A method for producing a metal particle having a core-shell structure

Abstract

The application discloses a preparation method of metal particles with core-shell structure, which comprises the following steps: preheating inert gas flow loaded with high-melting-point metal powder, and then passing into flowing low-melting-point metal vapor to make the low-melting-point metal condense on the surface of the high-melting-point metal powder to form a low-melting-point metal shell layer; the temperature of the low-melting-point metal vapor is T1, the preheating temperature is T2, T1>T2, and the difference between T1 and T2 is 50-200 DEG C. In the preparation method, the gas flow loaded with low-temperature high-melting-point metal powder is passed into the flowing high-temperature low-melting-point metal vapor; due to the temperature difference and the flowing state of the low-melting-point metal vapor, the low-melting-point metal can quickly condense on the surface of the high-melting-point metal, so that a uniform, composition-unsegregated and well-bonded coating layer is formed on the surface of the high-melting-point metal powder, and the mechanical properties of the composite material made of the metal particles with core-shell structure are improved.

Description

Technical Field

[0001] This invention belongs to the field of materials, specifically relating to a method for preparing core-shell structured metal particles. Background Technology

[0002] Surface modification of metal particles is an important component of metal composite engineering technology, especially significant for improving the original properties of metal composites. Refractory metals have high strength, hardness, and high temperature resistance, but poor plasticity and are difficult to form. Low-melting-point metals have low density and are easy to form, but have poor strength. By coating the surface of metal particles with metal, it is possible to integrate the properties of multiple metals and prepare excellent composite materials that combine the properties of multiple metals, which is of great significance to the development of metal matrix composites. However, due to the non-overlapping melting temperature windows between metals with large melting point differences, it is impossible to achieve the coating of high-melting-point metals with low-melting-point metals through conventional methods. In addition, the coatings between immiscible metals prepared in existing technologies all suffer from poor interfacial bonding, component segregation, and loose structure, which limit the development of metal composites. Summary of the Invention

[0003] In order to overcome at least one of the technical problems existing in the prior art, one of the objectives of the present invention is to provide a method for preparing core-shell structured metal particles.

[0004] The second objective of this invention is to provide a core-shell structured metal particle.

[0005] The third objective of this invention is to provide a metal composite material.

[0006] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0007] The first aspect of this invention provides a method for preparing core-shell structured metal particles, comprising the following steps:

[0008] An inert gas stream carrying high-melting-point metal powder is preheated and then introduced into flowing low-melting-point metal vapor, causing the low-melting-point metal to condense on the surface of the high-melting-point metal powder to form a low-melting-point metal shell, thus obtaining the product.

[0009] The temperature of the low-melting-point metal vapor is T1, and the preheating temperature is T2, where T1 > T2 and the difference between T1 and T2 is 50–200°C. The surface temperature of the high-melting-point metal powder is lower than that of the low-melting-point metal vapor. When the high-melting-point metal powder enters the low-melting-point metal vapor, the low-melting-point metal vapor condenses on the low-temperature surface of the high-melting-point metal to form a low-melting-point metal shell.

[0010] Preferably, the flow rate of the low-melting-point metal vapor is 0.5 to 2 m / min.

[0011] Preferably, the flowing low-melting-point metal vapor is achieved by introducing heated inert gas into a reaction chamber filled with low-melting-point metal vapor at a flow rate of 0.5 to 2 m / min. The flowing inert gas drives the low-melting-point metal vapor to flow, thereby realizing the flow of low-melting-point metal.

[0012] Preferably, the flow rate of the inert gas stream carrying the high melting point metal powder is 1 to 7 m / min.

[0013] Preferably, the inert gas stream carrying the high-melting-point metal powder is introduced from the bottom of the low-melting-point metal vapor. The main purpose of using the bottom-up blowing method for the high-melting-point metal powder is to increase the floating distance of the high-melting-point metal particles, providing sufficient time to help the low-melting-point metal condense on the surface of the high-melting-point metal, thereby improving the coating rate.

[0014] Preferably, the low-melting-point metal is selected from Mg, Zn, and Al.

[0015] Preferably, the high-melting-point metal is selected from one of Ti, Nb, and Mo.

[0016] Preferably, the difference in melting points between the high-melting-point metal and the low-melting-point metal is not less than 1000°C.

[0017] Preferably, the mass ratio of the low-melting-point metal to the high-melting-point metal powder is (2-5):1.

[0018] Preferably, the vapor pressure of the low-melting-point metal vapor is 1 to 3 MPa.

[0019] Preferably, the vapor concentration of the low-melting-point metal vapor is 25-55%. The formula for calculating the vapor concentration is: V 低熔点金属蒸汽 / (V 低熔点金属蒸汽 +V 惰性气体 )×100%.

[0020] Preferably, the thickness of the low-melting-point metal shell is 0.1–5 μm.

[0021] Preferably, both the low-melting-point metal and the high-melting-point metal are pretreated with acid before use; more preferably, both the low-melting-point metal and the high-melting-point metal are pretreated with acid before use and then dried.

[0022] Preferably, the acid solution is a citric acid solution; more preferably, the acid solution is a citric acid solution with a mass concentration of 5-10%.

[0023] Preferably, the low-melting-point metal particle size is 0.5 to 1 mm.

[0024] Preferably, the particle size of the high-melting-point metal is 100μm to 700μm.

[0025] Preferably, the pretreatment time is 30–60 min. The purpose of using acid for pretreatment is to reduce the oxygen content on the surface of low-melting-point and high-melting-point metals, prevent the formation of impurities, and improve the coating rate, bonding, and safety.

[0026] Preferably, the drying temperature is 75–100°C.

[0027] Preferably, the drying time is 3 to 5 hours.

[0028] Preferably, the preparation method is as follows: an inert gas stream carrying high-melting-point metal powder is preheated, and then introduced into low-melting-point metal vapor with a flow rate of 0.5 to 2 m / min at a flow rate of 1 to 7 m / min, while the gas is evacuated at a evacuation rate of 0.5 to 2 m / min, so that the low-melting-point metal condenses on the surface of the high-melting-point metal powder to form a low-melting-point metal shell layer, thus obtaining the product.

[0029] Preferably, the preparation method is carried out under the protection of an inert gas.

[0030] When the preparation process is completed and excess low-melting-point metal needs to be discharged, the inert gas inlet rate is 1-3 m / min and the pumping rate is 3-8 m / min.

[0031] To obtain metal particles with a thicker core-shell structure, high-melting-point metal powder coated with a low-melting-point metal shell can be preheated and then blown into flowing low-melting-point steam using inert gas, causing the low-melting-point metal to continue to condense, thereby obtaining metal particles with a thicker core-shell structure.

[0032] A second aspect of the present invention provides a core-shell structured metal particle, which is prepared using the preparation method provided in the first aspect of the present invention.

[0033] A third aspect of the present invention provides a metal composite material, comprising core-shell structured metal particles prepared by the preparation method provided in the first aspect of the present invention, or core-shell structured metal particles provided in the second aspect of the present invention.

[0034] The beneficial effects of the present invention are as follows: The preparation method of the present invention involves gas-flowing high-melting-point metal powder carrying low temperature into flowing low-melting-point metal vapor at a higher temperature. Due to the temperature difference and the fact that the low-melting-point metal vapor is in a flowing state, the low-melting-point metal can be rapidly condensed on the surface of the high-melting-point metal, thereby forming a uniform coating layer with no component segregation and good interfacial bonding on the surface of the high-melting-point metal powder, thereby improving the mechanical properties of the composite material made from the core-shell structured metal particles.

[0035] Furthermore, the preparation method in this invention employs inert gas protection to isolate water and oxygen, reducing the risk of oxidation, avoiding the introduction of oxygen impurities into the core-shell structured metal particles, and improving the coating effect. Attached Figure Description

[0036] Figure 1 This is a schematic diagram of the coating equipment used in the preparation methods of Examples 1 and 2.

[0037] Figure 2 The flowchart shows the preparation process of the core-shell structured metal particles in Examples 1 and 2.

[0038] Figure 3 SEM images of the core-shell structured metal particles in Example 1 and Comparative Example 1.

[0039] Figure 4 SEM images of the core-shell structured metal particles in Example 2 and Comparative Example 2.

[0040] Figure 5 The images show SEM images of the Mo / Mg composite materials in Example 2 and Comparative Example 2.

[0041] Figure 6 The image shows the surface energy spectrum of the core-shell structured metal particles in Example 2.

[0042] Figure 7 The image shows the surface energy spectrum of the core-shell structured metal particles in Comparative Example 2.

[0043] Figure 8 The stress-strain curves of the Mo / Mg composite materials in Example 2 and Comparative Example 2 are shown in the test diagrams. Detailed Implementation

[0044] The specific implementation of the present invention will be further described in detail below with reference to the accompanying drawings and examples, but the implementation and protection of the present invention are not limited thereto. It should be noted that any processes not specifically described in detail below are those that can be implemented or understood by those skilled in the art by referring to the prior art. Reagents or instruments used without specified manufacturers are all conventional products that can be purchased commercially.

[0045] During the research and development process, the inventors attempted to use existing coating methods to coat low-melting-point metals onto the surface of high-melting-point metals. However, in experiments, by changing the low-melting-point metal, the high-melting-point metal, and the metal coating method, the inventors were unable to produce core-shell structured metal particles with uniform coating, no metal segregation, and homogeneous composition. Furthermore, the following common problems were discovered:

[0046] (1) Due to the large melting point difference between low-melting-point metals and high-melting-point metals, the two metals cannot be directly mixed in their molten state when prepared by conventional methods because their melting point windows do not overlap. Taking the coating of Mg and Mo as an example, Mg and Mo have a large melting point difference, which is close to 2000℃. Moreover, Mg and Mo are immiscible, and it is difficult to achieve uniform coating of Mg on the surface of Mo powder by conventional preparation methods.

[0047] (2) Density Issues: The significant density difference between the two metals leads to severe stratification during composite formation, resulting in uneven coating and microstructure. Taking Mg-Mo coated powder as an example, traditional gas atomization methods for preparing Mg-Mo coated powder suffer from uneven surface coating due to the high density and rapid descent of Mo particles and the short condensation time of Mg vapor. Mechanical methods also present challenges, such as the easy oxidation and stratification of Mg.

[0048] (3) The two metals do not melt together, have poor bonding, and the bonding interface is not tight, so the coating layer is prone to cracks or peeling.

[0049] (4) The cost is high. Traditional atomization methods require repeated coating, which increases time and raw material costs and is not conducive to production.

[0050] (5) Impurities and safety issues: Traditional preparation methods cannot isolate oxygen, and low-melting-point metals are easily oxidized, resulting in impurities and safety issues.

[0051] Based on the common shortcomings of existing technologies, the inventors, through numerous trials, finally discovered that introducing a low-temperature inert gas carrying high-melting-point metal powder into a high-temperature flowing low-melting-point metal vapor causes the high-temperature low-melting-point metal to condense on the surface of the low-temperature high-melting-point metal powder, forming a dense, uniform, and non-segregated low-melting-point metal shell. When the high-temperature low-melting-point metal vapor encounters the low-temperature high-melting-point metal powder, it rapidly condenses on the surface of the high-melting-point metal, forming a coating shell. Because the low-melting-point metal vapor is flowing, uniform and rapid coating can be achieved.

[0052] The structural schematic diagrams of the coating devices used in Embodiments 1 and 2 of this invention are shown below. Figure 1 As shown, the coating equipment includes a reaction chamber and a collector. The collector is located at the bottom of the reaction chamber. A cooling water circulation pipe is provided on the outer wall of the reaction chamber. An exhaust system, a heating component, and a feeding system A are provided at the top of the reaction chamber. A feeding system B is provided on the bottom side wall of the reaction chamber. Feeding system A is used to add low-melting-point metal powder and protective gas, and feeding system B is used to add high-melting-point metal powder and protective gas.

[0053] Example 1

[0054] Reference Figure 2The process flow diagram in the image illustrates a method for preparing core-shell structured metal particles. The specific preparation steps are as follows:

[0055] (1) Process the magnesium block into Mg powder with a particle size of 0.5-1mm, soak the Mg powder in a 5% citric acid solution for 30 minutes, wash, filter and dry, and store in an oxygen-free environment for later use.

[0056] (2) Evacuate the reaction chamber to a vacuum level of 10. -3 Stop evacuating when the pressure reaches 0.1 MPa, then fill with argon gas until the pressure reaches 0.1 MPa. Repeat the above steps 3 times. Heat the reaction chamber at a rate of 10 °C / min until it reaches 350 °C and then hold it at that temperature.

[0057] (3) Add 5 kg of Mg powder to the reaction chamber. During the addition process, continuously purge with argon gas at a rate of 3 m / min and pump out at a rate of 2 m / min. Heat the reaction chamber at a rate of 20 °C / min until it reaches 1050 °C. Hold the temperature for 120 min, then stop argon gas purging and continue pumping until the gas pressure in the reaction chamber drops to 10 °C. -2 Stop pumping air at MPa.

[0058] (4) The Ti metal powder was soaked in a 20% citric acid solution for 2 hours, cleaned with alcohol, and then dried in an oxygen-free environment at a temperature of 75°C for 3 hours.

[0059] (5) 1 kg of pretreated Ti powder was heated to 850 °C under an inert atmosphere and then blown upwards from the bottom of the reaction chamber at a blowing rate of 2 m / min and a pumping rate of 0.8 m / min. After the Ti powder was completely blown in, the heat preservation was stopped. At this time, the steam pressure in the reaction chamber was 2 MPa and the steam concentration was 50%. When the low-melting-point metal vapor encountered the low-temperature high-melting-point metal powder, it continuously condensed on the surface of the high-melting-point metal powder to form core-shell coated particles of low-melting-point metal coated with high-melting-point metal. The coated metal particles slowly fell to the bottom of the reaction chamber.

[0060] (6) After the reaction chamber is cooled to room temperature, the collector is removed to obtain Mg-coated Ti metal particles, which are the core-shell structured metal particles in this example, denoted as Mg-Ti, with a Mg coating thickness of 2 μm.

[0061] Example 2

[0062] Reference Figure 2 The process flow diagram in the image illustrates a method for preparing core-shell structured metal particles. The specific preparation steps are as follows:

[0063] (1) Process the magnesium block into Mg powder with a particle size of 0.5-1mm, soak the Mg powder in a 5% citric acid solution for 30 minutes, wash, filter and dry, and store in an oxygen-free environment for later use.

[0064] (2) Evacuate the reaction chamber to a vacuum level of 10. -3 Stop at MPa, then fill with argon gas until it reaches 0.1 MPa, and repeat the above steps 3 times; heat the reaction chamber at a heating rate of 10℃ / min, and hold at 350℃.

[0065] (3) Add 5 kg of Mg powder to the reaction chamber. During the addition process, argon gas is continuously introduced at a rate of 3 m / min, and the evacuation rate is 2 m / min. The reaction chamber is heated at a rate of 20 °C / min until it reaches 1050 °C. After heating, the temperature is maintained, the argon gas introduction is stopped, and the evacuation is continued until the gas pressure in the reaction chamber drops to 10 °C. -2 Stop pumping air at MPa.

[0066] (4) Soak 2.5 kg of metallic Mo powder in a 20% citric acid solution for 2 hours, clean it with alcohol, and then dry it in an oxygen-free environment at a temperature of 75°C for 3 hours.

[0067] (5) Heat the pretreated Mo powder to 950°C in an inert atmosphere, and then blow it into the reaction chamber from the bottom upwards at a blowing rate of 2 m / min and a pumping rate of 0.5 m / min. After the Mo powder is completely blown in, stop the heat preservation. At this time, the steam pressure in the reaction chamber is 2 MPa and the steam concentration is 50%.

[0068] (6) After the reaction chamber is cooled to room temperature, the collector is removed to obtain Mg-coated Mo metal particles, which are the core-shell structured metal particles in this example, denoted as Mg-Mo, with a Mg coating thickness of 3 μm.

[0069] 100g of the Mg-Mo prepared in this example and 300g of Mg powder were simultaneously loaded into a powder mixer at a speed of 100r / min for 5h. The uniformly mixed Mg / Mo composite powder was sintered by spark plasma and then extruded into a Mo / Mg composite material.

[0070] Comparative Example 1

[0071] This example provides a method for preparing core-shell structured metal particles, the specific preparation steps of which are as follows:

[0072] (1) Vacuum dry Ti powder for later use.

[0073] (2) Place excess magnesium powder in the evaporation source and place the treated Ti powder in the spraying device container.

[0074] (3) Evacuate the sealed reaction vessel to a pressure below -0.5 kPa and maintain the pressure for 0.5 hours; fill the sealed reaction vessel with high-purity argon gas, control the pressure at 1.5 kPa, maintain the pressure for 0.5 hours, and repeat the operation 5 times.

[0075] (4) Pre-melt 5 kg of Mg metal at the evaporation source, degas the sealed reaction vessel for 2 min, and after degassing and vacuuming, the pressure is below -0.5 kPa.

[0076] (5) Heat the sealed reaction vessel at a rate of 30℃ / min, and when the temperature reaches 1000℃, keep it at that temperature for 6 hours.

[0077] (6) Set the nozzle height and spray 1 kg of Ti powder at high pressure intervals for 5 seconds. The powder falls freely to achieve evaporation and deposition. At this time, the steam pressure in the reaction chamber is 2 MPa and the steam concentration is 50%.

[0078] (7) Cool the sealed reaction vessel to room temperature, remove the sample recovery device, and obtain the Mg-coated Ti metal particle material, which is the core-shell structured metal particle in this example. The thickness of the Mg coating layer is 1 μm.

[0079] Comparative Example 2

[0080] This example provides a method for preparing core-shell structured metal particles, the specific preparation steps of which are as follows:

[0081] (1) Dry the Mo powder under vacuum and set aside.

[0082] (2) Place 5 kg of magnesium powder in the evaporation source and place the treated Mo powder in the spraying device container.

[0083] (3) Evacuate the sealed reaction vessel to a pressure below -0.5 kPa and maintain the pressure for 0.5 hours; fill the sealed reaction vessel with high-purity argon gas, control the pressure at 1.5 kPa, maintain the pressure for 0.5 hours, and repeat the operation 7 times.

[0084] (4) Pre-melt the Mg metal of the evaporation source, degas the sealed reaction vessel for 1 minute, and after degassing and vacuuming, the pressure is below -0.5KPa.

[0085] (5) Heat the sealed reaction vessel at a rate of 30℃ / min, and then keep it at 1000℃ for 6 hours.

[0086] (6) Set the nozzle height, spray 2.5 kg of Mo powder at high pressure intervals for 5 seconds, and spray at high pressure intervals. The powder falls freely to achieve evaporation and deposition. At this time, the steam pressure in the reaction chamber is 2 MPa and the steam concentration is 50%.

[0087] (7) Cool the sealed reaction vessel to room temperature, remove the sample recovery device, and obtain Mg-coated Mo metal particles, which are the core-shell structured metal particles in this example. The thickness of the Mg coating layer is 2 μm.

[0088] 100g of the Mg-coated Mo metal particles prepared in this example and 300g of Mg powder were simultaneously loaded into a powder mixer at a speed of 100r / min for 5h. The uniformly mixed Mg / Mo composite powder was then sintered by spark plasma and extruded into a Mo / Mg composite material.

[0089] Performance testing:

[0090] (1) Surface morphology test

[0091] The surface morphology of the core-shell structured metal particles in Examples 1-2 and Comparative Examples 1-2 was tested using scanning electron microscopy. The specific test results are as follows: Figure 3 and Figure 4 As shown, where, Figure 3 (a) and Figure 3 (b) SEM images of the core-shell structured metal particles in Example 1 and Comparative Example 1, respectively; Figure 4 (a) and Figure 4 (b) SEM images of the core-shell structured metal particles from Example 2 and Comparative Example 2, respectively. Figure 3 and Figure 4 It is evident that the surface of the core-shell structured metal particles obtained in Examples 1 and 2 is not a regular sphere. This irregular spherical structure avoids the molding difficulties and porosity / density defects caused by regular spheres when preparing composite materials, thus improving the mechanical properties of the metal composites. In contrast, the core-shell structured metal particles obtained in Comparative Examples 1 and 2 are regular spheres. During composite material preparation, these regular spheres cause molding difficulties and porosity / density defects in the metal composites. Figure 3 and Figure 4 The gray spheres are Ti particles, and the silver-white particles on the surface of the spheres are Mg particles. Compared with Comparative Examples 1 and 2, the metal particles prepared in Examples 1 and 2 have more Mg particles coated on their surface and are more evenly distributed. The shell structure is more complete, the shell structure is tight, the coating is uniform, and there is no component segregation. The Ti core and the Mg coating layer exhibit an adhesive bond, which helps to improve the performance of the composite material containing the metal particles.

[0092] The surface morphology of the Mo / Mg composite materials in Example 2 and Comparative Example 2 was tested using scanning electron microscopy. The specific test results are as follows: Figure 5 As shown, where, Figure 5 (a) and Figure 5 (b) SEM images of the metal particles in the Mo / Mg composite materials of Example 2 and Comparative Example 2, respectively; Figure 5 It can be seen that the Mo / Mg composite material prepared in Example 2 has a compact internal structure, with Mo particles uniformly distributed within the composite material without significant segregation. Furthermore, the tight bond between the Mo particles and Mg is clearly evident, reflecting the strong core-shell structure of the Mg-coated Mo metal particle material prepared in Example 2. In contrast, the composite material in Comparative Example 2, containing Mg-coated Mo metal particles prepared by conventional methods, exhibits severe internal component segregation and Mo particle agglomeration, significantly reducing the mechanical properties of the composite material.

[0093] (2) Surface energy spectrum testing

[0094] The surface morphology of the core-shell structured metal particles in Example 2 and Comparative Example 2 were tested respectively, and the specific test results are as follows: Figure 6 and Figure 7 As shown, where, Figure 6 The surface energy spectrum of the core-shell structured metal particles in Example 2; Figure 7 This is the surface energy spectrum of the core-shell structured metal particles in Comparative Example 2. Figure 6 and Figure 7 As can be seen, the core-shell structured metal particles in Example 2 have an intact overall structure and a compact core-shell structure. Furthermore, EDS analysis revealed a highly uniform distribution of the Mg coating layer without any segregation or agglomeration. In contrast, the core-shell structured metal particles in Comparative Example 2 exhibit a smaller and less uniform Mg coating layer distribution on their surface. This indicates that conventional methods result in less surface adhesion during the preparation of core-shell structured metal particles, failing to achieve a good coating effect. Additionally, the uneven distribution of Mg on the surface, along with segregation, leads to a reduction in the mechanical properties of the composite material.

[0095] (3) Mechanical property analysis

[0096] According to ASTM-E8 standard, the yield strength, tensile strength, and elongation of the Mo / Mg composite materials in Example 2 and Comparative Example 2 were tested respectively. The specific test results are as follows: Figure 8 As shown in Table 1 below.

[0097] Table 1. Test results of mechanical properties of Mo / Mg composite materials

[0098] Yield strength (MPa) Tensile strength (MPa) Elongation (%) Example 2 162 268 14.1 Comparative Example 2 137 175 13.2

[0099] Depend on Figure 8As shown in Table 1, compared with Comparative Example 2, Example 1 of the present invention uses metal particles with a more uniform and dense core-shell structure, which can significantly improve the mechanical properties of the composite material. Among them, the tensile strength is increased by 93 MPa, which is 53%.

[0100] In summary, this invention uses a high-melting-point metal as the core, vaporizing a low-melting-point metal and then condensing it on the surface of the high-melting-point metal to form a uniformly coated and tightly bonded core-shell structured metal powder. Composite materials prepared using this core-shell structured metal powder exhibit no component segregation and excellent density. Furthermore, the preparation method of this invention is simple and easy to operate, enabling the coating of metals with large melting point differences and immiscibility, simplifying the preparation process of metal composite materials, improving their performance, and having significant implications for the development of metal matrix composites.

[0101] The embodiments of the present invention have been described in detail above. However, the present invention is not limited to the above embodiments. Within the scope of knowledge possessed by those skilled in the art, various changes can be made without departing from the spirit of the present invention. Furthermore, the embodiments of the present invention and the features thereof can be combined with each other unless otherwise specified.

Claims

1. A method for preparing core-shell structured metal particles, characterized in that: Includes the following steps: An inert gas stream carrying high-melting-point metal powder is preheated and then introduced into flowing low-melting-point metal vapor, causing the low-melting-point metal to condense on the surface of the high-melting-point metal powder to form a low-melting-point metal shell, thus obtaining the product. The temperature of the low-melting-point metal vapor is T1, the preheating temperature is T2, T1>T2 and the difference between T1 and T2 is 50~200℃; The flow rate of the low-melting-point metal vapor is 0.5~2 m / min; The flow rate of the inert gas stream carrying high-melting-point metal powder is 1~7 m / min; The inert gas stream carrying high-melting-point metal powder is introduced from the bottom of low-melting-point metal vapor. The difference in melting points between the high-melting-point metal and the low-melting-point metal is not less than 1000℃; The mass ratio of the low-melting-point metal to the high-melting-point metal powder is (2~5):1; The low-melting-point metal is selected from one of Mg, Zn, and Al; The high-melting-point metal is selected from one of Ti, Nb, and Mo.

2. The method for preparing core-shell structured metal particles according to claim 1, characterized in that: The low-melting-point metal vapor has a vapor pressure of 1-3 MPa and a vapor concentration of 25-55%. And / or, the thickness of the low-melting-point metal shell is 0.1~5μm.

3. The method for preparing core-shell structured metal particles according to claim 1, characterized in that: The preparation method is as follows: an inert gas flow carrying high melting point metal powder is preheated, and then introduced into low melting point metal vapor with a flow rate of 0.5-2 m / min at a flow rate of 1-7 m / min and the gas is evacuated at a evacuation rate of 0.5-2 m / min, so that the low melting point metal condenses on the surface of the high melting point metal powder to form a low melting point metal shell layer, thus obtaining the product.

4. The method for preparing core-shell structured metal particles according to any one of claims 1 to 3, characterized in that: The preparation method is carried out under the protection of an inert gas.

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