RU2703319C1 - Magnetically soft nanocrystalline material based on iron - Google Patents

Abstract

FIELD: metallurgy.

SUBSTANCE: invention relates to metallurgy, particularly to amorphous and nanocrystalline magnetically soft iron-based alloys, which are obtained in the form of a thin strip by melt casting on the surface of a cooling body and its high-speed hardening and used mainly for making transformers cores and throttles from the strip. Magnetically soft material based on iron contains, at.%: Fe – 84–85, B – 7–9, P – 3–5, Si – 1–2, Mo – 1–2, Cu – 0.5–1, wherein magnetically soft material has a nanocrystalline structure with grain size of 10–20 nm. Saturation magnetization makes 1.8 Tl and more, and coercive force makes 2–15 A/m.

EFFECT: material is characterized by high saturation magnetization while maintaining low coercive force.

1 cl, 11 dwg, 3 ex

Description

The invention relates to the field of metallurgy, in particular to amorphous and nanocrystalline soft magnetic alloys based on iron, obtained in the form of a thin tape by casting the melt on the surface of the cooling body and its high-speed quenching, and used mainly for the manufacture of transformer cores and chokes from the tape.

Amorphous and nanocrystalline iron-based metallic materials have a high level of physical properties required by soft magnetic materials. Low coercive force, high saturation magnetization, high electrical resistance make these alloys in demand for the electrical industry as energy-efficient materials in the cores of transformers and chokes. Recently, a number of patents have been published that protect compositions and technologies for producing soft magnetic materials based on iron with an amorphous and nanocrystalline structure, with a magnetic saturation induction of about 1.5 T or more.

The patent documents presented below are the closest in composition to the materials being developed and contain more than 70 at. % iron. Patent RU 2434970 C1 (publ. 11/27/2011) protects a high-induction amorphous alloy with low electromagnetic losses obtained by casting in a tape containing, at. %: boron 6.0-9.0, silicon 7.5-10.0, carbon 0.5-1.5, phosphorus 1.0-2.5, nitrogen 0.1-0.5, sulfur 0, 1-0.5, hydrogen 0.01-0.02, oxygen 0.01-0.015, iron - the rest. The combined introduction of oxygen, hydrogen, phosphorus and boron reduces the critical hardening rate and improves the glass-forming ability of the alloy, increases the critical thickness of the tape to 50 microns.

The disadvantage of this material is the relatively low value of saturation induction compared with the proposed material, as well as the presence of a small amount of non-metallic additives - sulfur, nitrogen, oxygen and hydrogen, and the complexity of controlling their content in the alloy.

Patent CN 101800109 B (application publ. 11.08.2010) discloses an amorphous alloy based on iron with high soft magnetic properties of the composition: Fe _(100-xyzw) B _x Si _y C _z P _w , where x is in the range from 4 to 20, y from 3.5 to 5, z from 1.8 to 2.3, w from 0 to 10, the rest is Fe. The document notes the desired ratio of the sum of the components achieved by Fe _79.5 B ₁₂ Si _3.5 C ₂ P ₃ or Fe _79.5 B ₁₃ Si _3.5 C ₂ P ₂ or Fe _79.5 B ₁₁ Si _3.5 C alloys ₂ P ₄ having a magnetic induction of 1.3-1.64 T.

Patent RU 2483135 C1 (publ. 05.27.2013) protects an alloy of the composition Fe _(100-XYZ) B _X P _Y Cu _Z with an amorphous phase as the main phase, where the iron content is from 79 to 86 at. %, boron from 4 to 13 at. %, phosphorus from 1 to 10 at. % and copper from 0.5 to 1.5 at. %, possessing a saturation magnetic induction of 1.6 T and a coercive force of 20 A / m.

The disadvantage of the inventions CN 101800109 B and RU 2483135 C1 is the relatively low values of the induction of saturation and high coercive force compared with the proposed material.

Closest to the proposed invention is the patent RU 2509821 C2 (publ. 20.03.2014) discloses a nanocrystalline alloy based on iron and a method for its preparation. The authors add carbon to the alloy and limit the ratio of copper to phosphorus, resulting in Fe _a B _b Si _c P _x C _y Cu _z , where in at. %: a 79-86, b 5-13, s 0-8, x 1-8, y 0-5, z 0.4-1.4 and z / x 0.08-0.8, and Fe _a B _b Si _c P _x C _y Cu _z , where at at. %: a 81-86, b 6-10, s 2-8, x 2-5, y 0-4, z 0.4-1.4 and z / x 0.08-0.8. The claimed method of heat treatment of a material at which the heating rate is 100 ° C per minute or more to a temperature not lower than the crystallization temperature, allows to obtain a nanocrystalline alloy structure.

The disadvantage of this invention is the relatively low values of the induction of saturation and magnetic permeability, as well as a high coercive force compared with the proposed material.

The technical result of this invention is to obtain a high saturation magnetization value of 1.8 T while maintaining a low coercive force in the range of 2-15 A / m due to the given chemical composition of the soft magnetic material based on iron.

The contents of chemical elements in the alloys indicated in the invention and the heat treatment regimes provide optimal combinations of magnetic properties.

The technical result is achieved as follows: soft magnetic material based on iron, containing boron, phosphorus, silicon, characterized by the combined alloying with molybdenum and copper, in the following ratio of components, at. %:

Fe 84-85;

B - 7-9;

P - 3-5;

Si is 1-2;

Mo is 1-2;

Cu - 0.5-1,

in this case, the soft magnetic material has a nanocrystalline structure with a grain size of 10–20 nm, a saturation magnetization of 1.8 T or more, and a coercive force in the range of 2–15 A / m.

Description of the drawings.

In FIG. 1 - X-ray diffraction pattern of a sample of a metal strip from an alloy of Fe ₈₄ B ₈ P _3,5 Si _1,5 Mo ₂ Cu ₁ ;

In FIG. 2 - Hysteresis loop of the alloy Fe ₈₄ B ₈ P _3,5 Si _1,5 Mo ₂ Cu ₁ ;

In FIG. 3 - Microstructure of an alloy sample Fe ₈₄ B ₈ P _3,5 Si _1,5 Mo ₂ Cu ₁ after heat treatment;

In FIG. 4 - Hysteresis loop of the alloy Fe ₈₄ B ₈ P _3,5 Si _1,5 Mo ₂ Cu ₁ after heat treatment;

In FIG. 5 - Graph of changes in the magnetic permeability of the alloy Fe ₈₄ B ₈ P _3,5 Si _1,5 Mo ₂ Cu ₁ after heat treatment;

In FIG. 6 - X-ray diffraction pattern of a sample of a metal strip of alloy Fe ₈₅ B ₈ P _3,5 Si _1,5 Mo ₁ Cu ₁ ;

In FIG. 7 - X-ray diffraction pattern of a sample of a metal strip of alloy Fe ₈₅ B ₈ P _3,5 Si _1,5 Mo ₁ Cu ₁ after heat treatment;

In FIG. 8 - Hysteresis loop of the alloy Fe ₈₅ B ₈ P _3,5 Si _1,5 Mo ₁ Cu ₁ after heat treatment;

In FIG. 9 - X-ray diffraction pattern of a sample of a metal strip from an alloy of Fe ₈₄ B ₈ P _3.75 Si _1.75 Mo ₂ Cu _0.5 ;

In FIG. 10 - X-ray diffraction pattern of a sample of a metal strip from an alloy of Fe ₈₄ B ₈ P _3.75 Si _1.75 Mo ₂ Cu _0.5 after heat treatment;

In FIG. 11 - Hysteresis loop of the alloy Fe ₈₄ B ₈ P _3.75 Si _1.75 Mo ₂ Cu _0.5 after heat treatment.

The implementation of the invention

The compositions of the alloys for carrying out the invention are described by the following formula (in at.%): Fe _a B _b P _c Si _d Mo _e Cu _f , where a from 84 to 85, b from 7 to 9, c from 3 to 5, d from 1 up to 2, e from 1 to 2, f from 0.5 to 1. In this material, based on the studies, it was found that the element - iron, Fe, is the main element providing the ferromagnetic properties of the material, its content is 84-85 at. % is due to obtaining a high saturation induction value of the proposed material, non-metal elements — boron B, phosphorus P, silicon Si — in the indicated amounts provide high amorphizability of alloys to obtain materials with the initial amorphous structure — a matrix in which, due to the presence of alloying elements — copper Cu from 0 , 5 to 1 at. %, and molybdenum Mo from 1 to 2 at. %, in the process of heat treatment nanocrystals with a size of 10-20 nm will be formed.

To solve this problem, the following technology is proposed: pure (99.9% purity) metals and metal alloys Fe - 3 wt. % B and Fe - 8.8 wt. % P is fused in a vacuum electric arc furnace on a copper water-cooled hearth. The elements of boron B and phosphorus P are introduced in the form of ligatures to ensure their complete inclusion in the alloy, by minimizing their evaporation compared to using them as pure powders or lump material. Melting is carried out in an argon atmosphere, all charge materials are subsequently remelted, turning the resulting ingots and re-melting (thus, after four remelts, the ingots are uniform in chemical composition). Smelted ingots go to remelting in order to obtain samples in the form of a metal tape. The ingots obtained in an electric arc furnace are remelted in a spinning machine with an induction heater. A portion is placed in a quartz ampoule with an opening of less than 1 mm at the end. After melting, argon is fed into the quartz ampoule and the melt is injected onto a copper disk rotating at a speed of 40 m / s. Based on the studies, it was found that the heat treatment of the material when heated in vacuum at a pressure of 10 ^-3 Pa, to prevent oxidation of the material, at a speed of 60-100 ° / min in the range (530-560) ° C, exposure for 5-10 minutes and cooling at a speed of 60-100 ° / min, provides the formation of a nanocrystalline structure with grains of a solid solution based on iron. A study of the structure of the obtained and heat-treated materials is carried out using x-ray diffraction analysis, as well as by transmission electron microscopy. The magnetic properties of the alloys, saturation magnetization Ms are estimated on a vibration magnetometer in a maximum magnetic field of 800 kA / m, coercive force Hc on a permeameter on toroidal samples in constant current mode and a maximum magnetizing field of 800 A / m, magnetic permeability in a solenoid field of intensity 5 A / m in the frequency range from 1 kHz to 10 MHz.

Example 1

Alloy No. 1 was obtained as follows:

Alloy composition (at.%):

- Fe 84;

- AT 8;

- P 3.5;

- Si 1.5;

- Mo 2;

- Cu 1.

For the preparation of the alloy used charge materials of pure metals (99.99 wt% purity). The charge materials were melted in an argon atmosphere in an arc furnace at a voltage of 200 V. All charge materials were subsequently remelted, the ingots obtained were inverted and re-melted, and after four re-melts the ingots were homogeneous in chemical composition.

Samples of metal tapes were obtained as a result of rapid cooling on a rotating copper disk. The ingots obtained in an electric arc furnace were remelted in a spinning machine with an induction heater. A portion was placed in a quartz ampoule with an opening of less than 1 mm at the end. After this, the ampoule was fixed in the holder. After reaching a high vacuum, melting is carried out, after melting, argon is fed into the quartz ampoule and the melt is injected onto a rotating copper disk at a speed of 40 m / s. Heat treatment of samples of this material was carried out in an inert atmosphere (in vacuum at a pressure of 10 ^-3 Pa), heating was carried out at a speed of 60 ° / min to 530 ° C, with exposure for 5 minutes and subsequent cooling at a speed of 100 ° / min.

The study of the initial structure of the obtained metal tapes was carried out using x-ray diffraction analysis (Fig. 1). Evaluation of the magnetic properties of the alloys: saturation magnetization Ms of the obtained tapes was carried out on a vibration magnetometer in a maximum magnetic field of 800 kA / m (Fig. 2); The coercive force Hc of the obtained tapes was carried out on a permeameter on toroidal samples in a constant current mode and with a maximum magnetizing field of 800 A / m. Also, transmission electron microscopy performed an analysis of the structure of the samples after heat treatment (Fig. 3), the alloy under consideration has a nanocrystalline structure with a grain size of 10 nm, due to which low coercive forces of 2.5 A / m and a high saturation magnetization of 1.76 T are achieved. (Fig. 4) and magnetic permeability 11600 (Fig. 5).

Example 2

Alloy No. 2 was obtained as follows:

Alloy composition (at.%):

- Fe 85;

- AT 8;

- P 3.5;

- Si 1.5;

- Mo 1;

- Cu 1.

For the preparation of the alloy used charge materials of pure metals (99.99 wt% purity). The charge materials were melted in an argon atmosphere in an arc furnace at a voltage of 200 V. All charge materials were subsequently remelted, the ingots obtained were inverted and re-melted (thus, after four re-melts, the ingots were homogeneous in chemical composition).

Samples of metal tapes were obtained as a result of rapid cooling on a rotating copper disk. The ingots obtained in an electric arc furnace were remelted in a spinning machine with an induction heater. A portion was placed in a quartz ampoule with an opening of less than 1 mm at the end. After this, the ampoule was fixed in the holder. After reaching a high vacuum, melting is carried out, after melting, argon is fed into the quartz ampoule and the melt is injected onto a rotating copper disk at a speed of 40 m / s.

The study of the initial structure of the obtained metal tapes was carried out using x-ray diffraction analysis showed that the alloy has an amorphous structure (Fig. 6). Evaluation of the magnetic properties of the alloys: saturation magnetization Ms of the obtained tapes was carried out on a vibration magnetometer in a maximum magnetic field of 800 kA / m; The coercive force Hc of the obtained tapes was carried out on a permeameter on toroidal samples in a constant current mode and with a maximum magnetizing field of 800 A / m. Heat treatment of samples of this material was carried out in an inert atmosphere, in vacuum under a pressure of 10 ^-3 Pa, heating was carried out at a speed of 60 ° / min to 530 ° C, with holding for 5 minutes and subsequent cooling at a speed of 100 ° / min. An analysis of the structure of the samples after heat treatment was performed using X-ray diffractometry (Fig. 7), the alloy in question has a nanocrystalline structure with a grain size of 20 nm, the alloy has a coercive force of 13 A / m and a saturation magnetization of 1.80 T (Fig. 8).

Example 3

Alloy No. 3 was obtained as follows:

Alloy composition (at.%):

- Fe 84;

- AT 8;

- P 3.75;

- Si 1.75;

- Mo 2;

- Cu 1.

For the preparation of the alloy used charge materials of pure metals (99.99 wt% purity). The charge materials were melted in an argon atmosphere in an arc furnace at a voltage of 200 V. All charge materials were subsequently remelted, the ingots obtained were inverted and re-melted (thus, after four re-melts, the ingots were homogeneous in chemical composition).

Samples of metal tapes were obtained as a result of rapid cooling on a rotating copper disk. The ingots obtained in an electric arc furnace were remelted in a spinning machine with an induction heater. A portion was placed in a quartz ampoule with an opening of less than 1 mm at the end. After this, the ampoule was fixed in the holder. After reaching a high vacuum, melting is carried out, after melting, argon is fed into the quartz ampoule and the melt is injected onto a rotating copper disk at a speed of 40 m / s.

The study of the initial structure of the obtained metal tapes was carried out using x-ray diffraction analysis (Fig. 9). Evaluation of the magnetic properties of the alloys: saturation magnetization Ms of the obtained tapes was carried out on a vibration magnetometer in a maximum magnetic field of 800 kA / m; The coercive force Hc of the obtained tapes was carried out on a permeameter on toroidal samples in a constant current mode and with a maximum magnetizing field of 800 A / m. Heat treatment of samples of this material was carried out in an inert atmosphere (in vacuum at a pressure of 10 ^-3 Pa), heating was carried out at a speed of 60 ° / min to 560 ° C, with exposure for 5 minutes and subsequent cooling at a speed of 100 ° / min. An analysis of the structure of the samples after heat treatment was carried out by X-ray diffractometry (Fig. 10), the alloy in question has a nanocrystalline structure with a grain size of 13 nm, the alloy has a coercive force of 13 A / m or less and a saturation magnetization of 1.80 T (Fig. 11).

Claims (3)

Soft magnetic material based on iron, containing boron, phosphorus, silicon, molybdenum and copper, in the following ratio of components, at. %: Fe 84-85 AT 7-9 R 3-5 Si 1-2 Mo 1-2 Cu 0.5-1, Moreover, it has a nanocrystalline structure with a grain size of 10–20 nm, a saturation magnetization of 1.8 T or more, and a coercive force in the range of 2–15 A / m.

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