A low-temperature giant magnetostrictive material of manganese, cobalt, silicon, and germanium and its preparation method

Abstract

A low-temperature giant magnetostrictive material composed of four metals: Mn, Co, Si, and Ge, has the molecular formula MnCoSi. 1‑x Ge x Where x ranges from 0.06 to 0.07, the temperature- and magnetic field-induced variable magnetic phase transition of this material occurs between 150 K and 230 K, with a critical magnetic field of 0.2 to 0.8 T. The low-temperature magnetostriction exhibits anisotropic behavior in both the direction perpendicular to and parallel to the texture. Under a 1.4 T magnetic field, the magnetostrictive effect of the variable magnetic phase transition reaches a maximum of 2026 ppm in the direction parallel to the texture and a minimum of -1685 ppm in the direction perpendicular to the texture. This invention prepares a low-temperature magnetostrictive material with low cost, low-temperature variable magnetic phase transition performance, low critical magnetic field, resistance to breakage, good orientation, and a dense internal structure, thus expanding its applications and scope of use.

Description

Technical Field

[0001] This invention relates to the field of magnetic functional materials technology, specifically to a manganese-cobalt-silicon-germanium low-temperature giant magnetostrictive material and its preparation method. Background Technology

[0002] With the development of science and technology, low-temperature physics research has achieved significant breakthroughs in many fields such as superconductivity, superfluidity, magnetic refrigeration, and the fractional quantum Hall effect. However, research on low-temperature magnetostrictive materials is relatively limited. Compared to room-temperature magnetostrictive materials, low-temperature magnetostrictive materials can be applied in defense, industry, and other fields under low-temperature conditions. Currently, the most studied low-temperature magnetostrictive materials in existing technologies are mainly rare-earth-iron-based compounds with cubic Laves phases, which exhibit significant low-temperature magnetostrictive effects. For example, Tang Yanmei et al. discovered that PrFe... 1.9 Magnetostriction of approximately 2500 ppm can be generated at 200 K under a 3 T magnetic field. However, these rare-earth-iron-based low-temperature magnetostrictive materials are expensive due to the presence of rare-earth elements in their composition, and they are also quite brittle and easily damaged during use, thus hindering practical applications. Therefore, there is an urgent need to develop low-cost, reversible low-temperature giant magnetostrictive materials with low critical magnetic fields.

[0003] MnCoSi alloys are composed of inexpensive transition and main group elements, and their Nell temperature (T) is [missing information]. N The critical magnetic field (CMF) is approximately 380 K. Below the Nell temperature, a magnetic field can induce a metamagnetic phase transition in this alloy from an antiferromagnetic phase to a ferromagnetic phase, accompanied by significant lattice distortion. Therefore, this type of material is a potential magnetostrictive material. The Mn atoms determine the magnetism of this alloy system. The two nearest neighbor distances between Mn-Mn atoms are d1 and d2, respectively. Density functional theory calculations confirm that the magnitude of d1 determines the magnetic structure of the system. The positively modulated MnCoSi alloy exhibits an antiferromagnetic structure below the Nell temperature. At 200 K, the critical magnetic field driving the metamagnetic phase transition is as high as 8 T, which is very unfavorable for practical applications. Therefore, it is essential to reduce the critical magnetic field. Since the antiferromagnetic and ferromagnetic phases within the MnCoSi alloy have a mutually dependent and competitive relationship, and d1 is very close to the ferromagnetic region, external energy may disrupt this antiferromagnetic-ferromagnetic competitive relationship. Therefore, it is essential for the development of MnCoSi alloy-based magnetostrictive materials to induce the transformation of the antiferromagnetic phase into the ferromagnetic phase through certain processing steps and methods, thereby reducing the critical magnetic field. Summary of the Invention

[0004] The technical objective of this invention is to prepare a low-temperature magnetostrictive material that is low in cost, has low-temperature magnetic phase transition properties, a low critical magnetic field, is not easily broken, has good orientation, and a dense internal structure, so as to expand its applications and scope of use.

[0005] To achieve the above objectives, the present invention adopts the following technical solution: a low-temperature giant magnetostrictive material composed of four metals: Mn, Co, Si, and Ge, with the molecular formula MnCoSi. 1-x Ge x Where x is 0.06~0.07, the temperature and magnetic field-induced phase transition of this material occurs in the range of 150~230K, the critical magnetic field is 0.2~0.8T, the low-temperature magnetostriction exhibits anisotropic behavior in the direction perpendicular to the texture and parallel to the texture. Under the induction of a magnetic field of 1.4T, the magnetostriction effect of the phase transition in the direction parallel to the texture reaches the highest of 2026ppm, and the magnetostriction effect in the direction perpendicular to the texture reaches the lowest of -1685ppm.

[0006] Preferably, x = 0.07 in the molecular formula.

[0007] A method for preparing a low-temperature giant magnetostrictive material of manganese cobalt silicon germanium includes the following steps:

[0008] Step 1: According to the molecular formula MnCoSi 1-x Ge x The molar ratio of four metals, Mn, Co, Si, and Ge, was determined by mixing elemental Mn, Co, Si, and Ge separately. After thorough mixing, the mixture was placed in a copper crucible within an electric arc melting furnace, and the furnace was evacuated to a vacuum level of 1 × 10⁻⁶. -4 Pa, then under the condition of continuous introduction of high-purity argon gas, the mixed raw materials are repeatedly melted 3 to 4 times to obtain alloy blocks for later use;

[0009] Step 2: Place the alloy block obtained in Step 1 into a quartz glass tube. Then, first evacuate the quartz glass tube, and then seal it with an acetylene-oxygen flame.

[0010] Step 3: Place the sealed quartz glass tube from Step 2 into a muffle furnace, control the temperature inside the muffle furnace to rise continuously from room temperature to 1227℃, apply a strong magnetic field of 6T for strong magnetic field solidification treatment, and hold at this temperature for 50~60min. After that, remove the magnetic field and control the temperature inside the muffle furnace to drop to 850℃ at a rate of 2℃ / min. Then, after the temperature inside the muffle furnace naturally cools down to room temperature, take out the alloy sample for later use.

[0011] Step 4: Place the alloy sample obtained in Step 3 back into the muffle furnace and control the temperature inside the muffle furnace to rise continuously from room temperature to 850℃ at a heating rate of 10℃ / min. Perform annealing and heat preservation treatment for 72~80h. Then, control the temperature inside the muffle furnace to cool slowly to room temperature. After taking it out, the finished low-temperature giant magnetostrictive material is obtained.

[0012] Preferably, in step one, the mass accuracy of the four metallic elements Mn, Co, Si and Ge is 0.01 mg.

[0013] Preferably, in step one, the purity of the weighed Mn metal element is greater than 99%, and the purity of the three metal elements Co, Si and Ge is greater than 99.99%.

[0014] Preferably, in step one, a circulating water cooling system is required to cool the electric arc melting furnace during the melting process.

[0015] Preferably, in step three, the heating rate inside the muffle furnace is 10°C / min.

[0016] The beneficial effects of this invention are:

[0017] (1) MnCoSi prepared by the present invention 1-x Ge x Compared to rare-earth magnetostrictive materials, low-temperature giant magnetostrictive materials are more cost-effective due to their MnCoSi metal composition. They exhibit anisotropic behavior both perpendicular and parallel to the texture direction, with the highest magnetostriction reaching 2026 ppm parallel to the texture direction and the lowest reaching -1685 ppm perpendicular to it. The critical magnetic field can be reduced to as low as 0.2~0.8T, approaching that of rare-earth magnetostrictive material TbFe2. In other words, its magnetic phase transition occurs at low temperatures, the critical magnetic field is low, and the magnetostrictive material itself is not easily fractured, possessing a dense internal structure, which drives the development of MnCoSi... 1-x Ge x The application of alloys in low-temperature magnetostrictive materials has progressed and has a wide range of applications.

[0018] (2) The preparation process of this invention, on the one hand, achieves the adjustment of the magnetic phase transition temperature of the finished low-temperature giant magnetostrictive material by replacing Si in the alloy with a small amount of Ge, and also effectively reduces the critical magnetic field. On the other hand, the operation steps of solidification with a strong magnetic field of 6T and slow cooling at a cooling rate of 2℃ / min are used. By heating the alloy particles to a semi-solid state where solid particles and liquid matrix coexist at 1227℃, and isothermally treating them under the action of a strong magnetic field of 6T for a period of time before solidification, the magnetocrystalline anisotropy of the particle phase in the alloy material and the magnetic field strength are sufficiently strong, so that the magnetic force acting on the particle phase drives the particles to rotate and orient in the liquid matrix. After the subsequent solidification process, the orientation state of the particles will be fixed, forming an alloy sample with a specific orientation. After slow cooling, a finished low-temperature giant magnetostrictive material with both orientation and density is produced. The process itself is simple, easy to operate, and the finished product has excellent performance.

[0019] (3) The preparation method of the present invention provides a new design idea for the study of low-temperature magnetostrictive materials based on magnetic phase transition mechanism.

[0020] (4) The preparation method of the present invention effectively adjusts the minimum inter-atomic spacing d1 of Mn-Mn atoms in the MnCoSi alloy through vacuum sealing followed by strong magnetic field solidification and post-annealing, inducing the transformation from antiferromagnetic phase to ferromagnetic phase, thereby changing the magnetic structure of the alloy system and achieving the goal of reducing the critical magnetic field of the finished low-temperature giant magnetostrictive material. During the furnace cooling process after melting, the positively fractionated MnCoSi alloy suffers from cracks on the sample surface due to the huge internal stress generated by the martensitic phase transformation, resulting in poor mechanical properties. The process steps of the present invention are to improve the mechanical and magnetostrictive properties of the MnCoSi system. The alloy raw material is heated to a semi-solid state where solid particles and liquid matrix coexist, and then isothermally treated for a long time under a strong magnetic field before solidification, allowing the particle phase to complete the rotational orientation and solidification positioning in the liquid matrix. Subsequently, the huge internal stress generated by the martensitic phase transformation is slowly released through slow cooling, forming a MnCoSi alloy that is oriented, internally dense, not easily broken, and has good mechanical properties. 1-x Ge x Low-temperature giant magnetostrictive materials. Attached Figure Description

[0021] Figure 1 The XRD patterns of the low-temperature giant magnetostrictive materials prepared in Examples 1 and 2 are shown.

[0022] Figure 2 The isothermal magnetization curve of the low-temperature giant magnetostrictive material prepared in Example 1;

[0023] Figure 3 The isothermal magnetization curve of the low-temperature giant magnetostrictive material prepared in Example 2;

[0024] Figure 4 The magnetostriction curve of the low-temperature giant magnetostrictive material prepared in Example 1;

[0025] Figure 5 The magnetostriction curve is shown for the low-temperature giant magnetostrictive material prepared in Example 2. Detailed Implementation

[0026] The technical solution of the present invention will be further described below with reference to embodiments, so that those skilled in the art at low temperature can better understand the present invention and implement it. The embodiments given are only some embodiments of the present invention and are not intended to limit the present invention.

[0027] A low-temperature giant magnetostrictive material composed of four metals: Mn, Co, Si, and Ge, has the molecular formula MnCoSi. 1-xGe x Where 0.06≤x≤0.07, the temperature and magnetic field-induced phase transition of this material occurs in the range of 150K~230K, the critical magnetic field is 0.2~0.8T, the low-temperature magnetostriction exhibits anisotropic behavior in both the direction perpendicular to and parallel to the texture. Under the induction of a magnetic field of 1.4T, the magnetostriction effect of the phase transition in the direction parallel to the texture reaches the highest of 2026ppm, and the magnetostriction effect in the direction perpendicular to the texture reaches the lowest of -1685ppm.

[0028] Its preparation method mainly involves melting the prepared mixed raw materials, vacuum sealing, solidification in a strong magnetic field, and post-annealing, specifically including the following steps:

[0029] Step 1: Take Mn metal with a purity greater than 99%, Co metal with a purity greater than 99.99%, Si metal, and Ge metal as raw materials, and process them according to the molecular formula MnCoSi. 1-x Ge x The molar ratios of the four metals Mn, Co, Si, and Ge were used to calculate the required mass of the elemental metals. The materials were then weighed to an accuracy of 0.01 mg. After the elemental metals were thoroughly mixed, the mixture was poured into a copper crucible in an electric arc melting furnace. A vacuum was then created in the furnace to a vacuum level of 1 × 10⁻⁶. -4 Pa, then under the condition of continuous introduction of high-purity argon, the mixed raw materials are repeatedly melted 3 to 4 times. During the process, the electric arc melting furnace is cooled by a circulating water cooling system to obtain alloy blocks for later use.

[0030] Step 2: Place the alloy block obtained in Step 1 into a quartz glass tube, then use a mechanical pump to evacuate the quartz glass tube and seal it with an acetylene-oxygen flame.

[0031] Step 3: Place the sealed quartz glass tube from Step 2 into a muffle furnace. Control the temperature inside the muffle furnace to rise from room temperature to 1227℃ at a rate of 10℃ / min. Apply a strong magnetic field of 6T for strong magnetic field solidification treatment and hold at this temperature for 50-60 minutes. Then, remove the magnetic field and control the temperature inside the muffle furnace to decrease to 850℃ at a rate of 2℃ / min. After the temperature inside the muffle furnace naturally cools down to room temperature, take out the alloy sample for later use.

[0032] Step 4: Place the alloy sample obtained in Step 3 back into the muffle furnace and control the temperature inside the muffle furnace to rise continuously from room temperature to 850℃ at a heating rate of 10℃ / min. Perform annealing and heat preservation treatment for 72~80h. Then control the temperature inside the muffle furnace to cool slowly to room temperature. After taking it out, the textured finished low-temperature giant magnetostrictive material is obtained.

[0033] Example 1:

[0034] The low-temperature giant magnetostrictive material prepared in this embodiment specifically includes the following steps:

[0035] Step 1: Calculate the required mass of the elemental metal according to the molar ratio Mn:Co:Si:Ge = 1:1:0.94:0.06, and prepare the batch, accurate to 0.01 mg. Mix the elemental metal thoroughly, then pour the prepared raw materials into the copper crucible of the electric arc melting furnace. Cool the electric arc furnace using a circulating water cooling system. The vacuum degree should be 1×10⁻⁶. -4 High-purity argon gas was introduced under Pa, and the melting process was repeated 3 times.

[0036] Step 2: Place the smelted alloy block into a quartz glass tube, evacuate it using a mechanical pump, and then seal the quartz glass tube with an acetylene-oxygen flame.

[0037] Step 3: Place the quartz glass tube into a muffle furnace and heat it from room temperature to 1227°C. Then apply a strong magnetic field of 6T and hold it at this temperature for 50 minutes. After that, remove the magnetic field and lower the temperature to 850°C at a rate of 2°C / min. Remove the magnetic field and allow the furnace temperature to cool naturally to room temperature before taking out the alloy sample.

[0038] Step 4: After solidification in a strong magnetic field, the sample is placed in a muffle furnace and heated from room temperature to 850°C at a rate of 10°C / min, held at that temperature for 80 hours, and then slowly cooled to room temperature. The textured finished MnCoSi product is then removed. 0.94 Ge 0.06 Alloy materials.

[0039] Step 5: The finished MnCoSi... 0.94 Ge 0.06 The alloy material was cut into circular pieces with a diameter of 10 mm and a thickness of 5 mm along the direction perpendicular to the texture. After polishing, the pieces were used as samples for XRD testing.

[0040] Step 6: The finished MnCoSi... 0.94 Ge 0.06 The alloy material was wire-cut along the texture direction to form thin slices 10 mm long, 5 mm wide, and 3 mm thick. After polishing, these slices were used as samples for magnetostriction testing.

[0041] The test results are attached. Figure 1 , Figure 2 and Figure 4 As shown.

[0042] from Figure 1 It can be seen that, compared to the positively oriented MnCoSi alloy powder, the MnCoSi alloy powder solidified and oriented under a strong magnetic field... 0.94 Ge 0.06 The significant suppression of some diffraction peaks in the alloy sample indicates that the sample has achieved a certain degree of orientation. From Figure 2It can be seen that during the process of temperature rising from 150K to 230K, under the influence of a magnetic field of 0~1T, MnCoSi 0.94 Ge 0.06 The isothermal magnetization curves of the alloy samples exhibit a metamagnetic phase transition from an antiferromagnetic state to a ferromagnetic state. The critical magnetic field is as low as 0.2–0.8 T. From Figure 4 It can be seen that under the action of a 1.4T magnetic field, MnCoSi 0.94 Ge 0.06 The magnetostrictive effect of the alloy samples exhibits significant anisotropic behavior along both the parallel and perpendicular directions of the texture. The highest magnetostriction in the parallel direction reaches 2026 ppm, while the lowest in the perpendicular direction reaches -668 ppm.

[0043] Example 2:

[0044] The low-temperature giant magnetostrictive material prepared in this embodiment specifically includes the following steps:

[0045] Step 1: Calculate the required mass of the elemental metal according to the molar ratio Mn:Co:Si:Ge = 1:1:0.93:0.07, and prepare the batch, accurate to 0.01 mg. Mix the elemental metals thoroughly, then pour the prepared raw materials into the copper crucible of the electric arc melting furnace. Cool the electric arc furnace using a circulating water cooling system. The vacuum degree should be 1×10⁻⁶. -4 High-purity argon gas was introduced under Pa, and the melting process was repeated 4 times.

[0046] Step 2: Place the smelted alloy block into a quartz glass tube, evacuate it using a mechanical pump, and then seal the quartz glass tube with an acetylene-oxygen flame.

[0047] Step 3: Place the quartz glass tube into a muffle furnace and heat it from room temperature to 1227°C. Then apply a strong magnetic field of 6T and hold it at this temperature for 60 minutes. After that, remove the magnetic field and lower the temperature to 850°C at a rate of 2°C / min. Remove the magnetic field and allow the furnace temperature to cool naturally to room temperature before taking out the alloy sample.

[0048] Step 4: After solidification in a strong magnetic field, the sample is placed in a muffle furnace and heated from room temperature to 850°C at a rate of 10°C / min, held at that temperature for 72 hours, and then slowly cooled to room temperature. The textured finished MnCoSi product is then removed. 0.93 Ge 0.07 Alloy materials.

[0049] Step 5: The finished MnCoSi... 0.93 Ge 0.07 The alloy material was cut into circular pieces with a diameter of 10 mm and a thickness of 5 mm along the direction perpendicular to the texture. After polishing, the pieces were used as samples for XRD testing.

[0050] Step 6: The finished MnCoSi...0.93 Ge 0.07 The alloy material was wire-cut along the texture direction to form thin slices 10 mm long, 5 mm wide, and 3 mm thick. After polishing, these slices were used as samples for magnetostriction testing.

[0051] The test results are attached. Figure 1 , Figure 3 and Figure 5 As shown.

[0052] from Figure 1 It can be seen that, compared to the positively oriented MnCoSi alloy powder, the MnCoSi alloy powder solidified and oriented under a strong magnetic field... 0.93 Ge 0.07 Most of the diffraction peaks of the alloy sample were significantly suppressed, leaving only the (013) diffraction peak, indicating that the sample achieved a high degree of orientation. Figure 3 It can be seen that during the process of temperature rising from 150K to 230K, under the influence of a magnetic field of 0~1T, MnCoSi 0.93 Ge 0.07 The isothermal magnetization curves of the alloy samples exhibit a metamagnetic phase transition from an antiferromagnetic state to a ferromagnetic state, with the critical magnetic field reaching as low as 0.4–0.8 T. From Figure 5 It can be seen that under the action of a 1.4T magnetic field, MnCoSi 0.93 Ge 0.07 The alloy samples exhibited significant anisotropic behavior along both the parallel and perpendicular directions of the texture. The magnetostriction reached a maximum of 1933 ppm in the parallel direction and a minimum of -1685 ppm in the perpendicular direction.

Claims

1. A low-temperature giant magnetostrictive material of manganese, cobalt, silicon, and germanium, characterized in that: This material is composed of four metals: Mn, Co, Si, and Ge, and its molecular formula is MnCoSi. 1-x Ge x Where x is 0.06~0.07, the temperature and magnetic field induced phase transition of this material occurs in the range of 150~230K, the critical phase transition field is 0.2~0.8T, the low-temperature magnetostriction exhibits anisotropic behavior in the direction perpendicular to the texture and parallel to the texture. Under the magnetic field induced by 1.4T, the magnetostriction effect of the phase transition in the direction parallel to the texture reaches the highest of 2026ppm, and the magnetostriction effect in the direction perpendicular to the texture reaches the lowest of -1685ppm. The preparation method of the above-mentioned manganese-cobalt-silicon-germanium low-temperature giant magnetostrictive material includes the following steps: Step 1: According to the molecular formula MnCoSi 1-x Ge x The molar ratio of four metals, Mn, Co, Si, and Ge, was determined by mixing elemental Mn, Co, Si, and Ge separately. After thorough mixing, the mixture was placed in a copper crucible within an electric arc melting furnace, and the furnace was evacuated to a vacuum level of 1 × 10⁻⁶. -4 Pa, then under the condition of continuous introduction of high-purity argon gas, the mixed raw materials are repeatedly melted 3 to 4 times to obtain alloy blocks for later use; Step 2: Place the alloy block obtained in Step 1 into a quartz glass tube. Then, first evacuate the quartz glass tube, and then seal it with an acetylene-oxygen flame. Step 3: Place the sealed quartz glass tube from Step 2 into a muffle furnace, control the temperature inside the muffle furnace to rise continuously from room temperature to 1227℃, apply a strong magnetic field of 6T for strong magnetic field solidification treatment, and hold at this temperature for 50~60min. After that, remove the magnetic field and control the temperature inside the muffle furnace to drop to 850℃ at a rate of 2℃ / min. Then, after the temperature inside the muffle furnace naturally cools down to room temperature, take out the alloy sample for later use. Step 4: Place the alloy sample obtained in Step 3 back into the muffle furnace and control the temperature inside the muffle furnace to rise continuously from room temperature to 850℃ at a heating rate of 10℃ / min. Perform annealing and heat preservation treatment for 72~80h. Then, control the temperature inside the muffle furnace to cool slowly to room temperature. After taking it out, the finished low-temperature giant magnetostrictive material is obtained.

2. The manganese-cobalt-silicon-germanium low-temperature giant magnetostrictive material according to claim 1, characterized in that: In the molecular formula, x = 0.

07.

3. The manganese-cobalt-silicon-germanium low-temperature giant magnetostrictive material according to claim 1, characterized in that: In step one, the mass accuracy of the four metallic elements Mn, Co, Si and Ge is 0.01 mg.

4. The manganese-cobalt-silicon-germanium low-temperature giant magnetostrictive material according to claim 1, characterized in that: In step one, the purity of the Mn metal element is greater than 99%, and the purity of the Co, Si and Ge metal elements is greater than 99.99%.

5. The manganese-cobalt-silicon-germanium low-temperature giant magnetostrictive material according to claim 1, characterized in that: In step one, a circulating water cooling system is required to cool the electric arc melting furnace during the melting process.

6. The manganese-cobalt-silicon-germanium low-temperature giant magnetostrictive material according to claim 1, characterized in that: In step three, the heating rate inside the muffle furnace is 10°C / min.

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