Titanium particle reinforced magnesium-based composite material and its preparation method and application

Abstract

The present invention discloses a titanium particle reinforced magnesium-based composite material, its preparation method, and application. The composite material includes a magnesium alloy matrix and titanium particles distributed within the magnesium alloy matrix. The titanium particles have interfacial intermetallic compounds on their surfaces that are bonded to both the titanium particles and the magnesium alloy matrix. The preparation method comprises adding composite reinforced particles to a magnesium alloy melt and mixing them uniformly. The mixed melt is then cast and cooled, with the cooling rate controlled at 1.5 to 5 K / s. The composite reinforced particles include titanium particles and a metal coating layer coated on their surface. The titanium particles are subjected to surface metal coating treatment. Under casting conditions, the metal reacts with the magnesium alloy matrix and the titanium particles to form a stable intermetallic compound, thereby optimizing the bonding interface between the titanium particles and the magnesium alloy matrix. The metal matrix and the reinforced particles are pinned together by the intermetallic compound, thereby increasing the interfacial bonding strength and improving the tensile mechanical properties of the titanium particle reinforced magnesium-based composite material.

Description

Technical Field

[0001] The present invention relates to the technical field of magnesium-based composite materials, and in particular to a titanium particle reinforced magnesium-based composite material and a preparation method and application thereof. Background Art

[0002] Magnesium alloys have great application potential as lightweight materials, but their shortcomings of low strength, plasticity and elastic modulus limit their widespread application. Titanium has the characteristics of high melting point, high strength, good plasticity, and low mutual solubility with magnesium alloys. It is a commonly used reinforcement for the preparation of magnesium-based composites. In the currently disclosed methods for preparing titanium particle-reinforced magnesium-based composites, titanium particles are generally not subjected to surface pretreatment. Since titanium and magnesium basically do not react, the interfacial bonding between the titanium particles and the magnesium alloy matrix is ​​weak. When subjected to force, the reinforcing particles easily detach from the matrix, which limits the improvement of the mechanical properties of the composite material.

[0003] In view of this, the present invention is proposed. Summary of the Invention

[0004] The purpose of the present invention is to provide a titanium particle reinforced magnesium-based composite material and a preparation method and application thereof, so as to improve the mechanical properties of the titanium particle reinforced magnesium-based composite material.

[0005] The present invention is achieved in that:

[0006] In a first aspect, the present invention provides a titanium particle reinforced magnesium-based composite material, which includes a magnesium alloy matrix and titanium particles distributed in the magnesium alloy matrix, wherein the titanium particles have intermetallic compounds on their surfaces, and the intermetallic compounds improve the bonding strength between the titanium particles and the magnesium alloy matrix.

[0007] In a second aspect, the present invention also provides a method for preparing the above-mentioned titanium particle reinforced magnesium-based composite material, which comprises: adding composite reinforced particles after composite surface pretreatment into a magnesium alloy melt and mixing them evenly, then casting the mixed melt and cooling it, and controlling the cooling rate at 1.5 to 5K / s, wherein the composite reinforced particles include titanium particles and a metal coating layer coated on the surface of the titanium particles.

[0008] In a third aspect, the present invention also provides applications of the titanium particle reinforced magnesium-based composite material in the fields of automobile manufacturing, aerospace, electronic equipment and communications, sports equipment, and medical equipment.

[0009] The present invention has at least the following beneficial effects: an interfacial intermetallic compound is formed between the magnesium alloy matrix and the titanium particles used to enhance its strength. This interfacial intermetallic compound can simultaneously bond tightly to both the titanium particles and the magnesium alloy matrix, optimizing the interface between the titanium particles and the magnesium alloy matrix, pinning the magnesium alloy matrix and the titanium particles together, and improving the tensile mechanical properties of the titanium particle-reinforced magnesium-based composite material. The titanium particle-reinforced magnesium-based composite material is prepared by forming a stable interfacial intermetallic compound by in-situ reaction of the metal coating layer coated on the titanium particles with the titanium alloy matrix and the titanium particles under casting conditions. The preparation method is simple and easy, and the thickness of the interfacial intermetallic compound can be easily controlled. BRIEF DESCRIPTION OF THE DRAWINGS

[0010] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the following briefly introduces the drawings required for use in the embodiments. It should be understood that the following drawings only illustrate certain embodiments of the present invention and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other relevant drawings can be obtained based on these drawings without paying any creative work.

[0011] Figure 1 This is a SEM image of the spherical composite reinforcement particles used in Example 1, with a magnification of 5000 times;

[0012] Figure 2 This is a SEM photograph of the microstructure of the titanium particle reinforced magnesium-based composite material of Example 1, with a magnification of 3000 times;

[0013] Figure 3 This is the SEM photo of the tensile fracture of Example 1;

[0014] Figure 4 This is a SEM photograph of the microstructure of the titanium particle reinforced magnesium-based composite material in Comparative Example 1, with a magnification of 500 times;

[0015] Figure 5 This is the SEM photo of the tensile fracture of Comparative Example 1;

[0016] Figure 6 This is an SEM image of the composite reinforced particles used in Comparative Example 2;

[0017] Figure 7 This is an SEM image of the composite material prepared in Comparative Example 2;

[0018] Figure 8 This is the SEM photo of the tensile fracture of the composite material prepared in Comparative Example 2. DETAILED DESCRIPTION

[0019] To make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention are described clearly and completely below. Where specific conditions are not specified in the embodiments, conventional conditions or conditions recommended by the manufacturer are used. Where the manufacturer of the reagents or instruments is not specified, all are conventional products that can be purchased commercially.

[0020] The titanium particle reinforced magnesium-based composite material disclosed in the present invention, as well as its preparation method and application are described in detail below.

[0021] Through research and analysis of existing titanium particle-reinforced magnesium-based composites, the inventors discovered that directly adding titanium to magnesium alloys results in weak interfacial bonding between the titanium particles and the magnesium alloy matrix, due to the near-inert reaction between titanium and magnesium. This leads to weak interfacial bonding between the titanium particles and the magnesium alloy matrix, and the titanium particles easily detach from the matrix under tensile loads, resulting in poor tensile mechanical properties of the titanium particle-reinforced magnesium-based composites. Consequently, based on this research and implementation, the following technical solution was proposed.

[0022] Some embodiments of the present invention provide a titanium particle reinforced magnesium-based composite material, which includes a magnesium alloy matrix and titanium particles distributed in the magnesium alloy matrix, wherein the titanium particles have an interfacial intermetallic compound on the surface, and the interfacial intermetallic compound is bonded to both the titanium particles and the magnesium alloy matrix.

[0023] By forming an interfacial intermetallic compound between the magnesium alloy matrix and the titanium particles, the interfacial intermetallic compound can be tightly bonded to the titanium particles and the magnesium alloy matrix at the same time, thereby optimizing the bonding interface between the titanium particles and the magnesium alloy matrix, thereby pinning the magnesium alloy matrix and the titanium particles together, and improving the tensile mechanical properties of the titanium particle reinforced magnesium-based composite material.

[0024] It should be noted that the interfacial intermetallic compounds in the above embodiments include compounds formed by the reaction of the cladding metal with titanium and compounds formed by the reaction with the magnesium alloy matrix. The cladding metal can be any metal that can react with magnesium and titanium to form a stable interfacial compound, such as aluminum, zinc, copper, etc.

[0025] In some embodiments, the intermetallic compound at the interface includes Al-Ti compounds (such as AlTi, Ti3Al, TiAl3, etc.) and Al-Mg compounds (such as Mg 17 Al 12 wait).

[0026] Furthermore, in order to avoid too little interfacial intermetallic compounds, which is not conducive to improving the interface bonding strength, and to avoid too many or too large interfacial intermetallic compounds, which may lead to a decrease in alloy plasticity, in some embodiments, the interfacial intermetallic compounds are distributed in the form of block particles on the surface of the titanium particles, and the particle size of the interfacial intermetallic compounds is 0.5μm to 2μm, or the thickness of the coating layer is ≤1μm; the coverage rate of the interfacial intermetallic compounds on the surface of the titanium particles is ≥30%.

[0027] The calculation method of the coverage mentioned in the present invention is the ratio of the total length of the contact surface between the interfacial intermetallic compound and the titanium particle to the perimeter of the titanium particle.

[0028] Some embodiments of the present invention also provide a method for preparing the above-mentioned titanium particle reinforced magnesium-based composite material, which includes: adding composite reinforcing particles to a magnesium alloy melt and mixing them evenly, then casting the mixed melt and cooling it, and controlling the cooling rate at 1.5 to 5K / s. The composite reinforcing particles include titanium particles and a metal coating layer coated on the surface of the titanium particles.

[0029] Specifically, the inventors discovered through research that the interfacial reaction between the coating metal and titanium and magnesium primarily occurs during the cooling and solidification process after casting. Coating the titanium particles with a metal capable of interfacially reacting with titanium and magnesium (e.g., Al), followed by thorough mixing in a melt below the melting point of the metal and subsequent casting, allows the metal on the titanium particle surface to react in situ with titanium and magnesium to form stable intermetallic compounds, thereby optimizing the interface between the titanium particles and the magnesium alloy matrix. The resulting compounds pin the magnesium alloy matrix and the reinforcing particles together, enhancing interfacial bonding strength. Controlling the cooling rate is crucial during this process, as it affects the morphology of the interfacial product. If the cooling rate is less than 1.5 K / s, the solidification time is excessive, leading to excessive interfacial reactions, resulting in excessive interface thickness and excessively large intermetallic compounds, which in turn affect interfacial bonding strength. If the solidification rate exceeds 5 K / s, the interfacial reaction does not have enough time to occur, resulting in an excessively thin interface layer and insufficient intermetallic compounds, which is detrimental to improving interfacial bonding strength. Furthermore, excessively fast cooling rates hinder shrinkage feeding during solidification, leading to the formation of voids within the ingot.

[0030] Specifically, in some embodiments, the mass of the metal coating is 1% to 10% of the mass of the titanium particles. When the metal coating is an aluminum coating, the mass of the aluminum coating is 1% to 5% of the mass of the titanium particles. For example, the mass of the aluminum coating can be selected to be 1%, 2%, 3%, 4%, 5%, etc., of the mass of the titanium particles.

[0031] If the mass ratio of the coating layer to the titanium particles is less than 1%, too little metal will participate in the interface reaction, the amount of intermetallic compounds formed will be insufficient, and the pinning strengthening effect will be limited. If the mass ratio of the coating layer to the titanium particles is greater than 5%, severe interface reactions are likely to occur, excessive intermetallic compounds will be generated, and the plasticity of the composite material will be reduced.

[0032] It should be noted that when using metal coating layers such as copper and zinc, due to their high density, the corresponding number ratios need to be adaptively adjusted.

[0033] By controlling the cooling rate and the quality of the coating layer on the surface of the titanium particles, the particle size of the intermetallic compound at the composite material interface can be controlled to be 0.5μm to 2μm, or the coating layer thickness can be ≤1μm; the coating rate of the intermetallic compound on the surface of the titanium particles can be ≥30%.

[0034] Some embodiments of the present invention further disclose one or more methods for preparing titanium particle reinforced magnesium-based composite materials, which specifically include the following steps:

[0035] S1. Prepare composite reinforced particles.

[0036] Specifically, the coating metal is bonded to the surface of the titanium particles to form a metal coating layer by electric explosion coating, mechanical mixing, etc. In some embodiments, the coating metal is bonded to the surface of the titanium particles to coat the entire surface, and in some embodiments, the coating metal is dispersed and coated locally on the titanium particles.

[0037] Furthermore, in order to ensure that the titanium particles can be better dispersed in the magnesium alloy melt and form a uniform intermetallic compound layer at the interface, the average particle size of the titanium particles is 5μm to 50μm. If the average particle size of the titanium particles is less than 5μm, the particles are prone to agglomeration, and the agglomerated particles are easily coated into a mass during the coating process, making it difficult to form a coating layer on the surface of each particle. If the average particle size of the titanium particles is greater than 50μm, their reinforcing effect on the composite material is reduced, and large particles are prone to sedimentation during the casting process, causing macrosegregation.

[0038] It should be noted that the titanium particles mentioned in the embodiments of the present invention may be irregular in shape or spherical in shape.

[0039] S2, stirring casting.

[0040] Specifically, the composite reinforcement particles are added into the magnesium alloy melt and mixed evenly, and then the mixed melt is cast and cooled, with the cooling rate controlled at 1.5 to 5 K / s.

[0041] In some embodiments, the amount of composite reinforcement particles added is 2.5% to 30% by weight of the magnesium alloy melt. If the particle amount is less than 2.5% by weight, the reinforcement effect is not significant; if the particle amount is greater than 30% by weight, the melt viscosity is too high, the fluidity is poor, and a large number of metallurgical defects such as shrinkage cavities and porosity will form in the material, affecting the material properties.

[0042] In some embodiments, the composite reinforcement particles and the magnesium alloy melt are uniformly mixed by stirring, with a stirring time of 1 min to 5 min and a stirring speed of 500 r / min to 1000 r / min; the stirring is performed under vacuum or inert gas protection conditions.

[0043] It should be noted that the process used in the stirring stage is a conventional stirring casting process, as long as the particles and the magnesium alloy melt can be mixed evenly.

[0044] In some embodiments, when the composite reinforcing particles are added to the magnesium alloy melt, the temperature of the magnesium alloy melt is 575°C to 610°C. After uniform mixing, the mixed alloy melt is heated to 630°C to 660°C (generally lower than the melting temperature of the metal coating layer) and then cast, and the melt is cooled in the mold.

[0045] Some embodiments of the present invention also provide applications of the titanium particle reinforced magnesium-based composite material in the above embodiments in the fields of automobile manufacturing, aerospace, electronic equipment and communications, sports equipment, and medical equipment.

[0046] The features and performance of the present invention are further described in detail below with reference to the embodiments.

[0047] Example 1

[0048] This embodiment provides a titanium particle reinforced magnesium-based composite material, which is obtained by the following steps:

[0049] Titanium particles with an average particle size of 10 μm were coated with a pure aluminum coating using an electric explosion method to produce composite reinforced particles. The mass ratio of aluminum to titanium was 2.5%. The electric explosion method involves placing aluminum wire and titanium particles into an electric explosion chamber, which is evacuated and then filled with argon or other inert gas. A pulsed current is then applied to the aluminum wire. The high-density current causes the aluminum wire to instantly melt and vaporize into metal vapor, which then spreads across the surface of the titanium particles. Upon cooling, a uniform coating of a defined thickness is formed.

[0050] Its SEM photos are as follows Figure 1 As shown, it can be seen that this embodiment is partially coated, wherein the gray spheres are titanium particles and the white powder above is coated aluminum.

[0051] Composite reinforcement particles were added to an AZ91 magnesium alloy melt at a temperature of 585°C. The melt was stirred under vacuum or inert gas for 3 minutes at a speed of 750 rpm. After stirring, the matrix magnesium alloy was heated to 650°C and cast. The ingot was cooled in the mold at a rate of 3.5 K / s to produce a titanium particle-reinforced magnesium-based composite.

[0052] The SEM image of the titanium particle reinforced magnesium matrix composite is shown in Figure 2. Figure 2 (Magnified 3000 times) As shown in the figure, the white spherical particles are titanium particles, and the dark color is the AZ91 matrix. It can be seen that the blocky intermetallic compounds with a particle size of 0.2 to 0.75 μm are formed between the titanium and magnesium alloy matrices. The energy spectrum analysis shows that they are AlTi, Ti3Al, TiAl3, Al 12 Mg 17 The intermetallic compounds cover 52.8% of the titanium particles and pin the titanium particles to the AZ91 matrix.

[0053] Furthermore, the tensile fracture SEM photos of the titanium particle reinforced magnesium matrix composite are as follows: Figure 3 As shown, from Figure 3 It can be seen that the titanium particles are tightly bonded to the matrix, and the fracture surface shows the characteristics of ductile fracture.

[0054] Example 2

[0055] This embodiment is basically the same as embodiment 1, with the only difference being that the surface of the titanium particles is pretreated by chemical plating, and the surface is completely coated with pure aluminum, wherein the mass ratio of aluminum to titanium is 5%.

[0056] Example 3

[0057] The difference between this embodiment and embodiment 1 is that the cooling rate is 2K / s.

[0058] Example 4

[0059] The difference between this embodiment and embodiment 1 is that the cooling rate of the melt in the mold is 5K / s.

[0060] Example 5

[0061] The difference between this embodiment and embodiment 1 is that the amount of reinforcing particles added is , and the average particle size of the titanium particles is 45 μm.

[0062] Comparative Example 1

[0063] Titanium particles with an average particle size of 10 μm were not subjected to surface coating treatment. A composite material was prepared using the same process as in Example 1.

[0064] The SEM image of the titanium particle reinforced magnesium matrix composite is shown in Figure 2. Figure 4 As shown in the image (500x magnification), the white spherical particles are titanium particles and the darker ones are the AZ91 matrix. It can be seen that there is essentially no intermetallic compound formed between the titanium and magnesium alloy matrix.

[0065] The tensile fracture of the composite material prepared in this comparative example was observed by scanning electron microscopy, and the SEM image is as follows: Figure 5 As shown, from Figure 5 It can be seen that there is a gap between the titanium particles and the matrix, indicating that under the action of tensile force, the titanium particles are separated from the matrix.

[0066] Comparative Example 2

[0067] Titanium particles with an average particle size of 25 μm were coated with a pure aluminum coating layer on the surface by chemical plating, wherein the mass ratio of aluminum to titanium was 6.5%. Figure 6 As shown, it can be seen that this embodiment is completely covered.

[0068] The composite material was prepared by the same process as in Example 1. The SEM photo of the prepared composite material is shown in FIG. Figure 7 As shown in the image (magnified 2000 times), a large amount of compounds are generated at the interface, with an interface layer thickness of 3.3 to 4 μm, completely encapsulating the titanium particles. The bulk intermetallic compound particles have a size of 2.5 to 6.9 μm.

[0069] The tensile fracture of the composite material prepared in Comparative Example 2 was observed by scanning electron microscopy. The SEM image is as follows: Figure 8 As shown, it can be seen that the surface of the titanium particles is completely covered by the product titanium particles, and the fracture shows brittle fracture characteristics.

[0070] Comparative Example 3

[0071] The difference between this comparative example and Example 1 is that the cooling rate is 0.5 K / s.

[0072] Comparative Example 4

[0073] The difference between this comparative example and Example 1 is that the cooling rate is 7.2 K / s.

[0074] Comparative Example 5

[0075] The difference between this comparative example and Example 1 is that the casting temperature is 680°C.

[0076] Comparative Example 6

[0077] The difference between this comparative example and Example 1 is that the average particle size of the titanium particles is 3 μm.

[0078] Comparative Example 7

[0079] The difference between this comparative example and Example 1 is that the amount of composite reinforcement particles added is 35% of the mass of the magnesium alloy melt.

[0080] Test example

[0081] The mechanical properties of the titanium particle reinforced AZ91 magnesium-based composite materials prepared in Examples 1-5 and Comparative Examples 1-7 were tested in accordance with national standards GB / T 22315-2008 and GB / T 228.1-2010. The results are shown in Table 1.

[0082] Table 1 Mechanical properties test results of titanium reinforced magnesium matrix composite materials prepared in various embodiments and comparative examples

[0083]

[0084]

[0085] In summary, the titanium particles undergo surface coating treatment, forming a metal coating layer on their surface. Under casting conditions, the metal reacts with the magnesium alloy matrix and titanium particles to form a stable intermetallic compound, which optimizes the bonding interface between the titanium particles and the magnesium alloy matrix. The generated compound pins the metal matrix and the reinforcing particles together, increasing the interfacial bonding strength and, in turn, improving the tensile mechanical properties of the titanium particle-reinforced magnesium-based composite.

[0086] The foregoing description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Those skilled in the art will readily appreciate that various modifications and variations of the present invention are possible. Any modifications, equivalent substitutions, or improvements made within the spirit and principles of the present invention are intended to be within the scope of protection of the present invention.

Claims

1. A method for preparing a titanium particle reinforced magnesium-based composite material, characterized in that: The titanium particle reinforced magnesium-based composite material comprises a magnesium alloy matrix and titanium particles distributed in the magnesium alloy matrix, wherein the titanium particles have an interfacial intermetallic compound on the surface, and the interfacial intermetallic compound is bonded to both the titanium particles and the magnesium alloy matrix; The interface intermetallic compound is distributed on the surface of the titanium particle in the form of block particles, and the coating layer of the interface intermetallic compound has a thickness of ≤1 μm; The coverage rate of the interfacial intermetallic compound on the surface of the titanium particles is at least 30%; The intermetallic compound at the interface is an intermetallic compound formed by any one of aluminum, zinc and copper with titanium and magnesium; The preparation method comprises: adding composite reinforcement particles to a magnesium alloy melt and mixing them uniformly, then casting the mixed melt and cooling it, with the cooling rate controlled at 1.5-5K / s, wherein the composite reinforcement particles include titanium particles and a metal coating layer coated on the surface of the titanium particles; The metal coating layer is bonded to the surface of the titanium particles by explosive coating, chemical plating or mechanical mixing, and the metal coating layer locally and dispersedly coats the titanium particles; The mass of the metal coating layer is 1% to 10% of the mass of the titanium particles.

2. The preparation method according to claim 1, characterized in that The metal coating layer is bonded to the surface of the titanium particles by explosion coating.

3. The preparation method according to claim 1, characterized in that The metal coating layer is an aluminum coating layer, and the mass of the aluminum coating layer is 1% to 5% of the mass of the titanium particles; The average particle size of the titanium particles is 5 μm to 50 μm.

4. The preparation method according to any one of claims 1 to 2, characterized in that The added amount of the composite reinforcement particles is 2.5% to 30% of the mass of the magnesium alloy melt.

5. The preparation method according to any one of claims 1 to 2, characterized in that When the composite reinforcement particles are added to the magnesium alloy melt, the temperature of the magnesium alloy melt is 575° C. to 610° C. After uniform mixing, the mixed alloy melt is heated to 630° C. to 660° C. before casting.

6. The preparation method according to any one of claims 1 to 2, characterized in that The composite reinforcement particles and the magnesium alloy melt are uniformly mixed by stirring, the stirring time is 5 minutes to 45 minutes, and the stirring speed is 500 r / min to 1000 r / min; the stirring is performed under vacuum or inert gas protection conditions.

7. A titanium particle reinforced magnesium-based composite material prepared by the preparation method according to any one of claims 1 to 6.

8. The titanium particle reinforced magnesium-based composite material according to claim 7, characterized in that: The interface intermetallic compounds include Al-Ti compounds and Al-Mg compounds.

9. Use of the titanium particle reinforced magnesium-based composite material according to any one of claims 7 to 8 in the fields of automobile manufacturing, aerospace, electronic equipment and communications, sports equipment and medical equipment.

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