current is 1000-2000A, frequency is 5-100 Hz;
3. cooling stage
Cooling to 300 ℃ at a cooling rate of 50-100 ℃/s, and cooling to room temperature.
2. The flash annealing process of La-Fe-Si alloy according to claim 1, wherein: in the second step, the average heating rate is 7000-37500 ℃/s, and the average cooling rate is 100-5000 ℃/s.
3. The flash annealing process of La-Fe-Si based alloy according to claim 2, wherein: and step one, adopting a direct current heating mode, keeping the power of a direct current power supply constant after the heat preservation is finished, and entering a step two.
4. A flash annealing process of La-Fe-Si based alloy according to claim 3, wherein: and thirdly, spraying the alloy plate by using cooling inert gas to cool the alloy plate.
5. The flash annealing process of La-Fe-Si alloy according to any one of claims 1 to 4, wherein: the method also comprises the following steps: and (3) carrying out phase content statistics and standard magnetic performance test on the alloy plate processed in the step (III).
6. The flash annealing process of La-Fe-Si alloy according to any one of claims 1 to 4, wherein: the alloy plate is La-Fe-Si alloy plate with the thickness of 0.5-2 mm.
7. The flash annealing process of La-Fe-Si alloy according to claim 6, wherein: the alloy plate is La-Fe-Si-X alloy plate, and X is one or more of RE, B, C, co and H.
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| CN103059815B (en) * | 2011-10-24 | 2014-12-10 | 中国科学院物理研究所 | First-order phase transition La (Fe, si)13-based magnetocaloric effect materials with small hysteresis loss, its preparation method and use |
| CN104694813B (en) * | 2015-03-04 | 2017-07-28 | 中国科学院宁波材料技术与工程研究所 | LaFeSi base magnetic refrigerating materials and preparation method and application |
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