A method for improving the processability of terbium-dysprosium-ferromagnetic piezoelectric materials

Abstract

This invention provides a method for improving the processing performance of terbium-dysprosium-iron magnetostrictive materials, relating to the field of magnetic functional materials technology. The method includes: Step S1, casting terbium-dysprosium-iron alloys and Re-N alloys into ingots respectively; Step S2, preparing the Re-N alloy into rapidly quenched thin strips or powders; Step S3, uniformly laying or coating the Re-N alloy thin strips or powders onto the terbium-dysprosium-iron alloy ingots to obtain an intermediate; Step S4, subjecting the intermediate to grain boundary strengthening treatment to obtain a grain boundary-strengthened terbium-dysprosium-iron alloy ingot; Step S5, subjecting the grain boundary-strengthened terbium-dysprosium-iron alloy ingot to secondary tempering to obtain a gradient interface structure, thus obtaining the terbium-dysprosium-iron magnetostrictive material. This invention overcomes the intrinsic brittleness of grain boundaries in the preparation of polycrystalline terbium-dysprosium-iron alloys using traditional methods, improves the processing performance of terbium-dysprosium-iron materials, enhances the stability of such materials in applications, and improves the overall performance and application range of the materials.

Description

Technical Field

[0001] This invention relates to the field of magnetic functional technology, and in particular to a method for improving the processing performance of terbium-dysprosium magnetostrictive materials. Background Technology

[0002] Tb-Dy-Fe alloy, a novel magnetostrictive material, possesses superior room-temperature magnetostrictive properties, high stress values ​​generated by deformation, high Curie temperature, and high magneto-mechanical coupling coefficient, making it suitable for numerous applications in acoustic components, electronic components, sensors, and electromagnetic actuators. However, the inherent brittleness of the Laves phase, the main phase of Tb-Dy-Fe alloy, and the brittle rare-earth-rich Dy grain boundary phase limit its machinability. During processing, it is prone to chipping and other damage. Furthermore, it is susceptible to fracture failure in engineering applications, thus restricting its wider application.

[0003] To overcome the problems of brittleness, difficulty in processing, and fracture failure of Tb-Dy-Fe alloys, a common method is to first prepare the Tb-Dy-Fe alloy into powder, and then use sintering or bonding processes to shape it into the desired form. A common bonding method uses high-molecular organic materials such as epoxy resin as binders. This method can produce near-net-shape Tb-Dy-Fe composite materials with significantly improved mechanical properties, increased resistivity, and reduced eddy current losses. However, due to the large volume fraction of the binder and the inherent elasticity and plasticity of the organic material, the magnetostrictive effect of the internal Tb-Dy-Fe alloy powder particles is offset, resulting in a significant loss in the magnetostriction coefficient and energy density of the material.

[0004] While conventional sintering methods can achieve the desired shape for Tb-Dy-Fe alloys, they do not improve the brittleness of the material itself, and their magnetostrictive properties are significantly lower compared to oriented polycrystalline Tb-Dy-Fe alloys prepared by methods such as directional solidification.

[0005] Currently, there are no reported techniques for improving the machinability of oriented polycrystalline terbium-dysprosium iron alloys by controlling the gradient interface and interface coherence relationship between the brittle main phase and the ductile grain boundary phase through grain boundary strengthening. Summary of the Invention

[0006] Terbium-dysprosium-iron alloys prepared by traditional methods have rare-earth-rich grain boundary phases (mainly Dy-rich phases) at their grain boundaries. The interface between these grain boundary phases and the main phase (Laves phase) is incoherent, leading to high brittleness and difficult processing. To address these issues, this invention provides a method for improving the processing performance of terbium-dysprosium-iron magnetostrictive materials. Through grain boundary strengthening treatment, the traditional rare-earth-rich grain boundary phase transforms into a Re-MN ductile grain boundary phase. An interface with a compositional gradient is formed between the brittle main phase and the ductile grain boundary phase. This phase interface transforms into a coherent or semi-coherent interface, increasing interfacial bonding strength and reducing stress concentration at the phase interface. This improves mechanical properties such as bending strength, impact toughness, and tensile strength, significantly enhancing the material's processing characteristics. Specifically, the technical solution of this invention is as follows:

[0007] A method for improving the processing properties of terbium-dysprosium magnetostrictive materials includes:

[0008] Step S1: Cast the terbium-dysprosium-iron alloy and the Re-N alloy into ingots respectively;

[0009] Step S2: Prepare Re-N alloy into rapidly quenched thin strips or powders;

[0010] Step S3: Uniformly lay or coat Re-N alloy strips or powders onto terbium-dysprosium-iron alloy ingots, or introduce N elements by ion implantation to obtain an intermediate;

[0011] Step S4: Perform grain boundary strengthening treatment on the intermediate to obtain a grain boundary strengthened terbium-dysprosium-iron alloy ingot;

[0012] Step S5: The terbium-dysprosium-iron alloy ingot with grain boundary strengthening is subjected to secondary tempering to obtain a gradient interface structure, which realizes the coherent or semi-coherent interface between the brittle main phase and the ductile grain boundary phase, increases the interface bonding strength, and reduces the stress concentration at the phase interface to obtain the product.

[0013] The main component of terbium-dysprosium iron alloys is: Tb x Dy 1-x Fe y M z Where 0.25≤x≤0.50, 1.80≤y≤2.1, 0.01≤z≤0.1; M is selected from at least one of Nd, Ho, Pr, Co, Gd, La, Ce, Y, Mn, Mg, Al, Si, Ni, Ti, Cr, V, Nb, Cu, Ca, Sb, Bi, Zn, Ga, and Sn;

[0014] Re-N alloy: Re is selected from at least one of Tb, Dy, Nd, Ho, Pr, Gd, La, Ce, and Y; N is selected from at least one of Cu, Bi, Sb, and Ca.

[0015] This invention mainly utilizes grain boundary strengthening technology. By introducing Re-N alloy, the Dy-rich grain boundary phase in traditional terbium-dysprosium-iron magnetostrictive materials is transformed into a Re-MN multi-component grain boundary phase with strong toughness. However, the composition and structure of the Laves main phase are not affected. Thus, while ensuring a large magnetostriction coefficient, the mechanical properties of the material are significantly improved and its processing characteristics are enhanced. The characteristics of the Re-MN grain boundary phase are as follows: ① The Re-MN grain boundary phase has good strength and toughness, which can effectively prevent the propagation of cracks originating from the interior of the Laves main phase; ② The Laves main phase grains of the Re-MN grain boundary phase have good wettability, and during the grain boundary strengthening process, they can spread evenly along the main phase grains, achieving uniform distribution around the main phase grains, and forming a coherent or semi-coherent interface with the main phase to increase the bonding strength between the main phase grains and the grain boundary phase; ③ Elements such as Cu, Bi, Sb, and Ca in the Re-MN grain boundary phase have negative enthalpy formation with the main phase elements Tb and Dy, and positive enthalpy formation with the main phase element Fe, so that these elements enter the Laves main phase lattice less or not at all, thus ensuring that the magnetic properties of the main phase are not affected.

[0016] Introducing Re-N alloys can transform the Dy-rich grain boundary phase, which has an incoherent interface relationship with the main phase, into a tough Re-MN grain boundary phase. The Re-MN grain boundary phase and the main phase then become a coherent or semi-coherent interface, which significantly improves the mechanical properties of the material and greatly enhances its processing characteristics.

[0017] Furthermore, in step S1, the terbium-dysprosium-iron alloy is cast into ingots by vacuum induction melting, vacuum arc melting, or directional solidification; the Re-N alloy is cast into ingots by vacuum induction melting.

[0018] Furthermore, in step S1, the terbium-dysprosium-iron alloy ingot is a vacuum-melted, oriented polycrystalline solidified product, whose crystal axial orientation includes, but is not limited to, […]. <111> , <112> , <113> , <110> .

[0019] Furthermore, in step S2, the Re-N alloy ingot is made into a thin strip with a thickness of 20-200μm by melt quenching, or the Re-N alloy ingot is mechanically ball-milled, or milled with argon or nitrogen gas flow to make powder with a particle size of 20-50μm.

[0020] Furthermore, in step S3, 3-10 wt% (based on terbium-dysprosium-iron alloy ingots) of Re-N alloy strips or powders are laid or coated, or N element is introduced by ion implantation.

[0021] Furthermore, in step S4, the grain boundary strengthening treatment temperature is 700–1050℃, the heat treatment time is 1–4 hours, and the vacuum is evacuated to 5 × 10⁻⁶. -3 Argon gas is then introduced after Pa.

[0022] Furthermore, in step S5, the secondary tempering heat treatment temperature is 350-600℃, the heat treatment time is 1-4 hours, and a vacuum of 5×10⁻⁶ is applied. -3 After Pa, argon gas is introduced to a pressure of 0.05 MPa.

[0023] This invention also provides the mechanical and magnetostrictive properties of terbium-dysprosium magnetostrictive materials. The mechanical properties at room temperature are: flexural strength greater than 100 MPa, and fracture toughness greater than 2.8 MPa·m. 1 / 2 Tensile strength greater than 40 MPa; magnetostrictive property greater than 1200 × 10⁻⁶ under prestress of 10 MPa and magnetic field strength of 1000 Oe. -6 .

[0024] The beneficial effects of the technical solutions provided in the embodiments of the present invention include at least the following:

[0025] (1) Terbium-dysprosium-iron magnetostrictive materials are prepared by grain boundary strengthening treatment technology, focusing on the regulation of grain boundary structure (including the composition, structure, and interface structure of grain boundary phases), while the composition and crystal structure of the Laves main phase are not affected, thus ensuring that the super magnetostrictive properties of terbium-dysprosium-iron magnetostrictive materials are not affected.

[0026] (2) Terbium-dysprosium-iron magnetostrictive materials are prepared by grain boundary strengthening treatment technology, which transforms the Dy-rich grain boundary phase, which is incoherent with the main phase, into a Re-MN grain boundary phase with strong toughness. The Re-MN grain boundary phase and the main phase are transformed into a coherent or semi-coherent interface, which can effectively prevent the propagation of cracks originating from the interior of the Laves main phase, significantly improve the mechanical properties of the material, and improve the processing characteristics.

[0027] (3) Terbium-dysprosium magnetostrictive materials are prepared by grain boundary strengthening treatment technology. The elements such as Cu, Bi, Sb, and Ca in the Re-MN alloy have negative enthalpy with the main phase rare earth elements Tb and Dy and positive enthalpy with the main phase element Fe. This makes these elements enter the Laves main phase lattice less or not at all, thus not affecting the magnetic properties and overcoming the drawback of not being able to take into account both mechanical properties and magnetic properties.

[0028] (4) Terbium-dysprosium magnetostrictive materials were prepared by grain boundary strengthening treatment technology, which overcame the problems of excessive volume fraction of the adhesive phase in resin-bonded terbium-dysprosium magnetostrictive composite materials, resulting in low material density, a significant decrease in magnetostrictive performance and energy density, and an increase in excitation magnetic field. Attached Figure Description

[0029] To more clearly illustrate the technical solutions in the embodiments of the present invention, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0030] Figure 1 The alloy composition in Embodiment 1 of this invention is Tb 0.3 Dy 0.7 Fe 1.95 Bi 0.02 And after being treated with 3% mass fraction (DyNd) 0.4 Cu 0.6 Magnetostrictive properties of samples prepared after grain boundary strengthening treatment under different pre-stress conditions.

[0031] Figure 2 The alloy composition in Embodiment 2 of this invention is Tb 0.3 Dy 0.7 Fe 1.95 Gd 0.05 Sd 0.03 And after being treated with 5% mass fraction (DyHo) 0.35 (CuBi) 0.65 The force-displacement curve of the three-point bending resistance of the sample prepared after grain boundary strengthening treatment. Detailed Implementation

[0032] The technical solution of the present invention will now be described with reference to the accompanying drawings.

[0033] In embodiments of the present invention, words such as "exemplarily," "for example," etc., are used to indicate that something is an example, illustration, or description. Any embodiment or design described as "exemplary" in the present invention should not be construed as being more preferred or advantageous than other embodiments or designs. Specifically, the use of the word "exemplary" is intended to present the concept in a concrete manner. Furthermore, in embodiments of the present invention, the meaning expressed by "and / or" can be both, or either one.

[0034] In this embodiment of the invention, the terms "image" and "picture" may sometimes be used interchangeably. It should be noted that, without emphasizing the difference, their intended meanings are consistent. Similarly, the terms "of," "corresponding," and "corresponding" may sometimes be used interchangeably. It should be noted that, without emphasizing the difference, their intended meanings are consistent.

[0035] In this embodiment of the invention, sometimes a subscript such as W1 may be mistakenly written as a non-subscript form such as W1. When the difference is not emphasized, the meaning they express is the same.

[0036] To make the technical problems, technical solutions and advantages of the present invention clearer, a detailed description will be given below in conjunction with the accompanying drawings and specific embodiments.

[0037] Example 1:

[0038] Design alloy composition Tb separately 0.3 Dy 0.7 Fe 1.95 Bi 0.02 Alloy (atomic percentage) and (DyNd) 0.4 Cu 0.6 Alloy (atomic percentage), formulated according to the designed composition. Tb is prepared using directional solidification. 0.3 Dy 0.7 Fe 1.95 Bi 0.02 Alloy rods were wire-cut into 30 mm × 10 mm × 10 mm pieces. (DyNd) was prepared using a vacuum melting furnace. 0.4 Cu 0.6 The alloy ingot is wire-cut into 5mm×5mm×5mm pieces, placed in a quartz tube with a small hole at the bottom, and fixed in the induction coil of the vacuum spinning furnace. The furnace door is then sealed. The furnace cavity is evacuated until the vacuum level reaches 10... -2 At Pa, stop evacuation and purge with Ar gas. Repeat this evacuation and purging process twice, finally purging with high-purity Ar gas as a protective atmosphere. Melt (DyNd) using induction heating with a water-cooled copper coil. 0.4 Cu 0.6 The alloy block is then blown with high-pressure pure Ar gas (DyNd) through a vent pipe above the quartz tube. 0.4 Cu 0.6 The alloy is blown from a small hole at the bottom of a quartz tube onto a high-speed rotating water-cooled copper roller, completing the rapid quenching and spinning process to obtain (DyNd) with a thickness of 20-200 μm. 0.4 Cu 0.6 Alloy strip. Weigh out 3% by mass of (DyNd). 0.4 Cu 0.6 Alloy strips are evenly laid on Tb 0.3 Dy 0.7 Fe 1.95 Bi 0.02 On the alloy ingot. Place it in a vacuum sintering furnace and evacuate to 5×10. - 3 After being padded with argon gas to 0.05 MPa, the material was treated at 980℃ for 3 hours, followed by tempering heat treatment at 580℃ for 3 hours, ultimately yielding a terbium-dysprosium iron magnetostrictive material. Analysis and testing showed that, under a prestress of 10 MPa and a magnetic field strength of 1000 Oe, the magnetostrictive strain of this material was 1297 × 10⁻⁶. -6,like Figure 1 As shown, the low-field magnetostrictive strain is significantly improved compared to powder-bonded composites. The mechanical properties of this material were measured on five specimens, yielding an average flexural strength of 116.1 MPa and a fracture toughness of 2.93 MPa·m. 1 / 2 The tensile strength is 50.3 MPa. As a comparative experiment, TbB alloy strips were evenly laid on Tb... 0.3 Dy 0.7 Fe 1.95 Bi 0.02 On the alloy ingot, after grain boundary strengthening and tempering treatment using the same process, the magnetostrictive strain is 1025 × 10⁻⁶. -6 The flexural strength is 68.3 MPa, and the fracture toughness is 1.9 MPa·m. 1 / 2 The tensile strength is 32.2 MPa. Comparative results show that the Re-N alloy used in this invention can significantly improve the mechanical and processing properties of terbium-dysprosium iron while maintaining its high magnetostrictive properties.

[0039] Example 2:

[0040] Design alloy composition Tb separately 0.3 Dy 0.7 Fe 1.95 Gd 0.05 Sd 0.03 Alloy (atomic percentage) and (DyHo) 0.35 (CuBi) 0.65 Alloy (atomic percentage), formulated according to the designed composition. Tb is prepared using directional solidification. 0.3 Dy 0.7 Fe 1.95 Gd 0.05 Sd 0.03 Alloy rods were wire-cut into 30 mm × 12 mm × 12 mm pieces. These were then prepared using a vacuum melting furnace (DyHo). 0.35 (CuBi) 0.65 The alloy ingot is wire-cut into 5mm×5mm×5mm pieces, placed in a quartz tube with a small hole at the bottom, and fixed in the induction coil of the vacuum spinning furnace. The furnace door is then sealed. The furnace cavity is evacuated until the vacuum level reaches 10... -2 At Pa, stop evacuation and purge with Ar gas. Repeat this evacuation and purging process twice, finally purging with high-purity Ar gas as a protective atmosphere. Melt using induction heating with a water-cooled copper coil (DyHo). 0.35 (CuBi) 0.65 The alloy block is then blown into high-pressure pure Ar gas (liquid, DyHo) through a vent pipe above the quartz tube. 0.35 (CuBi) 0.65The alloy is blown from a small hole at the bottom of a quartz tube onto a high-speed rotating water-cooled copper roller, completing the rapid quenching and spinning process to obtain (DyHo) with a thickness of 20-200 μm. 0.35 (CuBi) 0.65 Alloy strip. (Finally, DyHo) 0.35 (CuBi) 0.65 Alloy strips were mechanically ball-milled to produce powder with a particle size of 20-50 μm. 5% (by mass) of (DyHo) was weighed out... 0.35 (CuBi) 0.65 Alloy powder is mixed with alcohol and evenly spread on Tb 0.3 Dy 0.7 Fe 1.95 Gd 0.05 Sd 0.03 On the alloy ingot. Place it in a vacuum sintering furnace and evacuate to 5×10. -3 After being padded with argon gas to 0.05 MPa, the material was treated at 1010 °C for 5 h, followed by tempering at 520 °C for 4 h, ultimately yielding a terbium-dysprosium iron magnetostrictive material. Analysis and testing showed that, under a prestress of 10 MPa and a magnetic field strength of 1000 Oe, the magnetostrictive strain of this material was 1231 × 10⁻⁶. -6 The room temperature mechanical properties of the material were measured. Five specimens were measured in each group of experiments, yielding an average flexural strength of 123.6 MPa. The load-displacement curve of one specimen is shown below. Figure 2 As shown, the flexural strength is significantly improved compared to that of directionally solidified ternary alloys and powder-bonded composites. Furthermore, its fracture toughness is 3.22 MPa·m. 1 / 2 The tensile strength is 52.7 MPa. As a comparative experiment, DyB alloy powder was mixed with alcohol and uniformly spread on Tb... 0.3 Dy 0.7 Fe 1.95 Gd 0.05 Sd 0.03 On the alloy ingot, after grain boundary strengthening and tempering treatment using the same process, the magnetostrictive strain is 982 × 10⁻⁶. -6 The flexural strength is 69.8 MPa, and the fracture toughness is 1.86 MPa·m. 1 / 2 The tensile strength is 30.1 MPa. Comparative results show that the Re-N alloy used in this invention can significantly improve the mechanical and processing properties of terbium-dysprosium iron while maintaining its high magnetostrictive properties.

[0041] Example 3:

[0042] Design alloy composition Tb separately 0.3 Dy 0.7 Fe 1.95 Gd0.05 Nb 0.08 Sd 0.03 Alloy (atomic percentage), formulated according to the designed composition. Tb is prepared using directional solidification. 0.3 Dy 0.7 Fe 1.95 Gd 0.05 Sd 0.03 The alloy rod was wire-cut into small pieces measuring 30 mm × 15 mm × 15 mm. Tb... 0.3 Dy 0.7 Fe 1.95 Gd 0.05 Nb 0.08 Sd 0.03 After being sanded, polished, cleaned with acetone, and dried, the alloy samples underwent Cu ion implantation in a metal vapor vacuum arc ion implanter at an implantation energy of 160 keV and an implantation dose of 0.8–8.9 × 10⁻⁶ kV. 17 cm -2 The beam current density is 45-52 µm·cm. -2 Tb after ion implantation 0.3 Dy 0.7 Fe 1.95 Gd 0.0 5Nb 0.08 Sd 0.03 The alloy sample was placed in a vacuum sintering furnace and evacuated to a vacuum level of 5 × 10⁻⁶. -3 After being padded with argon gas to 0.05 MPa, the material was treated at 950℃ for 3 hours, followed by tempering at 500℃ for 6 hours, ultimately yielding a terbium-dysprosium iron magnetostrictive material. Analysis and testing showed that, under a prestress of 10 MPa and a magnetic field strength of 1000 Oe, the magnetostrictive strain of this material was 1210 × 10⁻⁶. -6 The room temperature mechanical properties of the material were measured. Five specimens were measured in each group of experiments, yielding an average flexural strength of 105.3 MPa and a fracture toughness of 2.81 MPa·m. 1 / 2 Tensile strength 41.3 MPa.

[0043] The above description is merely a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention should be included within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.

Claims

1. A method for improving the processing properties of terbium-dysprosium-iron magnetostrictive materials, characterized in that, include: Step S1: Cast the terbium-dysprosium-iron alloy and the Re-N alloy into ingots respectively; Step S2: Prepare Re-N alloy into rapidly quenched thin strips or powders; Step S3: Uniformly lay or coat Re-N alloy strips or powders onto terbium-dysprosium-iron alloy ingots, or introduce N elements by ion implantation to obtain an intermediate; Step S4: Perform grain boundary strengthening treatment on the intermediate to obtain a grain boundary strengthened terbium-dysprosium-iron alloy ingot; Step S5: The grain boundary strengthened terbium-dysprosium-iron alloy ingot is subjected to secondary tempering to obtain a gradient interface structure and thus obtain terbium-dysprosium-iron magnetostrictive material. The main component of terbium-dysprosium iron alloys is: Tb x Dy 1-x Fe y M z Where 0.25≤x≤0.50, 1.80≤y≤2.1, 0.01≤z≤0.1; M is selected from at least one of Nd, Ho, Pr, Co, Gd, La, Ce, Y, Mn, Mg, Al, Si, Ni, Ti, Cr, V, Nb, Cu, Ca, Sb, Bi, Zn, Ga, and Sn; Re-N alloy: Re is selected from at least one of Tb, Dy, Nd, Ho, Pr, Gd, La, Ce, and Y; N is selected from at least one of Cu, Bi, Sb, and Ca; In step S4, the grain boundary strengthening treatment temperature is 700–1050℃, the heat treatment time is 1–4 hours, and the vacuum is evacuated to 5 × 10⁻⁶. -3 Argon gas is then introduced after Pa. In step S5, the secondary tempering heat treatment temperature is 350-600℃, the heat treatment time is 1-4 hours, and the vacuum is evacuated to 5×10⁻⁶. - 3 After Pa, argon gas is introduced to a pressure of 0.05 MPa.

2. The method according to claim 1, characterized in that, In step S1, terbium-dysprosium-iron alloys are cast into ingots by vacuum induction melting, vacuum arc melting, or directional solidification; Re-N alloys are cast into ingots by vacuum induction melting.

3. The method according to claim 1, characterized in that, In step S2, the Re-N alloy ingot is made into a thin strip with a thickness of 20-200μm by melt quenching, or the Re-N alloy ingot is made into powder with a particle size of 20-50μm by mechanical ball milling or by argon or nitrogen gas flow milling.

4. The method according to claim 1, characterized in that, In step S3, a 3-10 wt% Re-N alloy strip or powder is laid or coated.

5. The terbium-dysprosium magnetostrictive material prepared by the method according to any one of claims 1-4, characterized in that, The mechanical properties at room temperature are: flexural strength greater than 100 MPa, fracture toughness greater than 2.8 MPa·m. 1 / 2 It has a tensile strength greater than 40 MPa; at the same time, it maintains high magnetostrictive properties, with a magnetostrictive property greater than 1200 × 10⁻⁶ at a prestress of 10 MPa and a magnetic field strength of 1000 Oe. -6 .

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