A molybdenum-chromium-tin-aluminum intermediate alloy, a preparation method and application thereof

Abstract

This invention provides a molybdenum-chromium-tin-aluminum master alloy, its preparation method, and its applications. The master alloy comprises the following components in the indicated mass percentages: Mo: 24%-30%, Cr: 24%-30%, Sn: 10%-16%, Al: 30%-36%, and unavoidable impurities. The master alloy has a melting point of 1330℃-1350℃ and a density of 4.80 g·cm³. ‑3 -5.00 g·cm ‑3 The particle size D90 is 0.010mm-0.050mm. This molybdenum-chromium-tin-aluminum master alloy is prepared using a one-step method combined with radio frequency plasma spheroidization technology. It exhibits accurate chemical composition, high purity, uniform particle size, minimal elemental segregation, and low impurity content. This molybdenum-chromium-tin-aluminum master alloy shows promising application prospects and large-scale promotion potential in the TC17 titanium alloy field.

Description

Technical Field

[0001] This invention relates to alloy technology, and more particularly to a molybdenum-chromium-tin-aluminum master alloy, its preparation method, and its application. Background Technology

[0002] Titanium alloys possess excellent properties, such as high specific strength, superior corrosion resistance, and strong high-temperature resistance, making them widely used in aerospace, machinery, chemical engineering, metallurgy, energy, and military industries. With the continuous advancement of human exploration of space and the deep sea, the requirements for titanium alloys to operate under high temperature, high pressure, and high corrosion conditions are gradually increasing.

[0003] α+β type titanium alloys are a class of dual-phase titanium alloys possessing both an α phase (hexagonal close-packed structure) and a β phase (body-centered cubic structure). The phase ratio is adjusted by adding β-stabilizing elements (such as V, Mo, Cr, etc.). Due to their high strength, heat resistance, and excellent machinability, dual-phase titanium alloys are widely used in aerospace, medical, shipbuilding, chemical, and automotive industries. There are many types of titanium alloys with this structure, such as the foreign grades Ti-6242, Ti-5553, IMI834, and BT22, and the domestic grades TC4, TC11, TC17, and TC21.

[0004] TC17 titanium alloy is a heat-resistant, high-strength titanium alloy with an α+β dual-phase structure and a nominal composition of Ti-5Al-2Sn-2Zr-4Mo-4Cr. TC17 titanium alloy possesses high strength (up to 1300 MPa in the solution-aged state) and high hardenability (critical hardenability thickness up to 150 mm), while also exhibiting good fracture toughness, corrosion resistance, and thermal stability. It can be used to manufacture engine components such as fan discs and compressor discs, as well as fuselage structures such as landing gear and load-bearing frames. Currently, the common manufacturing process for TC17 titanium alloy involves mixing and pressing a mixture of sponge titanium, molybdenum-aluminum binary alloy, chromium-aluminum binary alloy, titanium-tin binary alloy, sponge zirconium, and aluminum briquettes into electrodes, followed by melting in a vacuum arc furnace to form ingots. The melting process requires a variety of materials with significant differences in melting point and density, which can easily lead to defects such as raw material burn-off and elemental segregation within the ingot during manufacturing.

[0005] Currently, the main methods for preparing multi-element intermediate alloys that provide raw materials for TC17 titanium alloy are the out-of-furnace aluminothermic method, which involves mixing the oxides of the required alloying elements with metallic aluminum and then using an aluminothermic reduction reaction; or the out-of-furnace aluminothermic method combined with vacuum induction melting, which involves first combining some alloying elements into a transition intermediate alloy and then using a vacuum induction melting process for final melting.

[0006] For example, CN103898390 A discloses a pentagonal master alloy for TC17 titanium alloy ingot smelting and its preparation method. The preparation process involves using aluminum as a reducing agent and molybdenum trioxide, tin dioxide, chromium trioxide, and zirconium dioxide as oxidizing agents, while simultaneously adding potassium chlorate and calcium fluoride. After uniform mixing, the materials are smelted using an out-of-furnace aluminothermic process to obtain an aluminum-molybdenum-tin-zirconium-chromium master alloy. This method has advantages such as simple equipment, convenient operation, and low investment. However, its disadvantage is that the prepared alloy ingot contains numerous oxide discoloration areas and oxide inclusions, which negatively impact the subsequent TC17 titanium alloy smelting, reducing the final quality of the TC17 titanium alloy ingot and components.

[0007] For example, CN102628130 A discloses an aluminum-tin-zirconium-molybdenum-chromium master alloy and its preparation method. The preparation process uses aluminum as a reducing agent and molybdenum trioxide and tin dioxide as oxidizing agents, employing an aluminothermic reduction reaction to prepare the aluminum-tin-molybdenum alloy. Then, the aluminum-tin-molybdenum alloy, chromium granules, sponge zirconium, metallic aluminum granules, and metallic tin granules are prepared into the aluminum-tin-zirconium-molybdenum-chromium master alloy using a vacuum induction melting process. This method has advantages such as uniform alloy composition and minimal elemental segregation. However, tin needs to be added twice, in oxide and elemental forms, making the preparation process relatively cumbersome and the production cycle long. Furthermore, the carbon crucible used needs to be coated with a layer of yttrium oxide, increasing production costs and hindering the widespread adoption of the process.

[0008] In summary, multi-component master alloys are mostly prepared using a one-step method (aluminothermic reduction) or a two-step method (aluminothermic reduction + vacuum induction melting). The aluminothermic reduction method is an out-of-furnace method, and the alloys prepared have a high impurity content, with internal oxide structures and elemental segregation regions, which cannot meet the requirements for pure smelting raw materials for TC17 titanium alloy. In the two-step method, the required equipment is too demanding, and the process flow is cumbersome, which is not conducive to the promotion of the process. Summary of the Invention

[0009] The purpose of this invention is to address the above-mentioned problems by proposing a molybdenum-chromium-tin-aluminum master alloy. This alloy is prepared by a one-step method combined with radio frequency plasma spheroidization technology. It has accurate chemical composition, high purity, uniform particle size, small elemental segregation, and low impurity content. This master alloy has good application prospects and large-scale promotion potential in the field of TC17 titanium alloy.

[0010] It should be noted that, in this invention, unless otherwise specified, the specific meaning of "comprising" in relation to composition and description includes both open-ended meanings such as "comprising," "including," etc., and closed-ended meanings such as "composed of," "consisting of," etc., and similar meanings.

[0011] To achieve the above objectives, the technical solution adopted by the present invention is: a molybdenum-chromium-tin-aluminum master alloy, comprising the following components in terms of mass percentage: Mo: 24%-30%, Cr: 24%-30%, Sn: 10%-16%, Al: 28%-37%, and unavoidable impurities.

[0012] Furthermore, the molybdenum-chromium-tin-aluminum master alloy comprises the following components in the following mass percentages: Mo: 25%-28%, Cr: 26%-29%, Sn: 12%-15%, Al: 32%-35%, and unavoidable impurities.

[0013] Furthermore, the impurities in the molybdenum-chromium-tin-aluminum master alloy are: Fe: 0.25% Max, Si: 0.20% Max, C: 0.05% Max, S: 0.05% Max, O: 0.10% Max, N: 0.05% Max, and other single impurity elements: 0.05% Max.

[0014] Furthermore, the melting point of the molybdenum-chromium-tin-aluminum master alloy is 1330℃-1350℃, and the density of the molybdenum-chromium-tin-aluminum master alloy is 4.80 g·cm³. -3 -5.00 g·cm -3 .

[0015] Furthermore, the particle size D90 of the molybdenum-chromium-tin-aluminum master alloy is 0.010mm-0.050mm.

[0016] Another objective of this invention is to disclose a method for preparing a molybdenum-chromium-tin-aluminum (MoCrSnAl) master alloy. This invention utilizes an aluminothermic reduction reaction combined with radio frequency plasma spheroidization technology to obtain a MoCrSnAl master alloy that meets the requirements for high-quality TC17 titanium alloy smelting. Specifically, the method for preparing the MoCrSnAl master alloy includes the following steps:

[0017] Step 1: Mix molybdenum trioxide, chromium trioxide, tin dioxide and aluminum powder in a mass ratio of (0.600-0.620):(0.610-0.620):(0.240-0.260):1, add to a reaction crucible, ignite and react at a temperature of 2150℃-2200℃ for 35s-45s to obtain a primary molybdenum-chromium-tin-aluminum alloy.

[0018] Step 2: Crush the molybdenum-chromium-tin-aluminum primary alloy using a crusher to obtain molybdenum-chromium-tin-aluminum primary alloy powder;

[0019] Step 3: Using the aforementioned molybdenum-chromium-tin-aluminum primary alloy powder as raw material, a molybdenum-chromium-tin-aluminum intermediate alloy is produced using radio frequency plasma spheroidization technology.

[0020] Furthermore, the purity of the molybdenum trioxide (MoO3) is ≥99.0%, the purity of the chromium trioxide (Cr2O3) is ≥99.0%, the purity of the tin dioxide (SnO2) is ≥99.0%, and the purity of the aluminum powder (Al) is ≥99.7%.

[0021] Furthermore, the particle size of the aluminum powder is 0.3mm-3.0mm.

[0022] Furthermore, before step 1, molybdenum trioxide, chromium trioxide, tin dioxide and aluminum powder are dried in a constant temperature drying room at 50℃-60℃ for 22h-24h to ensure that the moisture content of the reaction materials is ≤0.1% and the initial temperature is 40℃-50℃.

[0023] Furthermore, in step 1, the mass ratio of molybdenum trioxide, chromium trioxide, tin dioxide, and aluminum powder is 0.611:0.618:0.250:1.

[0024] Furthermore, in step 1, a primary molybdenum-chromium-tin-aluminum alloy is prepared using an aluminothermic reduction reaction, with the reaction crucible being an aluminum oxide (Al2O3) crucible. To fully utilize the slag (Al2O3) produced by the reaction, the furnace lining of the reaction apparatus is made of slag, which can effectively reduce the introduction of impurities and further reduce the impurity content in the alloy, thus saving costs and achieving the purpose of recycling raw materials.

[0025] Furthermore, the aluminothermic reduction reaction does not require heating. The igniter used is magnesium powder (Mg), aluminum powder, and calcium peroxide (CaO2). During use, the mixture is easily ignited by the combustion of the magnesium powder, aluminum powder, and calcium peroxide powder. As a side reaction, the heat generated initiates the main reaction.

[0026] Furthermore, before crushing in step 2, the molybdenum-chromium-tin-aluminum primary alloy is polished and cleaned to obtain a high-quality semi-finished alloy block. The molybdenum-chromium-tin-aluminum primary alloy (molybdenum-chromium-tin-aluminum quaternary alloy) prepared by the aluminothermic reduction reaction has a slight oxide layer on its appearance that can be removed by polishing. After polishing, the alloy is silvery bright and has good surface quality.

[0027] Furthermore, the particle size of the molybdenum-chromium-tin-aluminum primary alloy powder in step 2 is 0-0.3 mm.

[0028] Furthermore, the equipment used in the radio frequency plasma spheroidization technology described in step 3 is a radio frequency plasma spheroidization device (also known as a plasma spheroidization device), which consists of four parts: a high-frequency power supply system, a gas supply and powder delivery system, a reaction and collection system, and an auxiliary system.

[0029] Further, the specific steps of step 3, which uses the aforementioned molybdenum-chromium-tin-aluminum primary alloy powder as raw material and employs radio frequency plasma spheroidization technology to produce molybdenum-chromium-tin-aluminum master alloy, are as follows: First, turn on the gas supply system and fill the equipment with high-purity argon gas as the working gas, controlling the flow rate at 15 L·min. -1 Up to 20 L·min -1 Continue for 5-10 minutes to establish the desired atmosphere;

[0030] Then, the sheath gas valve was opened, and high-purity helium was introduced at a flow rate of 40 L / min. -1 -60 L·min -1 Inflation time: 5-6 minutes;

[0031] Turn on the high-frequency power supply and set the power to 25 kW-40 kW to generate a high-temperature plasma torch flame;

[0032] After the plasma torch flame stabilizes, the carrier gas argon is started to deliver molybdenum-chromium-tin-aluminum primary alloy powder at a feed rate of 40 g·min. -1 -100 g·min -1 Molybdenum-chromium-tin-aluminum (MCP-A) primary alloy powder carried by a carrier gas is melted into droplets in a high-temperature reaction chamber and then enters a cooling chamber. Under the combined action of an argon atmosphere and an auxiliary water cooling system in the cooling chamber, the molten droplets cool, solidify, and spheroidize to prepare the MCP-A master alloy. The preferred ratio of argon flow rate, helium flow rate, and powder feed rate is 3L-4L: 8L-12L: 8g-20g.

[0033] Furthermore, the purity of the argon gas is ≥99.99%.

[0034] Furthermore, the purity of the helium gas is ≥99.99%.

[0035] Furthermore, the pressure inside the high-temperature reaction chamber is 1.5 Pa to 2.5 Pa. The "high temperature" in the high-temperature reaction chamber refers to the very high temperature of the plasma core (8000℃-10000℃), rather than a stable and continuous high temperature throughout the reaction chamber.

[0036] Furthermore, the particle size D90 of the molybdenum-chromium-tin-aluminum master alloy is 0.010mm-0.050mm.

[0037] Another objective of this invention is to disclose the application of a molybdenum-chromium-tin-aluminum master alloy in the field of TC17 titanium alloy.

[0038] Furthermore, the mass ratio of molybdenum-chromium-tin-aluminum master alloy to Ti in the TC17 titanium alloy is 0.180-0.185:1.

[0039] The present invention relates to a molybdenum-chromium-tin-aluminum master alloy, which is a novel alloy suitable for the production of TC17 titanium alloy. In this alloy, four alloying elements, Mo, Cr, Sn and Al, are combined in an appropriate element ratio and prepared into a master alloy powder with small and uniform particle size. This avoids defects such as element segregation inside the titanium alloy ingot caused by element segregation inside the multi-element alloy raw materials.

[0040] This invention discloses a molybdenum-chromium-tin-aluminum master alloy, its preparation method, and its applications, which have the following advantages compared with existing technologies:

[0041] 1) This invention's molybdenum-chromium-tin-aluminum master alloy is a multi-element master alloy, primarily providing smelting raw materials for TC17 titanium alloy. Traditional multi-element alloys generally suffer from problems such as numerous internal oxidation regions and significant element segregation. In the preparation of TC17 titanium alloy, this not only easily introduces impurities such as oxygen and nitrogen but also easily causes uneven element distribution within the ingot. If multiple binary alloys are used for smelting, element loss is likely, resulting in a complex process and a long production cycle. This invention, through a reasonable element ratio and optimized preparation process, provides multiple alloying elements while reducing the types of raw materials, improving raw material purity, reducing the technical difficulty of vacuum consumable melting, and effectively reducing inclusions and element segregation defects in titanium alloy ingots.

[0042] 2) In the molybdenum-chromium-tin-aluminum master alloy of this invention, each element has a specific effect on the properties of TC17 titanium alloy: Mo can strengthen the β phase through solid solution, significantly reduce the phase transformation point, thereby improving the strength, hardness, high-temperature stability and creep resistance of the alloy; Cr is a eutectoid β-stabilizing element, existing in the β phase in the form of a substitutional solid solution, producing a solid solution strengthening effect; Sn has a large solid solubility in both α-Ti and β-Ti, and can improve the strength of titanium alloy by forming a substitutional solid solution; Al can stabilize the α phase, exert a good solid solution strengthening effect, promote the precipitation of the α phase during heat treatment and enhance the age hardening effect.

[0043] However, the content of each element must be strictly controlled: excessive Mo content may precipitate harmful δ phase, seriously impairing the ductility and fatigue life of the alloy; excessive Cr content may easily form brittle compounds such as TiCr2 inside the alloy, affecting the fracture performance of the titanium alloy; excessive Al content may form compound phases such as Ti3Al or TiAl at the grain boundaries, seriously impairing the alloy performance; if Sn content is too high, it will form the Ti3Sn hard and brittle phase, significantly reducing the alloy's plastic deformation capacity, exacerbating the risk of material embrittlement, and posing a threat to the safety of the component.

[0044] Therefore, the content of alloying elements such as Mo, Cr, Sn, and Al in the molybdenum-chromium-tin-aluminum master alloy of this invention is specifically designed to meet the TC17 titanium alloy preparation specification, aiming to simplify the process and reduce costs. Any changes beyond the composition range of this invention may have a significant impact on the composition or properties of the final titanium alloy.

[0045] 3) The molybdenum-chromium-tin-aluminum master alloy powder of the present invention is subjected to melting and spheroidizing treatment by high-temperature plasma torch, which can effectively remove oxygen, nitrogen and other low-melting-point impurities, thereby obtaining a high-purity molybdenum-chromium-tin-aluminum master alloy.

[0046] In summary, the method for preparing the molybdenum-chromium-tin-aluminum master alloy of this invention is simple, and the prepared molybdenum-chromium-tin-aluminum alloy has uniform composition and particle size, minimal elemental segregation, and low impurity content. This solves the problems of internal oxidation and elemental segregation in the preparation of TC17 titanium alloy using only aluminothermic reduction reaction, and the high equipment and process requirements and cumbersome procedures in the preparation of multi-component master alloys using vacuum induction melting. It also reduces ingot segregation during titanium alloy melting. The molybdenum-chromium-tin-aluminum master alloy of this invention has good application prospects and large-scale promotion potential in the field of TC17 titanium alloy. Attached Figure Description

[0047] Figure 1 This is a flowchart of the preparation method for a molybdenum-chromium-tin-aluminum master alloy. Detailed Implementation

[0048] The present invention will be further described below with reference to embodiments. The description of the technical features described below is based on representative embodiments and specific examples of the present invention, but the present invention is not limited to these embodiments and specific examples. It should be noted that:

[0049] Unless otherwise stated, all units used in this specification are international standard units, and all numerical values ​​and ranges appearing in this invention should be understood to include systematic errors that are unavoidable in industrial production.

[0050] In this specification, the range of values ​​referred to as "value A to value B" refers to the range including the endpoint values ​​A and B.

[0051] In this specification, the numerical range indicated by "above" or "below" refers to the numerical range that includes the stated number.

[0052] In this specification, the word "may" has two meanings: to perform a certain process and not to perform a certain process.

[0053] In this specification, the terms "optional" or "optional" are used to indicate the use or omission of certain substances, components, procedures, application conditions, etc.

[0054] In this instruction manual, when "room temperature" or "room temperature" is used, the temperature can be 15-25℃.

[0055] Unless otherwise specified, all reagents or instruments used in this instruction manual are commercially available products.

[0056] Example 1:

[0057] This embodiment discloses a molybdenum-chromium-tin-aluminum master alloy, designed with a Mo design value of 27%, a Cr design value of 27%, a Sn design value of 13%, and an Al design value of 33%.

[0058] The preparation method of the molybdenum-chromium-tin-aluminum master alloy includes the following steps:

[0059] The first step is to produce a primary molybdenum-chromium-tin-aluminum alloy using the aluminothermic reduction reaction method:

[0060] The production of molybdenum-chromium-tin-aluminum grade I alloy is carried out according to the following steps: furnace construction, furnace firing, material drying, batching, mixing, furnace loading, reaction, cooling, furnace dismantling, finishing, crushing, and sampling analysis.

[0061] Preparation of primary molybdenum-chromium-tin-aluminum alloys by the aluminothermic method:

[0062] The crucible was made of alumina refractory material and sintered in a natural gas sintering furnace for 7 hours. The sintering temperature was gradually increased from 30℃ to 600℃. After sintering, the temperature was held for 2 hours.

[0063] Molybdenum trioxide, chromium trioxide, tin dioxide, and aluminum powder were dried at 60°C for 24 hours.

[0064] The alloy mass ratio for the aluminothermic reaction process is calculated as follows: the mass ratio of molybdenum trioxide, chromium trioxide, tin dioxide, and metallic aluminum powder is 0.611:0.618:0.250:1.

[0065] The mixture of molybdenum trioxide, chromium trioxide, tin dioxide, and aluminum powder is placed into a special mixing tank and then put into a mixer at 10 r / min. -1 The materials are mixed at a rate of [missing information], with a mixing time of 20 minutes. Mixing requirements: All raw materials must be thoroughly and evenly mixed to ensure sufficient contact between them;

[0066] The mixed molybdenum trioxide, chromium trioxide, tin dioxide and aluminum powder were loaded into a preheated alumina crucible, ignited and reacted, and then cooled for 36 hours before being removed from the furnace to obtain a primary molybdenum-chromium-tin-aluminum alloy.

[0067] The oxide film on the surface of the alloy ingot is removed by grinding with a grinding wheel; it is then crushed to a particle size of 0-50mm by a crusher, and after magnetic separation and manual sorting to remove impurities such as ferromagnetic materials, it is sampled for analysis.

[0068] The second step is crushing with a crusher:

[0069] Semi-finished alloys that meet the design specifications, have a bright and dense structure, and are free of oxidation defects are crushed to a particle size of 0-0.3mm using a crusher.

[0070] The first step is to crush the alloy ingot to less than 50mm to facilitate sampling and component analysis. After the analysis is qualified, the second step is to crush it to less than 0.3mm for use as spheroidizing raw material.

[0071] The third step involves producing a molybdenum-chromium-tin-aluminum master alloy using a radio frequency plasma spheroidization process.

[0072] Turn on the radio frequency plasma spheroidization system, open the gas supply system, and fill the equipment with high-purity argon gas at a flow rate of 20 L / min. -1 Inflation time: 5 minutes; Open the sheath gas valve and fill with high-purity helium at a flow rate of 50 L / min. -1 The inflation time is 5 minutes. Once the gas in all chambers is flowing continuously and stably, turn on the high-frequency power supply (30kW). After a stable high-temperature plasma torch flame is generated, start the carrier gas feeding at a rate of 60 g / min. -1 ;

[0073] After the material is completely fed into the reaction chamber by the carrier gas system and the molybdenum-chromium-tin-aluminum primary alloy powder is melted and spheroidized into finer alloy powder, the system is shut off and cooled for 3 hours. The spheroidized powder is then collected to obtain the molybdenum-chromium-tin-aluminum intermediate alloy.

[0074] The chemical composition analysis of the molybdenum-chromium-tin-aluminum master alloy prepared in this embodiment was performed, and the results are shown in Table 1. The melting point of the molybdenum-chromium-tin-aluminum master alloy prepared in this embodiment is 1344℃, and the density is 4.90 g·cm³. -3 .

[0075] Example 2:

[0076] This embodiment discloses a molybdenum-chromium-tin-aluminum master alloy, designed with a Mo design value of 25%, a Cr design value of 26%, a Sn design value of 12%, and an Al design value of 37%.

[0077] The preparation method of the molybdenum-chromium-tin-aluminum master alloy includes the following steps:

[0078] The first step is to produce a primary molybdenum-chromium-tin-aluminum alloy using the aluminothermic reduction reaction method:

[0079] The production of molybdenum-chromium-tin-aluminum grade I alloy is carried out according to the following steps: furnace construction, furnace firing, material drying, batching, mixing, furnace loading, reaction, cooling, furnace dismantling, finishing, crushing, and sampling analysis.

[0080] Preparation of primary molybdenum-chromium-tin-aluminum alloys by the aluminothermic method:

[0081] The crucible was made of alumina refractory material and sintered in a natural gas sintering furnace for 7 hours. The sintering temperature was gradually increased from 30℃ to 600℃. After sintering, the temperature was held for 2 hours.

[0082] Molybdenum trioxide, chromium trioxide, tin dioxide, and aluminum powder were dried at 60°C for 24 hours.

[0083] The alloy mass ratio for the aluminothermic reaction process is calculated to be 0.548:0.574:0.224:1.

[0084] The mixture of molybdenum trioxide, chromium trioxide, tin dioxide, and aluminum powder is placed into a special mixing tank and then put into a mixer at 10 r / min. -1 The materials are mixed at a rate of [missing information], with a mixing time of 20 minutes. Mixing requirements: All raw materials must be thoroughly and evenly mixed to ensure sufficient contact between them;

[0085] The mixed molybdenum trioxide, chromium trioxide, tin dioxide and aluminum powder were loaded into a preheated alumina crucible, ignited and reacted, and then cooled for 36 hours before being removed from the furnace to obtain a primary molybdenum-chromium-tin-aluminum alloy.

[0086] The oxide film on the surface of the alloy ingot is removed by grinding with a grinding wheel; it is then crushed to a particle size of 0-50mm by a crusher, and after magnetic separation and manual sorting to remove impurities such as ferromagnetic materials, it is sampled for analysis.

[0087] The second step is crushing with a crusher:

[0088] Semi-finished alloys that meet the design specifications, have a bright and dense structure, and are free of oxidation defects are crushed to a particle size of 0-0.3mm using a crusher.

[0089] The third step involves producing a molybdenum-chromium-tin-aluminum master alloy using a radio frequency plasma spheroidization process.

[0090] Turn on the radio frequency plasma spheroidization system, open the gas supply system, and fill the equipment with high-purity argon gas at a flow rate of 15 L / min. -1 Inflation time: 5 minutes; Open the sheath gas valve and fill with high-purity helium at a flow rate of 40 L / min. -1 The inflation time is 5 minutes. Once the gas in all chambers is flowing continuously and stably, turn on the high-frequency power supply (25kW). After a stable high-temperature plasma torch flame is generated, start the carrier gas feeding at a rate of 40 g / min. -1 ;

[0091] After the material is completely fed into the reaction chamber by the carrier gas system and the molybdenum-chromium-tin-aluminum primary alloy powder is melted and spheroidized into finer alloy powder, the system is shut off and cooled for 3 hours. The spheroidized powder is then collected to obtain the molybdenum-chromium-tin-aluminum intermediate alloy.

[0092] The chemical composition analysis of the molybdenum-chromium-tin-aluminum master alloy prepared in this embodiment was performed, and the results are shown in Table 1. The melting point of the molybdenum-chromium-tin-aluminum master alloy prepared in this embodiment is 1342℃, and the density is 4.89 g·cm³. -3 .

[0093] Example 3:

[0094] This embodiment discloses a molybdenum-chromium-tin-aluminum master alloy, designed with a Mo design value of 28%, a Cr design value of 29%, a Sn design value of 15%, and an Al design value of 28%.

[0095] The preparation method of the molybdenum-chromium-tin-aluminum master alloy includes the following steps:

[0096] The first step is to produce a primary molybdenum-chromium-tin-aluminum alloy using the aluminothermic reduction reaction method:

[0097] The production of molybdenum-chromium-tin-aluminum grade I alloy is carried out according to the following steps: furnace construction, furnace firing, material drying, batching, mixing, furnace loading, reaction, cooling, furnace dismantling, finishing, crushing, and sampling analysis.

[0098] Preparation of primary molybdenum-chromium-tin-aluminum alloys by the aluminothermic method:

[0099] The crucible was made of alumina refractory material and sintered in a natural gas sintering furnace for 7 hours. The sintering temperature was gradually increased from 30℃ to 600℃. After sintering, the temperature was held for 2 hours.

[0100] Molybdenum trioxide, chromium trioxide, tin dioxide, and aluminum powder were dried at 60°C for 24 hours.

[0101] The alloy mass ratio for the aluminothermic reaction process is calculated to be 0.660:0.686:0.298:1.

[0102] The mixture of molybdenum trioxide, chromium trioxide, tin dioxide, and aluminum powder is placed into a special mixing tank and then put into a mixer at 10 r / min. -1 The materials are mixed at a rate of [missing information], with a mixing time of 20 minutes. Mixing requirements: All raw materials must be thoroughly and evenly mixed to ensure sufficient contact between them;

[0103] The mixed molybdenum trioxide, chromium trioxide, tin dioxide and aluminum powder were loaded into a preheated alumina crucible, ignited and reacted, and then cooled for 36 hours before being removed from the furnace to obtain a primary molybdenum-chromium-tin-aluminum alloy.

[0104] The oxide film on the surface of the alloy ingot is removed by grinding with a grinding wheel; it is then crushed to a particle size of 0-50mm by a crusher, and after magnetic separation and manual sorting to remove impurities such as ferromagnetic materials, it is sampled for analysis.

[0105] The second step is crushing with a crusher:

[0106] Semi-finished alloys that meet the design specifications, have a bright and dense structure, and are free of oxidation defects are crushed to a particle size of 0-0.3mm using a crusher.

[0107] The third step involves producing a molybdenum-chromium-tin-aluminum master alloy using a radio frequency plasma spheroidization process.

[0108] Turn on the radio frequency plasma spheroidization system, open the gas supply system, and fill the equipment with high-purity argon gas at a flow rate of 20 L / min. -1 Inflation time: 10 min; Open the sheath gas valve and fill with high-purity helium at a flow rate of 60 L / min. -1 The inflation time is 6 minutes. Once the gas in all chambers is flowing continuously and stably, turn on the high-frequency power supply (40kW). After a stable high-temperature plasma torch flame is generated, start the carrier gas feeding at a rate of 100 g / min. -1 ;

[0109] After the material is completely fed into the reaction chamber by the carrier gas system and the molybdenum-chromium-tin-aluminum primary alloy powder is melted and spheroidized into finer alloy powder, the system is shut off and cooled for 3 hours. The spheroidized powder is then collected to obtain the molybdenum-chromium-tin-aluminum intermediate alloy.

[0110] The chemical composition analysis of the molybdenum-chromium-tin-aluminum master alloy prepared in this embodiment was performed, and the results are shown in Table 1. The melting point of the molybdenum-chromium-tin-aluminum master alloy prepared in this embodiment is 1345℃, and the density is 4.94 g·cm³. -3 .

[0111] The chemical composition of the molybdenum-chromium-tin-aluminum master alloy in this embodiment of the invention is shown in Table 1:

[0112] Table 1. Main elemental composition of molybdenum-chromium-tin-aluminum master alloys in various embodiments

[0113]

[0114] The particle size distribution of the molybdenum-chromium-tin-aluminum master alloy powder prepared in the embodiments of the present invention was analyzed, and the results are shown in Table 2.

[0115] Table 2. Particle size distribution of molybdenum-chromium-tin-aluminum master alloy powder in various embodiments

[0116]

[0117] Analysis of the experimental data in Tables 1 and 2 shows that the composition of the molybdenum-chromium-tin-aluminum master alloys in Examples 1-3 is as expected, with fine and uniform particle size and no excessively large particles, verifying the reliability and quality stability of the preparation process of this invention.

[0118] Comparative Example

[0119] The advantage of this patent lies in its ability to remove impurities and refine the molybdenum-chromium-tin-aluminum alloy prepared using a one-step method, thereby improving powder uniformity. Therefore, the comparative example uses the primary molybdenum-chromium-tin-aluminum alloy prepared by the aluminothermic reduction reaction in Example 1, which is then crushed into powder using a conventional mechanical crushing method. The intermediate alloy powder after powdering was subjected to comprehensive chemical composition analysis, and the particle size analysis was performed. The results are shown in the table below. The comparative alloy has a melting point of 1341℃ and a density of 4.85 g·cm³. -3 .

[0120] Table 3. Main elemental chemical composition of comparative master alloys after powder preparation

[0121]

[0122] Table 4. Particle size distribution analysis of comparative master alloys after powder preparation

[0123]

[0124] Comparing the test data of the comparative master alloy and the master alloy prepared in Example 1, it can be found that the main elemental chemical composition of the comparative alloy after mechanical crushing and powdering differs significantly from the optimal range. The oxygen content of the alloy increases substantially after crushing and powdering, the fine powder yield (0.015mm-0.050mm) is low, and the overall quality of the alloy declines severely. Based on the test data of the examples and the comparative alloy, it is clear that compared with directly preparing master alloy powder using mechanical crushing, the preparation method of this invention can produce molybdenum-chromium-tin-aluminum master alloy powder with superior overall quality.

[0125] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A molybdenum-chromium-tin-aluminum master alloy, characterized in that, It includes the following components by mass percentage: Mo: 24%-30%, Cr: 24%-30%, Sn: 10%-16%, Al: 28%-37%, and unavoidable impurities.

2. The molybdenum-chromium-tin-aluminum master alloy according to claim 1, characterized in that, The melting point of the molybdenum-chromium-tin-aluminum intermediate alloy is 1330-1350℃, the density of the molybdenum-chromium-tin-aluminum intermediate alloy is 4.80g·cm -3 -5.00g·cm -3 .

3. The molybdenum-chromium-tin-aluminum master alloy according to claim 1, characterized in that, The particle size D90 of the molybdenum-chromium-tin-aluminum master alloy is 0.010mm-0.050mm.

4. A method for preparing the molybdenum-chromium-tin-aluminum master alloy according to any one of claims 1-3, characterized in that, Includes the following steps: Step 1: Mix molybdenum trioxide, chromium trioxide, tin dioxide and aluminum powder in a mass ratio of (0.600-0.620):(0.610-0.620):(0.240-0.260):1, add to a reaction crucible, ignite and react at a temperature of 2150℃-2200℃ for 35s-45s to obtain a primary molybdenum-chromium-tin-aluminum alloy. Step 2: Crush the molybdenum-chromium-tin-aluminum primary alloy to obtain molybdenum-chromium-tin-aluminum primary alloy powder; Step 3: Using the aforementioned molybdenum-chromium-tin-aluminum primary alloy powder as raw material, a molybdenum-chromium-tin-aluminum intermediate alloy is produced using radio frequency plasma spheroidization technology.

5. The method for preparing the molybdenum-chromium-tin-aluminum master alloy according to claim 4, characterized in that, Before step 1, molybdenum trioxide, chromium trioxide, tin dioxide and aluminum powder are dried in a constant temperature drying room at 50℃-60℃ for 22h-24h to ensure that the moisture content of the reaction materials is ≤0.1% and the initial temperature is 40℃-50℃.

6. The method for preparing the molybdenum-chromium-tin-aluminum master alloy according to claim 4, characterized in that, Before crushing in step 2, the molybdenum-chromium-tin-aluminum alloy is polished and cleaned.

7. The method for preparing the molybdenum-chromium-tin-aluminum master alloy according to claim 4, characterized in that, Step 3, using the aforementioned molybdenum-chromium-tin-aluminum primary alloy powder as raw material, involves the following specific steps for producing a molybdenum-chromium-tin-aluminum master alloy using radio frequency plasma spheroidization technology: First, turn on the gas supply system and fill the equipment with high-purity argon gas as the working gas, controlling the flow rate at 15 L·min. -1 Up to 20 L·min -1 Continue for 5-10 minutes to establish the desired atmosphere; Then, the sheath gas valve was opened, and high-purity helium was introduced at a flow rate of 40 L / min. -1 -60 L·min -1 Inflation time: 5-6 minutes; Turn on the high-frequency power supply and set the power to 25 kW-40 kW to generate a high-temperature plasma torch flame; After the plasma torch flame stabilizes, the carrier gas argon is started to deliver molybdenum-chromium-tin-aluminum primary alloy powder at a feed rate of 40 g·min. -1 -100 g·min -1 Molybdenum-chromium-tin-aluminum primary alloy powder carried by carrier gas is melted into droplets in a high-temperature reaction chamber and then enters a cooling chamber. Under the combined action of argon atmosphere and auxiliary water cooling system in the cooling chamber, the molten droplets are cooled, solidified, and spheroidized to prepare the molybdenum-chromium-tin-aluminum master alloy.

8. The method for preparing the molybdenum-chromium-tin-aluminum master alloy according to claim 7, characterized in that, The pressure inside the high-temperature reaction chamber is 1.5 Pa to 2.5 Pa.

9. The application of the molybdenum-chromium-tin-aluminum master alloy according to any one of claims 1-3 in the field of TC17 titanium alloy.

10. The application according to claim 9, characterized in that, The mass ratio of molybdenum-chromium-tin-aluminum master alloy to Ti in the TC17 titanium alloy is 0.180-0.185:1.

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