Ternary intermediate alloy applied to Ti-Al-Nb-Mn-B alloy and preparation method of ternary intermediate alloy

Abstract

The invention relates to the technical field of alloy preparation, and provides a ternary intermediate alloy applied to a Ti-Al-Nb-Mn-B alloy and a preparation method thereof.The ternary intermediate alloy is prepared from, by mass, 50%-60% of Nb, 20%-30% of Mn and the balance Al and other inevitable impurities; the ternary intermediate alloy is prepared through a metal reduction method, then the prepared ternary intermediate alloy is evenly mixed with sponge titanium, aluminum shots, Mn65Al alloy and boron powder in proportion, VAR smelting is carried out for multiple times, and the Ti-Al-Nb-Mn-B alloy containing multiple alloy elements is obtained. The Ti-Al-Nb-Mn-B alloy comprises the following chemical components in percentage by weight: 29%-32% of Al, 4%-6% of Nb, 2%-4% of Mn, 0.1%-0.3% of B and the balance of Ti and inevitable impurities. A Ti-Al-Nb-Mn-B alloy cast ingot prepared from the ternary intermediate alloy provided by the invention is free of intermediate alloy infusible substances, uniform and stable in component and low in cost.

Description

Technical Field

[0001] The present invention belongs to the technical field of alloy preparation, and in particular relates to a ternary master alloy applied to a Ti-Al-Nb-Mn-B alloy and a preparation method thereof. Background Art

[0002] Titanium alloy is a lightweight, high-temperature structural material with excellent performance, boasting high specific strength, high specific stiffness, excellent corrosion resistance, creep resistance, and oxidation resistance. It is currently commonly used in the manufacture of low-pressure turbine blades for aircraft engines. To meet the comprehensive performance requirements of components under complex operating conditions, the composition of titanium alloys is evolving from binary alloys to multi-element alloys. In this process, the addition of appropriate master alloys is crucial to ensuring the stability of titanium alloy properties. Failure to do so can lead to metallurgical defects such as high-density and low-density inclusions within the material.

[0003] Compared to conventional binary master alloys, diversified master alloys offer significantly improved physical properties, better matching the melting points of other raw materials and the base alloy, effectively improving the uniformity of alloy composition and reducing the probability of metallurgical defects within the alloy. Therefore, for titanium alloys, especially Ti-Al-Nb-Mn-B alloys containing low-melting-point, refractory, and volatile elements (such as Al, Nb, and Mn), the use of diversified master alloys is an ideal choice for their preparation.

[0004] However, in the existing Ti-Al-Nb-Mn-B alloy smelting process, Al is a low-melting-point element, Nb is a high-melting-point element, and Mn is a volatile element. Due to the large difference in melting points of the raw materials, smelting can easily lead to inclusion of the refractory element Nb, or inaccurate control of the alloying element content due to Mn volatilization. These defects can seriously affect the mechanical properties of the alloy.

[0005] In view of this, the present invention is proposed. Summary of the Invention

[0006] The present invention aims to provide a ternary master alloy for use in a Ti-Al-Nb-Mn-B alloy and a preparation method thereof. The ternary master alloy is used to prepare a Ti-Al-Nb-Mn-B alloy containing multiple alloying elements such as Al, Nb, Mn, and B, thereby avoiding the occurrence of high-melting-point inclusions in the Ti-Al-Nb-Mn-B alloy during a VAR preparation process and reducing the production cost of the ingot.

[0007] The purpose of the present invention is to solve the problem through the following technical solutions:

[0008] In a first aspect, the present invention provides a ternary master alloy comprising the following components by mass percentage:

[0009] Nb: 50-60%, Mn: 20-30%, the balance is Al and inevitable impurities;

[0010] Wherein, the mass ratio of Nb to Mn in the ternary master alloy is greater than 1.65.

[0011] Furthermore, the ternary master alloy is in granular form with a particle size of less than 5 mm.

[0012] Furthermore, the melting point of the ternary master alloy is 1100-1500° C., and does not contain Nb3Al, Nb2Al and NbAl3 high melting point phases.

[0013] In a second aspect, the present invention provides a method for preparing a ternary master alloy using a metallothermic reduction method, comprising the following steps:

[0014] S1. Weighing of raw materials: by mass, including: 0.1-0.3 parts of aluminum powder, 0.70-0.85 parts of niobium pentoxide, and 0.2-0.3 parts of manganese powder;

[0015] S2, adding 5-20% by weight of calcium fluoride and 0-10% by weight of potassium chlorate to the raw materials of S1, and mixing them uniformly to obtain the raw materials to be reacted;

[0016] S3. The raw materials to be reacted in S2 are subjected to an aluminothermic reduction reaction to prepare a ternary master alloy.

[0017] Furthermore, the metal thermal reduction method is an aluminothermic reduction method;

[0018] The aluminum powder is a reducing agent, niobium pentoxide is an oxidizing agent, manganese powder is an additive of manganese element, calcium fluoride is a slag-forming agent, and potassium chlorate is a heating agent.

[0019] Furthermore, the purity of the niobium pentoxide is ≥99.5%, the purity of the aluminum powder is ≥99.7%, and the purity of the manganese powder is ≥99.9%.

[0020] Furthermore, in S2, the raw materials, calcium fluoride and potassium chlorate are placed in a ball mill and stirred at a rotation speed of 500-700 r / min for 10-20 minutes.

[0021] Furthermore, the aluminothermic reduction reaction is carried out under the protection of an inert gas, with a reaction temperature of 1800-2200° C. and a reaction time of 2-4 hours.

[0022] In a third aspect, the present invention provides a Ti-Al-Nb-Mn-B alloy prepared using a ternary master alloy.

[0023] The chemical composition of the Ti-Al-Nb-Mn-B alloy, in terms of mass percentage, comprises the following:

[0024] Al: 29-32%, Nb: 4-6%, Mn: 2-4%, B: 0.1-0.3%, and the balance is Ti and inevitable impurities.

[0025] Compared with the prior art, the present invention has the following beneficial effects:

[0026] 1. The addition of Nb element to Ti-Al-Nb-Mn-B alloy is mainly achieved through the Nb-Al binary master alloy commonly used in titanium alloys. The Nb-Al binary master alloy contains high melting point phases Nb2Al and NbAl3. The use of the Nb-Al binary master alloy to prepare Ti-Al-Nb-Mn-B alloy ingots will contain high melting point inclusions; while the ternary master alloy composed of the three elements Nb, Mn and Al within the composition range proposed by the present invention has a melting point of 1100-1500°C, which is lower than the melting point of Ti-Al-Nb-Mn-B alloy, and does not contain high melting point phases such as Nb3Al, Nb2Al and NbAl3, greatly reducing the risk of high melting point inclusion defects caused by the large difference in melting points between the master alloy and the base alloy.

[0027] 2. The use of the ternary master alloy proposed in the present invention to prepare Ti-Al-Nb-Mn-B alloy can produce ingots without high-melting-point inclusions through VAR smelting, which greatly reduces costs. In addition, through repeated experiments, suitable slag-forming agents and exothermic agents are selected, and the appropriate ratio of aluminum powder, niobium pentoxide, and pure manganese is determined, ultimately obtaining a ternary master alloy with good performance. This improves the stability of the smelting process during the preparation of the Ti-Al-Nb-Mn-B alloy, ensures the uniformity of the chemical composition of the ingot, and ensures the stability of the structure and properties of the alloy. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] The accompanying drawings are incorporated in and constitute a part of this specification and, together with the description, serve to explain the principles of the invention.

[0029] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, for ordinary technicians in this field, other drawings can be obtained based on these drawings without any creative work.

[0030] Figure 1 This is a flow chart of the method for preparing a ternary master alloy according to the present invention;

[0031] Figure 2 This is the X-ray detection result of Ti-Al-Nb-Mn-B prepared from the ternary master alloy in Example 1 of the present invention;

[0032] Figure 3 This is the microstructure of the Ti-Al-Nb-Mn-B alloy prepared from the ternary master alloy in Example 1 of the present invention.

[0033] Figure 4 This is the X-ray detection result of Ti-Al-Nb-Mn-B prepared from the ternary master alloy in Example 2 of the present invention.

[0034] Figure 5 This is the microstructure of the Ti-Al-Nb-Mn-B alloy prepared from the ternary master alloy in Example 2 of the present invention. DETAILED DESCRIPTION

[0035] Exemplary embodiments will be described in detail herein, with examples illustrated in the accompanying drawings. In the following description, when referring to the drawings, identical numerals in different figures represent identical or similar elements, unless otherwise indicated. The embodiments described in the following exemplary embodiments are not intended to represent all possible embodiments consistent with the present invention. Instead, they are merely examples consistent with certain aspects of the present invention as detailed in the appended claims.

[0036] In order to enable those skilled in the art to better understand the technical solutions of the present invention, the present invention is described in further detail below with reference to the accompanying drawings and embodiments.

[0037] The present invention provides a ternary master alloy comprising the following components by mass percentage:

[0038] Nb: 50-60%, Mn: 20-30%, the balance is Al and inevitable impurities;

[0039] The mass ratio of Nb to Mn in the ternary master alloy is greater than 1.65.

[0040] Specifically, the ternary master alloy is granular with a particle size of less than 5 mm; and the melting point of the ternary master alloy is 1100-1500°C, that is, it can be 1100°C, 1200°C, 1300°C, 1400°C and 1500°C, etc.; and it does not contain Nb3Al, Nb2Al and NbAl3 high melting point phases, which can greatly reduce the risk of high melting point inclusion defects caused by the large difference in melting points between the master alloy and the base alloy.

[0041] The present invention also provides a method for preparing a ternary master alloy, such as Figure 1 As shown, the aluminothermic reduction method is adopted, comprising the following steps:

[0042] S1. Weighing of raw materials: by mass, including: 0.1-0.3 parts of aluminum powder, 0.70-0.85 parts of niobium pentoxide, and 0.2-0.3 parts of manganese powder; wherein aluminum powder serves as a reducing agent, niobium pentoxide serves as an oxidizing agent, and manganese powder serves as an additive of manganese element.

[0043] S2. Add 5-20% by weight of calcium fluoride and 0-10% by weight of potassium chlorate to the raw materials of S1, wherein calcium fluoride serves as a slagging agent and potassium chlorate serves as a heating agent. Place the raw materials, calcium fluoride and potassium chlorate in a ball mill and stir for 10-20 minutes at a speed of 500-700 r / min. After uniform mixing, obtain the raw materials to be reacted.

[0044] S3. The raw materials to be reacted in S2 are subjected to aluminothermic reduction reaction under the protection of inert gas, at a reaction temperature of 1800-2200° C. and a reaction time of 2-4 hours to prepare a ternary master alloy.

[0045] Preferably, the purity of the niobium pentoxide used in the present invention is ≥99.5%, the purity of the aluminum powder is ≥99.7%, and the purity of the manganese powder is ≥99.9%.

[0046] The Ti-Al-Nb-Mn-B alloy prepared by the ternary master alloy provided by the present invention comprises the following chemical components in the Ti-Al-Nb-Mn-B alloy, calculated by mass percentage:

[0047] Al: 29-32%, Nb: 4-6%, Mn: 2-4%, B: 0.1-0.3%, and the balance is Ti and inevitable impurities.

[0048] The method uses the ternary master alloy prepared by the present invention as a raw material, and includes the following steps, calculated by mass percentage: a) mixing the ternary master alloy with sponge titanium, aluminum beans, Mn65Al alloy and boron powder to prepare a target composition of: Al: 29-32%, Nb: 4-6%, Mn: 2-4%, B: 0.1-0.3%, and the balance being Ti and inevitable impurities; b) after pressing the electrode, performing VAR melting 2-3 times in a vacuum consumable arc furnace to obtain a Ti-Al-Nb-Mn-B alloy.

[0049] In order to further verify the performance of the Ti-Al-Nb-Mn-B alloy prepared by the ternary master alloy provided by the present invention, the following examples are provided for further explanation:

[0050] Example 1

[0051] First, the ternary alloy is prepared by a metallothermic reduction method, using aluminum as a reducing agent, niobium pentoxide as an oxidizing agent, pure manganese as a manganese element additive, calcium fluoride as a slag-forming agent, and potassium chlorate as a heating agent. During the metallothermic reduction smelting process, the weight ratio of aluminum powder, niobium pentoxide, and manganese powder is (0.1-0.3):(0.70-0.85):(0.2-0.3), the amount of calcium fluoride added is 5-20% of the total weight, and the amount of potassium chlorate added is 0-10% of the total weight. The element weight percentages of the ternary master alloy prepared by the aluminothermic reduction method are: Nb: 55.50%, Mn: 29.10%, and the balance is Al and unavoidable impurities.

[0052] Then, the prepared ternary master alloy is uniformly mixed with sponge titanium, aluminum beans, Mn65Al alloy and boron powder in proportion, electrodes are pressed, and then the electrodes are welded together. Then, three VAR melting processes are carried out in a vacuum consumable arc furnace to obtain a Ti-Al-Nb-Mn-B alloy containing multiple alloying elements, whose composition is Al: 30.56%, Nb: 4.77%, Mn: 3.04%, B: 0.23%, and the balance is Ti and unavoidable impurities.

[0053] in, Figure 2 The X-ray detection results of the Ti-Al-Nb-Mn-B alloy prepared from the ternary master alloy in Example 1 of the present invention are shown. Figure 3 The microstructure of the Ti-Al-Nb-Mn-B alloy prepared from the ternary master alloy in Example 1 of the present invention is shown.

[0054] Example 2

[0055] First, the ternary master alloy is prepared by a metallothermic reduction method, using aluminum as a reducing agent, niobium pentoxide as an oxidizing agent, pure manganese as a manganese element additive, calcium fluoride as a slag-forming agent, and potassium chlorate as a heating agent. During the metallothermic reduction smelting process, the weight ratio of aluminum powder, niobium pentoxide, and manganese powder is (0.1-0.3):(0.70-0.85):(0.2-0.3), the amount of calcium fluoride added is 5-20% of the total weight, and the amount of potassium chlorate added is 0-10% of the total weight. The element weight percentages of the ternary master alloy prepared by the metallothermic reduction method are: Nb: 54.80%, Mn: 29.30%, and the balance is Al and unavoidable impurities.

[0056] Then, the prepared ternary alloy is evenly mixed with sponge titanium, aluminum beans, Mn65Al alloy and boron powder in proportion, electrodes are pressed, and then the electrodes are welded together. Then, secondary VAR melting is carried out in a vacuum consumable arc furnace to obtain a Ti-Al-Nb-Mn-B alloy containing multiple alloy elements, whose composition is Al: 30.24%, Nb: 5.06%, Mn: 3.09%, B: 0.23%, and the balance is Ti and unavoidable impurities.

[0057] in, Figure 4 The X-ray detection results of the Ti-Al-Nb-Mn-B alloy prepared from the ternary master alloy in Example 2 of the present invention are shown. Figure 5 The microstructure of the Ti-Al-Nb-Mn-B alloy prepared from the ternary master alloy in Example 2 of the present invention is shown.

[0058] In addition to the ternary master alloys prepared by the metallothermic reduction method in the two aforementioned embodiments, wherein the weight percentages of the elements are: Nb: 55.50% or 54.80%, Mn: 29.10% or 29.30%, with the balance being Al and inevitable impurities, any other ternary master alloy prepared by the metallothermic reduction method having weight percentages of Nb: 50-60%, Mn: 20-30%, with the balance being Al and other inevitable impurities, falls within the scope of protection of the present invention. When the composition of the ternary master alloy is different, the components of the Ti-Al-Nb-Mn-B alloy prepared accordingly vary, and the components of the Ti-Al-Nb-Mn-B alloy are all within the range of: Al: 29-32%, Nb: 4-6%, Mn: 2-4%, B: 0.1-0.3%, with the balance being Ti and inevitable impurities.

[0059] Table 1 Composition of Ti-Al-Nb-Mn-B alloy prepared using ternary master alloy in Example 1

[0060] Location Al Nb Mn B head 30.54 4.82 3.03 0.23 middle 30.66 4.78 3.04 0.23 tail 30.47 4.73 3.06 0.22

[0061] Table 2 Composition of Ti-Al-Nb-Mn-B alloy prepared using ternary master alloy in Example 2

[0062] Location Al Nb Mn B head 30.57 5.06 3.20 0.24 middle 30.52 5.10 3.27 0.24 tail 30.22 4.92 3.12 0.25

[0063] It can be seen from Tables 1 and 2 that the Ti-Al-Nb-Mn-B alloy ingot prepared by the ternary master alloy provided by the present invention has uniform chemical composition, which ensures the stability of the alloy's structure and properties.

[0064] The foregoing description is intended only to provide specific embodiments of the present invention, which will enable those skilled in the art to understand and implement the present invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present invention.

[0065] It should be understood that the present invention is not limited to the above description and that various modifications and changes may be made without departing from the scope thereof. The scope of the present invention is limited only by the appended claims.

Claims

1. A ternary master alloy, characterized in that: Contains the following ingredients by mass percentage: Nb: 50-60%, Mn: 20-30%, the balance is Al and inevitable impurities; Wherein, the mass ratio of Nb to Mn in the ternary master alloy is greater than 1.

65.

2. The ternary master alloy according to claim 1, characterized in that: The ternary master alloy is in granular form with a particle size of less than 5 mm.

3. The ternary master alloy according to claim 1, characterized in that: The ternary master alloy has a melting point of 1100-1500° C. and does not contain Nb3Al, Nb2Al and NbAl3 high melting point phases.

4. A method for preparing the ternary master alloy according to any one of claims 1 to 3, characterized in that: The metal thermal reduction method includes the following steps: S1. Raw materials weighing: by mass, including: 0.1-0.3 parts of aluminum powder, 0.70-0.85 parts of niobium pentoxide, and 0.2-0.3 parts of manganese powder; S2, adding 5-20% by weight of calcium fluoride and 0-10% by weight of potassium chlorate to the raw materials of S1, and mixing them uniformly to obtain the raw materials to be reacted; S3. The raw materials to be reacted in S2 are subjected to an aluminothermic reduction reaction to prepare a ternary master alloy.

5. The method for preparing the ternary master alloy according to claim 4, characterized in that: The metal thermal reduction method is an aluminothermic reduction method; The aluminum powder is a reducing agent, niobium pentoxide is an oxidizing agent, manganese powder is an additive of manganese element, calcium fluoride is a slag-forming agent, and potassium chlorate is a heating agent.

6. The method for preparing the ternary master alloy according to claim 4, characterized in that: The purity of the niobium pentoxide is ≥99.5%, the purity of the aluminum powder is ≥99.7%, and the purity of the manganese powder is ≥99.9%.

7. The method for preparing the ternary master alloy according to claim 4, characterized in that: In S2, the raw materials, calcium fluoride and potassium chlorate are placed in a ball mill and stirred at a rotation speed of 500-700 r / min for 10-20 minutes.

8. The method for preparing the ternary master alloy according to claim 4, characterized in that: The aluminothermic reduction reaction is carried out under the protection of inert gas, the reaction temperature is 1800-2200° C., and the reaction time is 2-4 hours.

9. A Ti-Al-Nb-Mn-B alloy, characterized in that: Prepared by using the ternary master alloy according to any one of claims 1 to 3, The chemical composition of the Ti-Al-Nb-Mn-B alloy, in terms of mass percentage, comprises the following: Al: 29-32%, Nb: 4-6%, Mn: 2-4%, B: 0.1-0.3%, and the balance is Ti and inevitable impurities.

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