Method for manufacturing a Mg / TiAl composite material having a three-dimensional continuous linked structure using a molten metal decomposition method, and the Mg / TiAl composite material manufactured thereby.

Abstract

The present invention relates to a method for producing a Mg / TiAl composite material and a Mg / TiAl composite material produced thereby, comprising the steps of (a) immersing a precursor alloy (Ti-X) containing a metal (X) that is miscible with titanium (Ti) and dissolves in the molten metal into a molten magnesium (Mg) molten metal to produce a Mg / Ti composite material, (b) producing a titanium (Ti) porous structure from the Mg / Ti composite material, and (c) immersing the titanium (Ti) porous structure into a Mg-Al alloy molten metal to produce a Mg / TiAl composite material. By removing the magnesium matrix from the Mg / Ti composite material produced by the molten metal decomposition method (LMD) and then performing aluminum alloying using the Mg-Al alloy molten metal, it is possible to produce a Mg / TiAl composite material with excellent physical properties and a three-dimensional continuous linked structure without the remaining presence of elements such as copper (Cu) contained in the precursor alloy.

Description

[Technical Field]

[0001] The present invention relates to a method for producing Mg / TiAl composite materials, and more specifically, to a method for producing Mg / TiAl composite materials having a three-dimensional continuous linked structure using liquid metal dealloying (LMD). [Background technology]

[0002] Liquid metal dealloying (LMD) is a new decomposition method first reported to the academic community in 2011. It is known as the only decomposition method for creating three-dimensional continuous linked structures of non-precious metals because the process is simple and rapid, and oxidation can be suppressed during manufacturing.

[0003] The principle of the molten metal decomposition method utilizes the selective reaction between a precursor alloy and molten metal. When the precursor alloy is added to the molten metal, selective dissolution occurs, where only the elements of the precursor alloy that are highly miscible with the molten metal diffuse and leach out. The remaining insoluble elements of the precursor alloy self-organize into a three-dimensional continuous linked structure through interfacial diffusion. Simultaneously, the molten metal fills the voids left by the leaching of the highly miscible elements, forming a composite material with a three-dimensional continuous linked structure in which the two phases are infinitely linked. Furthermore, when the manufactured composite material is placed in an etching solution that selectively corrodes only one phase, a porous structure consisting of the uncorroded phase is formed. Composite materials produced by the molten metal decomposition method have a matrix-matrix structure in which the two metal materials are intertwined in a three-dimensional continuous linked structure, and possess nanoscale microstructure, resulting in excellent chemical and physical properties. However, to further improve the material's properties, a process of adding alloying elements is necessary.

[0004] For example, to increase the strength of magnesium (Mg) / titanium (Ti) composite materials produced by the molten metal decomposition method, the addition of additional alloying elements is necessary. Aluminum (Al) has high reactivity with Ti, so when added as an alloying element to Mg / Ti composite materials, high-strength TiAl is formed. Furthermore, Al has a low density and is less expensive than Mg and Ti, making it a suitable alloying element for the production of lightweight, high-strength composite materials.

[0005] To produce such high-strength Mg / TiAl composite materials using the molten metal decomposition method, one can consider adding the Al alloying element to either the TiCu precursor alloy or the molten Mg. However, if the added alloying element is miscible with both the precursor alloy and the molten metal, a problem arises in that the process speed of the molten metal decomposition method decreases sharply. [Overview of the Initiative] [Problems that the invention aims to solve]

[0006] To address the technical challenges described above, the present invention provides a method for producing an Mg / TiAl composite material, comprising the steps of: (a) immersing a precursor alloy (Ti-X) containing a metal (X) that is miscible with titanium (Ti) and dissolves into the molten metal in a molten magnesium (Mg) mixture to produce an Mg / Ti composite material; (b) producing a titanium (Ti) porous structure from the Mg / Ti composite material; and (c) immersing the titanium (Ti) porous structure in a molten Mg-Al alloy to produce an Mg / TiAl composite material (Figure 1).

[0007] In step (a) above, a molten metal containing magnesium (Mg) is prepared, and when the precursor alloy (Ti-X) is immersed in the molten metal, selective dissolution occurs in which only the metal (X), which has high miscibility with the molten metal among the elements constituting the precursor alloy, diffuses into the molten metal and flows out. Meanwhile, titanium (Ti), which is insoluble in the molten metal as another component of the precursor alloy, self-organizes a three-dimensional continuous linked structure through interfacial diffusion.

[0008] As a result of the dissolution of metal X into the molten metal and the self-assembly of titanium (Ti), voids are formed at the interface where the precursor alloy and the molten metal meet. The molten magnesium from which metal X has dissolved fills these voids, and the dissolution of metal X and the filling of the molten metal progress gradually from the surface to the interior of the precursor alloy, ultimately yielding a Mg / Ti composite material containing a matrix made of magnesium or a magnesium alloy and a matrix made of titanium or a titanium alloy.

[0009] On the other hand, the metal X contained in the precursor alloy is not particularly limited in type as long as it has a negative (-) enthalpy of mixing with magnesium and is miscible with magnesium. For example, the metal X may be copper (Cu), nickel (Ni), zinc (Zn), gallium (Ga), germanium (Ge), arsenic (As), rhodium (Rh), palladium (Pd), silver (Ag), cadmium (Cd), indium (In), tin (Sn), antimony (Sb), platinum (Pt), gold (Au), mercury (Hg), lead (Pb), or bismuth (Bi). In other words, the precursor alloy may be a Ti-Cu alloy, Ti-Ni alloy, Ti-Zn alloy, Ti-Ga alloy, Ti-Ge alloy, Ti-As alloy, Ti-Rh alloy, Ti-Pd alloy, Ti-Ag alloy, Ti-Cd alloy, Ti-In alloy, Ti-Sn alloy, Ti-Sb alloy, Ti-Pt alloy, Ti-Au alloy, Ti-Hg alloy, Ti-Pb alloy, or Ti-Bi alloy.

[0010] Next, in step (b), a matrix made of magnesium or a magnesium alloy is removed from the previously manufactured Mg / Ti composite material to produce a titanium (Ti) porous structure.

[0011] The method for removing the matrix made of magnesium or a magnesium alloy from the Mg / Ti composite material is not particularly limited. For example, a titanium (Ti) porous structure can be produced by immersing the Mg / Ti composite material in a solution containing an acid such as nitric acid, which is highly corrosive to magnesium or a magnesium alloy, and then holding it for a predetermined time to remove the matrix made of magnesium or a magnesium alloy.

[0012] Next, when the titanium (Ti) porous structure previously manufactured in step (c) is immersed in the Mg-Al alloy molten metal, the liquid phase of the Mg-Al alloy molten metal fills the spaces between the solid phase Ti skeleton structure, and at the same time, aluminum (Al) atoms, which have a much higher miscibility with titanium (Ti) than magnesium (Mg), rapidly diffuse from the liquid phase of the Mg-Al alloy molten metal to the surface of the solid phase Ti skeleton structure. As a result, the titanium (Ti) matrix gradually changes from pure Ti or Ti alloy → Ti with solid-solution Al elements → Ti3Al → TiAl, and the matrix consists of magnesium or a magnesium alloy, and titanium or a titanium alloy with solid-solution Al, or Ti x Al y A Mg / TiAl composite material with a three-dimensional continuous linked structure is obtained, having a matrix consisting of a second phase of morphology and a bi-continuous structure in which each is infinitely linked.

[0013] Furthermore, as another aspect of the invention, the present invention provides a Mg / TiAl composite material manufactured by the above manufacturing method, which has a hardness up to twice or more than that of a conventional Mg / Ti composite material manufactured by a molten metal decomposition method. [Effects of the Invention]

[0014] According to the method for producing Mg / TiAl composite materials of the present invention, by removing the magnesium matrix from an Mg / Ti composite material produced by the molten metal decomposition method (LMD) and then performing aluminum alloying using molten Mg-Al alloy, it is possible to produce a three-dimensional continuous linked structure Mg / TiAl composite material with excellent physical properties in a short time without any residual elements such as copper (Cu) contained in the precursor alloy. [Brief explanation of the drawing]

[0015] [Figure 1] Figure 1 is a process flowchart showing each step in the method for producing a Mg / TiAl composite material having a three-dimensional continuous linked structure using the molten metal decomposition method according to the present invention. [Figure 2] Figure 2 is a schematic diagram showing the process of manufacturing composite materials using the molten metal decomposition method in Examples 1 and 2 of this application and Comparative Examples 1 to 3. [Figure 3] Figure 3 shows scanning electron microscope (SEM) images of the surface and central part of the Mg / TiAl composite material samples prepared in Examples 1 and 2 and Comparative Examples 2 and 3 of this application. [Figure 4] Figure 4 shows scanning electron microscope (SEM) images and energy dispersive X-ray spectroscopy (EDS) results for the Mg / TiAl composite materials produced in Examples 1 and 2 of this application and the Mg / Ti composite material produced in Comparative Example 1. [Figure 5] Figure 5 shows scanning electron microscope (SEM) images and energy dispersive X-ray spectroscopy (EDS) results of the Mg / TiAl composite material as time elapsed during the Al alloying process (step 3) in the embodiment of this invention. [Figure 6] Figure 6 shows the results of measuring the hardness of the Mg / Ti composite material produced in Comparative Example 1 of this application and the Mg / TiAl composite material according to the time of the Al alloying process (step 3) in the example. [Modes for carrying out the invention]

[0016] In describing the present invention, if it is determined that a detailed description of related known functions or configurations would unnecessarily obscure the gist of the present invention, the detailed description thereof will be omitted.

[0017] Embodiments according to the concept of the present invention can be subject to various modifications and can have various forms. Thus, specific embodiments are illustrated in the drawings and described in detail in this specification or the application. However, this is not intended to limit the embodiments according to the concept of the present invention to a specific disclosed form, and should be understood to include all modifications, equivalents or alternatives included within the spirit and technical scope of the present invention.

[0018] The terms used in this specification are merely used to describe specific embodiments and are not intended to limit the present invention. Singular expressions shall include plural expressions unless the context clearly indicates a different meaning. Terms such as "comprising" or "having" in this specification are intended to specify that the described features, numerical values, steps, operations, components, parts, or combinations thereof exist, and do not preclude in advance the possibility of the existence or addition of one or more other features, numerical values, steps, operations, components, parts or combinations thereof.

[0019] Hereinafter, the present invention will be described in more detail with reference to embodiments.

[0020] The examples described herein can be modified into various different forms, and the scope of this specification should not be construed as being limited to the examples detailed below. The examples herein are provided to provide a more complete explanation of this specification to those of average knowledge in the industry. In these examples, as shown in Figure 2, Mg / TiAl composite materials were produced using the method for producing a three-dimensional continuous linked structure Mg / TiAl composite material according to the present invention (Examples 1 and 2), an Mg / Ti composite material produced using a TiCu precursor and pure magnesium (Mg) molten metal according to a conventional metal molten metal decomposition method (Comparative Example 1), an Mg / TiAl composite material produced using an aluminum (Al)-added precursor alloy (TiCuAl) and pure magnesium (Mg) molten metal (Comparative Example 2), and an Mg / TiAl composite material produced using a TiCu precursor and aluminum (Al)-added magnesium (Mg) molten metal (Comparative Example 3). The microstructure of each of these composite materials was observed, and their mechanical properties were measured and compared.

[0021] <Example 1> TiCu precursor alloy (Ti) containing titanium (Ti) and copper (Cu) in an atomic ratio of 30:70 30 Cu 70 Step 1 involves adding the material to molten pure Mg at 800°C for 30 minutes to produce an Mg / Ti composite material, then immersing this in a nitric acid (HNO3) solution for 24 hours to form a Ti porous structure (Step 2), and finally immersing this in molten Mg-3Al (wt%) at 800°C for 10 seconds and removing it to produce an Mg / TiAl composite material (Step 3).

[0022] <Example 2> TiCu precursor alloy (Ti 30 Cu 70 Step 1 involves adding the material to molten pure Mg at 800°C for 30 minutes to produce an Mg / Ti composite material, then immersing this in a nitric acid (HNO3) solution for 24 hours to form a Ti porous structure (Step 2), and finally immersing this in molten Mg-3Al (wt%) at 800°C for 1 hour and removing it to produce an Mg / TiAl composite material (Step 3).

[0023] <Comparative Example 1> According to the conventional general method for removing components from molten metal, the TiCu precursor alloy (Ti 30 Cu 70 ) was introduced into the pure Mg molten metal at 800 °C for 30 minutes to produce a Mg / Ti composite material.

[0024] <Comparative Example 2> As a method for producing a Mg / TiAl composite material by alloying aluminum (Al) with a TiCu precursor, a TiCuAl precursor alloy ((Ti 30 Cu 70 ) 97 Al3) was introduced into the pure Mg molten metal at 800 °C for 30 minutes to produce a Mg / TiAl composite material.

[0025] <Comparative Example 3> As a method for producing a Mg / TiAl composite material by alloying aluminum (Al) with a magnesium (Mg) molten metal, a TiCu precursor alloy (Ti 30 Cu 70 ) was introduced into the Mg-3Al (wt%) molten metal at 800 °C for 1 hour to produce a Mg / TiAl composite material.

[0026] Figure 3 is a scanning electron microscope (SEM) photograph regarding the surface part and the center part inside the sample of the Mg / TiAl composite material samples produced in Example 1 and 2 of the present application and Comparative Examples 2 and 3.

[0027] Referring to Figure 3, in Comparative Example 2, due to the addition of Al to the precursor alloy, the LMD reaction rate of the precursor in the Mg molten metal decreased rapidly, and despite the 1-hour LMD treatment, the Cu element in the precursor was not completely dealloyed and remained as the Mg2Cu phase in both the surface part and the center part of the produced composite material. Therefore, decomponentization did not occur completely, and it was not possible to produce a Mg / TiAl composite material.

[0028] Furthermore, in Comparative Example 3, the addition of Al to the molten Mg caused a sharp decrease in the LMD reaction rate, similar to Comparative Example 2. Despite 1 hour of LMD treatment, the dealloying of Cu was not completely completed, and a large amount of Cu (49.6 wt%) remained in the center of the manufactured composite material. On the other hand, the Al concentration in the composite material was very low, less than 0.5 wt%. Therefore, decomposition was significantly reduced, and it was not possible to manufacture a Mg / TiAl composite material.

[0029] In contrast, in Example 1, the composite material produced by immersing a Ti porous structure manufactured by immersing it in a nitric acid solution in Mg-3Al (wt%) molten metal for 10 seconds contained no Cu even in the center, indicating that complete decomposition was achieved. This composite material is composed of a TiAl matrix in which an α-Ti phase with a small amount of Al dissolved in Ti and a Ti3Al phase coexist, and an α-Mg matrix with a small amount of Al dissolved in it, and the size of each matrix is ​​fine. Furthermore, it has a uniform structure with almost no difference in microstructure between the surface and the center of the composite material. Therefore, it was confirmed that Cu is completely decompositioned and that it is possible to manufacture a Mg / TiAl composite material with a high-strength three-dimensional continuous linked structure.

[0030] Furthermore, the composite material produced in Example 2 by immersing a Ti porous structure in Mg-3Al (wt%) molten metal for 1 hour demonstrates that Cu is completely decompositionalized. The produced composite material consists of a TiAl matrix in which Ti3Al phase and TiAl phase coexist, and an α-Mg matrix in which a small amount of Al is solid-dissolved, and the Al concentration in the composite material is very high, at 20 wt% or more. Also, similar to Example 1, it has a uniform structure with almost no difference in microstructure between the surface and the center of the composite material. Therefore, it was confirmed that it is possible to produce a Mg / TiAl composite material with a three-dimensional continuous linked structure that has high strength and is completely decompositionalized of Cu.

[0031] Figure 4 shows scanning electron microscope (SEM) images and energy dispersive X-ray spectroscopy (EDS) results for the Mg / TiAl composite materials produced in Examples 1 and 2 of this application and the Mg / Ti composite material produced in Comparative Example 1.

[0032] Referring to Figure 4, it can be confirmed that the Mg / Ti composite material produced in Comparative Example 1 achieved complete decomposition of Cu and is composed of an Mg matrix and a Ti matrix, with an area fraction ratio of 7:3 between the Ti matrix and the Mg matrix.

[0033] On the other hand, in the case of the Mg / TiAl composite material produced in Example 1, complete decomposition of Cu was achieved, and it was found that it was composed of a TiAl matrix and an α-Mg matrix in which α-Ti and Ti3Al phases coexist. Furthermore, it was confirmed that the size of the Ti matrix was finer than that of the Mg / Ti composite material produced in Comparative Example 1, and that the area fraction ratio of the TiAl matrix to the α-Mg matrix was an ideal 5:5 ratio.

[0034] Furthermore, in the Mg / TiAl composite material produced in Example 2, complete decomposition of Cu was achieved, and it was confirmed that it consisted of a TiAl matrix in which the Ti3Al phase and TiAl phase coexisted, and an α-Mg matrix. In addition, it was shown that the size of the Ti matrix was coarser than that of the Mg / Ti composite material produced in Comparative Example 1, and that the area fraction ratio of the TiAl matrix to the α-Mg matrix was 7:3.

[0035] Figure 5 shows scanning electron microscope (SEM) images and energy dispersive X-ray spectroscopy (EDS) results of the Mg / TiAl composite material over time during the Al alloying process (step 3) in the embodiment of this application.

[0036] In Examples 1 and 2 of this application, when producing Mg / TiAl composite materials, as the time spent immersing the Ti porous structure in the Mg-3Al (wt%) molten metal in step 3 (Al alloying step) increased, the Al concentration in the composite material increased, and a phase change from α-Ti → Ti3Al → TiAl occurred in the Ti matrix. After 1 hour of the Al alloying step, most of the TiAl matrix had changed to the TiAl phase, and it was shown that the size of the TiAl matrix increased as the process time increased.

[0037] Figure 6 shows the results of measuring the hardness of the Mg / Ti composite material produced in Comparative Example 1 of this application and the Mg / TiAl composite material according to the time of the Al alloying process (step 3) in the example.

[0038] Referring to Figure 6, the hardness of the Mg / TiAl composite material increased as the time of the Al alloying process increased. Furthermore, compared to the Mg / Ti composite material of Comparative Example 1, which was produced by a conventional molten metal decomposition method, it was found that the Mg / TiAl composite materials of Examples 1 and 2 produced by the present invention showed a hardness of 1.2 times or more when the time of step 3 was 10 seconds or more, and a hardness of 2.0 times or more when it was 1 hour or more.

[0039] Although embodiments of the present invention have been described above with reference to the attached drawings, those with ordinary skill in the art to which the present invention pertains will understand that the present invention can be implemented in other specific forms without altering its technical idea or essential features. Therefore, the embodiments described above are illustrative in all respects and should not be interpreted as limiting. [Industrial applicability]

[0040] According to the present invention, a three-dimensional continuous linked structure Mg / TiAl composite material with excellent physical properties can be manufactured in a short time.

Claims

1. (a) A process for producing an Mg / Ti composite material by immersing a precursor alloy (Ti-X) containing a metal (X) that is miscible with titanium (Ti) and dissolves into the molten metal in a molten metal containing magnesium (Mg); (b) A step of manufacturing a titanium (Ti) porous structure from the Mg / Ti composite material; and (c) A method for producing an Mg / TiAl composite material, comprising the step of immersing the titanium (Ti) porous structure in a molten Mg-Al alloy;

2. In the method according to claim 1, In step (a) above, A method for producing an Mg / TiAl composite material, characterized in that the precursor alloy is selected from the group consisting of Ti-Cu alloy, Ti-Ni alloy, Ti-Zn alloy, Ti-Ga alloy, Ti-Ge alloy, Ti-As alloy, Ti-Rh alloy, Ti-Pd alloy, Ti-Ag alloy, Ti-Cd alloy, Ti-In alloy, Ti-Sn alloy, Ti-Sb alloy, Ti-Pt alloy, Ti-Au alloy, Ti-Hg alloy, Ti-Pb alloy, and Ti-Bi alloy.

3. In the method of claim 2, In step (a) above, A method for producing an Mg / TiAl composite material, characterized by immersing a Ti-Cu alloy in a molten magnesium (Mg) mixture, allowing copper to dissolve into the molten metal, and filling the voids formed in the precursor alloy by the dissolution of copper with the molten metal to form an Mg / Ti composite material.

4. In the method according to claim 1, In step (b) above, A method for producing a Mg / TiAl composite material, characterized by immersing the Mg / Ti composite material in an acid solution to remove magnesium or a magnesium alloy from the Mg / Ti composite material in order to produce a titanium (Ti) porous structure.

5. In the method according to claim 1, In step (c) above, A method for producing an Mg / TiAl composite material, characterized by immersing the aforementioned titanium (Ti) porous structure in a molten Mg-3wt%Al alloy to produce an Mg / TiAl composite material.

6. In the method according to claim 1, (a) A precursor alloy (Ti) containing titanium (Ti) and copper (Cu) in an atomic ratio of 30:70 in a molten magnesium (Mg) ３０ Cu ７０ A process of manufacturing Mg / Ti composite material by immersing it in ) (b) The Mg / Ti composite material is treated with nitric acid (HNO ３ ) A step of immersing the Mg / Ti composite material in an aqueous solution to remove magnesium or magnesium alloy and produce a titanium (Ti) porous structure; and (c) A method for producing an Mg / TiAl composite material, comprising the step of immersing the titanium (Ti) porous structure in a Mg-3wt%Al alloy molten metal for 10 seconds to 2 hours.

7. A Mg / TiAl composite material manufactured by the manufacturing method described in any one of claims 1 to 6.

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