Manganese-containing titanium-aluminum alloy and smelting method thereof

Abstract

The invention belongs to the field of titanium-aluminum alloys, and particularly discloses a manganese-containing titanium-aluminum alloy and a smelting method thereof. According to the smelting method, a manganese-containing intermediate alloy is adopted as a raw material, the specific adding sequence of the raw material is controlled, a vacuum induction smelting means under a protective atmosphere is matched, and the manganese-containing titanium-aluminum alloy is prepared under the mutual cooperation and synergy effect by combining the control over the melt temperature and the refining time. According to the smelting method, the volatilization loss of the Mn element can be greatly reduced, and the consistency and uniformity of the manganese-containing titanium-aluminum alloy are improved; and meanwhile, an electrode block does not need to be additionally prepared, one-time smelting can be achieved, and the method is simple, easy to implement, environmentally friendly and suitable for large-range application and popularization.

Description

Technical Field

[0001] The invention belongs to the field of titanium-aluminum alloys, and in particular relates to a manganese-containing titanium-aluminum alloy and a smelting method thereof. Background Art

[0002] TiAl intermetallic compounds are formed with Ti and Al as the main alloying elements, roughly in a 1:1 molar ratio, and appropriate amounts of Mn, Nb, Cr, W, Mo, Si, B and other elements are added, so this type of alloy is also called γ-TiAl alloy. This type of alloy has a high melting point, and the alloying elements vary greatly. For example, Mn and Al have lower melting points and higher vapor pressures, while Nb, W, and Mo are high-melting-point refractory metal elements.

[0003] At present, TiAl alloy is mainly produced by multiple vacuum consumable melting (VAR), such as CN103820677B (a new type of β-γTiAl intermetallic compound material containing Mn and high Nb and its preparation method), CN103820672A (a Cr, Mn alloyed β-phase solidified high Nb-TiAl alloy and its preparation method), CN103834844B (a V, Mn alloyed β-phase solidified high Nb-TiAl alloy and its preparation method), CN102312111B (a method for melting TiAl alloy using vacuum consumable arc furnace), CN103773981B (a melting method for high Nb-TiAl-based alloy) and CN103555961A (a melting method for preparing large-size titanium aluminum alloy ingots), etc. This type of melting requires that sponge Ti, metal Al, and raw materials such as Cr, Nb, Mo, and W are pressed into electrode rods, and then vacuum consumable melting is performed. Secondly, in order to ensure that high-melting-point raw materials such as Nb, Mo, and W are fully melted, multiple vacuum consumable remelting or water-cooled copper crucible vacuum induction suspension melting are required. More melting times are likely to lead to greater volatilization losses of Al and Mn elements.

[0004] In addition, vacuum induction melting, plasma melting or electron beam cold hearth melting methods have also been developed to prepare TiAl alloys. For example, CN101121967B (a method for vacuum induction melting of TiAl-based alloys), CN104651662B (a method for vacuum induction melting of titanium-aluminum alloy targets) and CN1158397C (a technology for vacuum induction melting of titanium-aluminum alloys) use CaO crucibles to melt TiAl alloys, while CN111362708B (a refractory material for melting titanium-aluminum alloys and a method for preparing the same) uses titanium-containing calcium hexaaluminate as a crucible material, and CN113511907B (an entropy-stabilized refractory material for melting titanium-aluminum alloys and a method for preparing the same) uses a multi-component mixed oxide crucible. In addition to the use of oxide refractory materials, CN104278173B (a high-strength and high-plasticity TiAl alloy material and its preparation method), CN106636741A (a preparation method of TiAl alloy rods), CN103572082B (a high-Nb-TiAl alloy and its preparation method), CN106435234B (a method for removing inclusions in titanium-aluminum-based alloys), and CN104388714B (a smelting preparation method for large-size titanium-aluminum intermetallic compound ingots) all use water-cooled copper crucibles to suspend and smelt TiAl alloys. These smelting methods mainly focus on the interface reaction between the melt and the crucible and the purity of the alloy. By reducing the impurity elements in the melt, the purpose of reducing non-metallic and metallic inclusions is achieved, and less attention is paid to the volatilization loss of high vapor pressure elements in the alloy.

[0005] CN 110983079 A (a method for preparing a titanium alloy ingot containing volatile elements) introduces a smelting method for a titanium alloy containing volatile elements by primary smelting (ion cooling furnace) and secondary smelting (vacuum consumable arc furnace), and specifies parameters such as smelting atmosphere, smelting power, smelting current, stirring cycle, etc. However, the process is complicated, and the raw materials used, including the intermediate alloy, need to be pressed into electrode blocks before the primary smelting, and the intermediate alloy containing Mn needs to undergo primary smelting and secondary smelting. The long smelting time also makes it difficult to ensure the composition of the final alloy ingot. Summary of the invention

[0006] The purpose of the present invention is to solve the deficiencies of the prior art. Based on this, the present invention provides a simple smelting method for TiAl alloys containing volatile Mn elements, which can effectively reduce the large amount of Mn element burnout during the smelting process due to the high Mn vapor pressure, and ensure the consistency and uniformity of the composition of the smelted alloy.

[0007] To achieve the above object, the present invention provides a method for smelting a manganese-containing titanium-aluminum alloy, comprising the following steps:

[0008] S1: preparing raw materials of corresponding mass according to the nominal composition of the manganese-containing titanium-aluminum alloy, wherein the raw materials include a first raw material and a manganese-containing master alloy or metallic manganese, and the first raw material includes sponge titanium and metallic aluminum;

[0009] S2: placing the first raw material in a crucible for vacuum induction melting in a protective gas atmosphere, wherein the crucible is an oxide crucible or a water-cooled copper crucible;

[0010] S3: After all the first raw materials are melted, the manganese-containing master alloy or metallic manganese is added to continue vacuum induction melting under a protective gas atmosphere. After all the first raw materials are melted, the melt temperature is adjusted to ≤80° C., and the materials are refined and cast to obtain the manganese-containing titanium-aluminum alloy.

[0011] The present invention adopts manganese-containing master alloy or metallic manganese as raw material, controls the specific adding order of the raw materials, cooperates with the means of vacuum induction melting under a protective atmosphere, combines the control of melt temperature and refining time, and achieves the technical effect of ensuring the uniformity of the composition of the manganese-containing titanium-aluminum alloy while reducing the volatilization of the Mn component under the synergistic effect.

[0012] In some embodiments, the S2 in the smelting method includes the following specific process: vacuum induction melting the metallic aluminum and half the mass of the sponge titanium, and after all of them are melted, adding the remaining first raw material to continue vacuum induction melting. In the present invention, the components in the first raw material are also added in a specific order for vacuum induction melting, which can further reduce the volatilization of the Al component and further improve the composition uniformity of the final manganese-containing titanium-aluminum alloy ingot.

[0013] In some embodiments, the manganese-containing master alloy in the smelting method has a manganese content of 64%-70% by mass. The inventors have found that when the manganese-containing master alloy with this specific content is used, it has a relatively high melting point, which can ensure that after the manganese-titanium master alloy is added to the melt, it can be slowly released without causing local manganese enrichment in the melt and a large amount of volatilization loss, thereby further improving the composition uniformity of the final manganese-containing titanium-aluminum alloy ingot and further reducing the loss of Mn in the smelting process.

[0014] Wherein, the oxide crucible in S2 is a CaO crucible, a Y2O3 crucible or a CaZrO3 crucible, or other thermodynamically stable oxide crucibles. When the crucible is an oxide crucible, a vacuum melting process is adopted in S3, and the specific process includes: after the first raw material is completely melted, the manganese-containing master alloy or metallic manganese is added to continue vacuum induction melting under a protective gas atmosphere, and after all are melted, the melt temperature is adjusted to ≤80°C, refined, and cast to obtain the manganese-containing titanium-aluminum alloy;

[0015] When the crucible is a water-cooled copper crucible, a secondary vacuum melting process is adopted in S3, and the specific process includes: after the first raw material is completely melted, the manganese-containing intermediate alloy or metallic manganese is added to continue vacuum induction melting under a protective gas atmosphere, and after all are melted, the melt temperature is adjusted to ≤80°C, refined, and cooled to room temperature to obtain a molten alloy, and the molten alloy is turned upside down and continued to be vacuum induction melted under a protective gas atmosphere. After all are melted, the melt temperature is adjusted to ≤80°C, refined, and cast to obtain the manganese-containing titanium aluminum alloy.

[0016] Among them, when the manganese-titanium master alloy is prepared by the following preparation method, the technical effect can be further improved, which is specifically:

[0017] A method for preparing a manganese-titanium master alloy comprises the following steps:

[0018] According to the nominal composition of the manganese-titanium master alloy, corresponding parts by weight of sponge titanium and metal manganese are prepared; wherein the weight of the sponge titanium is recorded as 100 parts;

[0019] First, 25-50 parts (i.e. 1 / 4 to 1 / 2) of the sponge titanium and all the metallic manganese are used as the first raw material for vacuum induction melting. After the first raw material is completely melted, the remaining sponge titanium is added as the second raw material for vacuum induction melting. After the second raw material is completely melted, the manganese-titanium intermediate alloy (O≤0.04%, N≤0.01%) is obtained.

[0020] The inventors found that when the manganese content in the above-mentioned manganese-titanium master alloy is 64%-70% by weight, on the one hand, when the manganese-titanium master alloy with this specific content is used in the process of preparing titanium alloys and other alloys, the manganese-titanium master alloy with this specific content has a relatively high melting point, which can ensure that after the manganese-titanium master alloy is added to the melt, it can be slowly released without causing local manganese enrichment in the melt and large-scale volatilization loss (the component uniformity of the obtained manganese-titanium master alloy is better and also has a certain effect); on the other hand, the design of this specific content is also conducive to the method for preparing the manganese-titanium master alloy to achieve the effect of reducing the large-scale volatilization and burning loss of the Mn element and improving the component uniformity.

[0021] Among them, in the preparation method of the above-mentioned manganese-titanium master alloy, the vacuum induction melting mentioned can all be carried out in a vacuum induction melting furnace; vacuum induction melting is carried out in a protective gas atmosphere, and the protective gas is an inert gas such as argon or helium; wherein the gas pressure of the protective gas is 0.05MPa-0.1MPa. The above-mentioned first raw material is added to an oxide crucible for vacuum induction melting; the above-mentioned crucible is a thermodynamically stable oxide crucible or a water-cooled copper crucible such as a calcium oxide crucible, a yttrium oxide crucible, a zirconium oxide crucible or a calcium zirconate crucible. The above-mentioned second raw material can be placed in a secondary feeding bin of a vacuum induction melting furnace. The above-mentioned metal manganese is an electrolytic manganese sheet; the purity of the above-mentioned sponge titanium is greater than 99.8%, and the purity of the above-mentioned metal manganese is greater than 99.8%. In the above-mentioned preparation method, after the above-mentioned second raw material is completely melted, it is refined and then cast into a metal mold to obtain the above-mentioned manganese-titanium master alloy. Among them, the refining temperature is 1340℃-1400℃, and the time is 1min-5min.

[0022] In some other embodiments of the above-mentioned smelting method of manganese-containing titanium-aluminum alloy, the protective gas is an inert gas, and the gas pressure is 0.04MPa-0.1MPa. The first raw material also includes at least one of metal Nb, metal Cr, metal W, metal Mo, and metal Si; the manganese-containing master alloy is added simultaneously with TiB2 and high-purity graphite. The refining time is 1min-5min; the purity of the sponge titanium is ≥99.8%, and the purity of the metal aluminum is ≥99.95%.

[0023] Another aspect of the present invention provides a manganese-containing titanium-aluminum alloy (γ-TiAl alloy) obtained by the above-mentioned smelting method. In the manganese-containing titanium-aluminum alloy, Al is 42%-48%, Mn is 1%-8%, other elements are 0%-10%, and the balance is Ti, calculated by atomic percentage; the other elements include at least one of Nb, Cr, W, Mo, Si, C and B.

[0024] The beneficial effects of the present invention are as follows: the smelting method of the present invention can significantly reduce the volatilization loss of the Mn element and improve the consistency and uniformity of the manganese-containing titanium-aluminum alloy; at the same time, no additional electrode blocks need to be prepared, and one-time smelting can be achieved, which is simple, easy, green and environmentally friendly, and suitable for large-scale promotion and application. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 Shown is an electronic photograph of the alloy ingot prepared in Example 1;

[0026] Figure 2 Shown is an electron photograph of the alloy ingot prepared in Example 3. DETAILED DESCRIPTION

[0027] The following will be combined with the embodiments and drawings to clearly and completely describe the concept and technical effects of the present invention, so as to fully understand the purpose, scheme and effect of the present invention. It should be noted that the embodiments and features in the embodiments of the present invention can be combined with each other without conflict.

[0028] Example 1

[0029] A manganese-containing titanium-aluminum alloy, whose nominal composition by mass percentage includes: Al 28.6%, Mn 7.3%, and the remainder Ti. The preparation method thereof comprises the following steps:

[0030] The corresponding mass of raw materials is calculated according to the nominal composition of 5 kg of manganese-containing titanium-aluminum alloy (Ti-28.6Al-7.3Mn), namely 3040 grams of sponge titanium with a purity ≥99.8%, 1430 grams of industrial pure aluminum with a purity ≥99.95%, and 530 grams of TiMn master alloy (in terms of mass percentage, the Mn content in the TiMn master alloy is 68.91%, namely 365 grams of Mn, 165 grams of Ti, and the impurity O content of the TiMn master alloy is 76 ppm).

[0031] Use a CaO crucible for vacuum induction melting. Put all the industrial pure aluminum and half of the mass of sponge titanium into the CaO crucible and place it in a vacuum induction melting furnace. Put the remaining raw materials into the secondary feeding bin. Melt in an argon protective atmosphere with an argon pressure of 0.05MPa. Power on to melt the raw materials. After all the primary raw materials in the crucible are melted, slowly add the remaining sponge titanium. After all the sponge titanium is melted, add the TiMn intermediate alloy. After all the raw materials are melted, adjust the melt superheat to 50°C, refine for 2 minutes, and then cast to obtain an alloy ingot (i.e., manganese-containing titanium-aluminum alloy). Among them, Figure 1 Shown is an electron photograph of the alloy ingot.

[0032] Example 2

[0033] A titanium-aluminum alloy containing manganese, whose nominal composition is the same as that of Example 1. The preparation method thereof is different from that of Example 1 in that: instead of using TiMn master alloy, metal Mn is used as raw material:

[0034] Since the TiMn master alloy used in Example 1 has a higher melting point, the volatilization of the added metal Mn is less than that in Example 2, and therefore, 3% more Mn raw material is added.

[0035] The corresponding mass of raw materials is calculated based on the nominal composition of 5 kg of manganese-containing titanium-aluminum alloy (Ti-28.6Al-7.3Mn), namely 3205 grams of sponge titanium with a purity ≥99.8%, 1430 grams of industrial pure aluminum with a purity ≥99.95%, and 376 grams of metal Mn master alloy.

[0036] A CaO crucible is used for vacuum induction melting, all industrial pure aluminum and half the mass of sponge titanium are placed in a CaO crucible and placed in a vacuum induction melting furnace, and the remaining sponge titanium and metallic manganese are placed in a secondary feeding bin; the melting is carried out under an argon protective atmosphere, and the argon pressure is 0.05 MPa; power is turned on to melt the raw materials, and after all the primary raw materials in the crucible are melted, the remaining sponge titanium is slowly added, and after all the sponge titanium is melted, metallic manganese is added; after all the raw materials are melted, the superheat of the melt is adjusted to 50°C, and after refining for 2 minutes, casting is performed to obtain an alloy ingot.

[0037] Example 3

[0038] A manganese-containing titanium-aluminum alloy, whose nominal composition is the same as that of Example 1. The preparation method thereof is different from that of Example 1 in that: a water-cooled copper crucible is used; the smelting times are two times; and the preparation method specifically comprises the following steps:

[0039] Use a water-cooled copper crucible for vacuum induction melting. Put all the industrial pure aluminum and half the mass of sponge titanium into a water-cooled copper crucible and place it in a vacuum induction melting furnace. Put the remaining raw materials into a secondary feeding bin. Melt under an argon protective atmosphere with an argon pressure of 0.05MPa. Turn on the power to melt the raw materials. After all the primary raw materials in the crucible are melted, slowly add the remaining sponge titanium. After all the sponge titanium is melted, add the TiMn intermediate alloy. After all the raw materials are melted, adjust the melt superheat to 50°C, refine for 2 minutes, and then cool to room temperature. The ingot is condensed in the crucible. Then turn the ingot upside down and continue to perform vacuum induction melting under the same protective atmosphere. After all the raw materials are melted, adjust the melt superheat to 50°C, refine for 2 minutes, and then cast to obtain an alloy ingot (i.e., manganese-containing titanium-aluminum alloy). Among them, Figure 2 Shown is an electron photograph of the alloy ingot.

[0040] Example 4

[0041] A manganese-containing titanium-aluminum alloy, the preparation method of which is different from that of Example 1 in that the nominal composition is different from that of Example 1. The preparation method specifically comprises the following steps:

[0042] The corresponding mass of raw materials is calculated according to the nominal composition of 2kg of manganese-containing titanium-aluminum alloy (Ti-30.0Al-4.2Mn-1.9W-1.0Mo-0.03B-0.03C), namely 1190g of sponge titanium with a purity ≥99.8%, 600g of industrial pure aluminum with a purity ≥99.95%, 121g of TiMn master alloy (the master alloy Mn content is 68.91wt%, i.e., it contains 83.4g of Mn and 37.6g of Ti), 37.2g of metallic tungsten, 19.4g of metallic molybdenum, 31.1g of TiB2 powder (containing 1.9g of B element and 29.2g of titanium), and 0.6g of high-purity graphite.

[0043] A CaO crucible is used for vacuum induction melting. All industrial pure aluminum, metallic tungsten, metallic molybdenum and half the mass of sponge titanium are placed in a CaO crucible and placed in a vacuum induction melting furnace, and the remaining raw materials are placed in a secondary feeding bin; the melting is carried out under a protective atmosphere of argon gas, and the pressure of the argon gas is 0.05 MPa; power is turned on to melt the raw materials, and after all the primary raw materials in the crucible are melted, the remaining sponge titanium is slowly added, and after all the sponge titanium is melted, TiB2 and high-purity graphite are added, and finally the TiMn intermediate alloy is added; after all the raw materials are melted, the superheat of the melt is adjusted to 50°C, and after refining for 2 minutes, casting is performed to obtain an alloy ingot (i.e., a manganese-containing titanium-aluminum alloy).

[0044] Comparative Example 1 (no stepwise addition of titanium sponge)

[0045] A manganese-containing titanium-aluminum alloy, whose nominal composition is the same as that of Example 1, and whose preparation method is different from that of Example 1 in that: all industrial pure aluminum and all sponge titanium are put into a CaO crucible and placed in a vacuum induction melting furnace; the alloy is melted under an argon protective atmosphere with an argon pressure of 0.05 MPa; electricity is applied to melt the raw materials, and after all the raw materials in the crucible are melted, a TiMn intermediate alloy is added to continue the subsequent steps; the rest is the same as Example 1.

[0046] Due to the strong chemical activity of titanium, adding industrial pure aluminum and all sponge titanium to the crucible will lead to an increase in the Ti concentration in the melt, as well as an increase in the melting point of the melt and the impurity oxygen content.

[0047] Comparative Example 2 (TiMn master alloy not added step by step)

[0048] A manganese-containing titanium-aluminum alloy, whose nominal composition is the same as that of Example 1, and whose preparation method is different from that of Example 1 in that: all industrial pure aluminum, half of sponge titanium and TiMn master alloy are put into a CaO crucible and placed in a vacuum induction melting furnace; the alloy is melted under an argon protective atmosphere with an argon pressure of 0.05 MPa; and the raw materials are melted by electricity; the rest is the same as that of Example 1.

[0049] Since the TiMn master alloy is put into the crucible with the primary raw materials instead of being added for the second time later, the existence time of Mn in the melt is prolonged and the volatilization of the Mn element is greater.

[0050] Effect test

[0051] The element content of the manganese-containing titanium-aluminum alloys prepared in Examples 1-4 and Comparative Examples 1-2 was analyzed, and the results are shown in Table 1.

[0052] Table 1

[0053] Ti Mn O H Example 1 Bal. 7.18 0.056 0.0014 Example 2 Bal. 7.21 0.067 0.0015 Example 3 Bal. 7.20 0.039 0.0022 Example 4 Bal. 1.81 0.061 0.0011 Comparative Example 1 Bal. 7.20 0.112 0.0017 Comparative Example 2 Bal. 6.92 0.055 0.0012

[0054] It can be seen from Table 1 that the smelting method of the present invention for preparing the manganese-containing titanium-aluminum alloy can effectively reduce the large amount of volatilization and burning loss of the Mn element, thereby ensuring the consistency and uniformity of the components in the manganese-containing titanium-aluminum alloy.

[0055] The above is only a preferred embodiment of the present invention. The present invention is not limited to the above implementation. As long as the technical effect of the present invention is achieved by the same means, it should belong to the protection scope of the present invention. Within the protection scope of the present invention, its technical scheme and / or implementation method can have various modifications and changes.

Claims

1. A method for smelting a manganese-containing titanium-aluminum alloy, characterized in that: The following steps are involved: S1: preparing raw materials of corresponding mass according to the nominal composition of the manganese-containing titanium-aluminum alloy, wherein the raw materials include a first raw material and a manganese-containing master alloy or metallic manganese, and the first raw material includes sponge titanium and metallic aluminum; S2: placing the first raw material in a crucible for vacuum induction melting in a protective gas atmosphere, wherein the crucible is an oxide crucible or a water-cooled copper crucible; S3: After all the first raw materials are melted, the manganese-containing master alloy or metallic manganese is added to continue vacuum induction melting under a protective gas atmosphere. After all the first raw materials are melted, the melt temperature is adjusted to ≤80° C., and the materials are refined and cast to obtain the manganese-containing titanium-aluminum alloy.

2. The smelting method according to claim 1, characterized in that: The S2 includes the following specific process: vacuum induction melting the metal aluminum and half the mass of the sponge titanium, and after all of them are melted, adding the remaining first raw material to continue vacuum induction melting.

3. The smelting method according to claim 1, characterized in that: The oxide crucible in S2 is a CaO crucible, a Y2O3 crucible or a CaZrO3 crucible.

4. The smelting method according to claim 1, characterized in that: In the manganese-containing master alloy, manganese accounts for 64%-70% by mass.

5. The smelting method according to claim 1, characterized in that: When the crucible is an oxide crucible, a vacuum melting process is used in S3, and the specific process includes: after the first raw material is completely melted, the manganese-containing master alloy or metallic manganese is added to continue vacuum induction melting under a protective gas atmosphere, and after all are melted, the melt temperature is adjusted to ≤80°C, refined, and cast to obtain the manganese-containing titanium-aluminum alloy; When the crucible is a water-cooled copper crucible, a secondary vacuum melting process is adopted in S3, and the specific process includes: after the first raw material is completely melted, the manganese-containing intermediate alloy or metallic manganese is added to continue vacuum induction melting under a protective gas atmosphere, and after all are melted, the melt temperature is adjusted to ≤80°C, refined, and cooled to room temperature to obtain a molten alloy, and the molten alloy is turned upside down and continued to be vacuum induction melted under a protective gas atmosphere. After all are melted, the melt temperature is adjusted to ≤80°C, refined, and cast to obtain the manganese-containing titanium aluminum alloy.

6. The smelting method according to claim 1, characterized in that: The protective gas is an inert gas, and the gas pressure is 0.04MPa-0.1MPa.

7. The smelting method according to claim 1, characterized in that: The first raw material also includes at least one of metal Nb, metal Cr, metal W, metal Mo, and metal Si; the manganese-containing master alloy or metal manganese is added simultaneously with TiB2 and high-purity graphite.

8. The smelting method according to claim 1, characterized in that: The refining time is 1 min-5 min; and / or the purity of the titanium sponge is ≥99.8%, and the purity of the aluminum metal is ≥99.95%.

9. A manganese-containing titanium-aluminum alloy, characterized in that: Prepared by the preparation method according to any one of claims 1 to 8.

10. The manganese-containing titanium-aluminum alloy according to claim 9, characterized in that In terms of atomic percentage, in the manganese-containing titanium-aluminum alloy, Al accounts for 42%-48%, Mn accounts for 1%-8%, other elements account for 0%-10%, and the balance is Ti; the other elements include at least one of Nb, Cr, W, Mo, Si, C and B.

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