Method for refining solidification structure of yttrium alloy cast ingot

Abstract

The invention provides a method for refining a solidification structure of an yttrium-based alloy ingot, aims to solve the problem that the solidification structure of the alloy ingot is thick, and belongs to the technical field of non-ferrous metal materials. The yttrium-based alloy comprises the following components in percentage by weight: 3-5% of Al and the balance of high-purity metal yttrium. The smelting method comprises the steps of vacuumizing and alloy melting, and is characterized in that the alloy is molten according to chemical component ingredients in a protective atmosphere, and the alloy is repeatedly smelted for five times to enable the components to be uniform, so that an ingot casting structure with a fine solidification structure can be obtained. The refining agent adding method is simple, the smelting process is easy to control, additional equipment is not needed, and operation is convenient. A certain amount of aluminum element is introduced into the pure yttrium alloy, so that grains of the prepared Y-Al alloy are obviously refined, meanwhile, the compressive strength and plasticity of the Y-Al alloy are obviously improved, the brittleness of the Y-Al alloy is reduced, and the mechanical performance of the Y-Al alloy is improved.

Description

Technical Field

[0001] The present invention relates to the technical field of nonferrous metal materials, and in particular to a fine-grained yttrium-based alloy and a preparation method thereof. Background Art

[0002] The radioactive isotopes and solar power sources relied upon for nuclear deep space exploration, remote land and sea areas have disadvantages such as low energy density and short lifespan. Small mobile reactors can provide powerful power and mobility, and have convenient deployment methods. They are an important direction for the future development of advanced nuclear energy.

[0003] Nuclear criticality safety is the primary prerequisite for nuclear energy utilization. Most small reactor designs use zirconium hydride and yttrium hydride as core neutron moderator materials. Compared to zirconium hydride, yttrium hydride has superior high-temperature thermal stability. At the same temperature, the equilibrium hydrogen pressure of yttrium hydride is 3 to 4 orders of magnitude lower than that of zirconium hydride with the same hydrogen atomic ratio. This indicates that yttrium hydride is more stable at the same application temperature and is more suitable for high-temperature applications. The new generation of high-power small mobile reactors has higher design operating temperatures, and the advantages of high-temperature resistant yttrium hydride neutron moderators are becoming increasingly prominent.

[0004] In the early stages of small reactor development, zirconium hydride was used as the core neutron moderator material. Since 2018, with the advancement of yttrium metal purification technology, small mobile reactor designs have been moving towards high power and long life. Yttrium hydride moderators, with their high thermal stability, have become a research hotspot. Coarse yttrium metal grains are prone to cracking after hydriding, so grain refinement through alloying is one of the challenges in yttrium metal preparation. Summary of the Invention

[0005] In response to the shortcomings of the existing technology, the present invention provides a method for refining the solidification structure of yttrium alloy ingots. The method introduces a certain amount of aluminum element into metallic yttrium, so that the prepared Y-Al alloy material has a smaller grain size, while significantly improving the compressive strength and plasticity of the Y-Al alloy, reducing its brittleness, and improving its mechanical properties.

[0006] The present invention is achieved by adopting the following technical solutions:

[0007] A method for refining the solidification structure of a metal yttrium ingot, characterized in that it comprises the following steps:

[0008] Step 1: Follow Y 100-X Al X The mass ratio of the alloy is taken as Y and Al metals, where X is 3-5;

[0009] Step 2: placing the weighed raw materials into a crucible and performing vacuum arc melting in a vacuum non-consumable arc melting furnace to obtain an alloy ingot;

[0010] Step 3: After removing the oxide scale on the surface of the Y-Al alloy, perform forming processing to obtain Y-Al alloys of different sizes.

[0011] Preferably, step 1 is to mix metal yttrium and metal aluminum according to a specific composition ratio.

[0012] Preferably, in step 2, vacuum arc melting, vacuum treatment is first performed to make the vacuum degree -0.05MPa, and then after arcing, the melting current is adjusted to 180A, melting is performed to remove residual oxygen, and then the current is adjusted to 260A~300A for repeated melting treatment.

[0013] More preferably, the vacuum arc melting in step 2 is performed at a current of 270A to 300A for 5 to 10 melting cycles, each lasting 1 minute. The alloy ingot is flipped over after each melting cycle. Electromagnetic stirring is also required to ensure uniform composition of the alloy.

[0014] Compared with the prior art, the present invention has the following beneficial effects:

[0015] The present invention introduces 3-5wt% of metal aluminum into metal yttrium, thereby significantly reducing the grain size of the metal yttrium, while significantly improving the compressive strength and plasticity of the Y-Al alloy, reducing its brittleness and improving its mechanical properties. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0017] Figure 1 A Y provided by the present invention 100-X Al X Flow chart of alloy preparation method

[0018] Figure 2 Y obtained in Example 1 of the present invention 100-X Al X Alloy microstructure morphology;

[0019] Figure 3 The microstructure of the metal yttrium prepared in Comparative Example 1;

[0020] Figure 4 Y prepared in Comparative Example 2 100-X Nb X Alloy microstructure morphology;

[0021] Figure 5 Y prepared in Comparative Example 3 100-X Ti X Alloy microstructure morphology;

[0022] Figure 6 The compressive stress-strain curves of the memory alloys prepared in Example 1, Comparative Example 1, Comparative Example 2 and Comparative Example 3 of the present invention are shown.

[0023] Figure 7 Statistical diagram of the grain size of the yttrium-based alloys prepared in Example 1 and Comparative Examples 1, 2 and 3 of the present invention. DETAILED DESCRIPTION

[0024] Various exemplary embodiments of the present invention will now be described in detail. This detailed description should not be considered as limiting the present invention, but rather as a more detailed description of certain aspects, features, and embodiments of the present invention.

[0025] It should be understood that the terms described herein are intended only to describe particular embodiments and are not intended to limit the present invention. In addition, for numerical ranges herein, it should be understood that each intermediate value between the upper and lower limits of the range is also specifically disclosed. The intermediate value within any stated value or stated range, and each smaller range between any other stated value or intermediate value within the stated range, is also encompassed within the present invention. The upper and lower limits of these smaller ranges may be independently included or excluded within the scope.

[0026] Unless otherwise indicated, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the art. Although only preferred methods and materials are described herein, any methods and materials similar or equivalent to those described herein may also be used in the practice or testing of the present invention. All documents mentioned in this specification are incorporated by reference to disclose and describe the methods and / or materials associated with the documents. In the event of any conflict with any incorporated document, the contents of this specification shall prevail.

[0027] It will be apparent to those skilled in the art that various modifications and variations may be made to the specific embodiments described herein without departing from the scope or spirit of the invention. Other embodiments will be apparent to those skilled in the art from the description of the invention. The description and examples are intended to be exemplary only.

[0028] The words “include,” “including,” “have,” “contain,” etc. used in this document are open-ended terms, meaning including but not limited to.

[0029] Unless otherwise specified, the technical solutions described in the present invention are all conventional solutions in the field, and the reagents or raw materials used, unless otherwise specified, are purchased from commercial channels or have been disclosed.

[0030] In order to better understand the present invention, the content of the present invention is further illustrated below in conjunction with the examples, but the content of the present invention is not limited to the following examples.

[0031] Example 1

[0032] A method for refining the solidification structure of a metal yttrium ingot, comprising the following steps:

[0033] Step 1: Follow Y 100-X Al X The mass ratio of the alloy is taken as Y and Al metals, where X is 3-5;

[0034] Step 2: placing the weighed raw materials into a crucible and performing vacuum arc melting in a vacuum non-consumable arc melting furnace to obtain an alloy ingot;

[0035] Step 3: After removing the oxide scale on the surface of the Y-Al alloy, forming is performed to obtain Y-Al alloys of different sizes.

[0036] Comparative Example 1

[0037] A method for solidifying a metal yttrium ingot, comprising the following steps:

[0038] Step 1: Weigh a certain mass of metallic yttrium;

[0039] Step 2: placing the weighed raw materials into a crucible and performing vacuum arc melting in a vacuum non-consumable arc melting furnace to obtain an alloy ingot;

[0040] Step 3: After removing the oxide scale on the surface of the metal yttrium, forming processing is performed to obtain metal yttrium of different sizes.

[0041] Comparative Example 2

[0042] A method for solidifying an yttrium-based alloy ingot, comprising the following steps:

[0043] Step 1: Follow Y 100-X Nb X The mass ratio of the alloy is taken as Y and Nb metals, where X is 3-5;

[0044] Step 2: placing the weighed raw materials into a crucible and performing vacuum arc melting in a vacuum non-consumable arc melting furnace to obtain an alloy ingot;

[0045] Step 3: After removing the oxide scale on the surface of the Y-Nb alloy, the Y-Nb alloy is formed to obtain Y-Nb alloys of different sizes.

[0046] Comparative Example 3

[0047] A method for solidifying an yttrium-based alloy ingot, comprising the following steps:

[0048] Step 1: Follow Y 100-X Ti X The mass ratio of the alloy is taken as Y and Nb metals, where X is 3-5;

[0049] Step 2: placing the weighed raw materials into a crucible and performing vacuum arc melting in a vacuum non-consumable arc melting furnace to obtain an alloy ingot;

[0050] Step 3: After removing the oxide scale on the surface of the Y-Nb alloy, the Y-Nb alloy is formed to obtain Y-Nb alloys of different sizes.

[0051] Comparative Example 4

[0052] Step 1: Select high-purity raw materials according to the following percentages for mixing: Zr: 0.1wt%, Al: 0.01wt%, Cr: 6.4wt%, Nb: 0.1wt%, Ti: 0.01wt%, and the remainder is metallic yttrium and unavoidable impurities.

[0053] Step 2: Place the metal yttrium and five alloy elements into a vacuum suspension furnace for smelting. The vacuum degree of smelting is 10 -3 Pa, the room temperature pressure rise rate is <5Pa / h, and after smelting twice, the yttrium-based alloy ingot with uniform composition distribution is obtained; after the surface oxide scale of the yttrium-based alloy ingot is removed by a lathe, it is forged at 800℃ to obtain a yttrium-based alloy blank after forging; after the surface oxide scale of the yttrium-based alloy blank is removed by a lathe, it is formed to obtain yttrium-based alloy samples of different sizes and specifications.

[0054] from Figure 1 It can be seen that the preparation process of Example 1 of the present invention is simple and easy to operate.

[0055] from Figure 2-3 It can be seen that the yttrium-based alloy prepared in Example 1 of the present invention exhibits an obvious two-phase structure at room temperature compared with that in Comparative Example 1.

[0056] from Figure 5-7 As can be seen from the figure, both Comparative Example 3 and Example 1 have a dual-phase structure, and Example 1 is superior to Comparative Example 3 in both grain size and mechanical properties.

[0057] from Figure 6 It can be seen that the average grain size of the yttrium-based alloy prepared by the present invention is the smallest, and the grains are significantly refined compared with Comparative Example 1.

[0058] The yttrium-based alloy sample prepared in Comparative Example 4 also achieved the effect of grain refinement, and the average grain size obtained was about 150 μm. Compared with Example 1 of the present invention, the average grain size obtained in Example 1 of the present invention was smaller and the process was simpler.

[0059] from Figure 7 As can be seen from the graph, the yttrium-based alloy prepared by the present invention has a compressive strain of 30% and a compressive strength of 1000 MPa. Compared with other ratios, Example 1 of the present invention has better strength and plasticity.

[0060] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principles of the present invention. These improvements and modifications should also be regarded as within the scope of protection of the present invention.

Claims

1. A method for refining the solidification structure of a metal yttrium ingot, characterized in that: The following steps are involved: Step 1: Follow Y 100-X Al X The mass ratio of Y and Al metals in the alloy is weighed, where x is 3-5; Step 2: placing the weighed raw materials into a crucible and performing vacuum arc melting in a vacuum non-consumable arc melting furnace to obtain an alloy ingot; Step 3: After removing the oxide scale on the surface of the Y-Al alloy, forming processing is performed to obtain Y-Al alloys of different sizes.

2. The method for preparing a Y-Al alloy having a smaller grain size according to claim 1, wherein: Step 1: The composition ratio of metal yttrium and metal aluminum.

3. The method for preparing the Y-Al alloy according to claim 1, wherein: In the second step of vacuum arc melting, vacuum treatment is first performed to make the vacuum degree -0.05MPa, and then the melting current is adjusted to 180A after the arc is struck, and melting is performed to remove residual oxygen, and then the current is adjusted to 260A~300A for 5-10 melting treatments, each melting time is 1min. After a single melting is completed, the alloy ingot needs to be turned over, and the electromagnetic stirring function needs to be turned on to ensure the uniform composition of the alloy.

4. A method for refining the solidification structure of metal yttrium, characterized in that: Prepared by the method according to any one of claims 1 to 3.

Images