WO2023231267A1

WO2023231267A1 - Alloy and preparation method therefor

Info

Publication number: WO2023231267A1
Application number: PCT/CN2022/124955
Authority: WO
Inventors: 张舒博; 张文井; 陈浩; 刘伟
Original assignee: 清华大学
Priority date: 2022-05-30
Filing date: 2022-10-12
Publication date: 2023-12-07

Abstract

Provided are an ODS alloy and a preparation method therefor. The method comprises: laying alloy powder on a powder bed; increasing the oxygen content of the alloy powder before additive manufacturing; and performing additive manufacturing on the alloy powder to obtain an ODS alloy. According to the solution, a high-performance ODS alloy can be prepared by a simple process.

Description

Alloys and preparation methods thereof

Technical field

The present application relates to the field of additive manufacturing, and more specifically, to an alloy and a preparation method thereof.

Background technique

Oxide dispersion strengthened (ODS) alloys (or ODS metal materials) have excellent high-temperature mechanical properties, high-temperature creep properties and radiation resistance. Therefore, ODS alloys have wide applications in many fields. The ODS alloy preparation methods provided by related technologies are either complex and costly, or the prepared ODS alloy has poor performance. How to prepare high-performance ODS alloys using simple processes is a research hotspot in the field of ODS alloys.

Contents of the invention

The embodiments of the present application provide an alloy and a preparation method thereof, which can prepare high-performance ODS alloys with a simple process.

In a first aspect, a method for preparing an alloy is provided, which includes: laying alloy powder on a powder bed; increasing the oxygen content in the alloy powder before additive manufacturing; performing additive manufacturing on the alloy powder to obtain ODS alloy.

In conjunction with the first aspect, in a possible implementation of the first aspect, increasing the oxygen content in the alloy powder includes: increasing the oxygen content in the alloy powder, and allowing oxygen elements to be present in the alloy Evenly distributed in the powder.

In conjunction with the first aspect, in a possible implementation of the first aspect, increasing the oxygen content in the alloy powder includes: controlling the alloy powder to perform in-situ oxidation.

In conjunction with the first aspect, in a possible implementation of the first aspect, the oxide generated by the in-situ oxidation forms an oxide layer on the surface of the alloy powder.

In conjunction with the first aspect, in a possible implementation of the first aspect, the thickness of the oxide layer is greater than or equal to 10 nm.

In conjunction with the first aspect, in a possible implementation of the first aspect, the thickness of the oxide layer is 50 to 100 nm.

In conjunction with the first aspect, in a possible implementation of the first aspect, controlling the alloy powder to perform in-situ oxidation includes: controlling the oxygen concentration in the molding atmosphere chamber to cause the alloy powder to perform in-situ oxidation. .

In conjunction with the first aspect, in a possible implementation of the first aspect, the oxygen concentration in the molding atmosphere chamber is 300 to 5000 ppm.

In conjunction with the first aspect, in a possible implementation of the first aspect, the alloy powder includes a first oxidizing element and a second oxidizing element, and increasing the oxygen content in the alloy powder includes: controlling The first oxidizing element undergoes an oxidation reaction to obtain a first oxide; and performing additive manufacturing on the alloy powder to obtain an ODS alloy includes: performing additive manufacturing on the alloy powder, such that The second oxidizing element undergoes an oxidation reaction with the oxygen element in the first oxide to generate an ODS alloy that is dispersion strengthened based on the second oxide.

In conjunction with the first aspect, in a possible implementation of the first aspect, in the alloy powder, the content of the first oxidizing element is greater than the content of the second oxidizing element.

In conjunction with the first aspect, in a possible implementation of the first aspect, the oxidizing property of the first oxidizing element is less than the oxidizing property of the second oxidizing element.

In conjunction with the first aspect, in a possible implementation of the first aspect, the size of the second oxide is 1 to 10 nm.

Combined with the first aspect, in a possible implementation of the first aspect, the size of the second oxide is 1 to 3 nm.

In conjunction with the first aspect, in a possible implementation of the first aspect, the first oxidizing element and the second oxidizing element include two of the following: Ti, Al, Y, Zr, Mg, Si, Mn, Fe, Ni, Ca, V, Cr, Hf, Mo, Ta, Nb, W, Zn, Sc, Co and Cu.

In conjunction with the first aspect, in a possible implementation of the first aspect, the first oxidizing element is Fe, and the second oxidizing element is Ti.

In connection with the first aspect, in a possible implementation of the first aspect, the content of oxygen element in the ODS alloy is 0.05% to 0.5%.

In connection with the first aspect, in a possible implementation of the first aspect, the process used in the additive manufacturing is one of the following: a selective laser melting process, a laser directional deposition process, and a selective electron beam melting process.

In conjunction with the first aspect, in a possible implementation of the first aspect, the ODS alloy is alloy steel.

In conjunction with the first aspect, in a possible implementation of the first aspect, the alloy steel includes one or more of the following elements: Cr, W, Mn, Si, and Ti.

In a second aspect, a method for preparing an alloy is provided, including: delivering an alloy material to an additive manufacturing system, the alloy material containing a first oxidizing element and a second oxidizing element; performing additive manufacturing on the alloy material, An oxidation reaction occurs between the second oxidizing element and the oxygen element in the first oxide to generate an ODS alloy based on the second oxide for dispersion strengthening; wherein the first oxide is based on the first oxide. Oxides formed from sexual elements.

In conjunction with the second aspect, in a possible implementation of the second aspect, in the alloy powder, the content of the first oxidizing element is greater than the content of the second oxidizing element.

In conjunction with the second aspect, in a possible implementation of the second aspect, the oxidizing property of the first oxidizing element is less than the oxidizing property of the second oxidizing element.

Combined with the second aspect, in a possible implementation of the second aspect, the oxygen element content in the ODS alloy is 0.05% to 0.5%.

Combined with the second aspect, in a possible implementation of the second aspect, the size of the second oxide is 1 to 10 nm.

Combined with the second aspect, in a possible implementation of the second aspect, the size of the second oxide is 1 to 3 nm.

In conjunction with the second aspect, in a possible implementation of the second aspect, the first oxidizing element and the second oxidizing element include two of the following: Ti, Al, Y, Zr, Mg, Si, Mn, Fe, Ni, Ca, V, Cr, Hf, Mo, Ta, Nb, W, Zn, Sc, Co and Cu.

Combined with the second aspect, in a possible implementation of the second aspect, the first oxidizing element is Fe, and the second oxidizing element is Ti.

In conjunction with the second aspect, in a possible implementation of the second aspect, the process used in the additive manufacturing is one of the following: a selective laser melting process, a laser directional deposition process, and a selective electron beam melting process.

In conjunction with the second aspect, in a possible implementation manner of the second aspect, the ODS alloy is alloy steel.

In conjunction with the second aspect, in a possible implementation of the second aspect, the alloy steel includes one or more of the following elements: Cr, W, Mn, Si, and Ti.

A third aspect provides an alloy prepared based on the first aspect or any implementation of the first aspect.

A fourth aspect provides an alloy prepared based on the second aspect or any implementation of the second aspect.

Description of the drawings

Figure 1 is a schematic flow chart of a method for preparing an alloy provided by an embodiment of the present application.

Figure 2 is a TEM diffraction pattern of the ODS alloy steel prepared in Example 1 of the present application.

Figure 3 is a TEM image of the ODS alloy steel prepared in Example 1 of the present application.

Figure 4 is an EBSD diagram of the ODS alloy steel prepared in Example 1 of this application.

Figure 5 is an SEM image of the ODS alloy steel prepared in Example 1 of the present application.

The markings in the drawing are: 1-oxide, 2-ferrite, 3-oxide layer.

Detailed ways

The alloy matrix of ODS alloy (or ODS metal material) is distributed with oxide dispersion strengthening phases that are ultra-stable in various extreme environments. Therefore, ODS alloy has excellent high-temperature mechanical properties, high-temperature creep properties and radiation resistance, and is very suitable for working environments with demanding requirements on metal properties. For example, ODS alloys are suitable for working environments with extremely high temperatures or high radiation, such as aviation, aerospace, nuclear reactors and other working environments.

In order to obtain ODS alloys, traditional technology usually uniformly mixes alloy powder and oxide particles, and makes the oxide particles evenly enter the alloy powder based on mechanical alloying technology. Mechanical alloying technology uses high-energy grinders or ball mills to repeatedly deform, cold weld, and crush alloy powders to achieve atomic level alloying between elements. The mechanical alloying process is a complex physical and chemical process, and the alloying process is very easy to introduce gas molecules or other impurity elements. After the oxide particles enter the metal powder through mechanical alloying technology, traditional technology will continue to use powder metallurgy methods, such as hot isostatic pressing, hot extrusion, etc., to prepare bulk ODS alloys. Since oxide particles tend to aggregate at the grain boundaries of the alloy matrix, the problem of aggregation and growth of oxides will inevitably occur during the powder metallurgy process (the oxides themselves have a tendency to aggregate and grow), resulting in the final The size of the oxide particles in the prepared ODS alloy is large, which seriously affects the final performance of the ODS alloy (generally speaking, the oxide particles in the ODS alloy need to be maintained at the nanometer level to have a good strengthening effect). In summary, it can be seen that the ODS preparation process provided by traditional technology has many problems such as complex process flow, high cost, and low ODS molding quality. The existence of the above problems has greatly restricted the promotion and application of ODS alloys.

In order to simplify the preparation process of ODS alloy and improve the forming quality of ODS alloy, related technologies have proposed an ODS alloy preparation method based on additive manufacturing process. The following describes additive manufacturing and ODS alloy preparation methods based on additive manufacturing.

Additive manufacturing may also be called 3D printing or rapid prototyping. There are many types of additive manufacturing technologies. The additive manufacturing technology mentioned in the embodiments of this application refers to metal additive manufacturing technology. The so-called metal additive manufacturing technology uses metal powder/wire as raw materials, high-energy beams (laser/electron beams/arcs/plasma beams, etc.) as cutting tools, based on computer three-dimensional data models, and using the principle of discrete-stacking. A new manufacturing technology that melts metal materials and deposits them layer by layer under the control of software and CNC systems to create high-performance metal components.

The forming process of metal additive manufacturing can include powder bed selective fusion forming process and simultaneous material feeding forming process. The powder bed selective melting molding process may include, for example, the following processes: selective laser melting (SLM) process, laser directional deposition process, and selective electron beam melting process. Simultaneous material feed forming processes may include, for example, the following processes: laser three-dimensional forming processes, electron beam fuse deposition processes, and arc additive manufacturing processes.

Compared with the traditional technologies mentioned above, additive manufacturing technology is more economical, efficient, and can be prepared in large quantities. It is very suitable for manufacturing parts with complex structures. Therefore, it can promote the development of ODS alloys in extreme service fields such as aerospace, aviation, and nuclear energy. application. In addition, the additive manufacturing process uses high-energy beams for molding. It has the characteristics of a micron-scale small melt pool and a cooling rate of 10 ³ to 10 ⁶ k/s, which can greatly reduce the problem of oxide aggregation and growth during the molding process ( Because during the processing, the oxide may not have time to gather to a certain size before solidifying.) Therefore, the ODS alloy preparation method based on the additive manufacturing process can form a fine-grained structure, thereby further improving the high-temperature mechanical properties and thermal creep properties of the ODS alloy.

For ODS alloy preparation methods based on additive manufacturing, how to introduce oxides into the alloy is the first problem to be solved. In response to the above problems, one possible solution is to oxidize the alloy powder during the powdering process, thereby introducing oxide particles into the alloy powder. There are many problems with introducing oxides into the milling process. First of all, the oxidation of alloy powder during the powder making process will result in the formation of larger and more stable oxide particles in the powder, which cannot form finer and dispersed oxides. The strengthening caused by large-sized oxides The effect is very limited. Secondly, the powder making process usually requires the use of multiple processes to process and process the powder. If the powder is oxidized during this process, it is difficult to ensure that the oxidation of the powder is uniform. In other words, the introduction of oxides during the powdering process is likely to result in the formation of different amounts of oxides at different locations in the alloy powder. In addition, after the alloy powder is oxidized, the fluidity may become poor, thereby affecting the subsequent powder feeding quality and the molding effect of additive manufacturing.

In addition to the above-mentioned methods of introducing oxides in the powdering process, oxides can also be introduced in the additive manufacturing process. For example, the oxygen concentration in the molding atmosphere chamber (or printing chamber) can be controlled during the additive manufacturing process, so that the alloy powder reacts with the oxygen in the molding atmosphere chamber under the action of high-energy beams. In this way, the alloy obtained through additive manufacturing will contain a certain amount of oxides, thus forming an ODS alloy. However, generally speaking, the gas in the molding atmosphere chamber uses chemically stable inert gases such as nitrogen and argon. Even if oxygen is added, the oxygen concentration is not likely to be too high, otherwise it is likely to affect the final molding quality. Therefore, it is often difficult to introduce sufficient oxygen elements when introducing oxides during the additive manufacturing process, resulting in low oxygen content and limited strengthening effects in the prepared ODS alloys.

In order to improve the performance of the ODS alloy prepared based on the additive manufacturing process, the alloy preparation method provided in this application will be described in detail below with reference to Example 1.

Embodiment 1

Figure 1 is a schematic flow chart of the method for preparing ODS alloy provided in Embodiment 1. The method in Figure 1 includes steps S12 to S16. Each step in Figure 1 can be completed by the additive manufacturing system through automatic control. In some embodiments, before performing the steps of Figure 1, the alloy powder may be prepared first. The alloy powder can be prepared in a variety of ways. For example, the raw materials can be proportioned according to the composition of the alloy powder, and the alloy powder can be prepared by using vacuum atomization powdering technology and/or rotating electrode technology.

Referring to step S12 in Figure 1, alloy powder (or alloy raw material powder) is laid on the powder bed. For example, an additive manufacturing system can use a powder spreading mechanism to lay alloy powder on a powder bed (or matrix).

Continuing to refer to step S14, before additive manufacturing, the oxygen content in the alloy powder is increased. That is to say, before manufacturing, a certain amount of oxygen element can be introduced into the alloy powder in advance to increase the oxygen content in the prepared ODS alloy. For example, before additive manufacturing, the oxidizing elements in the alloy powder can be used to undergo an oxidation reaction to adsorb a large amount of oxygen in advance.

In some embodiments, the process of step S14 can be controlled so that oxygen element is uniformly introduced into the alloy powder. The oxygen element is evenly distributed in the alloy powder, which is equivalent to providing more nucleation sites for the subsequent oxide nucleation and growth process. More nucleation sites usually nucleate independently and do not aggregate and grow with each other. , which is beneficial to the formation of ODS alloy with finely dispersed oxides.

This embodiment does not specifically limit the method of introducing oxygen element into the alloy powder. In some embodiments, the oxidation reaction between the alloy powder and oxygen element can be controlled to introduce oxygen element into the alloy powder. Since the oxidation reaction occurs before additive manufacturing, in some embodiments, the oxidation process may be called pre-oxidation of the alloy powder.

Pre-oxidation of alloy powder can be achieved through in-situ oxidation technology. For example, in-situ oxidation of alloy powders can be achieved by controlling the oxygen concentration in the molding atmosphere chamber. As an example, oxygen or carbon dioxide can be added in the molding atmosphere chamber, so that the oxidizing elements in the alloy powder react with the oxygen or carbon dioxide in the molding atmosphere chamber, thereby performing in-situ oxidation of the alloy powder. Before additive manufacturing, controlling the oxidation reaction between the oxidizing elements in the alloy powder and the oxygen element in the molding atmosphere chamber can uniformly introduce a large amount of oxygen elements into the alloy powder in advance, which is beneficial to the subsequent formation of ODS alloys with finely dispersed oxides. . Further, since the above steps are performed after the alloy powder has been spread out, the powder can be fully contacted with the gas in the molding atmosphere chamber, and the conditions of each powder particle are almost exactly the same, so the oxidation of each powder particle is The degree is almost exactly the same.

Continuing to refer to step S16 in Figure 1, after obtaining the alloy powder with increased oxygen content, the alloy powder is subjected to additive manufacturing to obtain an ODS alloy. This additive manufacturing can use metal additive manufacturing processes. Alternatively, the additive manufacturing process can use an additive manufacturing process based on high-energy beams and powder coating. For example, in some embodiments, the additive manufacturing may use one of the following processes: a selective laser melting process, a laser directional deposition process, and a selective electron beam melting process.

According to the above, it can be seen that in this embodiment, oxygen is introduced after the powder has been spread on the powder bed, so there is no need to consider the impact of the introduction of oxygen on the fluidity of the powder. In addition, this embodiment does not need to mix oxides into the alloy powder in advance, which greatly reduces the time cost. It only needs to control the printing process to oxidize the alloy powder, simplifying the preparation process of the ODS alloy and reducing the preparation cost. Furthermore, in this embodiment, the oxygen element is introduced in advance before additive manufacturing, so that a large amount of oxygen element is adsorbed in the alloy powder, thereby avoiding the insufficient oxygen content in the ODS alloy caused by the introduction of oxygen element again during the additive manufacturing process. question.

Before additive manufacturing, the higher the oxygen content in the alloy powder and the more uniform the distribution of oxygen elements in the alloy powder, the better the performance of the final ODS alloy. Therefore, in some embodiments, step S14 in FIG. 1 may include: controlling the alloy powder to perform in-situ oxidation to form an oxide layer. Taking ODS alloy steel as an example, the oxide layer may include Fe oxide, for example. The formation of the oxide layer can ensure that the alloy powder has a sufficient amount of oxygen on the one hand, and ensures that the oxygen element is evenly distributed in the alloy powder on the other. In addition, since the oxide layer is on the surface of the alloy raw material powder, the oxide layer will be directly affected by the laser during the additive manufacturing process. Compared with the oxide particles, the energy barrier for the oxide layer to participate in the reaction is greatly reduced, making the reaction more uniform. , so that the oxide can be further refined with the help of additive manufacturing processes.

In some embodiments, an oxide layer can be formed on the surface of the alloy powder by controlling the oxygen concentration in the molding atmosphere chamber. For example, the oxygen concentration in the molding atmosphere chamber can be controlled at 300 to 5000 ppm (such as 500 ppm) to form the above-mentioned oxide layer on the surface of the alloy powder. The thickness of the oxide layer can be adjusted by adjusting the content of oxidizing elements in the alloy powder and the oxygen concentration in the molding atmosphere chamber. The thicker the oxide layer, the more oxygen element is introduced into the alloy powder, and the oxide content in the final ODS alloy will also increase accordingly. In some embodiments, the thickness of the oxide layer may be greater than or equal to 10 nm. For example, the thickness of the oxide layer can be between 50 and 200 nm (such as between 50 and 100 nm).

In some embodiments, during step S16, oxygen element may be further introduced into the alloy powder to further increase the oxygen content of the ODS alloy. That is to say, in addition to pre-introducing oxygen element through step S14, the oxygen content of the ODS alloy can also be further increased during the additive manufacturing process. For example, the oxygen concentration in the molding atmosphere chamber during the additive manufacturing process can be controlled so that the oxygen element in the molding atmosphere chamber undergoes an oxidation reaction with the oxidizing elements in the alloy powder under the action of high-energy beams, thereby further improving the quality of the ODS alloy. of oxygen content.

In some embodiments, the oxygen content (mass percentage) of the oxide in the ODS alloy is 0.05% to 0.5%.

In some embodiments, before step S12 is performed, the oxygen content in the alloy powder may be 0. Alternatively, the alloy powder may also contain a certain amount of oxygen element.

In some embodiments, before performing step S12, alloy powder may be prepared according to certain parameters and/or performance indicators. Of course, the properties and/or parameters of the alloy powder can be selected according to actual needs, and are not specifically limited in the embodiments of the present application. For example, the properties and/or parameters of the alloy powder need to meet the following indicators: particle size 15-53μm, D50 36μm, sphericity >90%, fluidity <20s, and bulk density >4.1g/cm3.

In some embodiments, the ODS alloy obtained in step S16 may be a bulk ODS alloy, such as an ODS alloy product of a certain shape.

In some embodiments, the oxides in the ODS alloy may be nanoscale oxides, and therefore, the ODS alloy may be called a nano-ODS alloy.

In some embodiments, the ODS alloy may be, for example, ODS alloy steel. The ODS alloy steel may include, for example, ODS ferritic steel and/or ODS martensitic steel. In addition to Fe and C elements, ODS alloy steel can also include one or more of the following elements: Cr, W, Mn, Si and Ti.

In some embodiments, the process parameters of additive manufacturing in step S16 can be configured according to the shape and/or performance requirements of the ODS alloy to be processed. For example, in some embodiments, the process parameters of additive manufacturing can adopt The following configuration: laser power is 180-220W, scanning speed is 700-1000mm/s, scanning pitch is 80-120μm, layer thickness is 30μm, rotation angle is 67°, and the scanning strategy is stripe mode.

Embodiment 2

Embodiment 2 provides a more specific way of generating oxides based on Embodiment 1. The oxide generation method provided in Example 2 can enable the oxide to be dispersed in the ODS alloy in a smaller size, thereby improving the formability of the ODS alloy.

Specifically, in Embodiment 2, the alloy powder may include a first oxidizing element and a second oxidizing element. Before additive manufacturing, an oxidation reaction between the first oxidizing element and the oxygen element can be used to obtain the first oxide (corresponding to step S14 of Embodiment 1). That is to say, the first oxidizing element can be used to introduce oxygen element into the alloy powder, thereby increasing the oxygen content in the alloy powder. Then, additive manufacturing can be performed on the alloy powder, so that the second oxidizing element reacts with the oxygen element in the first oxide to generate an ODS alloy that is dispersion strengthened based on the second oxide (corresponding to Embodiment 1) Step S16). That is to say, the second oxidizing element can rob the oxygen element in the first oxide, thereby obtaining an ODS alloy that is dispersion strengthened based on the second oxide.

The additive manufacturing process melts the alloy powder area by area, and the melted alloy powder will quickly solidify and form in a very short time. The above characteristics of additive manufacturing can avoid the aggregation and growth of oxides to a certain extent. On this basis, the implementation provided in Embodiment 2 also introduces the process of recombining the oxide (that is, the process of the second oxidizing element robbing the oxygen in the first oxide to form the second oxide in the above-mentioned very short period of time). ), the process of reorganizing the oxide will consume a certain amount of time, so that the second oxide formed during the additive manufacturing process has no time to gather and grow up, so that the large particle oxide (first oxide) can be refined to obtain ODS alloy with finely dispersed oxides.

In some embodiments, the first oxide can be formed by in-situ oxidation of the first oxidizing element, thereby uniformly introducing the oxygen element into the alloy powder. The oxygen element is evenly distributed in the alloy powder, so that there are more nucleation sites for the second oxide. During the additive manufacturing process, the second oxides nucleate individually, which can effectively reduce the probability of oxide aggregation and growth.

In some embodiments, a uniform oxide layer can be formed on the surface of the alloy powder by in-situ oxidation of the first oxidizing element. The uniform oxide layer on the surface of each powder can ensure that the second oxidizing element in the powder can react with the oxide layer more fully and evenly, thereby generating finer and more dispersed oxides.

In some embodiments, in order to cause the first oxidizing element to be oxidized earlier than the second oxidizing element, the contents (such as mass percentage) of the first oxidizing element and the second oxidizing element in the alloy powder can be controlled such that the first oxidizing element is oxidized before the second oxidizing element. The content of the oxidizing element is greater than the content of the second oxidizing element. For example, the ODS alloy can use the first oxidizing element as the matrix, and control the content (mass percentage) of the second oxidizing element to 0.05% to 0.5%. For example, the ODS alloy is an alloy steel in which the first oxidizing element is Fe and the second oxidizing element is Ti. In terms of mass percentage, the various elements of the alloy powder can adopt the following proportions: Cr: 8.90%, W: 0.82%, Mn: 0.23%, Si: 0.086%, Ti: 0.27%, C: 0.075%, Fe: bal. .

In some embodiments, the oxidizing property of the first oxidizing element may be less than the oxidizing property of the second oxidizing element. The oxidizing property of the second oxidizing element is greater than the oxidizing property of the first oxidizing element, which helps the second oxidizing element to snatch oxygen element from the first oxidizing element during the additive manufacturing process, effectively increasing the oxidation rate of the second oxidizing element. Content in ODS. For example, the first oxidizing element and the second oxidizing element include two of the following: Ti, Al, Y, Zr, Mg, Si, Mn, Fe, Ni, Ca, V, Cr, Hf, Mo, Ta, Nb, W, Zn, Sc, Co and Cu.

In some embodiments, the first oxidizing element is Fe and the second oxidizing element is Ti. For example, the alloy powder is Fe-0.27Ti-9Cr-1W, where Fe is the first oxidizing element and Ti is the second oxidizing element. Fe and O are oxidized in situ to form an oxide layer with a thickness of 50nm-200nm. As an oxygen-active element that is more active than Fe, Ti reacts with Fe oxides under the action of high-energy beams (such as lasers) to generate very fine and dispersed titanium oxides in situ.

In some embodiments, the second oxide has a size of 1 to 10 nm. For example, the size of the second oxide may be 1 to 3 nm. The size of the oxide in the traditional ODS alloy preparation method based on additive manufacturing is usually much larger than 10 nm (usually at least 30 to 50 nm). Using the technical solution provided in this embodiment, the size of the oxide in the ODS alloy can be controlled. Below 10nm, a high-performance nano-ODS alloy is formed. In addition, using the technical solution provided by the embodiments of this application, the molding density of the ODS alloy can reach 99.8%, and its mechanical properties and service time under extreme conditions have been optimized.

It should be noted that, on the premise of no conflict, Embodiment 2 can be combined with various solutions provided in Embodiment 1. For the sake of brevity, details will not be described here.

Embodiment 3

Embodiment 3 is similar to Embodiment 2. The alloy powder includes a first oxidizing element and a second oxidizing element, wherein the oxide formed by the first oxidizing element is the first oxide, and the oxide formed by the second oxidizing element is is the second oxide. During the additive manufacturing process, the second oxidizing element reacts with the oxygen element in the first oxide to form the second oxide. The main difference between Embodiment 3 and Embodiment 2 is that Embodiment 3 does not limit the timing of introducing the first oxide. In some embodiments, the first oxide in Embodiment 3 can be introduced during the ingot casting and/or pulverizing process. In other embodiments, the method described in Embodiment 2 can be used to introduce the first oxide after powder coating and before additive manufacturing.

In addition, Embodiment 2 adopts a powder bed selective melting molding process based on powder spreading, and Embodiment 3 does not limit this process. For example, in the third embodiment, a powder bed selective melting molding process can be used for additive manufacturing, or a simultaneous material feeding molding process can be used for additive manufacturing.

It should be noted that, on the premise of no conflict, Embodiment 3 can be combined with various solutions provided in Embodiment 2. For the sake of brevity, details will not be described here.

Example 1: Preparation of low activation ODS alloy steel

The elemental composition of the low activation ODS alloy to be prepared in Example 1, in mass percentage, includes: Cr: 8.90%, W: 0.82%, Mn: 0.23%, Si: 0.086%, Ti: 0.27%, C: 0.075 %, Fe: bal..

Step 1: Use vacuum atomization powdering technology to smelt Fe, Cr, W, Mn, Ti, C, and Si element raw materials according to the element formula to obtain alloy powder suitable for additive manufacturing.

Step 2: The alloy powder obtained in step 1 is formed using SLM280 equipment through additive manufacturing technology. The laser rapidly solidifies and melts the swept powder according to the set path. The laser parameters are: laser power: 200W, scanning speed: 600mm/s, scanning pitch 120μm, layer thickness 30μm, rotation angle 67°, scanning strategy is stripe mode. During the additive manufacturing process, the oxygen concentration in the molding atmosphere chamber is controlled to 500ppm, which allows the alloy powder to be oxidized before melting, adsorbing a large amount of oxygen on the surface, and forming an oxide layer of tens of nanometers or more.

After step 2, the ODS alloy sample obtained in step 2 is cut from the substrate for microstructure characterization and mechanical property testing. As shown in Figure 2-3, Figure 2 is the diffraction spot of the central dark field pattern set, and Figure 3 is the corresponding precipitated phase. It can be seen that the sample matrix obtained in step 3 contains a large number of finely dispersed 1-3nm oxides. 1 precipitated phase, the elemental composition is Ti and O.

As shown in Figure 4, the structure of the sample obtained in step 2 is ultrafine-grained ferrite 2, with an average grain size of 1-2um. This is due to the refining effect of fine dispersed oxide particles on the grains.

As shown in Figure 5, in step 2, the powder can be oxidized before melting, and a large amount of oxygen is adsorbed on the surface to form an oxide layer 3 of more than 50-100 nanometers. Among them, the elemental composition of the oxide layer is Fe and O.

The tensile test results of the ODS alloy sample are as follows: the tensile strength at room temperature is 1200MPa, the elongation is 18%, the tensile strength at 600°C is 930MPa, and the elongation at break is 14%. The performance of this ODS alloy sample is improved by more than 150% compared to the low activation steel produced by ordinary additive manufacturing. It is comparable to the ODS low activation steel prepared by traditional methods (mechanical alloying), and the forming quality and cost are superior to traditional methods.

In addition to the above-mentioned method for preparing an ODS alloy, embodiments of the present application also provide an ODS alloy prepared based on any of the previous embodiments.

Those skilled in the art will understand that the features described in the various embodiments and/or claims of the present disclosure may be combined or/or combined in various ways, even if such combinations or combinations are not explicitly described in the present disclosure. In particular, various combinations and/or combinations of features recited in the various embodiments and/or claims of the disclosure may be made without departing from the spirit and teachings of the disclosure. All such combinations and/or combinations fall within the scope of this disclosure.

The embodiments of the present disclosure have been described above. However, these examples are for illustrative purposes only and are not intended to limit the scope of the present disclosure. Although each embodiment is described separately above, this does not mean that the measures in the various embodiments cannot be used in combination to advantage. The scope of the disclosure is defined by the appended claims and their equivalents. Without departing from the scope of the present disclosure, those skilled in the art can make various substitutions and modifications, and these substitutions and modifications should all fall within the scope of the present disclosure.

Claims

A method for preparing alloys, characterized by comprising:

Laying alloy powder on a powder bed;

increasing the oxygen content in the alloy powder prior to additive manufacturing;

The alloy powder is subjected to the additive manufacturing to obtain an ODS alloy.
The method of claim 1, wherein increasing the oxygen content in the alloy powder includes:

Increase the oxygen content in the alloy powder and make the oxygen element evenly distributed in the alloy powder.
The method according to claim 1 or 2, characterized in that increasing the oxygen content in the alloy powder includes:

The alloy powder is controlled to undergo in-situ oxidation.
The method of claim 3, wherein the oxide generated by the in-situ oxidation forms an oxide layer on the surface of the alloy powder.
The method of claim 4, wherein the thickness of the oxide layer is greater than or equal to 10 nm.
The method according to claim 5, wherein the thickness of the oxide layer is 50-100 nm.
The method according to any one of claims 3-6, wherein controlling the alloy powder to perform in-situ oxidation includes:

The oxygen concentration in the molding atmosphere chamber is controlled so that the alloy powder is oxidized in situ.
The method according to claim 7, characterized in that the oxygen concentration in the molding atmosphere chamber is 300 to 5000 ppm.
The method according to any one of claims 1 to 8, wherein the alloy powder includes a first oxidizing element and a second oxidizing element, and increasing the oxygen content in the alloy powder includes:

Controlling the oxidation reaction of the first oxidizing element to obtain a first oxide;

The additive manufacturing is performed on the alloy powder to obtain the ODS alloy, which includes:

The additive manufacturing is performed on the alloy powder to cause an oxidation reaction between the second oxidizing element and the oxygen element in the first oxide to generate an ODS alloy that is dispersion strengthened based on the second oxide.
The method according to claim 9, characterized in that, in the alloy powder, the content of the first oxidizing element is greater than the content of the second oxidizing element.
The method according to claim 9 or 10, characterized in that the oxidizing property of the first oxidizing element is less than the oxidizing property of the second oxidizing element.
The method according to any one of claims 9-11, characterized in that the size of the second oxide is 1 to 10 nm.
The method of claim 12, wherein the second oxide has a size of 1 to 3 nm.
The method according to any one of claims 9-13, wherein the first oxidizing element and the second oxidizing element include two of the following: Ti, Al, Y, Zr, Mg , Si, Mn, Fe, Ni, Ca, V, Cr, Hf, Mo, Ta, Nb, W, Zn, Sc, Co and Cu.
The method according to any one of claims 9-14, wherein the first oxidizing element is Fe and the second oxidizing element is Ti.
The method according to any one of claims 1 to 15, characterized in that the content of oxygen element in the ODS alloy is 0.05% to 0.5%.
The method according to any one of claims 1 to 16, characterized in that the process used in the additive manufacturing is one of the following: selective laser melting process, laser directional deposition process, and selective electron beam melting process .
The method according to any one of claims 1-17, characterized in that the ODS alloy is alloy steel.
The method of claim 18, wherein the alloy steel includes one or more of the following elements: Cr, W, Mn, Si and Ti.
A method for preparing alloys, characterized by comprising:

delivering an alloy material to the additive manufacturing system, the alloy material including a first oxidizing element and a second oxidizing element;

Additive manufacturing is performed on the alloy material to cause an oxidation reaction between the second oxidizing element and the oxygen element in the first oxide to generate an ODS alloy that is dispersion strengthened based on the second oxide; wherein, the third A monooxide is an oxide formed based on the first oxidizing element.
An alloy produced based on the method of any one of claims 1-19.
An alloy produced based on the method of claim 20.