阅读说明：本技术 一种增材制造用高镍共晶高熵合金粉体及其制备方法 (High-nickel eutectic high-entropy alloy powder for additive manufacturing and preparation method thereof ) 是由 金莹 金霞 刘平 张腾辉 翁子清 史金光 于 2020-04-27 设计创作，主要内容包括：本发明涉及一种增材制造用高镍共晶高熵合金粉体及其制备方法,高熵合金粉体主要包含铝、铁、铬、钴、镍、硅和硼元素,其中铝原子摩尔比为0.5～1.5,铁原子摩尔比为1.0～1.5,铬原子摩尔比为0.8～1.5,钴原子摩尔比为0.5～1.0,镍原子摩尔比为1.0～2.5,硅原子摩尔比为0～0.05,硼原子摩尔比为0～0.05,粉体制备方法按下述步骤进行：一、利用真空感应熔炼炉制备高熵合金母合金；二、利用无坩埚感应熔炼雾化炉制备高熵合金粉体。本发明制备的高熵合金粉体成球形或者近球形,形成共晶组织,降低了低熔点元素的烧损和多元素合金的成分偏析,能够更有效的实现耐高温专用零件的快速精密制造和再制造修复；本发明避免了传统单相高熵合金材料或强度不高或塑性不好的问题。(The invention relates to high-nickel eutectic high-entropy alloy powder for additive manufacturing and a preparation method thereof, wherein the high-entropy alloy powder mainly comprises aluminum, iron, chromium, cobalt, nickel, silicon and boron, the molar ratio of aluminum atoms is 0.5-1.5, the molar ratio of iron atoms is 1.0-1.5, the molar ratio of chromium atoms is 0.8-1.5, the molar ratio of cobalt atoms is 0.5-1.0, the molar ratio of nickel atoms is 1.0-2.5, the molar ratio of silicon atoms is 0-0.05, and the molar ratio of boron atoms is 0-0.05, and the preparation method of the powder comprises the following steps: firstly, preparing a high-entropy alloy master alloy by using a vacuum induction smelting furnace; secondly, preparing the high-entropy alloy powder by using a crucible-free induction melting atomization furnace. The high-entropy alloy powder prepared by the invention is spherical or nearly spherical, forms eutectic structures, reduces the burning loss of low-melting-point elements and the component segregation of multi-element alloy, and can more effectively realize the rapid precision manufacturing and remanufacturing repair of high-temperature-resistant special parts; the invention avoids the problems of low strength or poor plasticity of the traditional single-phase high-entropy alloy material.)

1. The high-nickel eutectic high-entropy alloy powder for additive manufacturing is characterized by comprising aluminum, iron, chromium, cobalt, nickel, silicon and boron, wherein the molar ratio of aluminum is 0.5-1.5, the molar ratio of iron is 1.0-1.5, the molar ratio of chromium is 0.8-1.5, the molar ratio of cobalt is 0.5-1.0, the molar ratio of nickel is 1.0-2.5, the molar ratio of silicon is 0-0.05, and the molar ratio of boron is 0-0.05.

2. The high-nickel eutectic high-entropy alloy powder for additive manufacturing according to claim 1, wherein the molar ratio of chromium atoms is 0.8 to 1.3, and the molar ratio of nickel atoms is 1.5 to 2.5.

3. The high-nickel eutectic high-entropy alloy powder for additive manufacturing according to claim 1, wherein the aluminum element is mixed by 1.02-1.05 times.

4. The high-nickel eutectic high-entropy alloy powder for additive manufacturing according to claim 1, wherein the aluminum element is mixed by 1.05 times.

5. A preparation method of high-nickel eutectic high-entropy alloy powder for additive manufacturing is characterized by comprising the following steps:

(1) preparing a high-entropy alloy master alloy by using a vacuum induction smelting furnace, specifically weighing each metal simple substance or intermediate alloy with a determined molar ratio, and putting the weighed metal simple substance or intermediate alloy into a magnesia crucible; starting a vacuum induction smelting furnace mechanical pump to vacuumize to below 10Pa, then starting smelting, wherein the smelting power is 40-70 KW, the smelting time is 25-60 min, and electromagnetic stirring is performed in the smelting process to make the components of the molten alloy uniform; after the smelting is finished, casting the alloy melt into a water-cooling copper mold to obtain a cylindrical high-entropy alloy master alloy bar with uniform components;

(2) preparing high-entropy alloy powder by using a crucible-free induction melting atomization furnace, polishing oxide skins on the surfaces of mother alloy bars, and turning the heads of the bars into 45-degree cones; loading the processed high-entropy alloy bar on a lifting clamp of a crucible-free induction melting atomization furnace, opening a vacuum pump to vacuumize to 0.1-1 Pa, and filling protective atmosphere; starting a rotating bar to rotate and descend, adjusting the rotating speed to be 10-30 rpm, adjusting the descending speed to be 10-25cm/min, and stopping descending after the conical tip of the bar penetrates into the induction coil; and (2) starting a high-frequency induction heating power supply, wherein the heating power is 20-45 kW, when the bar begins to melt, after the high-entropy alloy liquid drops drop into the atomizing nozzle, an atomizing gas valve is opened and atomization powder preparation is started, the atomizing pressure is kept at 3.0-6.5 MPa in the atomizing process, and the high-entropy alloy liquid drops are atomized into powder under the crushing and cooling effects of an atomizing medium.

6. The high-nickel eutectic high-entropy alloy powder for additive manufacturing and the preparation method thereof according to claim 5, wherein the purity of the metal simple substance or the intermediate alloy in the step (1) is 99.95%.

7. The high-nickel eutectic high-entropy alloy powder for additive manufacturing and the preparation method thereof according to claim 5, wherein the protective atmosphere in the step (2) is high-purity argon.

8. The high-nickel eutectic high-entropy alloy powder for additive manufacturing and the preparation method thereof of claim 5, wherein the prepared powder is spherical or nearly spherical, the structure of the powder is eutectic structure, and the powder is composed of body-centered cubic phase and face-centered cubic phase and is uniformly and alternately distributed.

9. The application of the high-nickel eutectic high-entropy alloy powder for additive manufacturing is characterized in that the powder is mainly applied to the field of additive manufacturing and comprises selective laser melting and coaxial powder feeding laser cladding, wherein the powder with the particle size of 0-53 mu m is mainly applied to the field of selective laser melting, and the powder with the particle size of 53-250 mu m is mainly applied to the field of coaxial powder feeding laser cladding.

Technical Field

The invention relates to the field of powder metallurgy, in particular to high-nickel eutectic high-entropy alloy powder for additive manufacturing and a preparation method thereof.

Background

The traditional high-entropy alloy is easy to form a simple face-centered cubic, simple body-centered cubic or close-packed hexagonal structure. Generally speaking, the face-centered cubic structure high-entropy alloy has good thermodynamic stability, super ductility and remarkable work hardening performance, but low strength; the high-entropy alloy with the body-centered cubic or close-packed hexagonal structure has high strength but poor ductility. The eutectic high-entropy alloy has high strength and ductility, so that the eutectic high-entropy alloy is suitable for various engineering applications and draws wide attention of people.

The additive manufacturing belongs to a rapid quenching forming process, and on one hand, the defects existing in the preparation process of the as-cast high-entropy alloy can be avoided; on the other hand, by utilizing the rapid solidification technology, the eutectic high-entropy alloy material has the technical advantages of enhancing the nucleation capability of a simple solid solution, improving the solid solubility limit, refining the structure, reducing the component segregation, improving the mechanical property and the like. Currently, high-entropy alloy powder is mostly prepared by pure metal powder in proportion and then mechanically mixed or ball milled in high energy (such as CN104841930B and CN 109550957B). However, the simple mechanical mixing is difficult to realize the uniform control of the powder components, and the high-energy ball milling method cannot meet the basic requirements of additive manufacturing on the sphericity and the granularity of the powder, so that the formability, the uniformity of the structure and the stability of the performance of parts are poor, and the method is far away from the industrial practical production application. The gas atomization method is widely applied as a rapid solidification technology, and the defects can be avoided by utilizing the gas atomization method to prepare the high-entropy alloy powder material. The uniformity and stability of the performance of the powder are the key points for improving the formability, the structure and the performance stability of the additive manufacturing eutectic high-entropy alloy, and are the basis for realizing industrial application of the high-performance high-entropy alloy powder.

Disclosure of Invention

The invention provides high-nickel eutectic high-entropy alloy powder for additive manufacturing and a preparation method thereof, aiming at solving the problems of low high-entropy alloy or high-temperature strength or plasticity and powder preparation process in the prior art.

In order to achieve the above object, the present invention provides the following technical solutions,

the high-nickel eutectic high-entropy alloy powder for additive manufacturing is characterized by comprising aluminum, iron, chromium, cobalt, nickel, silicon and boron, wherein the molar ratio of aluminum is 0.5-1.5, the molar ratio of iron is 1.0-1.5, the molar ratio of chromium is 0.8-1.5, the molar ratio of cobalt is 0.5-1.0, the molar ratio of nickel is 1.0-2.5, the molar ratio of silicon is 0-0.05, and the molar ratio of boron is 0-0.05.

Further, the molar ratio of the chromium atoms is 0.8-1.3, and the molar ratio of the nickel atoms is 1.5-2.5.

Further, in order to ensure the component accuracy, the aluminum element is mixed according to the proportion of 1.02-1.05 times; if silicon or boron element is added into the powder, the proportion is 1.05 times.

Further, the high-nickel eutectic high-entropy alloy powder for additive manufacturing and the preparation method thereof are as follows:

(1) preparing a high-entropy alloy master alloy by using a vacuum induction smelting furnace, specifically weighing each metal simple substance or intermediate alloy with a determined molar ratio, and putting the weighed metal simple substance or intermediate alloy into a magnesia crucible; starting a vacuum induction smelting furnace mechanical pump to vacuumize to below 10Pa, then starting smelting, wherein the smelting power is 40-70 KW, the smelting time is 25-60 min, and electromagnetic stirring is performed in the smelting process to make the components of the molten alloy uniform; after the smelting is finished, casting the alloy melt into a water-cooling copper mold to obtain a cylindrical high-entropy alloy master alloy bar with uniform components;

(2) preparing high-entropy alloy powder by using a crucible-free induction melting atomization furnace, polishing oxide skins on the surfaces of mother alloy bars, and turning the heads of the bars into 45-degree cones; loading the processed high-entropy alloy bar on a lifting clamp of a crucible-free induction melting atomization furnace, opening a vacuum pump to vacuumize to 0.1-1 Pa, and filling protective atmosphere; starting a rotating bar to rotate and descend, adjusting the rotating speed to be 10-30 rpm, adjusting the descending speed to be 10-25cm/min, and stopping descending after the conical tip of the bar penetrates into the induction coil; and (2) starting a high-frequency induction heating power supply, wherein the heating power is 20-45 kW, when the bar begins to melt, after the high-entropy alloy liquid drops drop into the atomizing nozzle, an atomizing gas valve is opened and atomization powder preparation is started, the atomizing pressure is kept at 3.0-6.5 MPa in the atomizing process, and the high-entropy alloy liquid drops are atomized into powder under the crushing and cooling effects of an atomizing medium.

Further, in order to ensure the purity of the high-nickel eutectic high-entropy alloy powder for additive manufacturing, when the alloy bar is smelted in the step one, a metal simple substance or an intermediate alloy is selected, and the purity is 99.95%.

Further, in the process of preparing the powder by atomization in the second step, the protective gas and the atomization medium are both high-purity argon.

Furthermore, the prepared powder is spherical or nearly spherical, the structure of the powder is eutectic structure, and the powder is composed of body-centered cubic phase and face-centered cubic phase and is uniformly and alternately distributed.

Further, the powder is mainly applied to the field of additive manufacturing and comprises selective laser melting and coaxial powder feeding laser cladding, wherein the powder with the particle size of 0-53 mu m is mainly applied to the field of selective laser melting, and the powder with the particle size of 53-250 mu m is mainly applied to the field of coaxial powder feeding laser cladding.

Compared with other traditional methods, the high-entropy alloy powder prepared by the preparation method of the high-nickel eutectic high-entropy alloy spherical powder for additive manufacturing has the following advantages:

1. the high-entropy alloy powder prepared by the crucible-free gas atomization process has less non-metal inclusions, and the defect of the high-entropy alloy powder material caused by excessive impurity elements in the additive manufacturing application is avoided.

2. The high-nickel eutectic high-entropy alloy powder is fully metallurgically bonded to form an eutectic structure, the structures are uniformly and alternately distributed, the microsegregation of the powder structure is reduced, the physical and chemical properties (such as melting points and the like) of the powder are uniform and stable, and the stability of additive manufacturing process parameters is controlled, so that the good comprehensive mechanical properties of a formed part are ensured.

3. The silicon and boron elements are added into the high-nickel eutectic high-entropy alloy powder, so that the problem of surface oxidation in the coaxial powder feeding laser cladding additive manufacturing process can be effectively solved. Because the silicon and the boron are self-fluxing elements, when the silicon and the boron are melted by laser, the silicon and the boron react with non-metallic impurity elements in the atmosphere to generate scum which is easy to fall off and is deposited on the surface of the high-nickel eutectic high-entropy alloy laser cladding layer, thereby ensuring the quality of a laser repair area of a workpiece.

Drawings

FIG. 1 is a flow chart of the preparation of high-nickel eutectic high-entropy alloy powder.

FIG. 2 is a powder morphology diagram of a high-nickel eutectic high-entropy alloy with particle size of 0-53 μm.

FIG. 3 is a powder morphology diagram of high-nickel eutectic high-entropy alloy with particle size of 53-250 μm.

FIG. 4 is an XRD spectrum of the high-nickel eutectic high-entropy alloy powder.

Detailed Description

The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments.

Taking preparation of al0.5crfeconi2.1si0.02b0.03 high-nickel eutectic high-entropy alloy powder as an example, the process flow is shown in fig. 1, and the specific operation process is as follows:

calculating the weight of a metal simple substance or an intermediate alloy of each alloy element according to the molar ratio of Al0.5CrFeCoNi2.1Si0.02B0.03 high-nickel eutectic high-entropy alloy, wherein aluminum is calculated according to the molar ratio of 0.51, and silicon and boron are calculated according to the molar ratios of 0.021 and 0.032 respectively; putting the weighed metal simple substance or intermediate alloy into a magnesia crucible; starting a vacuum induction smelting furnace mechanical pump to vacuumize to below 10Pa, then starting smelting, wherein the smelting power is 50KW, the smelting time is 35min, and in the smelting process, electromagnetic stirring is performed to make the components of the alloy melt uniform; after the smelting is finished, casting the alloy melt into a water-cooling copper mold to obtain a cylindrical high-entropy alloy master alloy bar with uniform components, the diameter of 50mm and the length of 700 mm; polishing oxide skin on the surface of the master alloy bar, and turning the head of the bar into a 45-degree conical shape; loading the processed high-entropy alloy on a lifting clamp of a crucible-free induction melting atomization furnace, opening a vacuum pump to vacuumize to 0.5Pa, and filling high-purity argon as a protective atmosphere; starting the rotating bar to rotate and descend, adjusting the rotating speed to be 15rpm, and the descending speed to be 20cm/min, and stopping descending after the conical tip of the bar penetrates into the induction coil; the high-frequency induction heating power supply is started, the heating power is 35kW, when the bar begins to melt, the high-entropy alloy liquid drops are dripped into the atomizing nozzle, the atomizing valve is opened, atomization powder preparation is started, the atomizing pressure is kept at 5.5MPa in the atomizing process, and under the crushing and cooling effects of the atomizing medium, the high-entropy alloy liquid drops are atomized into powder.

After the prepared high-entropy alloy powder is sorted by a mechanical vibration sieve, two kinds of powder with different particle sizes of 0-53 microns and 53-250 microns are respectively sieved, wherein the powder with the particle size of 0-53 microns is used in the field of selective laser melting, and the powder with the particle size of 53-250 microns is used in the field of coaxial powder feeding laser cladding.

The morphology of the high-nickel eutectic high-entropy alloy powder prepared by the process is shown in fig. 2 and 3, wherein fig. 2 shows the powder with the granularity of 0-53 mu m, and fig. 3 shows the granularity of 53-250 mu m; FIG. 4 is an XRD spectrum of the high-nickel eutectic high-entropy alloy powder.

The above description is only for the preferred embodiment of the present invention, but the scope of the present invention is not limited thereto, and any person skilled in the art should be able to cover the technical scope of the present invention and the equivalent alternatives or modifications according to the technical solution and the inventive concept of the present invention within the technical scope of the present invention.