Aluminum-titanium-tin-zirconium-molybdenum-chromium six-element intermediate alloy, preparation method and application thereof

Abstract

This invention discloses a method for preparing a six-element master alloy of aluminum, titanium, tin, zirconium, molybdenum, and chromium, comprising the following steps: Step S1, thoroughly mixing an appropriate amount of potassium chlorate (a heating agent) with aluminum powder, titanium dioxide, tin dioxide, zirconium dioxide, molybdenum trioxide, chromium trioxide, and a slagging agent; Step S2, loading the uniformly mixed materials into a reaction vessel, performing a compaction treatment, and then igniting the mixture. The resulting molten alloy sinks, while slag used to protect the molten alloy floats to the surface. After cooling, the molten alloy yields an initial aluminum-titanium-tin-zirconium-molybdenum-chromium alloy block; Step S3, the alloy block is refined and crushed to obtain the aluminum-titanium-tin-zirconium-molybdenum-chromium master alloy. The method for preparing the six-element master alloy of aluminum, titanium, tin, zirconium, molybdenum, and chromium provided by this invention achieves a one-time preparation through a self-propagating reaction, resulting in a more uniform alloy composition. This effectively improves the alloying degree of TC17 and Ti1000, prevents component segregation and inclusions, and enhances the performance of titanium alloys such as TC17 and Ti1000. This invention also provides an aluminum-titanium-tin-zirconium-molybdenum-chromium master alloy prepared by the above method.

Description

Technical Field

[0001] This invention relates to the field of alloy materials technology, specifically to a special intermediate alloy for titanium alloys containing elements such as Al, Mo, Cr, Sn, and Zr, such as TC17 and Ti1000, and particularly to a six-element intermediate alloy of aluminum, titanium, tin, zirconium, molybdenum, and chromium, its preparation method, and its application. Background Technology

[0002] When TC17 and Ti1000 titanium alloys are prepared by adding Al-Mo master alloy, Al-Sn master alloy, sponge zirconium, and metallic Cr, defects such as segregation and inclusions are prone to occur in TC17 and Ti1000 titanium alloys due to the high melting point and density of metallic Cr, coupled with the large reaction heat effect and poor quality stability of Al-60Mo master alloy. This severely restricts the preparation of TC17 and Ti1000 titanium alloy ingots, especially large-sized ingots, which cannot meet the subsequent performance requirements of titanium materials.

[0003] The elemental ranges of Al, Mo, and Cr in Φ720mm TC17 titanium alloy ingots produced using multiple binary master alloys are controlled at 0.4%, 0.3%, and 0.4%, respectively. The elemental ranges of Al, Mo, and Cr in Φ820mm Ti1000 titanium alloy ingots produced using the same binary master alloys are controlled at 0.4%, 0.4%, and 0.5%, respectively. Subsequent processing of TC17 and Ti1000 bars also exhibits relatively more β-spot problems due to localized compositional segregation. The alloying method using high-melting-point elements, the control of impurity elements in large-size industrial-grade ingots, and the increased segregation due to larger dimensions (≥Φ820mm) all constrain the production of large-size ingots. Currently, production remains at the trial production stage and cannot be industrialized.

[0004] Therefore, it is necessary to provide a new intermediate alloy to solve the technical problems of large-scale ingot production. Summary of the Invention

[0005] The technical problem to be solved by the present invention is to provide a method for preparing a six-element master alloy of aluminum, titanium, tin, zirconium, molybdenum and chromium, which is prepared in one step through a self-propagating reaction. The alloy composition is more uniform, which can effectively improve the alloying degree of TC17 and Ti1000, prevent the occurrence of component segregation and inclusions, and improve the performance of titanium alloys such as TC17 and Ti1000.

[0006] The technical solution of the present invention is as follows:

[0007] A method for preparing a six-element master alloy of aluminum, titanium, tin, zirconium, molybdenum, and chromium includes the following steps:

[0008] Step S1: Mix an appropriate amount of the exothermic agent potassium chlorate with aluminum powder, titanium dioxide, tin dioxide, zirconium dioxide, molybdenum trioxide, chromium trioxide and slagging agent in a specific ratio.

[0009] Step S2: The uniformly mixed materials are loaded into the reaction vessel, compacted, and then ignited. The resulting molten alloy sinks, while the slag used to protect the molten alloy floats to the surface. After the molten alloy cools, an initial aluminum-titanium-tin-zirconium-molybdenum-chromium alloy block is obtained.

[0010] Step S3: The alloy block is finely processed and crushed to obtain an aluminum-titanium-tin-zirconium-molybdenum-chromium master alloy. The mass percentages of each component in the aluminum-titanium-tin-zirconium-molybdenum-chromium master alloy are as follows:

[0011] Titanium: 11-15%, Molybdenum: 21%-25%, Chromium: 21%-25%, Tin: 10%-14%, Zirconium: 10%-14%, Balance: Aluminum and unavoidable impurities.

[0012] Furthermore, the proportions of each component in the raw material, expressed as a weight percentage, are as follows:

[0013] Titanium dioxide: 8.97%-12.38%, tin dioxide: 6.28%-8.68%, zirconium dioxide: 12.71%-16.21%, molybdenum trioxide: 15.25%-18.55%, chromium trioxide: 15.17%-17.79%, potassium chlorate: 3.46%-4.27%, slagging agent: 4.34%-4.59%, balance being aluminum powder.

[0014] Furthermore, in step S2, the slag temperature is controlled at 1680-1720℃.

[0015] Furthermore, the titanium dioxide, tin dioxide, zirconium dioxide, molybdenum trioxide, chromium trioxide and slagging agent in the raw materials are first dried and then mixed, wherein the drying temperature is 80-120℃ and the drying time is 10-20h.

[0016] Furthermore, the titanium dioxide, chromium trioxide, potassium chlorate, tin dioxide, and zirconium dioxide in the raw materials need to be passed through a 2.0×2.0 sieve before being mixed with other alloying elements.

[0017] This invention also provides a six-element master alloy of aluminum, titanium, tin, zirconium, molybdenum, and chromium, prepared by the above method. The mass percentages of each component in the aluminum-titanium-tin-zirconium-molybdenum-chromium master alloy are as follows:

[0018] Titanium: 11-15%, Molybdenum: 21%-25%, Chromium: 21%-25%, Tin: 10%-14%, Zirconium: 10%-14%, Balance: Aluminum and unavoidable impurities.

[0019] This invention also provides the application of an aluminum-titanium-tin-zirconium-molybdenum-chromium hexa-element master alloy in TC17 or Ti1000 materials.

[0020] Compared with existing technologies, the six-element master alloy of aluminum, titanium, tin, zirconium, molybdenum, and chromium provided by this invention and its preparation method have the following advantages:

[0021] I. The method for preparing the six-element master alloy of aluminum, titanium, tin, zirconium, molybdenum, and chromium provided by this invention is obtained in one step through a self-propagating reaction. The reaction process is stable, with uniform heat in different reaction zones. The molten slag formed continuously transfers heat to the alloy liquid, prolonging the solidification time of the alloy liquid and increasing the self-diffusion time of chromium and aluminum elements in the alloy liquid (refining process), resulting in a more uniform alloy composition. During titanium alloy casting, it can effectively improve the alloying degree of TC17 and Ti1000, effectively reduce alloy composition segregation, and improve the performance of titanium alloys such as TC17 and Ti1000.

[0022] II. ZrO2 can form solid solutions or compounds with oxides such as Al2O3 and MgO, which have similar properties. This can be seen from the ZrO2-Al2O3 phase diagram (e.g., Figure 1 As shown, ZrO2 and Al2O3 compounds or solid solutions are formed under different compositions and temperatures. This means that during alloy preparation, not all ZrO2 is reduced by Al, and some unreacted ZrO2 forms solid solutions or compounds with Al2O3, resulting in a low Zr content in the alloy. Therefore, the aluminum-titanium-tin-zirconium-molybdenum-chromium six-element master alloy provided by this invention, by increasing the amount of ZrO2 added, yields an aluminum-titanium-tin-zirconium-molybdenum-chromium master alloy that meets the requirements for zirconium content and stability.

[0023] Third, tin has a boiling point of 2270℃, lower than molybdenum's melting point of 2610℃. Since there is no overlap in the liquid temperatures of these two elements, vacuum induction melting is not feasible. Using the alloy preparation method provided by this invention, a six-element master alloy can be formed between tin and aluminum, zirconium, chromium, and titanium through a self-propagating reaction. Attached Figure Description

[0024] To more clearly illustrate the technical solutions in the embodiments of the present invention, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0025] Figure 1 The phase diagram of ZrO2 and Al2O3 in the alloy;

[0026] Figure 2 This is a schematic diagram of longitudinal sampling of an ingot prepared using the aluminum-titanium-tin-zirconium-molybdenum-chromium hexa-element master alloy of the present invention.

[0027] Figure 3 A schematic diagram of transverse sampling of an ingot prepared using the aluminum-titanium-tin-zirconium-molybdenum-chromium hexa-element master alloy of the present invention;

[0028] Figure 4This is a longitudinal main element composition distribution diagram of an ingot prepared using the aluminum-titanium-tin-zirconium-molybdenum-chromium hexa-element master alloy of the present invention;

[0029] Figure 5 This is a lateral main element composition distribution diagram of an ingot prepared using the aluminum-titanium-tin-zirconium-molybdenum-chromium six-element master alloy of the present invention. Detailed Implementation

[0030] To enable those skilled in the art to better understand the technical solutions in the embodiments of the present invention, and to make the above-mentioned objectives, features and advantages of the present invention more apparent and understandable, the specific embodiments of the present invention will be further described below.

[0031] It should be noted that the descriptions of these embodiments are for the purpose of aiding understanding the present invention, but do not constitute a limitation thereof. Furthermore, the technical features involved in the various embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0032] A method for preparing a six-element master alloy of aluminum, titanium, tin, zirconium, molybdenum, and chromium includes the following steps:

[0033] Step S1: Mix an appropriate amount of potassium chlorate (the exothermic agent) with aluminum powder, titanium dioxide, tin dioxide, zirconium dioxide, molybdenum trioxide, chromium trioxide, and slagging agent in a specific ratio, and mix thoroughly. The proportions of each component in the raw materials by weight percentage are as follows:

[0034] Titanium dioxide: 8.97%-12.38%, tin dioxide: 6.28%-8.68%, zirconium dioxide: 12.71%-16.21%, molybdenum trioxide: 15.25%-18.55%, chromium trioxide: 15.17%-17.79%, potassium chlorate: 3.46%-4.27%, slagging agent: 4.34%-4.59%, balance being aluminum powder.

[0035] Specifically, the raw materials—titanium dioxide, tin dioxide, zirconium dioxide, molybdenum trioxide, chromium trioxide, and slag-forming agent—are first dried before being mixed. The drying temperature is 80-120℃, and the drying time is 10-20 hours. The purpose of drying the raw materials is to remove moisture from the powder, preventing the introduction of hydrogen elements due to moisture, which severely affects the brittleness of the titanium alloy; it also avoids appearance defects such as porosity in the alloy blocks caused by moisture. The slag-forming agent used is conventional calcium fluoride. Calcium fluoride is an alkaline slag-forming agent that can lower the melting point of slag and improve its fluidity, and it is widely used in the metallurgical field.

[0036] After the raw materials are dried, titanium dioxide, chromium trioxide, potassium chlorate, tin dioxide, and zirconium dioxide need to be passed through a 2.0×2.0 sieve before being mixed with other alloying elements. This is to eliminate the problem of uneven mixing caused by powder agglomeration or particle size differences. Using this method, the materials can be fully mixed, and after the self-propagating reaction, the composition of different alloy blocks is uniform.

[0037] Step S2: The uniformly mixed materials are loaded into the reaction vessel, compacted, and then ignited. The resulting molten alloy sinks, while the slag used to protect the molten alloy floats to the surface. After the molten alloy cools, an initial aluminum-titanium-tin-zirconium-molybdenum-chromium alloy block is obtained.

[0038] In this invention, an exothermic agent is added to the alloy raw materials to continuously transfer heat to the alloy liquid, prolonging the solidification time of the alloy liquid and increasing the self-diffusion time of each metal element in the alloy liquid (refining process), resulting in a more uniform alloy composition. Specifically, the slag temperature is controlled at 1680-1720℃, preferably 1700℃.

[0039] Step S3: The alloy block is finely finished and crushed to obtain an aluminum-titanium-tin-zirconium-molybdenum-chromium master alloy with a clean surface, free of oxides and other metallic and non-metallic impurities. The mass percentage of each component in the aluminum-titanium-tin-zirconium-molybdenum-chromium master alloy is as follows:

[0040] Titanium: 11-15%, Molybdenum: 21%-25%, Chromium: 21%-25%, Tin: 10%-14%, Zirconium: 10%-14%, Balance: Aluminum and unavoidable impurities.

[0041] Examples 2-6

[0042] Based on the preparation method of Example 1, six-element master alloys with different alloy compositions were obtained by adjusting the proportions of each raw material. Details are as follows:

[0043] Table 1: Composition Ratio of Raw Materials (by weight percentage)

[0044] aluminum powder Titanium dioxide Tin dioxide Zirconium dioxide Molybdenum trioxide Chromium trioxide Potassium chlorate Slag-forming agent Example 2 26.76％ 12.38％ 6.28％ 12.71％ 18.55％ 15.17％ 3.62％ 4.54％ Example 3 25.23％ 11.29％ 7.98％ 15.11％ 15.25％ 16.28％ 4.27％ 4.59％ Example 4 26.44％ 9.71％ 6.77％ 16.21％ 17.46％ 15.60％ 3.46％ 4.34％ Example 5 25.89％ 10.57％ 7.42％ 13.31％ 16.81％ 17.79％ 3.65％ 4.57％ Example 6 26.35％ 8.97％ 8.68％ 14.79％ 16.12％ 17.13％ 3.53％ 4.43％

[0045] Table 2: Component proportions of the prepared intermediate alloy (by weight percentage)

[0046] Ti Mo Cr Sn Zr Al and unavoidable impurities Example 2 15 25 21 10 10 19 Example 3 14 21 23 13 14 15 Example 4 12 24 22 11 13 18 Example 5 13 23 25 12 11 16 Example 6 11 22 24 14 12 17

[0047] Example 7 Application Example

[0048] Taking the intermediate alloy of Example 3 as an example, the application of the hexa-element intermediate alloy prepared in this invention in the titanium alloy material TC17 is described in detail.

[0049] The method for preparing TC17 titanium alloy using the hexa-element intermediate alloy of Example 3 includes the following steps:

[0050] (1) The weight percentage of each element is as follows: Al: 4.5%~5.5%, Mo: 3.5%~4.5%, Sn: 1.5%~2.5%, Cr: 3.5%~4.5%, Zr: 1.5%~2.5%, O: 0.08%~0.13%, with the balance being Ti and unavoidable impurities. The total amount of impurity elements shall not exceed 0.30%, and the sum of the weight percentages of the above components shall be 100%. The alloy content of Al-Ti-Sn-Zr-Mo-Cr, Al-60Mo, Al-37Sn, and Al-bean was calculated based on the percentage content of Al, Mo, Sn, Cr, and Zr (the alloy element content of Al, Mo, Sn, Cr, and Zr is basically provided by the Al-Ti-Sn-Zr-Mo-Cr hexa-element alloy, and only a small amount of Al-60Mo, Al-37Sn, and Al-bean binary alloys need to be added). Granular Al-60Mo and Al-bean binary alloys and shavings of Al-37Sn binary alloy were weighed and mixed with small particles of sponge titanium with a particle size of 0.83mm to 12.7mm for single-piece electrode mixing. The mixture was then pressed into large single-weight electrode blocks using a large hydraulic press. The oxygen element in the electrode blocks was provided by the raw materials, such as sponge titanium. When the oxygen element provided by the raw materials could not meet the required ratio, TiO2 was used to adjust the oxygen content.

[0051] (2) The pressed electrode block is welded into a consumable electrode by argon plasma arc in a vacuum welding box. The welding current is 250A to 600A and the welding voltage is 30V to 70V. The weld point is required to be silver-white or light yellow to prevent metallurgical defects such as weld point oxidation and high-density inclusions.

[0052] (3) The consumable electrode obtained in step (2) was vacuum melted three times in a vacuum furnace to obtain an ingot with a diameter of 820mm. The specific melting parameters are as follows:

[0053] One-time melting: crucible size Φ650mm, pre-melting vacuum degree ≤2.0Pa, leakage rate ≤0.93Pa / min, melting voltage 25V~38V, melting current 15kA~20kA, arc stabilizing current DC 10.0A, cooling time 7.0h.

[0054] Secondary melting: Crucible specifications Φ750mm, pre-melting vacuum degree ≤1.0Pa, leakage rate ≤0.70Pa / min, melting voltage 23V~35V, melting current 9kA~18kA, arc stabilizing current AC 10.0A / 20S, cooling time 8.0h.

[0055] Three melting processes: crucible size Φ820mm, pre-melting vacuum degree ≤1.0Pa, leakage rate ≤0.70Pa / min, melting voltage 23V~35V, melting current 10kA~19kA, arc stabilization current AC 8.0A / 2S, cooling time 10.0h, thus obtaining TC17 titanium alloy ingot with a size of Φ820mm.

[0056] Sampling and chemical composition analysis were performed on 5 points along the longitudinal direction (head, top, middle, bottom, and tail) and 15 points along the cross-section of the 7.0-ton industrial-grade TC17 titanium alloy ingot with a diameter of Φ820mm prepared in Example 7 (sampling points are as follows). Figure 2 and Figure 3 (As shown). The results of the longitudinal and transverse elemental chemical composition analysis of the ingot are shown in Tables 1 and 2:

[0057] Table 1: Elemental composition analysis results of longitudinal section of TC17 ingot with Φ820mm specification

[0058]

[0059]

[0060] Table 2: Elemental composition analysis results of transverse lateral portion of TC17 ingot with Φ820mm specification

[0061]

[0062] Please refer to the following: Figure 4 and Figure 5 ,in Figure 4 This is a longitudinal main element composition distribution diagram of an ingot prepared using the aluminum-titanium-tin-zirconium-molybdenum-chromium hexa-element master alloy of the present invention; Figure 5 This is a lateral main element composition distribution diagram of the ingot prepared using the aluminum-titanium-tin-zirconium-molybdenum-chromium hexa-element master alloy of the present invention. (Refer to Tables 1 and 2.) Figure 4 , Figure 5 The data shows that the main components and impurity element analysis results of the Φ820mm 7.0t TC17 ingot prepared based on the hexa-element alloy all meet the standard requirements, and the overall deviation is small. The ingot composition has good uniformity, and the range of the main elements is also small: the maximum deviation of Al is 0.152%, the maximum range of Cr is 0.24%, the maximum range of Zr is 0.11%, the maximum range of Mo is 0.13%, the maximum range of Sn is 0.10%, and the range of O is 0.0%. This indicates that the intermediate alloy used has a uniform composition and the impurity elements are controlled at very low levels, which fully meets the requirements for ingot composition control.

[0063] Example 8: Production of TC17 titanium alloy using multiple binary alloys

[0064] Using the same production process and smelting process as in Example 7, this example uses TC17 steel with a diameter of Φ820mm produced from binary alloys such as Al-Mo, Al-Sn, and Ti-Sn, and pure alloy additives such as HZr-1 and metallic Cr. The same elemental analysis methods as in Example 7 were employed, and the compositional analysis results are shown in Tables 3 and 4.

[0065] Table 3: Elemental composition analysis results of TC17 ingots produced using binary alloys (vertical direction)

[0066]

[0067]

[0068] Table 4: Elemental composition analysis results of TC17 ingots produced using binary alloys

[0069]

[0070] As can be seen from Tables 3 and 4, the chemical composition and impurity element analysis results of TC17 with a specification of Φ820mm produced based on binary alloys such as Al-Mo, Al-Sn, and Ti-Sn, as well as pure alloy additives such as HZr-1 and metallic Cr, all meet the standard requirements. However, there are some deviations in the composition, which are shown in Tables 5 and 6.

[0071] Table 5: Comparison of longitudinal elemental deviations in TC17 ingots produced from hexa-elemental and binary alloys

[0072]

[0073] Table 6: Comparison of Lateral Elemental Deviations in TC17 Ingots Produced from Hexa-Metallic Alloys and Binary Alloys

[0074]

[0075] As shown in Tables 5 and 6, the titanium alloy material prepared using the hexa-element master alloy of the present invention has smaller deviations in each component than the titanium alloy material prepared using the binary alloy. This indicates that the hexa-element master alloy of the present invention has a uniform composition, which can effectively reduce alloy component segregation and improve the performance of the titanium alloy material during titanium alloy casting.

[0076] The embodiments of the present invention have been described in detail above, but the present invention is not limited to the described embodiments. For those skilled in the art, various changes, modifications, substitutions, and variations made to these embodiments without departing from the principles and spirit of the present invention still fall within the protection scope of the present invention.

Claims

1. A method for preparing a six-element master alloy of aluminum, titanium, tin, zirconium, molybdenum, and chromium, characterized in that, When applied to TC17 or Ti1000 materials, the process includes the following steps: Step S1: Mix an appropriate amount of the exothermic agent potassium chlorate with aluminum powder, titanium dioxide, tin dioxide, zirconium dioxide, molybdenum trioxide, chromium trioxide, and slagging agent in a specific ratio. The proportions of each component in the raw materials by weight percentage are as follows: Titanium dioxide: 8.97%-12.38%, tin dioxide: 6.28-8.68%, zirconium dioxide: 12.71-16.21%, molybdenum trioxide: 15.25-18.55%, chromium trioxide: 15.17-17.79%, potassium chlorate: 3.46%~4.27%, slagging agent: 4.34%~4.59%, balance: aluminum powder; Step S2: The uniformly mixed materials are loaded into the reaction vessel, compacted, and then ignited. The resulting molten alloy sinks, while the slag used to protect the molten alloy floats to the surface. After the molten alloy cools, an initial aluminum-titanium-tin-zirconium-molybdenum-chromium alloy block is obtained. Step S3: The alloy block is finely processed and crushed to obtain an aluminum-titanium-tin-zirconium-molybdenum-chromium master alloy. The mass percentages of each component in the aluminum-titanium-tin-zirconium-molybdenum-chromium master alloy are as follows: Titanium: 11-15%, Molybdenum: 21%-25%, Chromium: 21%-25%, Tin: 10%-14%, Zirconium: 10%-14%, Balance: Aluminum and unavoidable impurities.

2. The method for preparing the six-element master alloy of aluminum, titanium, tin, zirconium, molybdenum, and chromium according to claim 1, characterized in that, In step S2, the slag temperature is controlled at 1680-1720℃.

3. The method for preparing the six-element master alloy of aluminum, titanium, tin, zirconium, molybdenum, and chromium according to claim 1, characterized in that, The raw materials, including titanium dioxide, tin dioxide, zirconium dioxide, molybdenum trioxide, chromium trioxide, and slagging agent, are first dried before being mixed. The drying temperature is 80-120℃ and the drying time is 10-20h.

4. The method for preparing the six-element master alloy of aluminum, titanium, tin, zirconium, molybdenum, and chromium according to claim 3, characterized in that, Titanium dioxide, chromium trioxide, potassium chlorate, tin dioxide, and zirconium dioxide in the raw materials need to be passed through a 2.0×2.0 sieve before being mixed with other alloying elements.

5. A six-element master alloy of aluminum, titanium, tin, zirconium, molybdenum, and chromium, characterized in that, Prepared by the method according to any one of claims 1-4.

6. The application of the aluminum-titanium-tin-zirconium-molybdenum-chromium hexa-element master alloy as described in claim 5 in TC17 or Ti1000 materials.

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