METHOD FOR MANUFACTURING METAL COMPOSITE THROUGH LIQUID METAL DEALLOYING USING MOLTEN Mg-Ca ALLOY AND Ti-BASED PRECURSOR ALLOY, AND METAL COMPOSITE MANUFACTURED THEREBY

Abstract

A method includes immersing a precursor alloy (Ti—X), which includes titanium (Ti) and a metal (X) that has miscibility with Ti and also with the melt and is thereby dissolved into the melt, into a melt containing magnesium (Mg) and calcium (Ca) to produce an Mg / Ti composite material. Since the Ca alloying element contained in the Mg—Ca alloy melt has high miscibility with Cu, it promotes the dealloying behavior in which Cu diffuses into the melt, thereby greatly shortening the process time required for fabricating the composite material. In addition, the Ca alloying element contained in the Mg—Ca alloy melt is dissolved in the Mg matrix, thereby increasing the volume fraction of the Mg matrix in the composite material, reducing the coarsening rate of Ti, and simultaneously improving the strength of the composite material through solid-solution strengthening of the Mg matrix.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application is a continuation of International Application No. PCT / KR2024 / 005465 filed on Apr. 23, 2024, which claims priority to Korean Patent Application No. 10-2023-0054151 filed on Apr. 25, 2023, the entire contents of which are herein incorporated by reference.TECHNICAL FIELD

[0002] The present invention relates to a method for manufacturing a metal composite material comprising magnesium and titanium, and more particularly, to a method for manufacturing a metal composite material comprising magnesium and titanium having a three-dimensional continuous interconnected structure by using a liquid metal dealloying (LMD) method.BACKGROUND ART

[0003] The liquid metal dealloying (LMD) method is a new dealloying technique first reported in academia in 2011, and it is known as the only dealloying method capable of producing a three-dimensional continuous interconnected structure of non-precious metals, since the process is simple and fast and oxidation can be suppressed during fabrication.

[0004] The principle of liquid metal dealloying is based on the selective reaction between a precursor alloy and a liquid metal. When the precursor alloy is immersed in the melt, only those elements in the precursor alloy that have high miscibility with the melt diffuse into and dissolve into the melt, causing selective dissolution. The remaining insoluble elements in the precursor alloy self-organize into a three-dimensional continuous interconnected structure through interfacial diffusion. At the same time, the vacant space left by the dissolved miscible elements is filled by the liquid metal, thereby forming a composite material having a three-dimensional continuous interconnected structure in which the two phases are infinitely interconnected.

[0005] Furthermore, when the fabricated composite material is immersed in an etching solution that selectively corrodes only one phase, a porous structure consisting of the non-corroded phase is formed. The composite material produced by the liquid metal dealloying method has a matrix-matrix structure in which two metallic materials are entangled with each other in a three-dimensional continuous interconnected structure, and because it possesses a fine microstructure on the nano or micro scale, it exhibits excellent chemical and physical properties.

[0006] However, when fabricating a composite material through the liquid metal dealloying method, as the thickness of the precursor alloy specimen used increases, the time required for the dealloying reaction to be completed through to the center of the specimen increases drastically. Such slow dealloying not only prolongs the required process time and lowers productivity, but also causes coarsening of the phase composed of the insoluble elements in the precursor alloy, thereby deteriorating the properties of the finally obtained composite material.

[0007] For example, when an Mg / Ti composite material is fabricated by immersing a Ti—Cu precursor alloy into a pure magnesium (Mg) melt according to a known liquid metal dealloying method, the thicker the Ti—Cu precursor used, the longer it takes to completely dealloy the Cu element in the center of the precursor to fabricate the Mg / Ti composite material. During this process, coarsening of the Ti phase occurs, leading to deterioration in the properties of the fabricated Mg / Ti composite material.

[0008] Accordingly, in order to improve the process efficiency of the liquid metal dealloying method and enhance the properties of the finally obtained composite material, it is required to promote the dealloying of the elements in the precursor that have high miscibility with the liquid metal, so that the composite material can be fabricated in a short period of time.SUMMARYTechnical Problem

[0009] The technical problem to be solved by the present invention is to provide a method capable of manufacturing a metal composite material at a significantly faster rate than the conventional liquid metal dealloying method, without causing deterioration of the properties of the finally obtained metal composite material, and to provide a metal composite material manufactured thereby.Technical Solution

[0010] In order to achieve the above-described technical problem, the present invention provides a method for manufacturing a metal composite material, comprising a step of immersing a precursor alloy (Ti—X), which includes titanium (Ti) and a metal (X) that has miscibility with Ti and is dissolved into the melt, into a melt containing magnesium (Mg) and calcium (Ca) to produce an Mg / Ti composite material.

[0011] To fabricate the Mg / Ti composite material, when an Mg—Ca alloy melt containing magnesium (Mg) and calcium (Ca) is prepared and the precursor alloy (Ti—X) is immersed therein, only the metal (X) among the elements constituting the precursor alloy that has high miscibility with the melt diffuses into and dissolves into the melt, thereby causing selective dissolution. Meanwhile, titanium (Ti), another component of the precursor alloy that is insoluble in the melt, self-organizes into a three-dimensional continuous interconnected structure through interfacial diffusion.

[0012] As a result of the dissolution of metal X into the melt and the self-organization of titanium (Ti) as described above, voids are formed at the interface between the precursor alloy and the melt, and the Mg—Ca alloy melt, from which the metal X has been dissolved, fills the voids. Consequently, with the progressive dissolution of metal X and filling of the melt from the surface of the precursor alloy toward the inside, an Mg / Ti composite material comprising an Mg matrix with Ca dissolved therein and a matrix composed of titanium or a titanium alloy is finally obtained.

[0013] At this time, the Ca added to the melt has high miscibility with the metal X, thereby promoting the dealloying behavior in which the metal element X diffuses out into the melt, and thus has the effect of greatly shortening the process time for fabricating the Mg / Ti composite material. In addition, the Ca added to the melt is dissolved in the Mg matrix, thereby increasing the volume fraction of the Mg matrix in the composite material, reducing the coarsening rate of Ti, and simultaneously enhancing the strength of the composite material through solid-solution strengthening of the Mg matrix.

[0014] Meanwhile, the metal X included in the precursor alloy is not particularly limited in type as long as it has a negative enthalpy of mixing with titanium, magnesium, and calcium, and thus is miscible with titanium, magnesium, and calcium. 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), iridium (Ir), platinum (Pt), gold (Au), mercury (Hg), lead (Pb), or bismuth (Bi). That is, 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—Ir alloy, Ti—Pt alloy, Ti—Au alloy, Ti—Hg alloy, Ti—Pb alloy, or Ti—Bi alloy.

[0015] In addition, the content of calcium (Ca) in the melt containing magnesium (Mg) and calcium (Ca) is not particularly limited and, for example, may be 10 wt % or less.

[0016] Furthermore, in order to further improve the properties of the Mg / Ti composite material fabricated as described above, the present invention provides a method for manufacturing an Mg / TiAl composite material in which aluminum (Al) is added as an alloying element, the method comprising: (a) immersing a precursor alloy (Ti—X), which includes titanium (Ti) and a metal (X) that has miscibility with Ti and is dissolved into the melt, into an Mg—Ca alloy melt containing magnesium (Mg) and calcium (Ca) 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 into an Mg—Al alloy melt to produce an Mg / TiAl composite material.

[0017] Since step (a) is identical to the above-described method for manufacturing an Mg / Ti composite material, its description is omitted herein.

[0018] In step (b), a titanium (Ti) porous structure is fabricated by removing the matrix composed of magnesium or a magnesium alloy from the Mg / Ti composite material prepared in the previous step.

[0019] The method of removing the magnesium alloy matrix from the Mg / Ti composite material is not particularly limited. For example, the Mg / Ti composite material may be immersed in a solution containing an acid such as nitric acid, which has high corrosivity to magnesium alloys, and maintained for a predetermined period of time, thereby removing the magnesium alloy matrix and producing the titanium (Ti) porous structure.

[0020] Next, in step (c), when the previously fabricated titanium (Ti) porous structure is immersed into an Mg—Al alloy melt, the liquid Mg—Al alloy melt fills the spaces between the solid Ti skeletal structures, and aluminum (Al) atoms, which have much higher miscibility with titanium (Ti) than with magnesium (Mg), rapidly diffuse and migrate from the liquid Mg—Al alloy melt to the surface of the solid Ti skeletal structure. Accordingly, the titanium (Ti) matrix gradually transforms from pure Ti or a Ti alloy→Ti with Al atoms dissolved→Ti3Al→TiAl. As a result, an Mg / TiAl composite material having a three-dimensional continuous interconnected structure with a bi-continuous configuration, in which the matrix composed of magnesium or a magnesium alloy and the matrix composed of titanium or a titanium alloy with Al dissolved therein or in the form of a TixAly second phase are each infinitely interconnected, is obtained.

[0021] Furthermore, in another aspect, the present invention provides metal composite materials such as Mg / Ti composite materials and Mg / TiAl composite materials manufactured according to the above-described method.Advantageous Effects

[0022] According to the method for manufacturing a metal composite material through the liquid metal dealloying method of the present invention, the Ca alloying element contained in the Mg—Ca alloy melt has high miscibility with Cu, thereby promoting the dealloying behavior in which Cu diffuses into the melt, and thus the process time required for fabricating the composite material can be greatly shortened compared to the conventional technique using a pure magnesium melt.

[0023] In addition, the Ca alloying element contained in the Mg—Ca alloy melt is dissolved in the Mg matrix, thereby increasing the volume fraction of the Mg matrix in the composite material, reducing the coarsening rate of Ti, and simultaneously improving the strength of the composite material through solid-solution strengthening of the Mg matrix.DESCRIPTION OF DRAWINGS

[0024] FIG. 1 is a schematic diagram showing the process of manufacturing Mg / Ti composite materials by utilizing the liquid metal dealloying method with Mg-1Ca (wt %) melt or pure Mg melt in Examples 1 and 2 of the present invention and Comparative Examples 1 and 2.

[0025] FIG. 2 shows the results of measuring the time required for the dealloying of Cu using Mg-1Ca (wt %) melt or pure Mg melt in the Examples and Comparative Examples of the present invention.

[0026] FIG. 3 shows scanning electron microscope (SEM) images and energy dispersive X-ray spectroscopy (EDS) results of Mg / Ti composite materials, according to the process time of the liquid metal dealloying method using Mg-1Ca (wt %) melt or pure Mg melt in the Examples and Comparative Examples of the present invention.

[0027] FIG. 4 shows scanning electron microscope (SEM) images of the Mg / Ti composite materials manufactured according to Example 1 of the present invention and Comparative Example 1.

[0028] FIG. 5 shows scanning electron microscope (SEM) images of the Mg / Ti composite materials manufactured according to Example 2 of the present invention and Comparative Example 2.DETAILED DESCRIPTION

[0029] In describing the present invention, detailed descriptions of well-known functions or configurations will be omitted when it is determined that such descriptions would unnecessarily obscure the gist of the present invention.

[0030] Embodiments in accordance with the concept of the present invention may be modified in various ways and may have various forms, and thus particular embodiments are illustrated in the drawings and described in detail in this specification or application. However, this is not intended to limit embodiments according to the concept of the present invention to particular disclosed forms, but should be understood to include all modifications, equivalents, or substitutes falling within the spirit and scope of the present invention.

[0031] The terminology used in this specification is employed merely to describe specific embodiments, and is not intended to limit the present invention. Unless the context clearly indicates otherwise, singular expressions include the plural. In this specification, terms such as “comprise” or “have” are intended to designate the presence of the stated features, numbers, steps, operations, components, parts, or combinations thereof, but should be understood not to preclude the possibility of the presence or addition of one or more other features, numbers, steps, operations, components, parts, or combinations thereof.

[0032] Hereinafter, the present invention will be described in more detail with reference to examples.

[0033] The embodiments according to this specification may be modified in various different forms, and the scope of this specification should not be construed as limited to the embodiments described below. The embodiments of this specification are provided to more fully explain the present invention to those of ordinary skill in the art.

[0034] In this embodiment, as shown in FIG. 1, a liquid metal dealloying method is presented in which Ca, capable of promoting the dealloying of Cu constituting the Ti—Cu precursor, is added to the Mg melt. Accordingly, the microstructures and mechanical properties of Mg / Ti composite materials fabricated by the liquid metal dealloying method using a Ti—Cu precursor and an Mg—Ca melt (Examples 1 and 2) were observed and compared with those of Mg / Ti composite materials fabricated by the conventional liquid metal dealloying method using a Ti—Cu precursor and pure magnesium (Mg) melt (Comparative Examples 1 and 2).Example 1

[0035] A Ti—Cu precursor alloy (Ti30Cu70), which includes titanium (Ti) and copper (Cu) at an atomic ratio of 30:70, was immersed in an Mg-1Ca (wt %) alloy melt at 800° C. for 10 minutes and then removed to fabricate an Mg / Ti composite material.Example 2

[0036] A Ti—Cu precursor alloy (Ti30Cu70) was immersed in an Mg-1Ca (wt %) alloy melt at 800° C. for 60 minutes and then removed to fabricate an Mg / Ti composite material.Comparative Example 1

[0037] According to a conventional general liquid metal dealloying method, a Ti—Cu precursor alloy (Ti30Cu70) was immersed in pure Mg melt at 800° C. for 30 minutes and then removed to fabricate an Mg / Ti composite material.Comparative Example 2

[0038] According to a conventional general liquid metal dealloying method, a Ti—Cu precursor alloy (Ti30Cu70) was immersed in pure Mg melt at 800° C. for 60 minutes and then removed to fabricate an Mg / Ti composite material.

[0039] FIG. 2 shows the results of measuring the time required for the dealloying of Cu using an Mg-1Ca (wt %) melt or pure Mg melt in the Examples and Comparative Examples of the present invention.

[0040] Referring to FIG. 2, when using an Mg-1Ca (wt %) melt as in the Examples of the present invention, dealloying of Cu was completed within 10 minutes after immersing the precursor alloy into the melt (Cu content in the precursor s 1 wt %), whereas in the Comparative Examples using pure Mg melt, dealloying of Cu was not completed until after 30 minutes of immersion.

[0041] As described above, the fact that Cu dealloying was completed more quickly in the Examples than in the Comparative Examples is because Ca present in the Mg-1Ca (wt %) melt has high miscibility with Cu, and the degree of this miscibility is higher than that between Cu and Mg (enthalpy of mixing ΔHmix of Ca—Cu: −13 kJ / mol, ΔHmix of Mg—Cu: −3 kJ / mol). Therefore, dealloying of Cu from the precursor alloy is promoted in the Mg-1Ca (wt %) melt compared to the pure Mg melt.

[0042] FIG. 3 shows scanning electron microscope (SEM) images and energy dispersive X-ray spectroscopy (EDS) results of Mg / Ti composite materials according to the process time of the liquid metal dealloying method using an Mg-1Ca (wt %) melt or pure Mg melt in the Examples and Comparative Examples of the present invention.

[0043] According to FIG. 3, in Comparative Example 1, dealloying of Cu in the pure Mg melt was completed after 30 minutes, and it was confirmed that an Mg / Ti composite material having a three-dimensional continuous interconnected structure and composed of a pure Mg matrix and a pure Ti matrix was fabricated.

[0044] In contrast, in Example 1, dealloying of Cu in the Mg-1Ca (wt %) melt was completed after 10 minutes, and it was found that an Mg / Ti composite material having a three-dimensional continuous interconnected structure and including an Mg matrix composed of an α-Mg phase in which 0.6 wt % Ca was dissolved was fabricated. Since Ca does not have miscibility with Ti, it is not dissolved in the Ti matrix. However, because Ca has miscibility with Mg (enthalpy of mixing ΔHmix of Ca—Ti: 43 kJ / mol, ΔHmix of Ca—Mg: −6 kJ / mol), Ca is dissolved in the Mg matrix, resulting in the fabrication of an Mg / Ti composite material including an α-Mg matrix with Ca dissolved therein.

[0045] FIG. 4 shows scanning electron microscope (SEM) images of the Mg / Ti composite materials fabricated according to Example 1 and Comparative Example 1.

[0046] Referring to FIG. 4, the Mg / Ti composite material fabricated in Comparative Example 1 exhibited a volume fraction ratio of the Mg matrix to the Ti matrix of 30:70, with the area of the Ti matrix being much larger, and its hardness was measured to be 115.2 Hv.

[0047] In the Mg / Ti composite material fabricated in Example 1, the volume fraction of the Mg matrix significantly increased compared to Comparative Example 1, resulting in an ideal ratio of 51:49 between the Mg matrix and the Ti matrix. Moreover, although the volume fraction of the Mg matrix, which has relatively lower strength than the Ti matrix, increased greatly compared to Comparative Example 1, the hardness of the Mg / Ti composite material was measured to be 107.4 Hv, which was not significantly different from that of Comparative Example 1. This is because Ca contained in the Mg-1Ca (wt %) melt used for the fabrication of the Mg / Ti composite material was dissolved in the Mg matrix, thereby forming an α-Mg matrix with superior properties compared to pure Mg, and because the Ti matrix was refined.

[0048] Therefore, although the immersion time in the melt was greatly reduced to one-third (10 minutes in Mg-1Ca (wt %) melt versus 30 minutes in pure Mg melt), the Mg / Ti composite material fabricated in Example 1 exhibited a nearly ideal volume fraction ratio of 50:50 between the Ti matrix and the Mg matrix. The closer the volume fraction is to the ideal 50:50, the greater the interfacial area between the Ti matrix and the Mg matrix, thereby providing excellent mechanical and chemical properties.

[0049] FIG. 5 shows scanning electron microscope (SEM) images of the Mg / Ti composite materials fabricated according to Example 2 and Comparative Example 2.

[0050] According to FIG. 5, in Comparative Example 2, as in Comparative Example 1, the volume fraction ratio of the Mg matrix to the Ti matrix was 30:70, with the volume fraction of the Ti matrix being much higher, and the average size of the Ti matrix was found to be 3.4 μm.

[0051] In Example 2, as in Example 1, the volume fraction ratio of the Mg matrix to the Ti matrix was an ideal 48:52, and the average size of the Ti matrix was confirmed to be 2.9 μm, which was finer than that in Comparative Example 2.

[0052] As described above, embodiments of the present invention have been explained with reference to the accompanying drawings. However, it will be understood by those skilled in the art that the present invention can be carried out in various other specific forms without changing its technical spirit or essential characteristics. Therefore, the embodiments described above should be understood as illustrative in all respects and not restrictive.INDUSTRIAL APPLICABILITY

[0053] According to the present invention, by using the liquid metal dealloying method with an Mg—Ca alloy melt, the process time required for fabricating a composite material can be greatly shortened compared to the conventional technique using a pure magnesium melt, and a composite material with improved strength can be manufactured.

Examples

example 1

[0035]A Ti—Cu precursor alloy (Ti30Cu70), which includes titanium (Ti) and copper (Cu) at an atomic ratio of 30:70, was immersed in an Mg-1Ca (wt %) alloy melt at 800° C. for 10 minutes and then removed to fabricate an Mg / Ti composite material.

example 2

[0036]A Ti—Cu precursor alloy (Ti30Cu70) was immersed in an Mg-1Ca (wt %) alloy melt at 800° C. for 60 minutes and then removed to fabricate an Mg / Ti composite material.

CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application is a continuation of International Application No. PCT / KR2024 / 005465 filed on Apr. 23, 2024, which claims priority to Korean Patent Application No. 10-2023-0054151 filed on Apr. 25, 2023, the entire contents of which are herein incorporated by reference.TECHNICAL FIELD

[0002] The present invention relates to a method for manufacturing a metal composite material comprising magnesium and titanium, and more particularly, to a method for manufacturing a metal composite material comprising magnesium and titanium having a three-dimensional continuous interconnected structure by using a liquid metal dealloying (LMD) method.BACKGROUND ART

[0003] The liquid metal dealloying (LMD) method is a new dealloying technique first reported in academia in 2011, and it is known as the only dealloying method capable of producing a three-dimensional continuous interconnected structure of non-precious metals, since the process is simple and fast and oxidation can be suppressed during fabrication.

[0004] The principle of liquid metal dealloying is based on the selective reaction between a precursor alloy and a liquid metal. When the precursor alloy is immersed in the melt, only those elements in the precursor alloy that have high miscibility with the melt diffuse into and dissolve into the melt, causing selective dissolution. The remaining insoluble elements in the precursor alloy self-organize into a three-dimensional continuous interconnected structure through interfacial diffusion. At the same time, the vacant space left by the dissolved miscible elements is filled by the liquid metal, thereby forming a composite material having a three-dimensional continuous interconnected structure in which the two phases are infinitely interconnected.

[0005] Furthermore, when the fabricated composite material is immersed in an etching solution that selectively corrodes only one phase, a porous structure consisting of the non-corroded phase is formed. The composite material produced by the liquid metal dealloying method has a matrix-matrix structure in which two metallic materials are entangled with each other in a three-dimensional continuous interconnected structure, and because it possesses a fine microstructure on the nano or micro scale, it exhibits excellent chemical and physical properties.

[0006] However, when fabricating a composite material through the liquid metal dealloying method, as the thickness of the precursor alloy specimen used increases, the time required for the dealloying reaction to be completed through to the center of the specimen increases drastically. Such slow dealloying not only prolongs the required process time and lowers productivity, but also causes coarsening of the phase composed of the insoluble elements in the precursor alloy, thereby deteriorating the properties of the finally obtained composite material.

[0007] For example, when an Mg / Ti composite material is fabricated by immersing a Ti—Cu precursor alloy into a pure magnesium (Mg) melt according to a known liquid metal dealloying method, the thicker the Ti—Cu precursor used, the longer it takes to completely dealloy the Cu element in the center of the precursor to fabricate the Mg / Ti composite material. During this process, coarsening of the Ti phase occurs, leading to deterioration in the properties of the fabricated Mg / Ti composite material.

[0008] Accordingly, in order to improve the process efficiency of the liquid metal dealloying method and enhance the properties of the finally obtained composite material, it is required to promote the dealloying of the elements in the precursor that have high miscibility with the liquid metal, so that the composite material can be fabricated in a short period of time.SUMMARYTechnical Problem

[0009] The technical problem to be solved by the present invention is to provide a method capable of manufacturing a metal composite material at a significantly faster rate than the conventional liquid metal dealloying method, without causing deterioration of the properties of the finally obtained metal composite material, and to provide a metal composite material manufactured thereby.Technical Solution

[0010] In order to achieve the above-described technical problem, the present invention provides a method for manufacturing a metal composite material, comprising a step of immersing a precursor alloy (Ti—X), which includes titanium (Ti) and a metal (X) that has miscibility with Ti and is dissolved into the melt, into a melt containing magnesium (Mg) and calcium (Ca) to produce an Mg / Ti composite material.

[0011] To fabricate the Mg / Ti composite material, when an Mg—Ca alloy melt containing magnesium (Mg) and calcium (Ca) is prepared and the precursor alloy (Ti—X) is immersed therein, only the metal (X) among the elements constituting the precursor alloy that has high miscibility with the melt diffuses into and dissolves into the melt, thereby causing selective dissolution. Meanwhile, titanium (Ti), another component of the precursor alloy that is insoluble in the melt, self-organizes into a three-dimensional continuous interconnected structure through interfacial diffusion.

[0012] As a result of the dissolution of metal X into the melt and the self-organization of titanium (Ti) as described above, voids are formed at the interface between the precursor alloy and the melt, and the Mg—Ca alloy melt, from which the metal X has been dissolved, fills the voids. Consequently, with the progressive dissolution of metal X and filling of the melt from the surface of the precursor alloy toward the inside, an Mg / Ti composite material comprising an Mg matrix with Ca dissolved therein and a matrix composed of titanium or a titanium alloy is finally obtained.

[0013] At this time, the Ca added to the melt has high miscibility with the metal X, thereby promoting the dealloying behavior in which the metal element X diffuses out into the melt, and thus has the effect of greatly shortening the process time for fabricating the Mg / Ti composite material. In addition, the Ca added to the melt is dissolved in the Mg matrix, thereby increasing the volume fraction of the Mg matrix in the composite material, reducing the coarsening rate of Ti, and simultaneously enhancing the strength of the composite material through solid-solution strengthening of the Mg matrix.

[0014] Meanwhile, the metal X included in the precursor alloy is not particularly limited in type as long as it has a negative enthalpy of mixing with titanium, magnesium, and calcium, and thus is miscible with titanium, magnesium, and calcium. 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), iridium (Ir), platinum (Pt), gold (Au), mercury (Hg), lead (Pb), or bismuth (Bi). That is, 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—Ir alloy, Ti—Pt alloy, Ti—Au alloy, Ti—Hg alloy, Ti—Pb alloy, or Ti—Bi alloy.

[0015] In addition, the content of calcium (Ca) in the melt containing magnesium (Mg) and calcium (Ca) is not particularly limited and, for example, may be 10 wt % or less.

[0016] Furthermore, in order to further improve the properties of the Mg / Ti composite material fabricated as described above, the present invention provides a method for manufacturing an Mg / TiAl composite material in which aluminum (Al) is added as an alloying element, the method comprising: (a) immersing a precursor alloy (Ti—X), which includes titanium (Ti) and a metal (X) that has miscibility with Ti and is dissolved into the melt, into an Mg—Ca alloy melt containing magnesium (Mg) and calcium (Ca) 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 into an Mg—Al alloy melt to produce an Mg / TiAl composite material.

[0017] Since step (a) is identical to the above-described method for manufacturing an Mg / Ti composite material, its description is omitted herein.

[0018] In step (b), a titanium (Ti) porous structure is fabricated by removing the matrix composed of magnesium or a magnesium alloy from the Mg / Ti composite material prepared in the previous step.

[0019] The method of removing the magnesium alloy matrix from the Mg / Ti composite material is not particularly limited. For example, the Mg / Ti composite material may be immersed in a solution containing an acid such as nitric acid, which has high corrosivity to magnesium alloys, and maintained for a predetermined period of time, thereby removing the magnesium alloy matrix and producing the titanium (Ti) porous structure.

[0020] Next, in step (c), when the previously fabricated titanium (Ti) porous structure is immersed into an Mg—Al alloy melt, the liquid Mg—Al alloy melt fills the spaces between the solid Ti skeletal structures, and aluminum (Al) atoms, which have much higher miscibility with titanium (Ti) than with magnesium (Mg), rapidly diffuse and migrate from the liquid Mg—Al alloy melt to the surface of the solid Ti skeletal structure. Accordingly, the titanium (Ti) matrix gradually transforms from pure Ti or a Ti alloy→Ti with Al atoms dissolved→Ti3Al→TiAl. As a result, an Mg / TiAl composite material having a three-dimensional continuous interconnected structure with a bi-continuous configuration, in which the matrix composed of magnesium or a magnesium alloy and the matrix composed of titanium or a titanium alloy with Al dissolved therein or in the form of a TixAly second phase are each infinitely interconnected, is obtained.

[0021] Furthermore, in another aspect, the present invention provides metal composite materials such as Mg / Ti composite materials and Mg / TiAl composite materials manufactured according to the above-described method.Advantageous Effects

[0022] According to the method for manufacturing a metal composite material through the liquid metal dealloying method of the present invention, the Ca alloying element contained in the Mg—Ca alloy melt has high miscibility with Cu, thereby promoting the dealloying behavior in which Cu diffuses into the melt, and thus the process time required for fabricating the composite material can be greatly shortened compared to the conventional technique using a pure magnesium melt.

[0023] In addition, the Ca alloying element contained in the Mg—Ca alloy melt is dissolved in the Mg matrix, thereby increasing the volume fraction of the Mg matrix in the composite material, reducing the coarsening rate of Ti, and simultaneously improving the strength of the composite material through solid-solution strengthening of the Mg matrix.DESCRIPTION OF DRAWINGS

[0024] FIG. 1 is a schematic diagram showing the process of manufacturing Mg / Ti composite materials by utilizing the liquid metal dealloying method with Mg-1Ca (wt %) melt or pure Mg melt in Examples 1 and 2 of the present invention and Comparative Examples 1 and 2.

[0025] FIG. 2 shows the results of measuring the time required for the dealloying of Cu using Mg-1Ca (wt %) melt or pure Mg melt in the Examples and Comparative Examples of the present invention.

[0026] FIG. 3 shows scanning electron microscope (SEM) images and energy dispersive X-ray spectroscopy (EDS) results of Mg / Ti composite materials, according to the process time of the liquid metal dealloying method using Mg-1Ca (wt %) melt or pure Mg melt in the Examples and Comparative Examples of the present invention.

[0027] FIG. 4 shows scanning electron microscope (SEM) images of the Mg / Ti composite materials manufactured according to Example 1 of the present invention and Comparative Example 1.

[0028] FIG. 5 shows scanning electron microscope (SEM) images of the Mg / Ti composite materials manufactured according to Example 2 of the present invention and Comparative Example 2.DETAILED DESCRIPTION

[0029] In describing the present invention, detailed descriptions of well-known functions or configurations will be omitted when it is determined that such descriptions would unnecessarily obscure the gist of the present invention.

[0030] Embodiments in accordance with the concept of the present invention may be modified in various ways and may have various forms, and thus particular embodiments are illustrated in the drawings and described in detail in this specification or application. However, this is not intended to limit embodiments according to the concept of the present invention to particular disclosed forms, but should be understood to include all modifications, equivalents, or substitutes falling within the spirit and scope of the present invention.

[0031] The terminology used in this specification is employed merely to describe specific embodiments, and is not intended to limit the present invention. Unless the context clearly indicates otherwise, singular expressions include the plural. In this specification, terms such as “comprise” or “have” are intended to designate the presence of the stated features, numbers, steps, operations, components, parts, or combinations thereof, but should be understood not to preclude the possibility of the presence or addition of one or more other features, numbers, steps, operations, components, parts, or combinations thereof.

[0032] Hereinafter, the present invention will be described in more detail with reference to examples.

[0033] The embodiments according to this specification may be modified in various different forms, and the scope of this specification should not be construed as limited to the embodiments described below. The embodiments of this specification are provided to more fully explain the present invention to those of ordinary skill in the art.

[0034] In this embodiment, as shown in FIG. 1, a liquid metal dealloying method is presented in which Ca, capable of promoting the dealloying of Cu constituting the Ti—Cu precursor, is added to the Mg melt. Accordingly, the microstructures and mechanical properties of Mg / Ti composite materials fabricated by the liquid metal dealloying method using a Ti—Cu precursor and an Mg—Ca melt (Examples 1 and 2) were observed and compared with those of Mg / Ti composite materials fabricated by the conventional liquid metal dealloying method using a Ti—Cu precursor and pure magnesium (Mg) melt (Comparative Examples 1 and 2).Example 1

[0035] A Ti—Cu precursor alloy (Ti30Cu70), which includes titanium (Ti) and copper (Cu) at an atomic ratio of 30:70, was immersed in an Mg-1Ca (wt %) alloy melt at 800° C. for 10 minutes and then removed to fabricate an Mg / Ti composite material.Example 2

[0036] A Ti—Cu precursor alloy (Ti30Cu70) was immersed in an Mg-1Ca (wt %) alloy melt at 800° C. for 60 minutes and then removed to fabricate an Mg / Ti composite material.Comparative Example 1

[0037] According to a conventional general liquid metal dealloying method, a Ti—Cu precursor alloy (Ti30Cu70) was immersed in pure Mg melt at 800° C. for 30 minutes and then removed to fabricate an Mg / Ti composite material.Comparative Example 2

[0038] According to a conventional general liquid metal dealloying method, a Ti—Cu precursor alloy (Ti30Cu70) was immersed in pure Mg melt at 800° C. for 60 minutes and then removed to fabricate an Mg / Ti composite material.

[0039] FIG. 2 shows the results of measuring the time required for the dealloying of Cu using an Mg-1Ca (wt %) melt or pure Mg melt in the Examples and Comparative Examples of the present invention.

[0040] Referring to FIG. 2, when using an Mg-1Ca (wt %) melt as in the Examples of the present invention, dealloying of Cu was completed within 10 minutes after immersing the precursor alloy into the melt (Cu content in the precursor s 1 wt %), whereas in the Comparative Examples using pure Mg melt, dealloying of Cu was not completed until after 30 minutes of immersion.

[0041] As described above, the fact that Cu dealloying was completed more quickly in the Examples than in the Comparative Examples is because Ca present in the Mg-1Ca (wt %) melt has high miscibility with Cu, and the degree of this miscibility is higher than that between Cu and Mg (enthalpy of mixing ΔHmix of Ca—Cu: −13 kJ / mol, ΔHmix of Mg—Cu: −3 kJ / mol). Therefore, dealloying of Cu from the precursor alloy is promoted in the Mg-1Ca (wt %) melt compared to the pure Mg melt.

[0042] FIG. 3 shows scanning electron microscope (SEM) images and energy dispersive X-ray spectroscopy (EDS) results of Mg / Ti composite materials according to the process time of the liquid metal dealloying method using an Mg-1Ca (wt %) melt or pure Mg melt in the Examples and Comparative Examples of the present invention.

[0043] According to FIG. 3, in Comparative Example 1, dealloying of Cu in the pure Mg melt was completed after 30 minutes, and it was confirmed that an Mg / Ti composite material having a three-dimensional continuous interconnected structure and composed of a pure Mg matrix and a pure Ti matrix was fabricated.

[0044] In contrast, in Example 1, dealloying of Cu in the Mg-1Ca (wt %) melt was completed after 10 minutes, and it was found that an Mg / Ti composite material having a three-dimensional continuous interconnected structure and including an Mg matrix composed of an α-Mg phase in which 0.6 wt % Ca was dissolved was fabricated. Since Ca does not have miscibility with Ti, it is not dissolved in the Ti matrix. However, because Ca has miscibility with Mg (enthalpy of mixing ΔHmix of Ca—Ti: 43 kJ / mol, ΔHmix of Ca—Mg: −6 kJ / mol), Ca is dissolved in the Mg matrix, resulting in the fabrication of an Mg / Ti composite material including an α-Mg matrix with Ca dissolved therein.

[0045] FIG. 4 shows scanning electron microscope (SEM) images of the Mg / Ti composite materials fabricated according to Example 1 and Comparative Example 1.

[0046] Referring to FIG. 4, the Mg / Ti composite material fabricated in Comparative Example 1 exhibited a volume fraction ratio of the Mg matrix to the Ti matrix of 30:70, with the area of the Ti matrix being much larger, and its hardness was measured to be 115.2 Hv.

[0047] In the Mg / Ti composite material fabricated in Example 1, the volume fraction of the Mg matrix significantly increased compared to Comparative Example 1, resulting in an ideal ratio of 51:49 between the Mg matrix and the Ti matrix. Moreover, although the volume fraction of the Mg matrix, which has relatively lower strength than the Ti matrix, increased greatly compared to Comparative Example 1, the hardness of the Mg / Ti composite material was measured to be 107.4 Hv, which was not significantly different from that of Comparative Example 1. This is because Ca contained in the Mg-1Ca (wt %) melt used for the fabrication of the Mg / Ti composite material was dissolved in the Mg matrix, thereby forming an α-Mg matrix with superior properties compared to pure Mg, and because the Ti matrix was refined.

[0048] Therefore, although the immersion time in the melt was greatly reduced to one-third (10 minutes in Mg-1Ca (wt %) melt versus 30 minutes in pure Mg melt), the Mg / Ti composite material fabricated in Example 1 exhibited a nearly ideal volume fraction ratio of 50:50 between the Ti matrix and the Mg matrix. The closer the volume fraction is to the ideal 50:50, the greater the interfacial area between the Ti matrix and the Mg matrix, thereby providing excellent mechanical and chemical properties.

[0049] FIG. 5 shows scanning electron microscope (SEM) images of the Mg / Ti composite materials fabricated according to Example 2 and Comparative Example 2.

[0050] According to FIG. 5, in Comparative Example 2, as in Comparative Example 1, the volume fraction ratio of the Mg matrix to the Ti matrix was 30:70, with the volume fraction of the Ti matrix being much higher, and the average size of the Ti matrix was found to be 3.4 μm.

[0051] In Example 2, as in Example 1, the volume fraction ratio of the Mg matrix to the Ti matrix was an ideal 48:52, and the average size of the Ti matrix was confirmed to be 2.9 μm, which was finer than that in Comparative Example 2.

[0052] As described above, embodiments of the present invention have been explained with reference to the accompanying drawings. However, it will be understood by those skilled in the art that the present invention can be carried out in various other specific forms without changing its technical spirit or essential characteristics. Therefore, the embodiments described above should be understood as illustrative in all respects and not restrictive.INDUSTRIAL APPLICABILITY

[0053] According to the present invention, by using the liquid metal dealloying method with an Mg—Ca alloy melt, the process time required for fabricating a composite material can be greatly shortened compared to the conventional technique using a pure magnesium melt, and a composite material with improved strength can be manufactured.

Examples

example 1

[0035]A Ti—Cu precursor alloy (Ti30Cu70), which includes titanium (Ti) and copper (Cu) at an atomic ratio of 30:70, was immersed in an Mg-1Ca (wt %) alloy melt at 800° C. for 10 minutes and then removed to fabricate an Mg / Ti composite material.

example 2

[0036]A Ti—Cu precursor alloy (Ti30Cu70) was immersed in an Mg-1Ca (wt %) alloy melt at 800° C. for 60 minutes and then removed to fabricate an Mg / Ti composite material.

Claims

1. A method for manufacturing a metal composite material, comprising a step of immersing a precursor alloy (Ti—X), which includes titanium (Ti) and a metal (X) that has miscibility with Ti and is dissolved into a melt, into a melt containing magnesium (Mg) and calcium (Ca) to produce an Mg / Ti composite material.

2. The method for manufacturing a metal composite material according to claim 1, wherein the melt contains 10 wt % or less of calcium (Ca).

3. The method for manufacturing a metal composite material according to claim 1,wherein the precursor alloy is selected from the group consisting of 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—Ir alloy, Ti—Pt alloy, Ti—Au alloy, Ti—Hg alloy, Ti—Pb alloy, and Ti—Bi alloy.

4. The method for manufacturing a metal composite material according to claim 1,wherein a Ti—Cu alloy is immersed in a melt containing magnesium (Mg) and calcium (Ca), copper being dissolved into the melt, and the melt being filled into voids formed in the precursor alloy due to the dissolution of copper, thereby forming the Mg / Ti composite material.

5. The method for manufacturing a metal composite material according to claim 4, comprising a step of immersing a precursor alloy (Ti30Cu70), which includes titanium (Ti) and copper (Cu) at an atomic ratio of 30:70, into an Mg-1 wt % Ca melt composed of 99 wt % magnesium (Mg) and 1 wt % calcium (Ca) for 10 minutes or less to produce the Mg / Ti composite material.

6. The method for manufacturing a metal composite material according to claim 1, comprising:(a) immersing a precursor alloy (Ti—X), which includes titanium (Ti) and a metal (X) that has miscibility with Ti and also with the melt and is thereby dissolved into the melt, into a melt containing magnesium (Mg) and calcium (Ca) 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 into an Mg—Al alloy melt to produce an Mg / TiAl composite material.

7. The method for manufacturing a metal composite material according to claim 6,wherein, in step (b), the Mg / Ti composite material is immersed in an acid solution to remove magnesium or a magnesium alloy from the Mg / Ti composite material, thereby producing the titanium (Ti) porous structure.

8. The method for manufacturing a metal composite material according to claim 6,wherein, in step (c), the titanium (Ti) porous structure is immersed in an Mg-3 wt % Al alloy melt to produce the Mg / TiAl composite material.

9. The method for manufacturing a metal composite material according to claim 6, comprising:(a) immersing a precursor alloy (Ti30Cu70), which includes titanium (Ti) and copper (Cu) at an atomic ratio of 30:70, into a melt containing magnesium (Mg) and calcium (Ca) to produce an Mg / Ti composite material;(b) immersing the Mg / Ti composite material in an aqueous nitric acid (HNO3) solution to remove magnesium or a magnesium alloy from the Mg / Ti composite material, thereby producing a titanium (Ti) porous structure; and(c) immersing the titanium (Ti) porous structure in an Mg-3 wt % Al alloy melt for 10 seconds to 2 hours to produce an Mg / TiAl composite material.

10. A metal composite material manufactured by the method according to claim 1.

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