CN116033982A

CN116033982A - Alloy and preparation method thereof

Info

Publication number: CN116033982A
Application number: CN202280004189.4A
Authority: CN
Inventors: 张舒博; 张文井; 陈浩; 刘伟
Original assignee: Tsinghua University
Current assignee: Tsinghua University
Priority date: 2022-05-30
Filing date: 2022-10-12
Publication date: 2023-04-28

Abstract

An ODS alloy and a preparation method thereof are provided. The method comprises the following steps: paving alloy powder on a powder bed; increasing the oxygen content in the alloy powder prior to additive manufacturing; and carrying out additive manufacturing on the alloy powder to obtain the ODS alloy. The scheme can prepare high-performance ODS alloy by a simple process.

Description

Alloy and preparation method thereof

Technical Field

The present application relates to the field of additive manufacturing, and more particularly, to an alloy and a method of making the same.

Background

Oxide dispersion strengthened (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 been widely used in many fields. The ODS alloy preparation method provided by the related art is complex in process and high in cost, or the prepared ODS alloy is poor in performance. How to prepare high-performance ODS alloy by a simple process is a research focus in the field of ODS alloy.

Disclosure of Invention

The embodiment of the application provides an alloy and a preparation method thereof, which can prepare high-performance ODS alloy by a simple process.

In a first aspect, there is provided a method of preparing an alloy comprising: paving alloy powder on a powder bed; increasing the oxygen content in the alloy powder prior to additive manufacturing; and carrying out additive manufacturing on the alloy powder to obtain the ODS alloy.

With reference to the first aspect, in a possible implementation manner of the first aspect, the increasing the oxygen content in the alloy powder includes: increasing the oxygen content in the alloy powder and allowing an even distribution of oxygen elements in the alloy powder.

With reference to the first aspect, in a possible implementation manner of the first aspect, the increasing the oxygen content in the alloy powder includes: and controlling the alloy powder to perform in-situ oxidation.

With reference to the first aspect, in a possible implementation manner of the first aspect, the oxide generated by in-situ oxidation forms an oxide layer on the surface of the alloy powder.

With reference to the first aspect, in a possible implementation manner of the first aspect, a thickness of the oxide layer is greater than or equal to 10nm.

With reference to the first aspect, in a possible implementation manner of the first aspect, a thickness of the oxide layer is 50 to 100nm.

With reference to the first aspect, in a possible implementation manner of the first aspect, the controlling the alloy powder to perform in-situ oxidation includes: the oxygen concentration in the forming atmosphere chamber is controlled so that the alloy powder undergoes in situ oxidation.

With reference to the first aspect, in a possible implementation manner of the first aspect, an oxygen concentration in the forming atmosphere chamber is 300 to 5000ppm.

With reference to the first aspect, in a possible implementation manner of the first aspect, the alloy powder includes a first oxidizing element and a second oxidizing element, and the increasing the oxygen content in the alloy powder includes: controlling the first oxidizing element to perform an oxidation reaction to obtain a first oxide; said subjecting said alloy powder to said additive manufacturing to obtain an ODS alloy comprising: the additive manufacturing is performed on the alloy powder such that the second oxidizing element is oxidized with the oxygen element in the first oxide to produce an ODS alloy that is dispersion-strengthened based on the second oxide.

With reference to the first aspect, in a possible implementation manner of the first aspect, in the alloy powder, a content of the first oxidizing element is greater than a content of the second oxidizing element.

With reference to the first aspect, in a possible implementation manner of the first aspect, the first oxidizing element has an oxidizing property that is less than an oxidizing property of the second oxidizing element.

With reference to the first aspect, in a possible implementation manner of the first aspect, a size of the second oxide is 1 to 10nm.

With reference to the first aspect, in a possible implementation manner of the first aspect, a size of the second oxide is 1 to 3nm.

With reference to the first aspect, in one possible implementation manner 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.

With reference to the first aspect, in one possible implementation manner of the first aspect, the first oxidizing element is Fe, and the second oxidizing element is Ti.

With reference to the first aspect, in a possible implementation manner of the first aspect, a content of an oxygen element in the ODS alloy is 0.05% to 0.5%.

With reference to the first aspect, in a possible implementation manner of the first aspect, the process adopted by the additive manufacturing is one of the following: selective laser melting process, laser directional deposition process, and selective electron beam melting process.

With reference to the first aspect, in a possible implementation manner of the first aspect, the ODS alloy is alloy steel.

With reference to the first aspect, in one possible implementation manner 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, there is provided a method of preparing an alloy comprising: delivering an alloy material to an additive manufacturing system, the alloy material comprising a first oxidizing element and a second oxidizing element; additive manufacturing the alloy material, so that the second oxidizing element and oxygen element in the first oxide are subjected to oxidation reaction to generate ODS alloy which is subjected to dispersion strengthening based on the second oxide; wherein the first oxide is an oxide formed based on the first oxidizing element.

With reference to the second aspect, in a possible implementation manner of the second aspect, in the alloy powder, a content of the first oxidizing element is greater than a content of the second oxidizing element.

With reference to the second aspect, in a possible implementation manner of the second aspect, the oxidizing property of the first oxidizing element is smaller than the oxidizing property of the second oxidizing element.

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

With reference to the second aspect, in a possible implementation manner of the second aspect, a size of the second oxide is 1 to 10nm.

With reference to the second aspect, in a possible implementation manner of the second aspect, a size of the second oxide is 1 to 3nm.

With reference to the second aspect, in one possible implementation manner 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.

With reference to the second aspect, in a possible implementation manner of the second aspect, the first oxidizing element is Fe, and the second oxidizing element is Ti.

With reference to the second aspect, in a possible implementation manner of the second aspect, the process adopted by the additive manufacturing is one of the following: selective laser melting process, laser directional deposition process, and selective electron beam melting process.

With reference to the second aspect, in a possible implementation manner of the second aspect, the ODS alloy is alloy steel.

With reference to the second aspect, in a possible implementation manner of the second aspect, the alloy steel includes one or more of the following elements: cr, W, mn, si and Ti.

In a third aspect, there is provided an alloy prepared based on the first aspect or any implementation of the first aspect.

In a fourth aspect, there is provided an alloy prepared based on the second aspect or any one of the implementations of the second aspect.

Drawings

Fig. 1 is a schematic flow chart of a method for preparing an alloy according to an embodiment of the present application.

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

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

FIG. 4 is an EBSD chart of the ODS alloy steel prepared in example 1 of the present application.

FIG. 5 is an SEM image of an ODS alloy steel produced in example 1 of the present application.

The marks in the drawings are: 1-oxide, 2-ferrite, 3-oxide layer.

Detailed Description

Within the alloy matrix of the ODS alloy (or ODS metal material) is distributed an oxide dispersion strengthening phase that is ultra stable under a variety of extreme environments. Therefore, the ODS alloy has excellent high-temperature mechanical property, high-temperature creep property and radiation resistance, and is very suitable for working environments with severe requirements on metal properties. For example, ODS alloys are suitable for use in extremely high temperature or high emissivity operating environments, such as those of aviation, aerospace, nuclear reactors, and the like.

In order to be able to obtain an ODS alloy, the conventional technique generally mixes the alloy powder uniformly with oxide particles, and makes the oxide particles uniformly into the alloy powder based on a mechanical alloying technique. The mechanical alloying technology can utilize a high-energy grinder or a ball mill to repeatedly deform, cold weld and crush the alloy powder, so as to achieve the inter-element atomic level alloying. The mechanical alloying process is a complex physicochemical process, and the alloying process is very easy to introduce gas molecules or other impurity elements. After the oxide particles enter the metal powder by mechanical alloying techniques, conventional techniques continue to utilize powder metallurgy, such as hot isostatic pressing, hot extrusion, etc., to produce bulk ODS alloys. Since oxide particles tend to accumulate at the grain boundaries of the alloy matrix, the problem of aggregation and growth of oxide (oxide itself tends to aggregate and grow) inevitably occurs in the powder metallurgy process, resulting in a larger size of oxide particles in the finally produced ODS alloy, which seriously affects the final properties of the ODS alloy (in general, the oxide particles in the ODS alloy need to be maintained at a nano-scale for good strengthening effect). In summary, the ODS preparation process provided by the conventional technology has the problems of complex process flow, high cost, low ODS forming quality and the like, and the popularization and application of the ODS alloy are greatly limited by the problems.

In order to simplify the preparation process of the ODS alloy and improve the molding quality of the ODS alloy, the related technology proposes an ODS alloy preparation mode based on an additive manufacturing process. The following describes the preparation of ODS alloy based on additive manufacturing.

Additive manufacturing may also be referred to as 3D printing or rapid prototyping. Additive manufacturing techniques are numerous, and reference to additive manufacturing techniques in accordance with embodiments of the present application refers to metal additive manufacturing techniques. The metal additive manufacturing technology is a novel manufacturing technology for manufacturing high-performance metal components by taking metal powder/wire as a raw material, taking a high-energy beam (laser/electron beam/electric arc/plasma beam and the like) as a cutter, taking a computer three-dimensional data model as a basis, and using a discrete-stacking principle to melt and stack metal materials layer by layer under the control of software and a numerical control system.

The molding process of metal additive manufacturing may include a powder bed select zone melt molding process and a simultaneous material feed molding process. The powder bed zone selection melt forming process may include, for example, the following processes: selective laser melting (selective laser melting, SLM) process, laser directional deposition process, and selective electron beam melting process. The synchronous material feed forming process may include, for example, the following processes: laser stereolithography, electron beam fuse deposition, and arc additive manufacturing.

Compared with the prior art, the additive manufacturing technology is more economical and efficient, can be prepared in large quantities, is very suitable for manufacturing parts with complex structures, and can promote the application of ODS alloy in the extreme service fields of aerospace, aviation, nuclear energy and the like. In addition, the additive manufacturing process uses high energy beams for forming, and has a micron-sized small molten pool and 10 ³ ～10 ⁶ The cooling speed of k/s and the like can greatly reduce the problems of aggregation and growth of oxides in the forming process (because the oxides can be solidified and formed before being aggregated to a certain size in the processing process). Therefore, the ODS alloy preparation mode based on the additive manufacturing process can form fine grain structure, so that the high-temperature mechanical property and the thermal creep property of the ODS alloy are further improved.

For the preparation mode of ODS alloy based on additive manufacturing, how to introduce oxide into the alloy is the first problem to be solved. One possible solution to the above problems is to oxidize the alloy powder during the powder making process, thereby introducing oxide particles into the alloy powder. There are a number of problems with the introduction of oxides during the milling process. First, oxidation of the alloy powder during the powder making process results in the formation of larger and more stable oxide particles in the powder, which do not form finer dispersed oxides, and the strengthening effect of large size oxides is very limited. Secondly, the pulverizing process generally requires various processes for handling and processing the powder, and if the powder is oxidized in this process, it is difficult to ensure that the oxidation of the powder is uniform. That is, the introduction of oxides during the powdering process is highly likely to result in the formation of different amounts of oxides at different locations of the alloy powder. In addition, the alloy powder may have poor flowability after oxidation, thereby affecting the subsequent powder feeding quality and the molding effect of additive manufacturing.

In addition to the manner in which the oxide is introduced during the powdering process mentioned above, the oxide may also be introduced during additive manufacturing. For example, the oxygen concentration of the forming atmosphere chamber (or print cartridge) may be controlled during additive manufacturing such that the alloy powder reacts with oxygen in the forming atmosphere chamber under the influence of the high energy beam. Thus, the alloy obtained by additive manufacturing contains a certain amount of oxide, thereby forming an ODS alloy. However, in general, inert gases with stable chemical properties such as nitrogen and argon are used as the gases in the forming atmosphere chamber, and even if oxygen is added, the oxygen concentration is not easily too high, otherwise the final forming quality is likely to be affected. Therefore, the manner of introducing oxides during the additive manufacturing process often makes it difficult to introduce sufficient amounts of oxygen elements, resulting in a low oxygen content and limited strengthening effect in the prepared ODS alloy.

In order to enhance the performance of the ODS alloy produced based on the additive manufacturing process, the alloy production method provided in the present application is exemplified in detail with reference to example one.

Example 1

FIG. 1 is a flow chart showing a method for producing an ODS alloy according to an embodiment. The method of fig. 1 includes steps S12 to S16. The various steps in fig. 1 may be accomplished by the additive manufacturing system in an automated fashion. In some embodiments, the alloy powder may be prepared prior to performing the steps of fig. 1. The alloy powder can be prepared in various modes, for example, the alloy powder can be prepared by proportioning raw materials according to the components of the alloy powder and adopting a vacuum atomization powder preparation technology and/or a rotating electrode technology.

Referring to step S12 in fig. 1, alloy powder (or alloy raw material powder) is laid on a powder bed. For example, additive manufacturing systems may utilize a powder-laying mechanism to lay alloy powder on a powder bed (or substrate).

With continued reference to step S14, the oxygen content in the alloy powder is increased prior to additive manufacturing. That is, a certain amount of oxygen element may be introduced into the alloy powder in advance before manufacturing to increase the oxygen content in the produced ODS alloy. For example, prior to additive manufacturing, an oxidation reaction may occur with the oxidizing element in the alloy powder to adsorb a large amount of oxygen element in advance.

In some embodiments, the process of step S14 may be controlled such that oxygen is uniformly introduced into the alloy powder. The oxygen elements are uniformly distributed in the alloy powder, which is equivalent to providing more nucleation sites for the subsequent oxide nucleation growth process, and the more nucleation sites are usually nucleated respectively and do not mutually gather and grow up, thereby being beneficial to forming the ODS alloy with tiny and dispersed oxides.

The manner of introducing the oxygen element into the alloy powder is not particularly limited in this embodiment. In some embodiments, the oxidation reaction of the alloy powder with the oxygen element may be controlled to introduce the oxygen element into the alloy powder. Since this oxidation reaction occurs prior to additive manufacturing, in some embodiments, this oxidation process may be referred to as pre-oxidation of the alloy powder.

The pre-oxidation of the alloy powder may be achieved by in situ oxidation techniques. For example, in situ oxidation of the alloy powder may be achieved by controlling the oxygen concentration in the forming atmosphere chamber. As one example, oxygen or carbon dioxide may be added to the forming atmosphere chamber such that the oxidizing element in the alloy powder reacts with the oxygen or carbon dioxide in the forming atmosphere chamber to oxidize the alloy powder in situ. Before additive manufacturing, the oxidizing element in the alloy powder and the oxygen element in the forming atmosphere chamber are controlled to perform oxidation reaction, so that a large amount of oxygen element can be uniformly introduced into the alloy powder in advance, and the subsequent formation of ODS alloy with tiny and dispersed oxide is facilitated. Further, since the above steps are performed after the alloy powder has been spread, the powder can be sufficiently contacted with the gas in the molding atmosphere chamber, and the conditions of each powder particle are almost identical, and thus the degree of oxidation of each powder particle is almost identical.

With continued reference to step S16 in FIG. 1, after the alloy powder with increased oxygen content is obtained, the alloy powder is subjected to additive manufacturing to obtain an ODS alloy. The additive manufacturing may employ a metal additive manufacturing process. Alternatively, the additive manufacturing process may employ a high energy beam and powder-lay based additive manufacturing process. For example, in some embodiments, the additive manufacturing may employ one of the following processes: selective laser melting process, laser directional deposition process, and selective electron beam melting process.

From the above, it is understood that the present embodiment introduces the oxygen element after the powder has been spread on the powder bed, and thus does not need to consider the influence of the introduction of the oxygen element on the flowability of the powder. In addition, the embodiment does not need to mix oxides into alloy powder in advance, so that the time cost is greatly reduced, the printing process is only required to be controlled to oxidize the alloy powder, the preparation process of the ODS alloy is simplified, and the preparation cost is reduced. Further, in the embodiment, oxygen is introduced in advance before the additive manufacturing, so that a large amount of oxygen is adsorbed in the alloy powder, and the problem of insufficient oxygen content in the ODS alloy caused by reintroducing oxygen in the additive manufacturing process can be avoided.

The higher the oxygen content in the alloy powder, the more uniform the distribution of oxygen elements in the alloy powder, and the better the properties of the resulting ODS alloy prior to additive manufacturing. Thus, in some embodiments, step S14 in fig. 1 may include: the alloy powder is controlled to be oxidized in situ to form an oxide layer. For example, the oxide layer may contain an oxide of Fe, for example, as an ODS alloy steel. The formation of the oxide layer ensures, on the one hand, that the alloy powder has a sufficient amount of oxygen elements and, on the other hand, that the oxygen elements are uniformly distributed in the alloy powder. In addition, as the oxide layer is arranged on the surface of the alloy raw material powder, the oxide layer can be directly subjected to the action of laser in the additive manufacturing process, and compared with oxide particles, the energy barrier of the oxide layer participating in the reaction is greatly reduced, the reaction is more uniform, and thus, the oxide can be further refined by means of the additive manufacturing process.

In some embodiments, an oxide layer may be formed on the surface of the alloy powder by controlling the oxygen concentration in the forming atmosphere chamber. For example, the oxygen concentration in the forming atmosphere chamber may be controlled to 300 to 5000ppm (e.g., 500 ppm) so that the above oxide layer is formed on the surface of the alloy powder. The thickness of the oxide layer can be adjusted by adjusting the content of the oxidizing element in the alloy powder, the oxygen concentration in the molding atmosphere chamber, and the like. The thicker the oxide layer, the more oxygen element is incorporated into the alloy powder and the oxide content in the resulting ODS alloy will increase accordingly. In some embodiments, the oxide layer may have a thickness greater than or equal to 10nm. For example, the oxide layer may have a thickness between 50 and 200nm (e.g., between 50 and 100 nm).

In some embodiments, in performing step S16, an oxygen element may be further introduced into the alloy powder to further increase the oxygen content of the ODS alloy. That is, in addition to the preliminary introduction of oxygen element through step S14, the oxygen content of the ODS alloy can be further increased in the additive manufacturing process. For example, the oxygen concentration of the forming atmosphere chamber in the additive manufacturing process can be controlled so that the oxygen element in the forming atmosphere chamber is subjected to oxidation reaction with the oxidizing element in the alloy powder under the action of the high energy beam, thereby further increasing the oxygen content in the ODS alloy.

In some embodiments, the oxide in the ODS alloy has an oxygen content (mass percent) of 0.05% -0.5%.

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

In some embodiments, the alloy powder may be prepared according to certain parameters and/or performance criteria prior to performing step S12. Of course, the properties and/or parameters of the alloy powder may be selected according to actual requirements, which are not particularly limited in the embodiments of the present application. For example, the properties and/or parameters of the alloy powder need to meet the following criteria: particle size 15-53 μm, D50 36 μm, sphericity > 90%, flowability < 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 a shaped ODS alloy piece.

In some embodiments, the oxide in the ODS alloy may be a nano-scale oxide, and thus, the ODS alloy may be referred to as a nano-ODS alloy.

In some embodiments, the ODS alloy may be ODS alloy steel, for example. The ODS alloy steel may include, for example, ODS ferritic steel and/or ODS martensitic steel. The ODS alloy steel may include one or more of the following elements in addition to Fe element and C element: cr, W, mn, si and Ti.

In some embodiments, the process parameters of the additive manufacturing in step S16 may 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 the additive manufacturing may be configured as follows: the laser power is 180-220W, the scanning speed is 700-1000mm/s, the scanning interval is 80-120 mu m, the layer thickness is 30 mu m, the rotation angle is 67 degrees, and the scanning strategy is a strip mode.

Example two

The second embodiment provides a more specific oxide formation manner based on the first embodiment. The oxide generation mode provided in the second embodiment can enable the oxide to be dispersed in the ODS alloy in a finer size, so that the molding performance of the ODS alloy is improved.

Specifically, in the second embodiment, the alloy powder may include a first oxidizing element and a second oxidizing element. Prior to additive manufacturing, an oxidation reaction may be performed with the first oxidizing element and the oxygen element, thereby obtaining a first oxide (corresponding to step S14 of the first embodiment). That is, the oxygen element may be introduced into the alloy powder using the first oxidizing element, thereby increasing the oxygen content in the alloy powder. Next, additive manufacturing may be performed on the alloy powder such that the second oxidizing element and the oxygen element in the first oxide undergo an oxidation reaction to generate an ODS alloy that is dispersion-strengthened based on the second oxide (corresponding to step S16 of the first embodiment). That is, 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 region by region, and the melted alloy powder can be quickly solidified and molded in a short time. The above-described properties of additive manufacturing can avoid the problem of oxide aggregation and growth to some extent. On the basis, the implementation manner provided in the second embodiment also introduces a process of recombining oxide (namely, a process that the second oxidizing element robs oxygen in the first oxide to form the second oxide) within the short time, and the process of recombining oxide consumes a certain time, so that the second oxide formed in the additive manufacturing process is less aggregated and grown, and thus, large-particle oxide (the first oxide) can be thinned, and the ODS alloy with fine and dispersed oxide can be obtained.

In some embodiments, the first oxide may be formed by oxidizing the first oxidizing element in situ, thereby uniformly introducing the oxygen element into the alloy powder. Oxygen is uniformly distributed in the alloy powder, so that nucleation sites of the second oxide are relatively large, and the second oxide is respectively nucleated in the additive manufacturing process, thereby effectively reducing the probability of oxide aggregation and growth.

In some embodiments, a uniform oxide layer may be formed on the surface of the alloy powder by oxidizing the first oxidizing element in situ. The uniform oxide layer on the surface of each powder ensures that the second oxidizing element in the powder can react more fully and uniformly with the oxide layer, thereby generating more finely dispersed oxide.

In some embodiments, to oxidize the first oxidizing element prior to the second oxidizing element, the content (e.g., mass percent) of the first oxidizing element and the second oxidizing element in the alloy powder may be controlled such that the content of the first oxidizing element is greater than the content of the second oxidizing element. For example, the ODS alloy may have the first oxidizing element as a matrix, and the content (mass percent) of the second oxidizing element may be controlled to be 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. The alloy powder comprises the following elements in percentage by mass: cr:8.90%, W:0.82%, mn:0.23%, si:0.086%, ti:0.27%, C:0.075%, fe: bal.

In some embodiments, the first oxidizing element may be less oxidizing than the second oxidizing element. The second oxidizing element has higher oxidizing property than the first oxidizing element, which is helpful for the second oxidizing element to rob oxygen from the first oxidizing element in the additive manufacturing process, and effectively increases the content of the second oxide in the ODS. For example, the first oxidizing element and the second oxidizing element include two of: 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 the thickness of 50nm-200 nm. Ti is used as an oxygen active element which is more active than Fe, and reacts with the Fe oxide under the action of a high-energy beam (such as laser) to generate the very fine dispersed titanium oxide in situ.

In some embodiments, the second oxide has a size of 1 to 10nm. For example, the second oxide may have a size of 1 to 3nm. The size of the oxide in the conventional ODS alloy preparation mode based on additive manufacturing is usually far greater than 10nm (usually at least 30-50 nm), and by adopting the technical scheme provided by the embodiment, the size of the oxide in the ODS alloy can be controlled below 10nm, so that the high-performance nano ODS alloy is formed. In addition, by adopting the technical scheme provided by the embodiment of the application, the molding density of the ODS alloy can reach 99.8%, and the mechanical property and the service time under extreme conditions are optimized.

It should be noted that, on the premise of no conflict, the second embodiment may be combined with various schemes provided in the first embodiment, and for brevity, a detailed description is omitted here.

Example III

In the third embodiment, the alloy powder includes a first oxidizing element and a second oxidizing element, wherein the first oxidizing element forms an oxide that is a first oxide, and the second oxidizing element forms an oxide that is a second oxide. During additive manufacturing, the second oxidizing element reacts with the oxygen element in the first oxide to produce the second oxide. The main difference between the third embodiment and the second embodiment is that the third embodiment does not limit the timing of introducing the first oxide. In some embodiments, the first oxide of embodiment three may be introduced during ingot casting and/or milling. In other embodiments, the first oxide may be introduced after powder placement and prior to additive manufacturing in the manner described in embodiment two.

In addition, the second embodiment adopts a powder bed selective melting molding process based on powder spreading, and the third embodiment does not limit the process. For example, the third embodiment may be manufactured by additive manufacturing using a powder bed selective melt forming process, or by additive manufacturing using a simultaneous material feed forming process.

It should be noted that, on the premise of no conflict, the third embodiment may be combined with various schemes provided in the second embodiment, and for brevity, a detailed description is omitted here.

Example 1: preparation of low activation ODS alloySteel and method for producing same

The elemental composition of the low-activation ODS alloy to be produced in example 1, in mass%, includes: cr:8.90%, W:0.82%, mn:0.23%, si:0.086%, ti:0.27%, C:0.075%, fe: bal.

Step 1: and smelting Fe, cr, W, mn, ti, C, si element raw materials according to an element formula by a vacuum atomization powder making technology to obtain alloy powder suitable for additive manufacturing.

Step 2: and (3) carrying out a forming process on the alloy powder obtained in the step (1) by using slm280 equipment through an additive manufacturing technology, and rapidly solidifying and melting the scanned powder by laser according to a set path, wherein laser parameters are as follows: 200W, scanning speed: 600mm/s, a scanning pitch of 120 μm, a layer thickness of 30 μm, a rotation angle of 67℃and a scanning strategy of strip mode. In the additive manufacturing process, the oxygen concentration in the forming atmosphere chamber is controlled to be 500ppm, so that the alloy powder can be oxidized before melting, and a large amount of oxygen elements are adsorbed on the surface to form an oxide layer with the concentration of more than tens of nanometers.

After the step 2, the ODS alloy sample obtained in the step 2 is cut from the substrate, and microstructure characterization and mechanical property test are performed. As shown in FIGS. 2-3, FIG. 2 shows diffraction spots of the central dark field pattern, and FIG. 3 shows corresponding precipitated phases, it can be seen that the sample matrix obtained in the step 3 contains a large amount of finely dispersed 1-3nm oxide 1 precipitated phases, and the elemental compositions are Ti and O.

As shown in fig. 4, the structure of the sample obtained in step 2 is ultrafine grained ferrite 2, and the average grain size is 1-2um. This is due to the grain refinement of the finely dispersed oxide particles.

As shown in FIG. 5, the powder in step 2 can be oxidized before melting, and a large amount of oxygen elements are adsorbed on the surface to form an oxide layer 3 of 50-100 nanometers or more. Wherein the element composition of the oxide layer is Fe and O.

The tensile test result of the ODS alloy sample shows that the normal temperature tensile strength is 1200MPa, the elongation is 18%, the tensile strength is 930MPa at 600 ℃, and the elongation at break is 14%. Compared with the low-activation steel obtained by common additive manufacturing, the ODS alloy sample performance is improved by more than 150 percent, is comparable with that of the ODS low-activation steel prepared by the traditional mode (mechanical alloying), and has better molding quality and cost than that of the ODS low-activation steel prepared by the traditional mode.

In addition to the above-mentioned method of 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 appreciate that the features recited in the various embodiments of the disclosure and/or in the claims may be provided in a variety of combinations and/or combinations, even if such combinations or combinations are not explicitly recited in the disclosure. In particular, the features recited in the various embodiments of the present disclosure and/or the claims may be variously combined and/or combined without departing from the spirit and teachings of the present disclosure. All such combinations and/or combinations fall within the scope of the present disclosure.

The embodiments of the present disclosure are described above. However, these examples are for illustrative purposes only and are not intended to limit the scope of the present disclosure. Although the embodiments are described above separately, this does not mean that the measures in the embodiments cannot be used advantageously in combination. The scope of the disclosure is defined by the appended claims and equivalents thereof. Various alternatives and modifications can be made by those skilled in the art without departing from the scope of the disclosure, and such alternatives and modifications are intended to fall within the scope of the disclosure.

Claims

1. A method of making an alloy comprising:

paving alloy powder on a powder bed;

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

and carrying out additive manufacturing on the alloy powder to obtain the ODS alloy.

2. The method of claim 1, wherein said increasing the oxygen content of said alloy powder comprises:

increasing the oxygen content in the alloy powder and allowing an even distribution of oxygen elements in the alloy powder.

3. The method according to claim 1 or 2, wherein said increasing the oxygen content in the alloy powder comprises:

and controlling the alloy powder to perform in-situ oxidation.

4. A method according to claim 3, wherein the oxide formed by in situ oxidation forms an oxide layer on the surface of the alloy powder.

5. The method of claim 4, wherein the oxide layer has a thickness greater than or equal to 10nm.

6. The method of claim 5, wherein the oxide layer has a thickness of 50-100 nm.

7. The method of any one of claims 3-6, wherein the controlling the alloy powder to undergo in situ oxidation comprises:

the oxygen concentration in the forming atmosphere chamber is controlled so that the alloy powder undergoes in situ oxidation.

8. The method of claim 7, wherein the concentration of oxygen in the forming atmosphere chamber is 300 to 5000ppm.

9. The method of any one of claims 1-8, wherein the alloy powder includes a first oxidizing element and a second oxidizing element, the increasing the oxygen content in the alloy powder comprising:

controlling the first oxidizing element to perform an oxidation reaction to obtain a first oxide;

said subjecting said alloy powder to said additive manufacturing to obtain an ODS alloy comprising:

the additive manufacturing is performed on the alloy powder such that the second oxidizing element is oxidized with the oxygen element in the first oxide to produce an ODS alloy that is dispersion-strengthened based on the second oxide.

10. The method according to claim 9, wherein the content of the first oxidizing element is greater than the content of the second oxidizing element in the alloy powder.

11. The method of claim 9 or 10, wherein the first oxidizing element is less oxidizing than the second oxidizing element.

12. The method according to any one of claims 9-11, wherein the second oxide has a size of 1-10 nm.

13. The method of claim 12, wherein the second oxide has a size of 1-3 nm.

14. The method of any one of claims 9-13, wherein the first oxidizing element and the second oxidizing element comprise two of: ti, al, Y, zr, mg, si, mn, fe, ni, ca, V, cr, hf, mo, ta, nb, W, zn, sc, co and Cu.

15. The method of any one of claims 9-14, wherein the first oxidizing element is Fe and the second oxidizing element is Ti.

16. The method according to any one of claims 1 to 15, wherein the content of oxygen element in the ODS alloy is 0.05% to 0.5%.

17. The method of any one of claims 1-16, wherein the additive manufacturing employs a process that is one of: selective laser melting process, laser directional deposition process, and selective electron beam melting process.

18. The method according to any one of claims 1 to 17, wherein the ODS alloy is an alloy steel.

19. The method of claim 18, wherein the alloy steel comprises one or more of the following elements: cr, W, mn, si and Ti.

20. A method of making an alloy comprising:

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

additive manufacturing the alloy material, so that the second oxidizing element and oxygen element in the first oxide are subjected to oxidation reaction to generate ODS alloy which is subjected to dispersion strengthening based on the second oxide; wherein the first oxide is an oxide formed based on the first oxidizing element.

21. An alloy made based on the method of any one of claims 1-19.

22. An alloy made based on the method of claim 20.