Method for enhancing superconducting performance of MgB2 block by doping Fe-Ga alloy

Abstract

The invention discloses a method for enhancing the superconducting performance of a MgB2 block material by doping Fe-Ga alloy. The preparation method comprises the following steps: firstly, weighing, mixing, grinding and tabletting magnesium powder, boron powder and Fe-Ga alloy powder according to a certain mass ratio in a protective atmosphere to obtain a precursor block material; after vacuum sealing, putting the precursor block material into a heat treatment device for sintering; and after the temperature of the device is reduced to room temperature, taking out the block sample. When a magnetic field is applied externally, the Fe-Ga alloy with the magnetostrictive effect in the sample induces stress strain in the MgB2 superconductor under a strong field, and a strong pinning center with a wide action range and high pinning strength can be formed. According to the method, chemical doping is carried out on the MgB2 superconductor through the Fe-Ga alloy material with high magnetostriction performance, operation is convenient, cost is low, performance improvement is obvious, the current-carrying performance of MgB2 in a high field can be enhanced, and the superconducting performance and future application potential of MgB2 are greatly improved.

Description

Technical Field

[0001] The present invention belongs to the field of superconducting materials, and particularly relates to a method for enhancing the superconducting performance of MgB 2 bulk superconductors by doping with Fe-Ga alloy. Background Art

[0002] In 2001, the Akimitsu scientific group in Japan discovered the superconductivity of MgB 2 superconductors, and it has been more than 20 years since then. The critical transition temperature T 2 of MgB C superconductors reaches 39K, which is very close to the 40K limit in the BCS theory. Compared with high-temperature superconductors, it has smaller anisotropy and larger coherence length, which is more conducive to introducing flux pinning centers, and its structure is simpler. Compared with low-temperature superconductors, it can have a higher application temperature range (20K), greatly reducing the application cost. At the same time, because it can be used in the liquid hydrogen temperature range (20K), MgB 2 is considered to be the preferred material for future superconducting hydrogen electric propulsion. At present, constructing effective flux pinning centers by chemical doping is the key method to improve the superconducting performance of MgB 2 superconductors. The dopants mainly include carbon and its related compounds, metal elements, and metal oxides. However, through further in-depth exploration, it is found that it is difficult to significantly improve the current-carrying performance and pinning performance of MgB 2 by using conventional dopants. Therefore, it is necessary to find more novel and efficient dopants to form pinning centers with strong pinning force.

[0003] Although the pinning centers formed by traditional dopants are currently relatively mature and effective methods for improving the pinning performance of MgB 2 superconductors, the action range of this pinning mechanism is limited, and it can only effectively pin the flux lines in a very small range near the doping particles. At the same time, the flux pinning strength generated by the traditional pinning mechanism is limited, resulting in a great limitation in the improvement of the critical current density J C under an external magnetic field. Summary of the Invention

[0004] The purpose of the present invention is to solve the existing problems in current MgB 2 superconductors, and a method for enhancing the superconducting performance of MgB 2 bulk superconductors by doping with Fe-Ga alloy is proposed. Using Fe-Ga alloy powder with magnetostrictive effect as the dopant, the Fe-Ga alloy is effectively doped into MgB 2 superconductors through solid-phase sintering method. The Fe-Ga alloy and MgB 2The region between the lattices forms an effective stress field, which broadens the action range of the pinning centers, enabling them to trap more magnetic flux lines, thereby further enhancing the magnetic flux pinning force and superconducting current-carrying capacity under magnetic field of MgB 2 bulk materials, effectively enhancing the superconducting properties of MgB 2 bulk materials, providing a reliable and effective way for the large-scale practical development of MgB 2 superconductors.

[0005] To achieve the above object, the technical solution adopted in the present invention is as follows:

[0006] A method for enhancing the superconducting properties of MgB 2 bulk materials, comprising the following steps:

[0007] Step 1: Under a protective atmosphere, weigh, mix, and grind magnesium powder, boron powder, and Fe-Ga alloy powder for 45 - 75 min to fully mix the original powders, obtaining a mixed powder with sufficiently fine particles. Finally, use a powder press to press the mixed powder at a pressure of 10 - 20 MPa to form a cylindrical bulk with a height of 0.1 - 10 mm and a diameter of 1 - 5 mm, obtaining a precursor bulk.

[0008] The amounts of the magnesium powder and boron powder used satisfy the stoichiometric ratio of the chemical formula MgB 2 , and the mass ratio of the total mass of the magnesium powder and boron powder to the mass of the Fe-Ga alloy powder is 1 - x:x, where x = 0 - 0.2 and x is not 0.

[0009] It should be noted that during weighing, it is necessary to be accurate to the maximum accuracy of the instrument and read the powder weight only after the reading is stable.

[0010] Step 2: Place the precursor bulk in a crucible under a protective atmosphere, then place the crucible in a quartz tube, and seal the mouth of the quartz tube.

[0011] It should be noted that since part of the magnesium powder will volatilize during the sintering process, it is necessary to add an additional amount of magnesium powder, which is 1% - 2% of the calculated mass of magnesium powder, to the crucible to supplement the sample.

[0012] Step 3: Take out the quartz tube from the protective atmosphere and seal it under vacuum using a vacuum tube sealing machine.

[0013] The specific operation is as follows: First, cut about 5 cm of the quartz tube to connect one end of the valve and the connector of the vacuum tube sealing machine. Then, use the vacuum tube sealing machine to first evacuate the 5 cm quartz tube above the valve to a vacuum state, and then open the valve switch to evacuate the lower quartz tube to a vacuum state, maintaining the vacuum degree at 1.5×10 -3 ~2.5×10 -3After Pa, high temperature is used to completely seal the tube.

[0014] It should be noted that before taking out the quartz tube, you need to use a double-pagoda socket straight-through ball valve with a closed valve and a rubber ring to seal the tube mouth of the quartz tube to prevent air from entering the quartz tube before the vacuum tube is sealed, causing oxidation of the sample.

[0015] Step 4: Place the sealed quartz tube into a heat treatment device, set the temperature in the heat treatment device to rise from room temperature to 600-700°C at a rate of 1-20°C / min, and keep it warm for 1-10 hours.

[0016] It should be noted that the sintering temperature should not be too high to prevent MgB 2 The grains are grown too large.

[0017] Step 5: After the temperature inside the device drops to room temperature, take out the block material and store it in a dry and suitable environment.

[0018] Furthermore, the magnesium powder in step 1 has a particle size of 80-150 um and a purity of >99.9 wt %; the boron powder has a particle size of 250 nm and a purity of >99.9 %; and the Fe-Ga alloy powder has a particle size of about 0.5 um and a purity of ≥99.8 %.

[0019] Furthermore, the structural formula of the Fe-Ga alloy in step 1 is Fe 100-y Ga y , y=5~95.

[0020] Furthermore, the protective atmosphere in steps 1, 2, and 3 is an inert gas atmosphere such as argon, helium, nitrogen, etc., and its purity is 99.0-99.99%.

[0021] Furthermore, the heat treatment device in step 4 is a programmable heat treatment device such as a tube furnace, a box furnace or a muffle furnace, and the temperature is increased at a rate of 1 to 20°C / min.

[0022] The present invention is based on MgB 2 In order to solve the problem of low performance of the pinning center in the existing traditional dopant structure in superconductors, a Fe-Ga alloy doping enhanced MgB 2 The magnetostrictive properties of Fe-Ga alloy powders were effectively applied to MgB by solid phase sintering. 2 In superconductors, MgB 2 The formation of efficient flux pinning centers in superconductors greatly enhances the MgB 2 The superconducting properties of superconductors, which is MgB 2 It laid the foundation for the practical development of superconductors in the liquid hydrogen temperature range (20K).

[0023] The advantages of the present invention are:

[0024] (1) The present invention dopes MgB 2 superconductor with Fe-Ga alloy, providing a novel and reliable dopant for MgB 2 superconductor.

[0025] (2) By doping MgB 2 superconductor with Fe-Ga alloy powder which is a high-performance magnetostrictive material, stress and strain can be induced to form strong pinning centers in MgB 2 superconductor under strong magnetic fields (>1T), thereby enhancing the flux pinning force and superconducting current-carrying capacity of MgB 2 superconductor under magnetic fields, effectively improving the superconducting properties of MgB 2 .

[0026] (3) With Fe-Ga alloy powder of traditional magnetostrictive materials, the present invention can effectively dope MgB 2 superconductor by means of solid-phase sintering method at relatively low temperature conditions. The operation is simple and the cost is low, but the pinning performance and current-carrying performance of MgB 2 are significantly improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 Scanning electron microscope pictures of MgB 2 bulk materials with different Fe-Ga contents prepared in Examples 1-4;

[0028] Figure 2 Relationship (M-T) diagrams of magnetization intensity and temperature of MgB 2 bulk materials with different Fe-Ga contents prepared in Examples 1-4 under field cooling (FC) and zero-field cooling (ZFC) conditions at 20 Oe;

[0029] Figure 3 Relationship (J 2 -H) pictures of critical current density and external magnetic field strength of MgB C bulk materials with different Fe-Ga contents prepared in Examples 1-4 at 4.2 K;

[0030] Figure 4 Relationship (J 2 -H) pictures of critical current density and external magnetic field strength of MgB C bulk materials with different Fe-Ga contents prepared in Examples 1-4 at 20 K. DETAILED DESCRIPTION OF THE INVENTION

[0031] To make the objectives, technical solutions, and advantages of the present invention more clearly understood, the present invention will be further described in detail below with reference to embodiments and the accompanying drawings. The illustrative embodiments of the present invention and their descriptions are only used to explain the present invention and are not intended to limit the present invention.

[0032] In the following embodiments, the specific chemical formula of the Fe-Ga alloy used is Fe 83 Ga 17 . The particle size of the magnesium powder is 80 - 150 μm, and the purity > 99.9 wt%; the particle size of the boron powder is 250 nm, and the purity > 99.9%; the particle size of the Fe-Ga alloy powder is about 0.5 μm, and the purity ≥ 99.8%.

[0033] Example 1

[0034] A method for enhancing the superconducting properties of Fe-Ga alloy doped MgB 2 bulk materials, comprising the following steps:

[0035] Step 1: Under an argon protection atmosphere, weigh and mix the magnesium powder and boron powder according to the stoichiometric ratio of the chemical formula MgB 2 . Then grind for 60 min to fully mix the original powders and make the particles small enough. Finally, use a powder press to press the mixed powder at a pressure of 16 MPa to form a cylindrical bulk with a height of 0.5 mm and a diameter of 1 mm, obtaining a precursor bulk.

[0036] Step 2: Place the precursor bulk in a crucible under an argon protection atmosphere. At the same time, to make up for the magnesium deficiency caused by the volatilization of the magnesium powder, an additional 1.5% of magnesium powder needs to be added near the sample in the crucible. Then place the crucible in a quartz tube and seal the mouth of the quartz tube. Use a double-tower socket through-ball valve with a closed valve and a rubber ring to seal the mouth of the quartz tube to prevent air from entering the quartz tube before vacuum sealing, resulting in sample oxidation.

[0037] Step 3: Take out the quartz tube from the argon protection atmosphere and use a vacuum sealing machine for vacuum sealing. The specific operation is as follows: First, connect one end of the valve and the joint of the vacuum sealing machine with about 5 cm of the quartz tube cut, then use the vacuum sealing machine to first evacuate the 5 cm of the quartz tube above the valve to a vacuum state, then open the valve switch, evacuate the lower quartz tube to a vacuum state, and maintain the vacuum degree at 1.5×10 -3 ~2.5×10 -3 Pa, and then use high temperature for complete sealing.

[0038] Step 4: Place the sealed quartz tube in a muffle furnace, and set the temperature in the muffle furnace to rise from room temperature to 670 °C at a rate of 2 °C / min and keep it warm for 2 hours.

[0039] Step 5: After the temperature in the muffle furnace drops to room temperature, take out the bulk material and store it in a dry and suitable environment.

[0040] Figure 1 shows the scanning electron microscope image of the bulk material of (MgB 2 ) 1 (Fe-Ga) 0 prepared in Example 1. It can be seen that the grains of the bulk material are complete and the grain boundaries are clear. Figure 2 is the M-T curve image of the bulk material of (MgB 2 ) 1 (Fe-Ga) 0 prepared in Example 1 under the field-cooled (FC) and zero-field-cooled (ZFC) conditions at 20 Oe. It can be found that the diamagnetism of the sample is obvious, and T C reaches 37.5 K, and the superconducting width is relatively narrow, indicating that the superconducting phase in the MgB 2 superconductor is relatively pure and the crystal lattice is complete. Figure 3 And Figure 4 shows the critical current density diagram of the bulk material of (MgB 2 ) 1 (Fe-Ga) 0 prepared in Example 1 at 4.2 K and 20 K. Its J C is 4.2×10 4 A / cm 2 and 3.0×10 5 A / cm 2 .

[0041] Example 2

[0042] A method for enhancing the superconducting performance of MgB 2 bulk material doped with Fe-Ga alloy, comprising the following steps:

[0043] Step 1: Under the protection of argon atmosphere, weigh and mix magnesium powder, boron powder and Fe-Ga alloy powder. The dosages of the magnesium powder and boron powder satisfy the stoichiometric ratio of the chemical formula MgB 2 . The mass ratio of the total mass of the magnesium powder and boron powder to the mass of the Fe-Ga alloy powder is 0.97:0.03. Then grind for 60 min to fully mix the raw powders and make the particles small enough. Finally, use a powder press to press the mixed powder at a pressure of 16 MPa to form a cylindrical bulk with a height of 0.5 mm and a diameter of 1 mm, obtaining a precursor bulk material.

[0044] Step 2: Place the precursor bulk in a crucible under an argon protection atmosphere. At the same time, to make up for the magnesium deficiency caused by the volatilization of magnesium powder, an additional 1.5% magnesium powder needs to be added near the sample in the crucible. Then place the crucible in a quartz tube and seal the mouth of the quartz tube. Use a double-tower socket through-ball valve with a closed valve and a rubber ring to seal the mouth of the quartz tube to prevent air from entering the quartz tube before vacuum sealing, which may cause the sample to oxidize.

[0045] Step 3: Take out the quartz tube from the argon protection atmosphere and perform vacuum sealing with a vacuum tube sealing machine. The specific operation is as follows: First, cut about 5 cm of the part of the quartz tube connecting the valve and the joint of the vacuum tube sealing machine. Then use the vacuum tube sealing machine to first evacuate the 5 cm quartz tube above the valve to a vacuum state, and then open the valve switch to evacuate the lower quartz tube to a vacuum state. Keep the vacuum degree at 1.5×10 -3 ~2.5×10 -3 Pa and then completely seal the tube with high temperature.

[0046] Step 4: Place the sealed quartz tube in a muffle furnace and set the temperature in the muffle furnace to rise from room temperature to 670 °C at a rate of 2 °C / min and hold for 2 hours.

[0047] Step 5: After the temperature in the muffle furnace drops to room temperature, take out the bulk and store it in a dry and suitable environment.

[0048] Figure 1 Shows the scanning electron microscope image of the (MgB 2 ) 0.97 (Fe-Ga) 0.03 bulk prepared in Example 2. It can be seen that the grains of this bulk are also complete and the grain boundaries are relatively clear, which is beneficial to the grain boundary coupling strength of the sample. Figure 2 Shows the M-T curve images of the (MgB 2 ) 0.97 (Fe-Ga) 0.03 bulk prepared in Example 2 under field cooling (FC) and zero-field cooling (ZFC) conditions at 20 Oe. It can be found that the diamagnetism of the sample is significantly higher than that of other samples, and its T C is also 37.5 K, and the superconducting width is relatively narrow, indicating that when doped with a small amount, there are fewer heterophases in the MgB 2 superconductor and the superconducting performance is relatively high. Figure 3 And Figure 4 Shows the critical current density diagrams of the (MgB 2 ) 0.97 (Fe-Ga) 0.03 bulk prepared in Example 2 at 4.2 K and 20 K. Its J C is 1.7×10 5 A / cm2 and 9.5×10 5 A / cm 2 , which are 4 times and 3.2 times that of the sample in Example 1, respectively, and the current-carrying performance is significantly improved.

[0049] Example 3

[0050] A method for enhancing the superconducting performance of MgB 2 bulk materials by doping with Fe-Ga alloy, comprising the following steps:

[0051] Step 1: Under an argon protection atmosphere, weigh and mix magnesium powder, boron powder, and Fe-Ga alloy powder, wherein the amounts of the magnesium powder and boron powder satisfy the stoichiometric ratio of the chemical formula MgB 2 . The mass ratio of the total mass of the magnesium powder and boron powder to the mass of the Fe-Ga alloy powder is 0.95:0.05. Then grind for 60 min to fully mix the original powders and make the particles small enough. Finally, use a powder press to press the mixed powder at a pressure of 16 MPa to form a cylindrical bulk with a height of 0.5 mm and a diameter of 1 mm, obtaining a precursor bulk.

[0052] Step 2: Place the precursor bulk in a crucible under an argon protection atmosphere. At the same time, in order to make up for the magnesium deficiency caused by the volatilization of magnesium powder, an additional 1.5% magnesium powder needs to be added near the sample in the crucible. Then place the crucible in a quartz tube and seal the mouth of the quartz tube. Use a double-tower socket through-type ball valve with a closed valve and a rubber ring to seal the mouth of the quartz tube to prevent air from entering the quartz tube before vacuum sealing, resulting in sample oxidation.

[0053] Step 3: Take out the quartz tube from the protection atmosphere and use a vacuum sealing machine for vacuum sealing. The specific operation is as follows: First, connect one end of the quartz tube with a cut of about 5 cm to the joint of the valve and the vacuum sealing machine. Then use the vacuum sealing machine to evacuate the 5 cm quartz tube above the valve to a vacuum state first, and then open the valve switch to evacuate the lower quartz tube to a vacuum state, maintaining the vacuum degree at 1.5×10 -3 ~2.5×10 -3 Pa, and then use high temperature for complete sealing.

[0054] Step 4: Place the sealed quartz tube in a muffle furnace, and set the temperature in the muffle furnace to rise from room temperature to 670 °C at a rate of 2 °C / min and hold for 2 hours.

[0055] Step 5: After the temperature in the muffle furnace drops to room temperature, take out the bulk and store it in a dry and suitable environment.

[0056] Figure 1 Shows the (MgB 2 ) 0.95(Fe-Ga) 0.05 Scanning electron microscope image of the bulk material, showing that the grains of the bulk material are complete, the grain boundaries are relatively clear, and the sizes are uniform. Figure 2 Shows the (MgB prepared in Example 3 2 ) 0.95 (Fe-Ga) 0.05 M-T curve pictures of the (Fe-Ga) bulk material under field cooling (FC) and zero-field cooling (ZFC) conditions at 20 Oe. It can be found that the diamagnetism of the sample is obvious, its T C is 37.3 K, the superconducting width is relatively narrow. At this time, there are still relatively few impurity phases inside the MgB 2 superconductor, and the superconducting performance is relatively high. Figure 3 And Figure 4 Shows the (MgB prepared in Example 3 2 ) 0.95 (Fe-Ga) 0.05 Critical current density diagrams of the (Fe-Ga) bulk material at 4.2 K and 20 K. At 4.2 K @ 6 T and 20 K @ 2 T, J C are 1.3×10 5 A / cm 2 and 6.5×10 5 A / cm 2 , which are 3.1 times and 2.2 times that of the sample in Example 1, and the current-carrying performance is also higher than that of the undoped sample in Example 1.

[0057] Example 4

[0058] A method for enhancing the superconducting performance of MgB 2 bulk material by doping with Fe-Ga alloy, comprising the following steps:

[0059] Step 1: Under an argon protection atmosphere, weigh and mix magnesium powder, boron powder, and Fe-Ga alloy powder. The dosages of the magnesium powder and boron powder satisfy the stoichiometric ratio of the chemical formula MgB 2 . The mass ratio of the total mass of magnesium powder and boron powder to the mass of Fe-Ga alloy powder is 0.93:0.07. Then grind for 60 min to fully mix the raw powders and make the particles small enough. Finally, use a powder press to press the mixed powder at a pressure of 16 MPa to form a cylindrical block with a height of 0.5 mm and a diameter of 1 mm, obtaining a precursor bulk material.

[0060] Step 2: Place the precursor bulk material in a crucible under an argon protection atmosphere. At the same time, in order to make up for the magnesium deficiency caused by the volatilization of magnesium powder, an additional 1.5% of magnesium powder needs to be added near the sample in the crucible. Then place the crucible in a quartz tube and seal the mouth of the quartz tube. Use a double-tower socket straight-through ball valve with a closed valve and a rubber ring to seal the mouth of the quartz tube to prevent air from entering the quartz tube before vacuum sealing, resulting in sample oxidation.

[0061] Step 3: Take out the quartz tube from the argon protection atmosphere and seal it in a vacuum using a vacuum tube sealer. The specific operation is as follows: First, connect one end of the valve and the connector of the vacuum tube sealer with a section of quartz tube cut to about 5 cm. Then, use the vacuum tube sealer to evacuate the 5 cm quartz tube above the valve to a vacuum state, then open the valve switch and evacuate the lower quartz tube to a vacuum state. After maintaining the vacuum degree at 1.5×10 -3 ~2.5×10 -3 Pa, completely seal the tube with high temperature.

[0062] Step 4: Place the sealed quartz tube into a muffle furnace, set the temperature in the muffle furnace to rise from room temperature to 670 °C at a rate of 2 °C / min, and keep it warm for 2 hours.

[0063] Step 5: After the temperature in the muffle furnace drops to room temperature, take out the bulk material and store it in a dry and suitable environment.

[0064] Figure 1 Shows the scanning electron microscope image of the (MgB 2 ) 0.93 (Fe-Ga) 0.07 bulk material prepared in Example 4. It can be seen that the grains of the bulk material are complete, the grain boundaries are clear, and the morphology is still good. Figure 2 Shows the M-T curve images of the (MgB 2 ) 0.93 (Fe-Ga) 0.07 bulk material prepared in Example 4 under field cooling (FC) and zero-field cooling (ZFC) conditions at 20 Oe. It can be found that the diamagnetism of the sample decreases, its T C is 37.2 K, the superconducting width increases, and at this time, the impurity phase inside the MgB 2 superconductor begins to increase. Figure 3 And Figure 4 Shows the critical current density diagrams of the (MgB 2 ) 0.93 (Fe-Ga) 0.07 bulk material prepared in Example 4 at 4.2 K and 20 K. Its J C at 4.2 K@6 T and 20 K@2 T are 4 7.6×10 2 and 3.9×10 5 A / cm 2 respectively, and its current-carrying performance has increased by 81% and 30% compared to the sample in Example 1.

[0065] The specific embodiments described above further elaborate on the purpose, technical solution, and beneficial effects of the present invention. It should be understood that the above description is only for the specific embodiments of the present invention and is not used to limit the protection scope of the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

Claims

1. A method for enhancing the superconducting properties of MgB2 bulk by Fe-Ga alloy doping, characterized in that: The following steps are involved: Step 1: Under a protective atmosphere, magnesium powder, boron powder, and Fe-Ga alloy powder are mixed and ground, and the mixed powder is pressed into a cylindrical block by a powder tablet press at a pressure of 10 to 20 MPa to obtain a precursor block; The amount of the magnesium powder and the boron powder satisfies the stoichiometric ratio of the chemical formula MgB2, and the mass ratio of the total mass of the magnesium powder and the boron powder to the Fe-Ga alloy powder is 1-x:x, where x=0-0.2 and x is not 0; Step 2: Put the precursor block into a crucible under a protective atmosphere, then put the crucible into a quartz tube, and seal the quartz tube mouth; Step 3: Take out the quartz tube from the protective atmosphere and vacuum seal it with a vacuum tube sealer; Step 4: Place the sealed quartz tube into a heat treatment device, set the temperature in the heat treatment device to rise from room temperature to 600-700° C., and keep it warm for 1-10 hours; Step 5: After the temperature inside the device drops to room temperature, take out the block material and store it in a dry environment.

2. The method for enhancing the superconducting properties of MgB2 bulk by Fe-Ga alloy doping according to claim 1, characterized in that: In step 1, the particle size of the magnesium powder is 80-150 um, and the purity is greater than 99.9 wt %; the particle size of the boron powder is 250 nm, and the purity is greater than 99.9 %; the particle size of the Fe-Ga alloy powder is 0.5 um, and the purity is ≥ 99.8 %.

3. The method for enhancing the superconducting properties of MgB2 bulk by Fe-Ga alloy doping according to claim 1, characterized in that: The structural formula of the Fe-Ga alloy in step 1 is Fe 100-y Ga y , y=5~95.

4. The method for enhancing the superconducting properties of MgB2 bulk by Fe-Ga alloy doping according to claim 1, characterized in that: The grinding time in step 1 is 45 to 75 minutes.

5. The method for enhancing the superconducting properties of MgB2 bulk by Fe-Ga alloy doping according to claim 1, characterized in that: The vacuum degree during vacuum sealing in step 3 was maintained at 1.5×10 -3 ~2.5×10 -3 Pa.

6. According to the method for enhancing the superconducting properties of MgB2 bulk by Fe-Ga alloy doping as described in claim 1, the protective atmosphere in steps 1, 2, and 3 is an argon, helium or nitrogen atmosphere with a purity of 99.0 to 99.99%.

7. The method for enhancing the superconducting properties of MgB2 bulk by Fe-Ga alloy doping according to claim 1, characterized in that: The heat treatment device in step 4 is a tube furnace, a box furnace or a muffle furnace, and the temperature is increased at a rate of 1 to 20°C / min.

8. The method for enhancing the superconducting properties of MgB2 bulk by Fe-Ga alloy doping according to claim 1, characterized in that: In step 1, x=0.03-0.07.

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