IRON-BASED AMORPHOUS/NANOCRYSTALLINE ALLOY AND PREPARATION METHOD THEREFOR

Abstract

 The present invention provides an iron-based amorphous/nanocrystalline alloy as shown in formula Fe_{(100-a-b-c-d-e)}B_aSi_bP_cC_dCu_e, wherein d+(b/c)=0.85-1.3, and a viscosity coefficient η is (3.0-8.0)* 10^-3Pa/s. The present application further provides a preparation method for the iron-based amorphous/nanocrystalline alloy. According to the present application, the dynamic viscosity coefficient η is regulated by means of a change in the content of the elements in the alloy, such that the control range of viscosity of molten steel is ensured, the molten steel has higher purity, and the continuity of casting and the surface quality of a strip are guaranteed.

Description

[0001] This application claims the priority of Chinese Patent Application No. 202111583663.7, filed with the China National Intellectual Property Administration on December 22, 2021, and titled with "IRON-BASED AMORPHOU-NANOCRYSTALLINE ALLOY AND PREPARATION METHOD THEREFOR", which are hereby incorporated by reference in entirety.

FIELD

[0002] The present invention relates to the technical field of magnetic materials, and specifically relates to an iron-based amorphou-nanocrystalline alloy and a preparation method thereof.

BACKGROUND

[0003] At present, soft magnetic materials used as magnetic core, electric current transducer, magnetic sensor and pulse power magnetic component of transformer, motor or generator include silicon steel, ferrite, amorphous alloy and nanocrystalline alloy. Among them, silicon steel is cheap, has high magnetic flux density and strong machinability, however, the loss becomes larger at a high frequency, so it is difficult to make the silicon steel sheet thinner in the thickness. Ferrite has low saturation magnetic flux density, so the use of ferrite is limited under the condition of high power and high saturation magnetic induction. Co-based amorphous alloy is not only expensive, but also has low saturation magnetic flux density, therefore, when used in a high-power device, the components will be enlarged, and its thermodynamics is unstable, and the loss increases during use.

[0004] Iron-based amorphous alloy has advantages both in saturation magnetic flux density and loss at high power, and it is the most ideal magnetic material, and thus the development of amorphous ferromagnetic alloys with high saturation magnetic induction intensity is urgent. At present, the main way to prepare this material is to increase the content of Fe in iron-based amorphous. However, with the increase of Fe content, the thermal stability of the alloy decreases. In order to alleviate this problem, Sn, S, C, P and other elements are added. In U.S. patent No.6416.879, the saturation magnetic induction intensity is increased by adding P to the amorphous Fe-Si-B-C-P system to increase the Fe content. However, the patent also discloses that the long-term thermal stability is reduced due to the addition of P element, so the amorphous alloy in the above patent has not been manufactured by casting from their molten state. An amorphous alloy strip with high saturation magnetic induction intensity is provided in Japanese patent disclosure No.2009052064, which shows high thermal stability by adding Cr and Mn to control the height of the C deposition layer. U.S. Patent No.7425239 mentions that Fe-Si-B-C is selected at a certain level of Si: C ratio, thus achieving magnetic properties in addition to high ductility. However, the strip prepared by the above patents shows many defects on the surface, such as divisural line, slag line, scratch, inclusion and so on (as shown in Figures 1 and 2).

SUMMARY

[0005] The technical problem solved by the present invention is to provide an iron-based amorphou-nanocrystalline alloy. The iron-based amorphou-nanocrystalline alloy provided by the present application has high purity of molten steel, which can effectively improve the defects on the surface of the strip, effectively improve the lamination factor, and can obtain a product with excellent performance.

[0006] In view of this, the present application provides an iron-based amorphou-nanocrystalline alloy as shown in formula (I),

        Fe_{(100-a-b-c-d-e)}B_aSi_bP_cC_dCu_e     (I);

wherein, a, b, c, d and e respectively represent atomic percent content of the corresponding components, 1<a<12, 0.2≤b≤6, 2≤c≤6, 0.5≤ d≤4, 0.6≤e≤2, a+b+c+d+e=100; and d+ (b/c)=0.85-1.3.

[0007] Preferably, 5≤a≤12, 0.8≤b≤6, 2≤c≤5, 0.5≤d≤3, and 0.6≤e≤1.3.

[0008] Preferably, 8≤a≤12, 0.8≤b≤1.5, 3≤c≤5, 0.7≤d≤1.2, and 0.6≤e≤1.3.

[0009] Preferably, the atomic percent content of Fe ≥83.

[0010] Preferably, the impurity elements in the iron-based amorphou-nanocrystalline alloy are Al≤50ppm, Mn≤100ppm and Ti≤80ppm.

[0011] Preferably, the iron-based amorphou-nanocrystalline alloy has a viscosity coefficient η of (3.0-8.0)* 10^-3 Pals.

[0012] Preferably, d+ (b/c) =0.86-1.2, viscosity coefficient η is (4.1-6.9)* 10^-3 Pals.

[0013] Preferably, the iron-based amorphou-nanocrystalline alloy has an N < 100 and M < 200; wherein N is the frequency of slag line occurrence, iron-based amorphou-nanocrystalline alloy strip has a width of is 80-122 mm, and the frequency of slag line occurrence within one continuous meter is N=m*L, m is the number of slag lines, and L is the length of the slag lines in mm; and M is the frequency of impurity in a unit area of 3 mm*3 mm, wherein M=n*h, wherein n is the number of impurity, and h is the height of impurity in µm.

[0014] The present application also provides a method of preparing the iron-based amorphou-nanocrystalline alloy, which comprises steps of:
providing raw materials according to composition ratio, melting and calming each raw material, and then performing single-roller rapid quenching.

[0015] Preferably, the calming is performed for a time of 30-50 min.

[0016] The present application provides an iron-based amorphou-nanocrystalline alloy as shown in the formula Fe_{(100-a-b-c-d-e)}B_aSi_bP_cC_dCu_e, wherein, d+ (b/c)=0.85-1.3. The present application ensures the control range of molten steel viscosity through the change of the content of the above alloying elements, so that the molten steel has a high purity, and thus ensures the continuity of the casting and the surface quality of strip.

BRIEF DESCRIPTION OF DRAWINGS

[0017] 

Fig. 1 is a picture of slag line defects of iron-based amorphou-nanocrystalline alloy prepared in the prior art;

Fig. 2 is a picture of inclusion defects of iron-based amorphou-nanocrystalline alloy prepared in the prior art;

Fig. 3 is a graph showing the influence of elements in 1873K molten steel on the viscosity of liquid iron;

Fig. 4 is a photo of protrusion as surface defect and a dimensioning schematic diagram;

Fig. 5 is a process flow diagram of iron-based amorphou-nanocrystalline alloy prepared in the present application.

DETAILED DESCRIPTION

[0018] In order to further understand the present disclosure, the preferred embodiments of the present invention will be described below in conjunction with examples. However, it should be understood that these descriptions are only for further illustrating the features and advantages of the present disclosure, rather than limiting the claims of the present disclosure.

[0019] Based on the above, the present invention mainly provides illustration on that molten steel containing P system is difficult to be manufactured by casting. Researches proved that the reason why the iron-based amorphous alloy containing P is difficult to cast is the increase of P content. In order to ensure the high saturation magnetic induction, the content of high melting point oxide element Si in molten steel decreases, so the content of low melting point oxide in molten steel increases, which is difficult to be separated from the molten steel, resulting in the oxide being discharged with molten steel in the form of slag during casting, so it is difficult to cast.

[0020] In view of this, the present invention aims to improve the problem of strip surface defects caused by the poor thermal stability of the composition containing P, and the verified control means is to control the parameter η (i.e the dynamic viscosity of molten steel), so as to regulate the fluidity of molten steel, slag viscosity, etc., to obtain a liquid with very high purity of molten steel, thereby inhibiting the probability of strip surface defects from the source. Through the η control, it can ensure the extension of the casting time. The generation of the defect occurs at the beginning of the casting, and can continue with the extension of time, when the defect is sufficiently enlarged, cracks will be generated at the position of the defect, the process of crack initiation - growth - fracture leads to the stop of casting, which can also reduce the probability of the generation of defects in the first 30 minutes of casting by 70% and delay the time of defect generation to 1 h later, so as to effectively improve the pass rate of strip.

[0021] In sum, through two improvements, the strip with high saturation magnetic induction intensity can be obtained by casting, and the defects on the surface of the strip can be effectively improved to obtain excellent amorphous strip, thus effectively improve the lamination factor and obtain products with better performance in the manufacturing process of iron cores, transformers and other products in the application stage.

[0022] In view of this, the present application provides an iron-based amorphou-nanocrystalline alloy as shown in formula (I),

        Fe_{(100-a-b-c-d-e)}B_aSi_bP_cC_dCu_e     (I);

wherein, a, b, c, d and e respectively represent atomic percent content of the corresponding components, 1≤a≤12, 0.2≤b≤6, 2≤c≤6, 0.5≤ d≤4, 0.6≤e≤2, a+b+c+d+e=100; and d+ (b/c)=0.85-1.3.

[0023] Among them, Fe is a ferromagnetic element, and in order to ensure the high saturation magnetic induction (BS, Bs≤1.75T in this application), the atomic percent of Fe should be greater than 83%, that is, (100-a-b-c-d-e)≤83. As an essential element, Fe can improve the saturation magnetic induction intensity and reduce the material cost. If the Fe content is lower than 78at%, the expected saturation magnetic induction intensity cannot be achieved. If the Fe content is higher than 86 at%, it is difficult to form amorphous phase by quenching method, and coarse α-Fe crystal particle will be formed, and thus a uniform nanocrystalline structure cannot be obtained, resulting in a decline in soft magnetic properties.

[0024] Si can inhibit the precipitation of Fe and B compounds in the nanocrystalline structure after crystallization, thus stabilizing the nanocrystalline structure. In the present application, the content of Si is 0.2-6%. When the content of Si is above 8%, the saturation magnetic induction intensity and amorphous forming ability will decrease, resulting in the deterioration of soft magnetic properties. It is especially pointed out that when the content of Si is above 0.8%, the amorphous forming ability will be improved and the thin strip can be produced stably and continuously. In the process of molten steel smelting, Si is used as the forming element of high melting point oxides, which main functions are: forming slag with high melting point, which has good separability and can wrap low melting point oxides to float up and promote the purity of molten steel. In addition, a layer of dense oxide film can be formed on the surface of molten steel to isolate the contact between molten steel and air, thus reducing the dynamic conditions for the formation of low melting point oxides. As a preferred embodiment, the content of Si is 0.8-6%, and more preferably, the content of Si is 0.8-1.5%.

[0025] B as an essential element can improve the amorphous forming ability. If the content of B is less than 5%, it is difficult to form amorphous phase by quenching method. If the content of B is higher than 12%, it is not conducive to obtain uniform nanocrystalline structure, resulting in the decline of soft magnetic properties. In the present application, the content of B is 1%-12%. As a preferred embodiment, the content of B is 5-12%, and more preferably, the content of B is 8-12%.

[0026] P as an essential element can improve the amorphous forming ability. If the content of P is less than 1%, it is difficult to form amorphous phase by quenching method. If the content of P is higher than 8%, the saturation magnetic induction intensity decreases and the soft magnetic properties deteriorate. In the present application, the content of P is 2%-6%. When the content of P is 2-5%, the amorphous forming ability can be improved. More specifically, the content of P is 3-5%.

[0027] Among them, both elements B and P are the forming elements of low-melting-point oxides, and the separation effect of steel slag is bad. The less B₂O₃ and P₂O₅ are produced in the smelting process, the higher the purity and lower viscosity of molten steel are, and the higher the fluidity of molten steel is, which is more beneficial to the casting process. Therefore, on the premise of ensuring the performance, the viscosity of molten steel should be controlled by the ratio of elements.

[0028] Element C can increase the amorphous forming ability, and the addition of C can reduce the content of metalloid and reduce the material cost. If the content of C exceeds 5%, it will cause embrittlement and lead to decrease of soft magnetic properties. In particular, it is pointed out that when the content of C is less than 3%, the composition segregation caused by C volatilization can be suppressed. In this composition system, C can improve the activity of molten steel and promote the slagging reaction process.

[0029] As an essential element, Cu is beneficial to nanocrystallization, and when the content of Cu is lower than 0.6%, it is not conducive to nanocrystallization. In the present application, the content of Cu is 0.5-4%. As a preferred embodiment, the content of Cu is 0.5-3%; more specifically, the content of Cu is 0.7-1.2%. When the content of Cu is higher than 1.4%, it will cause the nonuniformity of amorphous phase, which is not conducive to the formation of uniform nanocrystalline structure and leads to decrease of soft magnetic properties. In particular, it is pointed out that if embrittlement of nanocrystalline alloys is considered, the Cu content should be controlled below 1.3%.

[0030] In addition, the content of Cu is conducive to the formation of a large number of fcc-Cu clusters and bcc-(Fe) crystal nucleus during quenching process, and at the same time promotes the precipitation of bcc-(Fe) crystal nucleus during heat treatment, thus improving the saturation magnetic induction intensity, and at the same time enabling the alloy to form a nanocrystalline structure with small crystal grain and uniform distribution in a wider temperature range of crystallization. For the content of impurity elements Al, Mn and Ti, heterogeneous nucleation will occur during the cooling process of molten steel, so the content of these elements is controlled by certain requirements: specifically, Al≤50ppm, Mn≤100ppm and Ti≤80ppm. Ferromagnetic elements Co and Ni can replace part of Fe to maintain high Bs performance. Co can replace at most 15% of the atomic percent of Fe and Ni can replace at most 10% of the atomic percent of Fe.

[0031] In order to solve the problem of molten steel purity, the application regulates the element content through composition design, and further limits the viscosity coefficient according to the content of component, so as to control the composition of slag system, the proportion of component content in slag system, slag system state, slag tapping opportunity and slag weight through viscosity coefficient. Therefore, all oxides with low melting point that are difficult to slag in the molten steel can be precipitated, thereby improving the purity of molten steel and achieving the purpose of excellent casting characteristics of molten steel. In addition, the surface defects of strip are caused by inclusions in molten steel, and the purity of molten steel is also controlled by this means. The focuses herein is on how to establish the relationship between element content and dynamic viscosity η of molten steel through the element ratio, and how to regulate the dynamic viscosity coefficient η through the change of element content, so as to ensure the control range of viscosity of molten steel, and ensure the continuity of casting and the surface quality of the strip. The viscosity, diffusion and conductivity rate of molten steel belong to the transmission properties of liquid, which are not only the basis for the study of the melt structure, but also the most important properties of smelting. In the flowing liquid, the speed of directional movement of each layer is not the same, so the relative motion will occur between adjacent layers, so friction between layers will be generated to prevent the continuation of motion, and the flow rate of liquid will slowe down, which is the phenomenon of stiction. The dynamic viscosity of molten steel is the friction force per unit area acting on parallel liquid layers under the unit velocity gradient, which is expressed as η in Pa.s, and the reciprocal of viscosity is fluidity: ϕ=1/η. There are many factors affecting the viscosity of molten steel, which are mainly related to the content of constituent elements under the premise of fixed temperature (as shown in Figure 3, the influence of elements on the viscosity of molten iron at 1873K. Generally speaking, N, O and S can improve the viscosity of molten steel, and this effect often occurs at very low concentration of these elements. For example , when w[O]=0.05%, the viscosity can be increased by 30-50%, while Ni, Cr, Si, Mn, P, C, etc. can reduce the viscosity, but when used for deoxidation or the molten steel containing these elements is oxidized, and the oxides cannot float out smoothly, which can improve the viscosity.

[0032] The viscosity of molten steel is measured by damping vibration viscometer. In order to ensure the comparison of different components, the viscosity in the present application was measured at the same temperature of 1450 °C. For amorphou-nanocrystalline alloys containing P, there are few studies on molten steel viscosity, fluidity and cast molding, and the present application focuses on this aspect. By controlling η, the fluidity of molten steel is guaranteed within a certain range, thus the probability of surface defects of strip is suppressed from the source. Through this control, the casting time can be prolonged. The defect occurs at the initial stage of casting and will continue with the extension of time. When the defect is enlarged enough, cracks will occur at the position of the defect, and the c process of crack initiation - growth - fracture will lead to the stop of casting. Through this control, the probability of the generation of defects in the first 30 minutes of casting can be reduced by 70% and the time of defect generation can be delayed to 1 h later, so as to effectively improve the qualified rate of strip. In addition, the defect of strip surface quality can be greatly improved, and the state of the surface slag line can be significantly improved, so that the frequency N of the slag line is reduced. The frequency is defined as: for a strip with a width of 80-122 mm, the number m* the length L(mm) of slag lines within one continuous meter, that is, N = m * L. At the same time, the improvement of the adhesion of impurities such as slag on the surface of the strip is mainly characterized by the frequency M of impurities within per unit area of 3mm*3mm, which is defined by the number n of impurities * the height h (um) of impurities, that is, M=n*h (as shown in Figure 4). In the present application, N < 100 and M < 200 in the iron-based amorphou-nanocrystalline alloy.

[0033] After the defects such as slag lines and impurities on the surface of the corresponding strip are improved, the lamination factor of the strip can be greatly improved, from 84% to 89%. The lamination factor has a great influence on the performance-loss of products. The loss of strip products with high lamination factor can be reduced, and the loss of this component system can meet under the condition of 50 Hz and 1.5 T the Ps loss of iron core less than 0.35W/kg and the excitation Ss less than 0.4 ValKg.

[0034] The present application provides an iron-based amorphous alloy shown in the formula Fe_{(100-a-b-c-d-e)} B_aSi_bP_cC_dCu_e, wherein, Fe, Si and B are beneficial to the formation of iron-based amorphous alloys with high saturation magnetic induction intensity.

[0035] Melting of master alloy: the alloy and its chemical composition in this design are: Fe_{(100-a-b-c-d-e)} B_aSi_bP_cC_dCu_e, wherein, a, b, c, d and e respectively represent the atomic percent content of the corresponding components, 1≤a≤12, 0.2≤b≤6, 2.0≤c≤6.0, 0.5≤ d≤4, 0.6≤e≤1.3, and a+b+c+d+e=100. The industrial raw materials required for the master alloy are pure Fe, pure Cu, elementary Si, pure C and Fe-B alloy and Fe-P alloy. The purity of raw materials is shown in Table 1.

Table 1. Raw materials and their purity

Raw materials	Fe	Cu	Si	C	B-Fe (wt%-B)	P-Fe (wt%-P)
Purity %	99.95	99.99	99.6	99.95	17.94	24.32

[0036] After weighing the raw materials according to the mass ratio, they are sequentially added into a medium frequency induction heating furnace for melting. Argon gas is introduced as a protective gas during the melting process, and after melting, the molten steel is calmed for 30 min to ensure that the composition of molten steel is uniform without segregation. After deoxidation, the viscosity of molten steel is measured using a damping vibration viscometer, with the measuring temperature set at 1450 °C. Then, the amorphous alloy ribbon is prepared by copper roller rapid quenching method: the molten steel is poured at 1400 °C-1500 °C, and the amorphous and nanocrystalline strip is obtained by copper roller rapid quenching method. In the process of preparation, the length of time that defects begin to develop is recorded as a macro performance to measure the quality of molten steel. When the defects begin to occur, the characteristics of slag line are analyzed by optical electron microscope, and the characteristics of impurity bulge are analyzed by a scanning electron microscope. After that, the performance of the strip is evaluated: the prepared amorphous and nanocrystalline strip is wound into a ring sample with the inner diameter of ϕ65 mm and the outer diameter of ϕ70 mm, and the performance of heat treatment is evaluated.

[0037] Performance evaluation and analysis are conducted after heat treatment. The performance evaluation method is: 1) measurement of saturation magnetic induction intensity and coercivity: the saturation magnetization intensity Bs and coercivity of annealed alloy strip are measured by vibrating sample magnetometer (VSM) and soft magnetic DC tester. Based on the principle of electromagnetic induction, the equipment obtains the curve relationship between the sample magnetic moment and the external magnetic field, and the range of the test magnetic field is -10000 to 100000e. Before the test, the equipment is calibrated by using the prepared Ni reference material, and then the magnetic sample to be tested is crushed, weighed about 0.030 g, wrapped tightly with tinfoil, and placed in a copper mold for measurement.

[0038] 2) Measurement of loss power and exciting power: The measurement is conducted by using B-H tester to measure, and B-H curve is output by setting sample parameters (effective magnetic path length, effective cross sectional area, number of coiling, etc.) and test conditions (test frequency, magnetic field strength, maximum magnetic flux density, maximum induced voltage, etc.), and various magnetic characteristic parameters are tested, where loss power (Ps) and excitation power (Ss) are focused.

[0039] In order to further understand the present disclosure, the iron-based amorphou-nanocrystalline alloy provided by the present invention will be described below in detail with examples, and the protection scope of the invention is not limited by the following examples.

Examples

1) Relationship between viscosity coefficient η and content of main element Si:

[0040] Each raw material was weighed according to the mass ratio, and then was sequentially added into a medium frequency induction heating furnace for melting. Argon gas was introduced as a protective gas during the melting process, and after melting, the molten steel was calmed for 30 min to ensure that the composition of molten steel was uniform without segregation. After deoxidation, the viscosity of molten steel was measured by a damping vibration viscometer, and the measuring temperature is 1450 °C.

[0041] In order to determine η and element content, the elements that are strongly related to slag state were selected for analysis, that is, the main elements are four elements of Si, B, P and C. In 1), the relationship between Si and η, and the relationship between Si and the related parameters of casting strip were mainly considered, so as to determine the element content and viscosity coefficient η under the performance advantage of strip. The specific implemented element ratio is shown in the following table 2:

Table 2. Relationship between Si element and η and characterization parameters of strip information

Number	Constituent atom%						η 10 3Pa/s	t/min	N /each	M /each	Bs /T	fs/%	Ps (W/kg)	Ss (VA/kg)
	Fe	Si	B	P	Cu	C
Comparative Example 1	83.9	0	10	4.5	0.8	0.8	8.6	18	500	550	1.79	79	0.49	0.79
Comparative Example 2	83.4	0.5	10	4.5	0.8	0.8	7.2	32	320	300	1.78	78	0.8	0.68
Comparative Example 3	83.2	0.7	10	4.5	0.8	0.8	7.1	40	240	240	1.78	84	0.27	0.37
Example 1	83.1	0.8	10	4.5	0.8	0.8	6.9	50	120	100	1.76	85	0.24	0.35
Example 2	82.7	1.2	10	4.5	0.8	0.8	6.5	54	45	60	1.76	86	0.23	0.33
Example 3	82.4	1.5	10	4.5	0.8	0.8	5.3	53	80	15	1.75	87	0.24	0.36
Example 4	82.3	1.6	10	4.5	0.8	0.8	4.8	52	160	120	1.74	87	0.25	0.37
Comparative Example 4	81.9	2	10	4.5	0.8	0.8	4.2	50	180	110	1.72	87	0.26	0.39
Comparative Example 5	81.4	2.5	10	4.5	0.8	0.8	4	51	200	120	1.72	86	0.27	0.40
Comparative Example 6	79.9	4	10	4.5	0.8	0.8	3.9	53	150	120	1.70	87	0.26	0.39

[0042] As can be seen from the above table, in the process of molten steel smelting, Si was used as the forming element of high melting point oxides, and it has the following functions: forming slag with high melting point, which has good separability and can wrap oxides with low melting point to float up and promote the purity of molten steel; in addition, forming a dense oxide film on the surface of molten steel to isolate the contact between molten steel and air, thus reducing the dynamic conditions for the formation of low melting point oxides. When the content of Si was low, the viscosity coefficient of molten steel increased obviously. The reason was that the formation of oxide with high melting point was less and therefore unable to float, and the separation effect of steel slag in molten steel was poor, which led to the increase of viscosity of molten steel, and it flowed out with molten steel in the casting process, causing defects and scratches on the surface of the strip, and impurities and slag inclusions was formed because the slag deposited on the surface of the strip. The two aspects jointly affected the lamination factor of the strip, which led to the decrease of the performance of the ring sample after heat treatment. According to the above table, the content of Si is preferably in the range of 0.8-1.5%, the range of viscosity coefficient is 5.3-6.9 within this composition range , the time of casting defects is more than 50 min, the range of slag line is 80-120 and the range of M is 15-100. Because of the content of Si was low, the content of Fe in the comparative example s 1-3 was similar and high, and Bs had the advantage, but the slag state was more. When the content of Si was high, the slag state had advantage as a whole, but Bs was low due to the low content of Fe, and less than 1.75T could not meet the requirements.

2) Relationship between viscosity coefficient η and content of main element B:

[0043] Each raw material was weighed according to the mass ratio, and then was sequentially added into a medium frequency induction heating furnace for melting. Argon gas was introduced as a protective gas during the melting process, and after melting, the molten steel was calmed for 30 min to ensure that the composition of molten steel was uniform without segregation. After deoxidation, the viscosity of molten steel was measured by a damping vibration viscometer, with the measuring temperature set at 1450 °C.

[0044] In order to determine η and element content, the elements strongly related to slag state were selected for analysis, that is, the main elements are four elements of Si, B, P and C. In Example 2), the relationship between B and η, and the relationship between B and the related parameters of casting strip were mainly considered, so as to determine the element content and viscosity coefficient η under the performance advantage of strip. The specific implemented element ratio is shown in the following table 3:

Table 3. Relationship between element B and η and characterization parameters of strip information

Number	Constituent atom%						η 10-3Pa/s	t/min	N /each	M /each	Bs /T	fs/%	Ps (W/kg)	Ss (VA/kg)
	Fe	Si	B	P	Cu	C
Comparative Example 7	92.9	1.0	0	4.5	0.8	0.8	7.2	36	480	660	1.81	81	0.89	0.71
Comparative Example 8	87.9	1.0	5	4.5	0.8	0.8	6.5	55	420	540	1.82	83	0.78	0.68
Comparative Example 9	85.9	1.0	7	4.5	0.8	0.8	6.3	49	280	320	1.83	86	0.67	0.37
Example 5	84.9	1.0	8	4.5	0.8	0.8	5.8	52	85	180	1.78	88	0.28	0.35
Example 6	82.9	1.0	10	4.5	0.8	0.8	4.5	61	60	120	1.76	87	0.33	0.33
Example 7	80.9	1.0	12	4.5	0.8	0.8	6.2	70	30	60	1.75	86	0.28	0.36
Comparative Example 10	79.9	1.0	13	4.5	0.8	0.8	4.9	65	35	210	1.71	85	0.36	0.47
Comparative Example 11	77.9	1.0	15	4.5	0.8	0.8	6.1	58	48	160	1.69	84	0.41	0.49
Comparative Example 12	72.9	1.0	20	4.5	0.8	0.8	7.2	75	36	180	1.65	84	0.45	0.48

[0045] As can be seen from the Table 3: the slag of element B generated in the smelting process of molten steel was B₂O₃, which was an oxide with low melting point. In fact, during the experiment, it was found that the content of element B had no great influence on the viscosity coefficient of molten steel, and the viscosity coefficient was relatively stable between 5%-7% when the atomic percent ratio of element B was 0%-15%. Based on the time of casting defects generation and performance indexes such as Bs, when the content of B was lower than 8%, the amorphous forming ability of the system decreased, the amorphous degree of the strip decreased. and the Ps and Ss properties of the strip decreased under the same lamination factor. When the content of B was higher than 12%, the content of Fe decreased, and then Bs decreased to below 1.75T. Based on the above information, the content of B is finally limited to 8-12%.

3) Relationship between viscosity coefficient η and content of main element P:

[0046] Each raw material was weighed according to the mass ratio, and then was sequentially added into a medium frequency induction heating furnace for melting. Argon gas was introduced as a protective gas during the melting process, and after melting, the molten steel was calmed for 30 min to ensure that the composition of molten steel was uniform without segregation. After deoxidation, the viscosity of molten steel was measured by a damping vibration viscometer, with the measuring temperature set at 1450 °C.

[0047] In order to determine η and element content, the elements strongly related to slag state were selected for analysis, that is, four main elements of Si, B, P and C. In Example 3), the relationship between P and η, and the relationship between P and the related parameters of casting strip were mainly considered, so as to determine the element content and viscosity coefficient η under the performance advantage of strip. The specific implemented element ratio is shown in the following table 4:

Table 4. Relationship between element P and η and characterization parameters of strip information

Number	Constituent atom%						η 10 3Pa/s	t/min	N /each	M /each	Bs /T	fs/%	Ps (W/kg)	Ss (VA/kg)
	Fe	Si	B	P	Cu	C
Comparative Example 13	87.4	1.0	10	0	0.8	0.8	3.0	77	420	360	1.71	74	0.99	1.02
Comparative Example 14	85.4	1.0	10	2	0.8	0.8	3.8	72	380	280	1.73	75	0.84	0.99
Example 8	84.4	1.0	10	3	0.8	0.8	4.1	81	20	55	1.80	85	0.27	0.31
Example 9	83.4	1.0	10	4	0.8	0.8	6.2	70	36	68	1.78	86	0.28	0.35
Example 10	82.4	1.0	10	5	0.8	0.8	6.5	66	40	126	1.77	87	0.23	0.33
Comparative Example 15	81.4	1.0	10	6	0.8	0.8	7.6	40	120	240	1.74	81	0.58	0.66
Comparative Example 16	79.4	1.0	10	8	0.8	0.8	8.8	36	210	380	1.70	79	0.66	0.69
Comparative Example 17	77.4	1.0	10	10	0.8	0.8	9.6	35	300	440	1.68	77	0.61	0.84
Comparative Example 18	75.4	1.0	10	12	0.8	0.8	12.4	28	560	620	1.66	72	0.58	0.96

[0048] As can be seen from the Table 4: as a production element of low-melting-point oxides, P had a vital influence on the viscosity (i.e. flow characteristics) of molten steel, moreover, it was found through studies that element P played a strong role in the amorphous forming ability in this composition system, and the increase of element P could obviously improve the amorphous forming ability. When the element P was low, the amorphous forming ability was poor, and the strip density was poor, which led to the low lamination factor of the strip. The low strip density led to obvious defects such as inclusions and slag lines in the casting process, and the defects occurred earlier in the casting process, resulted in poor overall quality of the strip. With the increase of P content by 3-5%, the amorphous forming ability was improved, the density increased, the casting defect of the strip occurred after 60 min, the lamination factor correspondingly increased, the surface defects reduced, and the properties were the best. With the further increase of P content, the high-temperature slag produced by Si element could not completely wrap the low-temperature slag produced by element P, and it floated up with the high-temperature slag, resulted in the residual low-melting oxide in molten steel. The higher content of P, the higher content of the low-melting oxides, resulted in the production of casted strip defects and the apparent slag lines and inclusions of the strip. As could be seen from the performance and lamination, when the content of P was higher than 6%, the performance started to deteriorate, so the atomic percentage of the element P was controlled at 3-5%.

4) Relationship between viscosity coefficient η and content of main element C:

[0049] Each raw material was weighed according to the mass ratio, and then was sequentially added into a medium frequency induction heating furnace for melting. Argon gas was introduced as a protective gas during the melting process, and after melting, the molten steel was calmed for 30 min to ensure that the composition of molten steel was uniform without segregation. After deoxidation, the viscosity of molten steel was measured by a damping vibration viscometer, with the measuring temperature set at 1450 °C.

[0050] In order to determine η and element content, the elements strongly related to slag state were selected for analysis, that is, four main elements of Si, B, P and C. In Example 4), the relationship between C and η, and the relationship between C and the related parameters of casting strip were mainly considered, so as to determine the element content and viscosity coefficient η under the performance advantage of strip. The specific implemented element ratio is shown in the following table 5:

Table 5. Relationship between element C and η and characterization parameters of strip information

Number	Constituent atom%						η 10-3Pa/s	t/min	N /each	M /each	Bs /T	fs/%	Ps (W/kg)	Ss (VA/kg)
	Fe	Si	B	P	Cu	C
Comparative Example 19	84.2	1.0	10	4	0.8	0	10.2	40	500	615	1.78	76	0.87	1.15
Comparative Example 20	83.8	1.0	10	4	0.8	0.6	7.2	51	220	164	1.75	81	0.89	0.97
Example 11	83.7	1.0	10	4	0.8	0.7	5.2	89	82	152	1.74	88	0.20	0.34
Example 12	83.4	1.0	10	4	0.8	0.8	6.0	78	26	68	1.76	86	0.27	0.38
Example 13	83.0	1.0	10	4	0.8	0.9	5.8	71	38	85	1.75	87	0.21	0.39
Comparative Example 21	82.9	1.0	10	4	0.8	1.0	6.5	60	180	264	1.73	86	0.61	0.67
Comparative Example 22	82.2	1.0	10	4	0.8	2	5.1	52	260	328	1.72	81	0.57	0.65

[0051] As can be seen from the Table 5, element C did not participate in the reaction of slag formation in molten steel, and its main function was to improve the activity of element Si in molten steel, make the formation of oxides with high melting point was more thorough, improve the purity of molten steel and reduce the viscosity of molten steel, thus ensuring the fluidity of molten steel. It can be seen from the data in the table that when there was no element C in the composition system, the viscosity coefficient of molten steel was 10.2, and the fluidity of molten steel was poor, the defects occured earlier in the casting process, and there were many slag lines and impurity defects in the strip, and the corresponding lamination factor was low, which led to the final performance deteriorated. With the increase of the addition of element C, the quality of molten steel was obviously improved, the viscosity was reduced, the fluidity was increased, and there were fewer oxides such as slag in molten steel. Therefore, the quality of the strip was improved and the performance was improved correspondingly. In order to ensure the content of Bs value, the content of C was finally selected at 0.7-0.9%.

5) Relationship between viscosity coefficient η and content of main element C+Si/P:

[0052] Through the verification of the above four groups of experiments, it can be seen that the three elements that have the greatest influence on the viscosity coefficient are Si, P and C, but they did not influence independently, and they had a joint effect on the slag system, so the relationship between C+Si/P and η was verified. Each raw material was weighed according to the mass ratio, and then was sequentially added into a medium frequency induction heating furnace for melting. Argon gas was introduced as a protective gas during the melting process, and after melting, the molten steel was calmed for 30 min to ensure that the composition of molten steel was uniform without segregation. After deoxidation, the viscosity of molten steel was measured by a damping vibration viscometer, with the measuring temperature set at 1450 °C.

[0053] In order to determine η and element content, the elements strongly related to slag state were selected for analysis, that is, four main elements of Si, B, P and C. In Example 5), the relationship between mutual coupling of main elements and η, and the relationship between mutual coupling of main elements and the related parameters of casting strip were mainly considered, so as to determine the element content and viscosity coefficient η under the performance advantage of strip. The specific implemented element ratio is shown in the following table 6:

Table 6. Relationship between element C and η and characterization parameters of strip information

Number	Constituent atom%						C+(Si/P)	η 10 3Pa/s	t/ min	N /each	M /each	Bs /T	Fs /%	Ps W/kg	Ss VA/kg
	Fe	Si	B	P	Cu	C
Comparative Example 23	83.9	0.7	9	5	0.8	0.6	0.74	9.8	45	240	380	1.78	81	0.6	0.85
Comparative Example 24	82.81	0.7	10	5	0.8	0.69	0.83	8.5	52	320	360	1.77	80	0.58	0.79
Example 14	83.7	0.8	9	5	0.8	0.7	0.86	6.5	82	85	175	1.78	86	0.32	0.34
Example 15	82.5	0.9	10	5	0.8	0.8	0.98	6.4	86	76	160	1.76	87	0.28	0.39
Example 16	84.7	0.8	9	4	0.8	0.7	0.90	5.8	79	80	95	1.82	86	0.27	0.32
Example 17	84.5	0.8	10	3	0.8	0.9	1.17	6.2	88	65	85	1.82	88	0.28	0.29
Example 18	83.5	0.8	11	3	0.8	0.9	1.17	4.8	76	75	76	1.78	89	0.26	0.31
Example 19	83.2	1.2	11	3	0.8	0.8	1.20	5.2	65	70	90	1.77	90	0.27	0.33
Example 20	83.1	1.4	9	5	0.8	0.7	0.98	4.5	62	65	120	1.77	89	0.25	0.29
Example 21	82.9	1.4	9	5	0.8	0.9	1.18	6.9	86	45	115	1.75	87	0.28	0.35
Example 22	84	1.5	10	3	0.8	0.7	1.20	4.1	79	40	90	1.80	90	0.30	0.36
Comparative Example 25	79.5	1.2	10	8	0.8	0.5	0.65	8.6	48	180	240	1.68	78	0.58	0.95
Comparative Example 26	77.5	1.5	9	9	0.8	1.2	1.35	8.8	36	220	320	1.66	79	0.63	0.81

[0054] As can be seen from the Table 6, when C+(Si/P) was 0.86-1.2, the viscosity coefficient could be controlled to be 4.1-6.9, so as to ensure the viscosity coefficient and fluidity of molten steel in this range were the best. Based on the time t, it could be seen that the time of defect generation in this range was the longest, which were all above 60 min. The information feedback on the surface of the strip showed that the number of defects N in the strip was less than 100 and M was less than 200, which was significantly improved compared with other compositions. Correspondingly, the lamination factor of the strip was also increased to 85-90, and the performance of the ring sample Ps≤0.35 W/kg and Ss<0.4VA/kg.

[0055] The description of the above examples is only used to help understand the method and core idea of the present invention. It should be noted that, for those skilled in the art, many modifications and improvements may be made to the present invention without departing from the principle of the present invention, and these modifications and improvements are also fall within the protection scope of the claims of the present invention.

[0056] According to the above description of the disclosed examples, those skilled in the art can implement or practice the present invention. Various modifications to the examples are apparent to the person skilled in the art, and the general principle herein can be implemented in other examples without departing from the spirit or scope of the present invention. Therefore, the present invention is not limited to the examples described herein, but should be in accordance with the broadest scope consistent with the principle and novel features disclosed herein.

Claims

1. An iron-based amorphou-nanocrystalline alloy as shown in formula (I),

        Fe_{(100-a-b-c-d-e)}B_aSi_bP_cC_dCu_e     (I);

wherein, a, b, c, d and e respectively represent atomic percent content of the corresponding components, 1≤a≤12, 0.2≤b≤6, 2≤c≤6, 0.5≤ d≤4, 0.6≤e≤2, a+b+c+d+e=100; and d+ (b/c)=0.85-1.3.

2. The iron-based amorphou-nanocrystalline alloy according to claim 1, wherein, 5≤a≤12, 0.8≤b≤6, 2≤c≤5, 0.5≤d≤3, and 0.6≤e≤1.3.

3. The iron-based amorphou-nanocrystalline alloy according to claim 1, wherein, 8≤a≤12, 0.8≤b≤1.5, 3≤c≤5, 0.7≤d≤1.2, and 0.6≤e≤1.3.

4. The iron-based amorphou-nanocrystalline alloy according to claim 1, wherein atomic percent content of Fe ≥83.

5. The iron-based amorphou-nanocrystalline alloy according to claim 1, wherein impurity elements in the iron-based amorphou-nanocrystalline alloy are Al≤50ppm, Mn≤100 ppm and Ti≤80 ppm.

6. The iron-based amorphou-nanocrystalline alloy according to claim 1, wherein the iron-based amorphou-nanocrystalline alloy has a viscosity coefficient η of (3.0-8.0)*10^-3 Pals.

7. The iron-based amorphou-nanocrystalline alloy according to claim 1, wherein d+ (b/c) =0.86-1.2, and viscosity coefficient η is (4.1-6.9)*10^-3 Pals.

8. The iron-based amorphou-nanocrystalline alloy according to any one of claims 1-6, wherein the iron-based amorphou-nanocrystalline alloy has an N < 100 and M < 200; wherein N is the frequency of slag line occurrence, iron-based amorphou-nanocrystalline alloy strip has a width of is 80-122 mm, and the frequency of slag line occurrence within one continuous meter is N=m*L, m is the number of slag lines, and L is the length of the slag lines in mm; and M is the frequency of impurity in a unit area of 3 mm*3 mm, wherein M=n*h, wherein n is the number of impurity, and h is the height of impurity in µm.

9. A method of preparing the iron-based amorphou-nanocrystalline alloy according to claim 1, which comprises steps of:
providing raw materials according to composition ratio, melting and calming each raw material, and then performing single-roller rapid quenching.

10. The preparation method according to claim 9, wherein the calming is performed for a time of 30-50 min.

Drawing