CN109023005B - A new type of soft magnetic high-entropy alloy resistant to high temperature of 600℃ - Google Patents

Abstract

A kind of soft magnetism high-entropy alloy of novel resistance to 600 DEG C of high temperature, belongs to new material technology field, including Fe, Co, Ni, Cr and Al element, the atomic percent of alloying component is expressed as Al_xNi_yCo_zFe_mCr_n, wherein x=10~25%, y+z=35~55%, m+n=25~45%, x+y+z+m+n=100%；And y=0~5%, 0.5≤m/n≤5.Material performance index are as follows: room temperature saturation magnetization M_S=90~150emu/g, coercivity H_C=1~15Oe；Saturation magnetization M at 600 DEG C_S=70~130emu/g, coercivity H_C=2~25Oe.The present invention realizes the tissue modulation that ferromagnetism BCC nanoparticle coherence in B2 matrix is precipitated by ingredient design, is a kind of soft magnetism high-entropy alloy of novel resistance to 600 DEG C of high temperature to utmostly improve the soft magnet performance of alloy, and preparation process is simple.

Description

A new type of soft magnetic high-entropy alloy resistant to high temperature of 600℃

technical field

The invention belongs to the technical field of new materials, and relates to a novel soft magnetic high-entropy alloy resistant to 600°C high temperature, in particular to a novel multi-principal B2-based soft magnetic high-entropy alloy with coherent precipitation of BCC nanoparticles and resistant to 600°C high temperature alloy.

Background technique

Due to its high saturation magnetization and low coercive force, soft magnetic materials can greatly improve the conversion efficiency of electromagnetic fields and reduce the loss of electric energy in long-distance transmission. They are important basic materials in the national economy. Soft magnetic materials not only meet the development needs of traditional industries, but also play an important role in emerging technologies and electronic information technologies that use electric drive devices and electronic control devices. With the development of materials, metal-based soft magnetic materials, soft ferrite materials, amorphous and nanocrystalline soft magnetic materials, and soft magnetic composite materials have come out one after another. The traditional soft magnetic alloy design method is to use one or two elements as the main components, and adjust the microstructure and structure of the alloy by adding other trace alloying elements, and finally adopt rolling and heat treatment technology to further improve the soft magnetic properties, which has the advantages of preparation Disadvantages such as complex process, high cost, and poor high-temperature soft magnetic properties.

High-entropy alloys, or multi-principal alloys, are characterized by the simultaneous presence of multiple principal constituent elements. A high-entropy alloy originally refers to an alloy composed of five or more elements mixed in an equimolar or nearly equimolar ratio, and the content of each element is between 5% and 35%. With the continuous development of high-entropy alloys, the number of main components can be reduced to quaternary, and the mixing ratio can also be relaxed to a non-equimolar ratio. The high entropy effect brought about by this multi-principal mixing makes alloys easier to form simple structures, such as body-centered cubic (BCC), face-centered cubic (FCC), hexagonal close-packed (HCP) solid solutions and their ordered superstructures (B2 -NiAl and L1 ₂ -Ni ₃ Al, etc.), is a new type of alloy with complex composition, which is expected to develop into a new high-performance engineering/functional alloy material suitable for extreme environments, and provides a new composition platform for alloy structure design . In the conventional high-entropy alloy AlxNiCoFeCr series, with the increase of Al content x, the alloy gradually transforms from a single-phase FCC to a dual-phase (FCC+BCC/B2), and finally a single-phase BCC/B2 structure; among them, the FCC phase is rich in Fe and Co elements are collected, Fe, Co and Cr elements are enriched in the BCC phase, and Al, Ni and Co elements are enriched in the B2 phase. According to the magnetic classification of elements, Fe, Co and Ni are ferromagnetic elements, Cr is an antiferromagnetic element, and Al is a paramagnetic element. From the magnetic point of view of the phase structure, the FCC phase itself is very weakly magnetic; the BCC phase usually exhibits ferromagnetism. According to FINEMET soft magnetic alloy (Fe _73.5 Si _13.5 B ₉ Nb ₃ Cu ₁ , at.%), only when the nano-scale ferromagnetic BCC particles are uniformly distributed on the substrate, the alloy exhibits excellent soft magnetic properties; and BCC The smaller the size of the nanoparticles, the lower the coercive force of the alloy. In fact, in most cases, when BCC coexists with the ordered B2 phase, a woven network-like AM decomposition structure is usually formed, which reduces the soft magnetic properties of the alloy (low saturation magnetization and high coercive force). The formation of the AM decomposition structure is caused by the large composition difference between the BCC and B2 phases, which makes the lattice constant mismatch between the two phases large. In a simple alloy system, it is difficult to adjust the lattice mismatch of BCC and B2 phase, but in a multi-component high-entropy system, it is expected to obtain a suitable BCC and B2 phase by changing the molar ratio between multiple principal components. Lattice mismatch, so that the woven network-like amplitude modulation decomposition structure is transformed into a coherent structure in which BCC nanoparticles are precipitated on the B2 matrix. So far, no B2-based soft magnetic high-entropy alloys with coherent precipitation of BCC nanoparticles have been reported.

Contents of the invention

The purpose of the present invention is to provide a new type of BCC nanoparticle coherent precipitation and high temperature resistance of 600 ° C for the microstructure morphology that is difficult to obtain in the B2-based alloy system with coherent precipitation of body-centered cubic ferromagnetic BCC nanoparticles. Multi-principal component B2-based soft magnetic high-entropy alloys.

In order to achieve the above object, the technical scheme adopted in the present invention is:

A new type of soft magnetic high-entropy alloy resistant to 600°C high temperature, said new soft magnetic high-entropy alloy resistant to 600°C high temperature includes Fe, Co, Ni, Cr, and Al elements, and the atomic percentage of its alloy composition is expressed as Al _x Ni _y Co _z Fe _m Cr _n , where x=10-25%, y+z=35-55%, m+n=25-45%, x+y+z+m+n=100%.

In addition, the following groups (a) and (b) need to be satisfied, then the corresponding elements contained can more easily obtain a new type of soft magnetic high-entropy alloy resistant to high temperatures of 600°C, and the present invention is more preferred.

(a) Ni element atomic percentage is y=0～5%;

(b) The atomic percent ratio of the Fe element to the Cr element is 0.5≤m/n≤5.

In addition, the new 600°C high-temperature-resistant soft magnetic high-entropy alloy has a special coherent structure morphology: ferromagnetic BCC nanoparticles are coherently precipitated on the ordered B2 phase matrix, thereby maximizing the soft magnetic properties of the alloy .

The idea of realizing the above-mentioned technical scheme is: firstly divide the transition metal TMs (Ni, Co, Fe, Cr) into two categories: B2 stable elements (Ni, Co) and BCC stable elements (Fe, Cr); then use the applicant's " Al-Ni-Co-Fe-Cr high-entropy alloy composition was designed using the "cluster + connected atom" structure model. The "cluster + connecting atom" model divides the solid solution structure into two parts: "cluster" and "connecting atom". The "cluster" is the nearest neighbor coordination polyhedron formed with an atom as the center, and the "connecting atom" is Atoms placed in the interstitial positions of the cluster stacking, usually in the next nearest neighbor shell of the cluster. For example, in the BCC structure, the cluster is a rhombic dodecahedron with a coordination number of 14, consisting of 8 atoms in the nearest neighbor shell and 6 atoms in the second nearest neighbor shell. In this way, a simple cluster composition formula [cluster] (connecting atoms) _X can be determined, that is, a cluster matches several X connecting atoms. In the Al-Ni-Co-Fe-Cr five-element high-entropy alloy system involved in this application, since Al and the transition metal element TMs all have strong interaction, and the interaction between the transition metal element TMs is relatively low. Weak, so all TMs elements can be averaged into a virtual element M, that is, "average atom M". Thus the Al-Ni-Co-Fe-Cr multi-element alloy system can be simplified into an Al-M pseudo-binary system, where Al is the solute atom and M is the solvent matrix atom. When the alloy is designed by the cluster composition method, the solute elements that have a strong interaction with the solvent M preferentially occupy the central position of the cluster, and the connecting atoms usually have a weak interaction with the solute, that is, [Al-M ₁₄ ] cluster; it should be pointed out that when the Al content is too high, Al will also occupy the position of the connecting atoms, thus forming a [Al-M ₁₄ ](Al,M) _X cluster formula, where X is the number of connecting atoms. In the above composition formula, the average atom M is a combination of multiple transition metal elements TMs mixed in different proportions, so the content of transition metal elements TMs can be adjusted to change M, and the content of Al elements is adjusted by the change in the number of connected atoms X , so as to form the final multi-element alloy composition atomic percentage (at.%) expression, Al _x Ni _y Co _z Fe _m Cr _n . According to the given composition formula of this cluster structure unit, it reveals the relationship between the composition, structure and performance of industrial alloys, and provides a new way of thinking for the implementation of alloy composition design and optimization.

Using the cluster composition method to design multi-principal high-entropy alloys has greatly improved the efficiency of developing high-performance alloys, but the coherent precipitation of BCC nanoparticles on the B2 matrix requires two other constraints. For the B2 phase, the Ni and Co elements involved in this application are easy to form the B2 phase with the Al element, and the elements Fe, Co and Cr are the main forming elements of the BCC phase. Among them, the interaction between Ni and Al is stronger. When the content of Ni is too much, Ni and Al will preferentially form the B2 phase, which will cause the Co element to diffuse into the BCC phase and make BCC a matrix. Therefore, in order to ensure that B2 is the matrix phase in this application, the content of Ni element needs to be strictly controlled, so that Co and Al preferentially form the B2 phase. At the same time, in order to ensure that the alloy of the present application has more excellent soft magnetic properties, it is necessary to ensure the content of ferromagnetic elements in the BCC nano-precipitated particles, that is, to ensure the content of Fe element. Therefore, the application further defines the atomic percentage content y, m and n of Ni, Fe and Cr elements, forming the following two conditions, as, (a) Ni element atomic percentage y=0～5%; (b) Fe element The ratio to the atomic percentage of the Cr element is 0.5≤m/n≤5.

The preparation method of the present invention is as follows: high-purity component raw materials are used for batching according to mass percentage; 15g of the prepared mixture is placed in the water-cooled copper crucible of the electric arc melting furnace, and then the non-consumable electric The arc melting method is used for smelting, and attention should be paid to repeated smelting at least 5 times to ensure that the alloy ingot with uniform composition is obtained; then the evenly smelted alloy ingot is melted, and the melt is sucked into the cylindrical copper mold cavity by the copper mold suction casting process, and the diameter is obtained. It is a rod-shaped sample of 6mm.

Use metallographic microscope (OM), scanning electron microscope (SEM), transmission electron microscope (TEM) and X-ray diffractometer (XRD, Cu K _α radiation, λ=0.15406nm) to detect alloy structure and structure; The room temperature and high temperature hysteresis loops are tested by VSM. Therefore, it is determined that the present invention is the above-mentioned novel soft magnetic high-entropy alloy resistant to high temperatures of 600°C. The atomic percentage of the alloy composition is expressed as Al _x Ni _y Co _z Fe _m Cr _n , where x=10~25%, y+z=35~55%, m+n=25~45%, x+y+z +m+n=100%. The performance index of the above-mentioned high-temperature-resistant soft magnetic high-entropy alloy material involved is: room temperature saturation magnetization M _S =90-150emu/g, coercive force H _C =1-15Oe; saturation magnetization M _S at 600°C =70~130emu/g, coercive force H _C =2~25Oe.

Compared with the prior art, the present invention has the advantages that: the present invention is a new type of soft magnetic high-entropy alloy designed and developed based on the cluster composition formula method developed by the applicant itself. By changing the Al content Adjust the lattice mismatch of the BCC/B2 phase with the ratio of transition metal TMs, so as to realize the regulation of the structure of BCC nanoparticles precipitated on the B2 matrix, and establish a composition control criterion, which shields the current "fried dishes" cumbersome experience Compound alloy design method; effectively improve the soft magnetic properties of B2-based high-entropy alloys, because BCC and B2 phases maintain a good coherent relationship at room temperature and high temperature, and have suitable lattice mismatches, resulting in Fe/Co-rich The BCC nanoparticles of ferromagnetic elements are precipitated on the B2 matrix, which makes the alloy have excellent soft magnetic properties at room temperature and high temperature, maximizes the saturation magnetization of the alloy, and reduces the coercive force, thereby alloying with multi-principal elements The B2-based soft magnetic high-entropy alloy was developed in the model; since the ferromagnetic BCC nanoparticles are coherently precipitated on the B2 matrix, the BCC nanoparticles are not easy to grow, so this coherent structure has excellent high-temperature structural stability, so that the alloy It can still maintain good soft magnetic properties in a high-temperature environment of 600 ° C, thereby obtaining a new type of soft magnetic high-entropy alloy resistant to 600 ° C high temperature. The typical performance indicators of its materials are: series alloys at room temperature saturation magnetization M _S =90~150emu/g, coercivity H _C =1~15Oe; saturation magnetization M _S =70~130emu/g at 600°C, coercivity Hc = 2 to _25Oe .

The effects and benefits of the present invention are: ①Through the design of the alloy, the addition content ratio of the constituent elements of the alloy is reasonable, thereby realizing a new type of soft magnetic high-entropy alloy resistant to 600°C high temperature; ②The preparation process of the alloy is simple, using Vacuum arc melting is enough; ③The microstructure with ferromagnetic BCC nanoparticles coherently precipitated on the B2 matrix makes the high-entropy alloy exhibit excellent soft magnetic properties.

Description of drawings

Fig. 1 is the TEM micrograph of the Al _17.65 Co _47.06 Fe _17.65 Cr _17.65 (at.%) alloy prepared in Example 1, dark BCC nanoparticles (diameter d ~ 10nm) coherently precipitated on the bright color B2 substrate;

Fig. 2 is the hysteresis loop diagram of the Al _17.65 Co _47.06 Fe _17.65 Cr _17.65 (at.%) alloy prepared in Example 1, in which the abscissa is the applied magnetic field, and the ordinate is the magnetization;

Fig. 3 is a coercivity diagram of the Al _17.65 Co _47.06 Fe _17.65 Cr _17.65 (at.%) alloy prepared in Example 1, in which the abscissa in the figure is the applied magnetic field, and the ordinate is the magnetization.

Detailed ways

The specific implementation manners of the present invention will be described in detail below in conjunction with the technical solutions.

Example 1: Al _17.65 Co _47.06 Fe _17.65 Cr _17.65 (at.%) alloy

Step 1: Alloy Preparation

A new type of soft magnetic high-entropy alloy Al _17.65 Co _47.06 Fe _17.65 Cr _17.65 (at.%) resistant to high temperature of 600°C. High-purity component raw materials are used, and the elements are dosed according to mass percentage, which is Al _9.24 Co _53.82 Fe _20.18 Cr _17.81 (wt.%). Put 15g of the prepared mixture into the water-cooled copper crucible of the arc melting furnace, and then use the non-consumable arc melting method to melt in the argon protective atmosphere, pay attention to repeated melting at least 5 times to ensure that the alloy ingot with uniform composition is obtained ; Melt the evenly smelted alloy ingot, and use the copper mold suction casting process to suck the melt into the cylindrical copper mold cavity to obtain a rod-shaped sample with a diameter of 6mm.

Step 2: Alloy structure and magnetic properties test

Utilize OM, SEM, TEM and XRD to detect the alloy microstructure and structure after the stabilization treatment, the results show that the alloy of the present invention has a specific nano-precipitation structure: BCC nanoparticles are coherently precipitated in the ordered phase B2 matrix, see accompanying drawing 1; Using a vibrating sample magnetometer (VSM) to test the hysteresis loop, the room temperature saturation magnetization M _S =110emu/g, the coercive force H _C =4Oe; the 600°C saturation magnetization M _S =102emu/g, the coercive force H _C = 7Oe.

At the same time, the chemical composition of a new 600°C high-temperature-resistant soft magnetic high-entropy alloy No. 1-21 shown in Table 1 below is the same as the source of this composition.

Example 2: Al _18.75 Ni _1.75 Co _43.50 Fe _24.00 Cr _12.00 (at.%) alloy

Step 1: Alloy Preparation

The invention relates to a novel soft magnetic high-entropy alloy Al _18.75 Ni _1.75 Co _43.50 Fe _24.00 Cr _12.00 (at.%) alloy resistant to a high temperature of 600°C. The high-entropy alloy uses high-purity component raw materials, and the elements are dosed according to mass percentage, Al _9.96 Ni _2.02 Co _50.50 Fe _26.40 Cr _12.29 (wt.%). Put 15g of the prepared mixture into the water-cooled copper crucible of the arc melting furnace, and then use the non-consumable arc melting method to melt in the argon protective atmosphere, pay attention to repeated melting at least 5 times to ensure that the alloy ingot with uniform composition is obtained ; Melt the evenly smelted alloy ingot, and use the copper mold suction casting process to suck the melt into the cylindrical copper mold cavity to obtain a rod-shaped sample with a diameter of 6mm.

Step 2: Alloy structure and magnetic properties test

Utilize OM, SEM, TEM and XRD to detect the alloy microstructure and structure after the stabilization treatment, and the results show that the alloy of the present invention has a specific nano-precipitation structure: BCC nanoparticles are coherently precipitated in the ordered phase B2 matrix; The hysteresis loop was tested by VSM, the saturation magnetization M _S =118emu/g at room temperature, the coercive force H _C =3Oe; the saturation magnetization M _S =112emu/g at 600°C, and the coercive force H _C =6Oe.

At the same time, the chemical components of the new 600°C high-temperature-resistant soft magnetic high-entropy alloys No. 1-21 shown in Table 1 below are all from the same source. As described above, the invention can be preferably carried out.

In addition, the chemical composition in the following Table 1 belongs to a new type of soft magnetic high-entropy alloy resistant to high temperature of 600°C. However, the composition of a new soft magnetic high-entropy alloy designed by this patent is not limited to this list. Among them, "-" indicates that the element is not added.

Table 1

The above-mentioned embodiment only expresses the implementation mode of the present invention, but can not therefore be interpreted as the limitation of the scope of the patent of the present invention, it should be pointed out that, for those skilled in the art, under the premise of not departing from the concept of the present invention, Several modifications and improvements can also be made, all of which belong to the protection scope of the present invention.

Claims (2)

1. A novel soft magnetic high-entropy alloy resistant to 600°C high temperature is characterized in that: the novel soft magnetic high-entropy alloy resistant to 600°C high temperature includes Fe, Co, Ni, Cr, and Al elements, and its alloy composition The atomic percentage of is expressed as Al _x Ni _y Co _z Fe _m Cr _n , among them, x=10～25%, y+z=35～55%, m+n=25～45%, x+y+z+m +n=100%; The new 600°C high-temperature-resistant soft magnetic high-entropy alloy also contains the following groups (a) and (b): (a) Ni element atomic percentage is y=0～5%; (b) The atomic percentage ratio of Fe element to Cr element is 0.5≤m/n≤5; The new 600°C high-temperature-resistant soft magnetic high-entropy alloy has a coherent structure: ferromagnetic BCC nanoparticles are coherently precipitated on the ordered phase B2 phase matrix. 2. A new 600°C high-temperature-resistant soft magnetic high-entropy alloy according to claim 1, characterized in that, the typical performance index of the soft magnetic high-entropy alloy is: the saturation magnetization M S of the series alloys at room temperature M _S =90 ~150emu/g, coercivity H _C =1~15Oe; at 600°C, saturation magnetization M _S =70~130emu/g, coercive force H _C =2~25Oe.