WO2023232787A1

WO2023232787A1 - Production of parts made of mgb2

Info

Publication number: WO2023232787A1
Application number: PCT/EP2023/064402
Authority: WO
Inventors: Yohann Thimont; Lionel Presmanes; Anastasia SKLYAROVA
Original assignee: Université Toulouse III - Paul Sabatier; Centre National De La Recherche Scientifique; Institut National Polytechnique De Toulouse
Priority date: 2022-06-02
Filing date: 2023-05-30
Publication date: 2023-12-07
Also published as: FR3136178A1

Abstract

The invention relates to a method for producing a part made of MgB₂ comprising: a) producing a preform by shaping a powder of MgB₂ particles by means of an additive manufacturing process on a powder bed, comprising the irradiation of the MgB₂ powder with laser radiation and b) a step of densifying the preform until the part made of MgB₂ is obtained.

Description

Title: Development of MgB parts

The present invention relates to a process for manufacturing a preformed part, in particular of a complex shape, in superconducting magnesium diboride or MgEL ceramic by an additive manufacturing technique.

Prior art

Superconducting materials are increasingly present in our daily lives. Superconducting parts find their applications in medicine, such as superconducting MRI coils in industry, magnets and magnetic shields in transport, or engine parts and potential levitation transport systems, and in many other areas.

Among these materials, MgEL is one of the most promising materials. MgEL is an intermetallic material whose structure consists of a stack of magnesium planes alternating with boron planes along its c axis. Although this compound has been known since the 1950s, its superconductivity was only discovered a few years ago. While thin films and powders exhibit anisotropic superconducting properties, sintered ceramics are isotropic.

However, MgEL superconducting ceramics are very difficult to shape and machine because the material is extremely hard (Hv = 18 GPa and Young's modulus = 400 MPa), fragile (K = 2 MPam ^1/2 ), difficult to sintering since only Spark Plasma Sintering allows optimal sintering, and its chemical composition is easily decomposed with temperature.

This material is of great interest in the context of superconducting applications (motors, magnetic screens, curvature elements, electricity storage, electromagnetic thrusters, etc.) in order to generate significant magnetic fields thanks to its high current density capacity. critical. These current densities are greater than those of oxide superconductors at high critical temperatures usually used such as YBa2Cu3O7 (ReYBCO) with identical cross sections. However, obtaining massive parts, particularly with complex shapes, is not possible to date. This is one of the major problems encountered until now in the use of MgB2 which is slowing down its development.

Furthermore, MgB2 is a very light material (2.5 g/cm ³ ) and is therefore interesting for on-board applications, such as in motors for electric aircraft, unlike ReBCO.

Applications involving large magnetic fields increasingly require the ability to produce complex magnetic field maps, which requires the parts of the superconducting material to also have complex shapes. Such applications in the case of MgB2 are made extremely difficult because it is not possible to machine it due to its high hardness (GPa) and brittleness.

There is therefore a need to have a process for manufacturing an MgB2 part making it possible to avoid the need for winding ribbons, as used in the case of oxides such as ReBCO, which is a technical operation. very delicate, and above all to have a complete superconducting current passage section corresponding to the true section of the material.

There is also a need to have such a manufacturing process so as to be able to reduce the size of the devices for the same magnetic performances and to avoid the loss of material due to machining or the wear of the tools. machining.

Summary of the invention

The invention meets this need using a process for manufacturing an MgB2 part comprising: a) the production of a preform by shaping a powder of MgB2 particles by means of a additive manufacturing technique on a powder bed, comprising the irradiation of the MgB2 powder with laser radiation, and b) a step of densification of the preform, until the MgB2 part is obtained.

In the context of the present invention, the process thus makes it possible, in particular from a commercial MgB2 powder, preferably previously deagglomerated, to spread it in a bed then to insolate it using a laser under atmosphere inert. The process is additive and makes it possible to build a preformed layer by layer. Through this process, the amount of material used can be reduced, thereby reducing raw material costs.

To date, no production of MgB2 material using additive manufacturing techniques has been reported in the literature.

Brief description of the drawings

The invention can be better understood on reading the detailed description which follows, non-limiting examples of its implementation, and on examining the figures:

[Fig 1] represents a diagram of the successive stages of an embodiment of the method according to the invention.

[Fig 2] represents the curve obtained in the example representing the mass fraction of the MgB2 phase as a function of the cumulative energy dose for the plate with a powder bed of 100 pm.

[Fig 3] represents XRD diagrams of samples A and B of the example after implementation of the process, namely step a) implementing the SLS technique and step b) implementing the S PS technique .

[Fig 4] represents magnetic moment curves as a function of temperature of samples obtained in the example. The insets show a photograph of sample A after step a) implementing the SLS technique then after step b) implementing the SPS technique, and the transition region for sample B in more detail ( to the right).

[Fig 5] represents a diagram of parts of more complex shape in MgB2 to be printed (scale in mm) and corresponding preformed parts, obtained experimentally.

detailed description

The invention relates to a method of manufacturing a part, in particular a preformed part, in particular of complex shape, of the MgB2 superconducting ceramic according to the invention, the method comprising the production of said part by shaping of a powder using an additive manufacturing technique.

Preferably, the additive manufacturing technique is a powder bed additive manufacturing technique. Preferably, the additive manufacturing technique, commonly called 3D printing techniques, implements a partial or complete fusion of powder particles by means of a light beam or electrons, in particular a light beam. Preferably, the light beam is a laser beam. In the context of the present invention, the additive manufacturing technique used is preferably direct metal laser sintering additive manufacturing, translation of Direct Metal Laser Sintering (DMLS).

The additive manufacturing technique by laser fusion on a powder bed comprises the deposition of at least one layer of powder then the partial or complete fusion of at least a part of the particles of the powder, preferably of all of the particles of the layer deposited by a selective supply of energy under the action of a laser beam.

In the context of the present invention, such a step allowing the production of a preform by shaping a powder of MgEL particles by means of an additive manufacturing technique on a powder bed is called step a), and is followed by a step b) of densification.

According to the terms of the invention, “densification” designates the possibility of manually extracting a preformed material via an increase in the density of the material, expressed in relation to the theoretical density of the material without porosity.

According to a variant, step a) and/or step b) is carried out under an inert atmosphere, in particular under argon.

The differences of the process according to the invention, and different embodiments are detailed below.

Powder bed additive manufacturing - step a)

Step a) of the method according to the invention comprises the production of a preform by shaping a powder of MgEL particles by means of an additive manufacturing technique on a powder bed, comprising the insolation of the MgEL powder with laser radiation. In a variant, the MgEL powder can be that marketed as boron powder from Pavezyum, Advanced Chemicals (Istanbul, Turkey).

Concerning the quality of this starting powder, the purity may in particular be greater than 90%, or even 95%, for example 97%.

As traces present in this powder, we can cite traces of MgO (for example 2%) and MgEL (for example 0.1%). In a variant, the median equivalent diameter of the particles of the MgB2 powder varies from 1 pm to 50 pm, in particular varies from 2 pm to 30 pm, preferably varies from 5 pm to 20 pm.

In a variant, the process comprises, prior to step a), a step of deagglomeration of the MgB2 particle powder.

Typically, this deagglomeration step can be carried out by placing the powder in a mixer and/or centrifuge, for example as sold under the name Centrifugal Mixer SK-300SII by the company Kakuhanter Planetary. Typically, the rotation speed can be between 800 rpm and 1500 rpm, in particular between 1000 rpm and 1400 rpm, for example at 1200 rpm.

The powder can be spread in beds of different thicknesses. In particular, the thickness of the powder bed can influence how powder sintering occurs. In fact, within the framework of the present invention, we can seek to aim for a temperature which avoids degradation of the MgB2 phase, in particular into Mg and B.

According to a variant, the thickness of the powder bed in step a) varies from 50 pm to 800 pm, in particular varies from 75 pm to 500 pm, preferably varies from 100 pm to 300 pm.

According to a variant, step a) is implemented by selective laser sintering (SLS or DMLS).

Any DMLS/SLS device known to those skilled in the art can be used, such as the M ProXLS 200 device marketed by the company 3D system.

The type of laser that can be used in the exposure carried out in step a) of the process is in particular a 300 W laser. Typically, a laser with a wavelength of 1064 nm can be used.

According to a variant embodiment, the production of a preform by shaping a powder of MgB2 particles by means of an additive manufacturing technique on a powder bed, comprises the insolation of the MgB2 powder with radiation laser, with a local cumulative energy density varying from 18 mJ/pm ² to 265 mJ/pm ² , i.e. a global non-cumulative macroscopic dose varying from 4 J/cm ² /pass to 70 J/cm ² /pass, of so as to obtain the preform based on an exposed MgB2 powder.

The insolation results in a densification of the preform. Thus, the densification of the MgB2 powder at the end of step a) can vary from 30% to 45%, preferably vary from 35% to 45%, expressed in relation to the theoretical density of the material without porosity. .

The optimization of laser exposure (dose, thickness) notably made it possible to provide the possibility of having preforms (35% densification) manipulated which can then be sintered under load and under an inert atmosphere during step b) detailed below.

The power of the laser radiation can in particular vary from 28 W to 115 W, in particular from 40 W to 95 W, even more particularly from 50 W to 85 W.

In terms of doses or energy density of laser radiation, they can vary from 4 J/cm ² /pass to 70 J/cm ² /pass, in particular vary from 4.5 J/cm ² /pass to 70 J /cm ² /pass, more particularly vary from 5 J/cm ² /pass to 70 J/cm ² /pass, preferably vary from 6 J/cm ² /pass to 60 J/cm ² /pass, and more preferably from 7 J/cm ² /pass to 50 J/cm ² /pass. In terms of cumulative dose, it can vary from 18 mJ/pm ² to 265 mJ/pm ² , in particular vary from 31 mJ/pm ² to 188 mJ/pm ² , and even more particularly from 53 mJ/pm ² to 144 mJ/pm ² .

The inventors were notably able to observe that too low laser doses, for example less than 4 J/cm ² /pass, can lead to ineffective sintering, in other words manifested by the fact that the powder remains in powder form while a larger dose, for example greater than 100 J/cm ² /pass, leads to the degradation of the MgEL phase, typically by the formation of impurity phases such as MgEL, Mg2EL, MgO or Mg, which causes undesirable properties in the samples obtained, in particular the loss of superconductivity. Furthermore, the cumulative energy dose can be adjusted by those skilled in the art as a function of the thickness of the selected powder bed.

According to a variant, the laser beam is moved at a speed varying from 100 mm/s to 1000 mm/s, in particular from 100 mm/s to 800 mm/s, in particular varying from 120 mm/s to 800 mm/s, more particularly varying from 120 mm/s to 500 mm/s, preferably varying from 150 mm/s to 300 mm/s, and more preferably varying from 150 mm/s to 250 mm/s.

According to a variant, the vector spacing of the laser beam varies from 50 pm to 250 pm, in particular varies from 75 pm to 175 pm, preferably varies from 100 pm to 150 pm.

According to a variant, the focusing of the laser beam varies from -50 mm to -20 mm, in particular varies from -50 mm to -30 mm, preferably varies from -50 mm to -40 mm. According to another alternative embodiment, step a) of the method according to the invention comprises the production of a preform by shaping a powder of MgB2 particles using an additive manufacturing technique on a powder bed , comprising the insolation of the MgB2 powder with laser radiation, with a macroscopic energy dose varying from 50 J/cm ² /pass to 90 J/cm ² /pass, so as to obtain a counterform based on an MgO powder and the preform based on an unexposed MgB2 powder adjacent to the MgO powder.

According to a variant of this embodiment, the energy dose of the laser radiation in step a) varies from 50 J/cm ² /pass to 90 J/cm ² /pass, in particular varies from 50 J/cm ² /pass at 80 J/cm ² /pass, preferably varies from 50 J/cm ² /pass to 70 J/cm ² /pass.

According to a variant of this embodiment, the power of the laser radiation in step a) varies from 70 W to 150 W, in particular varies from 70 W to 130 W, preferably varies from 70 W to 120 W.

According to a variant of this embodiment, the laser beam in step a) is moved at a speed varying from 100 mm/s to 800 mm/s, in particular varying from 120 mm/s to 500 mm/s, preferably varying from 150 mm/s to 250 mm/s.

According to a variant of this embodiment, the vector spacing of the laser beam in step a) varies from 50 pm to 250 pm, in particular varies from 75 pm to 175 pm, preferably varies from 100 pm to 150 pm.

According to a variant of this embodiment, the focusing of the laser beam in step a) varies from -50 mm to -20 mm, in particular varies from -50 mm to -30 mm, preferably varies from -50 mm to -40 mm.

The densification step of step b) may comprise a sintering step, in particular by densification under load, or an impregnation step, in particular with a conductive metal distinct from magnesium, and preferably with copper or a alloy of copper and silver.

According to a particular embodiment, step b) consists of a densification step under load.

According to a variant, the sintering step is carried out by densification under load, in particular by SPS or by hot pressing (in English “Hot Pressing”), in particular by SPS. The objective of this densification step b) is to achieve a hardness of the formed parts compatible with the desired applications. In other words, this densification step b), in particular by SPS treatment, reduces the fragility and porosity of the samples or parts obtained by implementing a single step a) as described previously.

SPS treatment is field-assisted sintering. Field-assisted sintering is also known by the English acronym “FAST” for “Field Assisted Sintering Technology”. By “field-assisted sintering” we mean assisted sintering under an electric field or magnetic field. Electric field-assisted sintering is also known under the name “flash sintering” and under the English acronyms “SPS” for “Spark Plasma Sintering” and “EC AS” for “Electric Current Assisted Sintering”. Powder matrices or sacrificial powders can be used as part of the implementation of step b), particularly with a view to facilitating demoulding. Among such powders, mention may in particular be made of powders such as SiC, Al2O3, MgAhCL and BN. Such powders can in particular be chosen so as to avoid interdiffusion and the formation of impurities due to parasitic reactions.

According to a variant, the densification step under load uses one or more sacrificial powders, and preferably at least silicon carbide.

As illustrated in the following example, it could be observed that the geometry of the part could thus be preserved.

According to a variant, the densification step under load is carried out at a temperature varying from 700°C to 1050°C, in particular varying from 750°C to 1000°C, preferably varying from 800°C to 950°C.

According to a variant, the densification step under load is carried out for a duration varying from 20 minutes to 120 minutes, in particular varying from 20 minutes to 90 minutes, preferably varying from 20 minutes to 60 minutes.

According to a variant, the densification step under load is carried out under a pressure varying from 10 MPa to 100 MPa, in particular varying from 20 MPa to 80 MPa, preferably varying from 40 MPa to 60 MPa.

According to another variant, the densification step of step b) comprises an impregnation step, in particular with a conductive metal distinct from magnesium, and preferably with copper or an alloy of copper and silver. Such a step makes it possible to fill the porosity by capillary action.

According to a particular embodiment, the present invention relates to a process as described above, characterized in that it comprises: a) the production of a preform by shaping a powder of MgEL particles by means of an additive manufacturing technique on a powder bed, comprising the insolation of the MgEU powder with laser radiation, with an energy dose varying from 4 J/cm ² /pass to 70 J/cm ² /pass, so as to to obtain the preform based on an exposed MgEU powder, and b) a step of densifying the preform, by sintering the exposed MgEU powder, until the MgEL part is obtained.

Figure 1 represents a diagram of the successive stages of the embodiment of the method described above.

Furthermore, Figure 5 represents a diagram of MgEL parts to be printed (scale in mm) and preformed experimentally obtained with laser powers of 63-74 W, a defocus at -50 mm, a scanning speed of 200 mm/ s, a spacing of 175 pm, and a powder bed thickness of 300 pm (corresponding to doses of 40 J/cm ² /pass J/cm ² /pass to 45 J/cm ² /pass).

The inventors have also developed a particular embodiment of the process using laser radiation with a high cumulative energy density in step a) making it possible to obtain a counterform in the form of a degraded MgEL powder. and/or decomposed MgO. In other words, the preform and the counterform are then contiguous during this step a). The part thus obtained at the end of step a), comprising the preform and the counterform can then be subjected to step b) to obtain the densified MgEL preform.

Thus, the present invention also relates to a process as described above, characterized in that it comprises: a) the production of a preform by shaping a powder of MgEL particles by means of a manufacturing technique additive on a powder bed, in an environment with oxygen, comprising the insolation of the MgEL powder with laser radiation, with an energy dose varying from 50 J/cm ² /pass to 90 J/cm ² /pass, preferably varying from 60 J/cm ² /pass to 80 J/cm ² /pass, so as to obtain a counterform based on an MgO powder and the preform based on an unexposed MgB2 powder contiguous to the MgO powder, and b) a step of densifying the preform, by sintering the unexposed MgB2 powder in step a), in a sintering oven under an inert atmosphere, followed by a step of depowdering the MgO powder, until obtaining the MgB2 piece.

According to a variant of this embodiment, the sintering step is carried out at a temperature varying from 700°C to 1050°C, in particular varying from 750°C to 1000°C, preferably varying from 800°C to 950°C. °C.

At the end of step b), the process can also include a subsequent step of demoulding the MgB2 part.

The MgB2 part may be a superconductor, whose critical temperature may be between 35 K and 39 K.

Preforms or parts obtained and their use

The inventors have shown that the process according to the present invention makes it possible to produce complex shapes. Typically, the size of the parts or patterns can advantageously be greater than 0.5 x 0.5 x 0.5 cm ³ to obtain good mechanical strength of the preformed parts. The method according to the present invention can thus be particularly adapted for the manufacture of massive objects of multicentimeter dimensions.

The inventors have also demonstrated that the process according to the present invention allows the manufacture of preforms, in particular densified to 35%, with good mechanical strength for large parts, without significant degradation of the MgB2 phase. The successive step of densification under load (SPS), in particular using a sacrificial powder such as a SiC powder, in order to avoid diffusion coupled with an undesirable reaction and for demolding purposes, makes it possible to increase the densification of the preformed while keeping the initial geometry of the preformed. Due to a shrinkage which can be significant, in particular 65%, in particular visible along the axis of application of the force, as illustrated in the example which follows, it may be advantageous to take it into account for satisfy the final dimensions of the parts. Furthermore, as shown in Figure 4, the inventors were able to show that samples presented the MgB2 phase and that the latter were superconductors with a critical temperature similar to that of samples obtained by the conventional route (38 K).

The method according to the present invention makes it possible to obtain complex 3D shapes. The preforms or parts obtained by the process according to the present invention can in particular be used for all types of applications using superconductors such as motors or alternators, in particular in the field of aeronautics, wind power, satellite trajectory correctors, magnetic levitation systems, thrusters, particularly for the field of magnetohydrodynamics or for launchers, magnetic shields and screenings (MAGLEV), energy storage systems (SMES), bending magnets and magnetic confinement systems, for example for particle accelerators, fusion reactors (ITER), maritime propulsion systems for submarines and boats, high-power electricity systems (superconducting shunts), magnetic field generation systems (IRM) or even electromagnetic launchers (S3EL).

The invention is not limited to the embodiments described above.

For example, MgEh parts may differ from those shown.

Examples

MATERIALS AND METHODS

A commercial powder (Pavezyum) with a purity greater than 95% and an agglomerate size less than 500 pm (particles from 1 pm to 50 pm) was used for the manufacture of the superconducting parts.

The purity of said powder, as well as the distribution of phases in the samples produced, were verified using the Bruker D8 diffractometer in the Bragg-Brentano configuration (30 < 29 < 65°, step 0.01°) and a CuKa wavelength radiation (40 kV, 40 mA). During acquisition, a nickel filter was used to eliminate Kp radiation and reduce fluorescence. Mixing of the raw powder was carried out for powder deagglomeration several days before the start of the process using the Kakuhanter Planetary Centrifugal Mixer SK-300SII equipment.

Mixing conditions: 1100 rpm, for a duration of 6 minutes for a maximum of 180 g of powder at one time.

The deagglomerated powder was introduced into the SLS apparatus.

SLS device used for step a): M ProXLS 200 marketed by the company 3D System (wavelength: 1070 nm) under an inert argon atmosphere (O2 < 800 ppm).

A thin layer of silicon was applied to the surface of the build plate to prevent slippage of the MgEL powder during fabrication of the first layer.

All samples obtained were studied using microscopy (KEYENCE VH-Z100R, SEM TESCAN VEGA3) and XRD techniques.

The superconductivity properties of the selected samples were studied using magnetic susceptibility measurements with the SQUID magnetometer (Quantum design MPMS 5) in zero field cooling (ZFC) and zero field cooling regimes. field of 20 Oe (FC) in the temperature range of 20 - 40 K.

Shape of samples or parts: Simple cubic shape. Each cube had a base area of 1 x 1 cm ² and a height of ~4.4 mm.

Powder bed thickness: 100 pm

Laser:

- hexagonal strategy of laser movement

- laser power (P): {30; 129} W

- laser scanning speed (v): {50; 800} mm/s

- distance between two passes of the laser (A): { 100; 250} p.m.

- laser spot size: 1000 pm

Device used for step b): Spark Plasma Sintering SPS Dr. Sinter 2080 marketed by the company Sumitomo.

RESULTS

Under the conditions identified above, the SLS manufacturing yield was ~85% (viable samples).

All synthesized samples were then studied by X-ray diffraction. Figure 2 presents the volume fraction of the MgEL phase in the sample as a function of the cumulative energy dose.

The highest value of the MgEL fraction was found for laser radiation doses between 4.5 J/cm ² /pass and 60 J/cm ² /pass.

According to the microscopic study, all samples, which received an energy dose less than 4 J/cm ² /pass, were fragile and had high porosity, indicating that the radiation energy of the laser beam does not is not sufficient to obtain complete sintering of the powder.

After an in-depth study, two samples containing an MgEL phase greater than 94% were selected.

These results were obtained under the following laser conditions:

- P = 66 W, v = 800 mm/s, A = 100 pm (sample A, i.e. a dose of 10 J/cm ² /pass also corresponding to a cumulative dose Ed = 89 mJ/pm ² ), and

- P = 84 W, v = 200 mm/s, A = 250 pm (sample B, i.e. a dose of 50 J/cm ² /pass, also corresponding to a cumulative dose Ed = 179 mJ/pm ² ).

The X-ray images of these samples are shown in Figure 3 (a, b).

The obtained samples show a similar XRD pattern with the same compounds.

Further processing by spark plasma sintering was carried out.

The samples were placed in graphite matrices with the additional SiC powder around the cube and heated to 800 °C under 0.1 kN in the 20 mm diameter matrix for 8 min.

Then, a uniaxial pressure of 15.7 kN was applied for 20 minutes and this temperature and pressure were maintained for an additional 20 minutes. Finally, the pressure and temperature were released for 16 minutes.

The parallelepiped samples obtained presented an undeformed geometry (Figure 4 inset) of their base surface, but their height was extremely reduced. Despite only one difference in SPS conditions, the X-ray diffraction pattern for sample B shows more impurity peaks (Figure 3 c,d), which can be explained by the presence of poorly removed SiC.

Regarding superconducting properties, magnetic susceptibility measurements show a clear transition to superconductivity at Te ~37.8 K in sample A, while the susceptibility curve of sample B grows again rapidly with the decrease in temperature just after the transition to the superconducting state (Te ~ 37.8 K) (figure 4).

Finally, the SPS conditions described above give a good result both for the composition of the phase obtained and for the preservation of the superconductivity properties.

CONCLUSIONS

Cumulative energy doses of 89 mJ/pm ² (dose 10 J/cm ² /pass) and 179 mJ/pm ² (50 J/cm ² /pass) received by the raw powder under certain SLS conditions, make it possible to obtain samples shaped with a virtually non-degenerate and superconducting MgEL phase.

The sample processed by SPS in an Ar atmosphere at 800 °C and 15.7 kN shows a clear transition to the superconducting state at ~37.8 K.

These results show that the process according to the present invention allows the manufacture of superconducting parts in MgB2 with complex shapes for all types of superconducting applications.

Claims

1. Process for manufacturing an MgB2 part comprising: a) the production of a preform by shaping a powder of MgB2 particles by means of an additive manufacturing technique on a powder bed, comprising the irradiation of the MgB2 powder with laser radiation, and b) a step of densification of the preform, until the MgB2 part is obtained.

2. Method according to claim 1, characterized in that the median equivalent diameter of the particles of the MgB2 powder varies from 1 pm to 50 pm, in particular varies from 2 pm to 30 pm, preferably varies from 5 pm to 20 pm .

3. Method according to any one of the preceding claims, characterized in that step a) is implemented by selective laser sintering.

4. Method according to any one of the preceding claims, characterized in that step b) comprises a sintering step, in particular by densification under load, or an impregnation step, in particular with a conductive metal distinct from magnesium , and preferably with copper or an alloy of copper and silver.

5. Method according to any one of the preceding claims, characterized in that it comprises: a) the production of a preform by shaping a powder of MgB2 particles by means of an additive manufacturing technique on powder bed, comprising the insolation of the MgB2 powder with laser radiation, with an energy dose varying from 4 J/cm ² /pass to 70 J/cm ² /pass, so as to obtain the base preform of an exposed MgB2 powder, and b) a step of densifying the preform, by sintering the exposed MgB2 powder, until the MgB2 part is obtained.

6. Method according to any one of the preceding claims, characterized in that step a) is carried out such that the densification of the MgB2 powder after exposure varies from 30% to 45%, preferably varies from 35%. at 45%, expressed in relation to the theoretical density without porosity.

7. Method according to any one of the preceding claims, characterized in that the energy dose of the laser radiation in step a) varies from 4.5 J/cm ² / increases to 70 J/cm ² /pass, in particular varies from 5 J/cm ² /pass to 70 J/cm ² /pass, even more particularly varies from 6 J/cm ² /pass to 60 J/cm ² /pass.

8. Method according to any one of the preceding claims, characterized in that the thickness of the powder bed in step a) varies from 50 pm to 800 pm, in particular varies from 75 pm to 500 pm, preferably varies from 100 pm p.m. to 300 p.m.

9. Method according to any one of the preceding claims, characterized in that the sintering step is carried out by densification under load, in particular by SPS or by hot pressing, in particular by SPS.

10. Method according to any one of claims 1 to 4, characterized in that it comprises: a) the production of a preform by shaping a powder of MgB2 particles by means of a manufacturing technique additive on a powder bed, in an environment with oxygen, comprising the insolation of the MgB2 powder with laser radiation, with an energy dose varying from 50 J/cm ² /pass to 90 J/cm ² /pass, so as to obtain a counterform based on an MgO powder and the preform based on an unexposed MgB2 powder adjoining the MgO powder, and b) a step of densifying the preform, by sintering of the unexposed MgB2 powder in step a), in a sintering furnace under an inert atmosphere, followed by a step of depowdering the MgO powder, until the MgB2 part is obtained.

11. Method according to the preceding claim, characterized in that the energy dose of the laser radiation in step a) varies from 50 J/cm ² /pass to 80 J/cm ² /pass, preferably varies from 50 J/cm ² /pass to 70 J/cm ² /pass.

12. Method according to any one of claims 10 or 11, characterized in that the thickness of the powder bed in step a) varies from 50 pm to 800 pm, in particular varies from 75 pm to 500 pm, preferably varies from 100 p.m. to 300 p.m.

13. Method according to any one of claims 10 to 12, characterized in that the sintering step is carried out at a temperature varying from 700 °C to 1050 °C, in particular varying from 750 °C to 1000 °C, preferably varying from 800°C to 950°C.

14. Method according to any one of the preceding claims, characterized in that it comprises a subsequent step of demolding the MgB2 part.

15. Method according to any one of the preceding claims, the MgB2 part being a superconductor having a critical temperature of between 35 K and