A particle reinforced aluminum matrix composite material with reduced interfacial defects and a method of making and using the same

Abstract

This invention discloses a particle-reinforced aluminum matrix composite material for reducing interfacial micro-defects, its preparation method, and its application. It belongs to the technical field of particle-reinforced metal matrix composites. The invention first prepares a core-shell reinforcement with a micron-sized reinforcement core and nano-high-entropy alloy particles as the shell. Then, it is fabricated with an aluminum plate to form a preform. Finally, an electric stirring friction processing technique is used, applying a high-density pulsed current while mechanically stirring. The local Joule heating effect of the pulsed current activates the high-entropy alloy, improving the wettability between the reinforcement particles and the aluminum matrix. The pulsed current and the high-entropy alloy work together to achieve in-situ healing of interfacial micro-defects. This invention solves the problem of weak interfacial bonding and susceptibility to defects in particle-reinforced aluminum matrix composites. The prepared composite material exhibits strong interfacial bonding, fine microstructure, and excellent performance, making it suitable for key load-bearing components in high-end equipment such as aerospace and rail transportation.

Description

Technical Field

[0001] This invention belongs to the technical field of particle-reinforced metal matrix composites, specifically relating to a particle-reinforced aluminum matrix composite material for reducing interfacial micro-defects, its preparation method, and its application. Background Technology

[0002] Particle-reinforced aluminum matrix composites have broad application prospects in high-end equipment fields such as aerospace and rail transportation due to their high specific strength, high specific stiffness, and good thermophysical properties. However, the preparation and service of this material system face the challenge of interface problems. Poor wettability and large differences in thermal expansion coefficients between the reinforcement and the aluminum matrix make it easy for defects such as micropores and microcracks to form at the interface in traditional powder metallurgy or casting processes. These defects can become stress concentration sources and crack initiation points under cyclic loading, seriously impairing the fatigue performance of the material.

[0003] Friction stir processing (FSM), a solid-state processing technique, is used in the preparation and modification of metal matrix composites. It enables uniform particle dispersion and matrix refinement. For example, Chinese patent CN 115319085 B discloses a method for preparing copper-based diamond composites using FSM. This method involves placing a mixture of copper powder, alloy element powder, and diamond powder / particles into a mold, fixing the mold on a friction stir apparatus, and utilizing the downward pressure, friction, and stirring force of the stirring head to prepare the copper-based diamond composite. This method improves the preparation efficiency of copper-based diamond composites, reduces preparation costs, and enables rapid prototyping of small sheet-like parts. Chinese patent CN 120816118 A discloses a method for manufacturing a bulk magnesium-based composite material with quantitatively regulated nanoparticle content. This method prepares a magnesium-based composite material by filling grooves with nanoparticles and layering them through multiple passes of friction stir processing. This achieves precise control and uniform dispersion of nanoparticle content, overcoming the problems of high defect rates and size limitations inherent in traditional methods.

[0004] Although friction stir processing is widely used in composite material preparation and microstructure control, existing friction stir processes have limited ability to control microscale defects at the composite material interface, making it difficult to completely eliminate these defects. Therefore, finding a method to prepare particulate-reinforced aluminum matrix composites that can reduce interfacial microdefects has become an urgent problem to be solved. Summary of the Invention

[0005] The technical problem to be solved by the present invention is to provide a particle-reinforced aluminum matrix composite material for reducing interfacial micro-defects, its preparation method and application, so as to solve the problems mentioned in the background art or achieve better technical effects.

[0006] In order to solve the above-mentioned technical problems, the inventors derived the technical solution of the present invention through practice and summarization. The present invention discloses a particle-reinforced aluminum matrix composite material for reducing interfacial micro-defects, comprising an aluminum matrix and a core-shell-like reinforcement.

[0007] The mass fraction of the core-shell reinforcement in the particle-reinforced aluminum matrix composite material is 1-30%.

[0008] In the core-shell reinforced body, the mass fraction of high-entropy alloy particles is 5-30%;

[0009] The high-entropy alloy particles are alloy particles with equal or near-equal atomic ratios composed of at least four main elements, and the particle size of the high-entropy alloy particles is 100~500nm.

[0010] Furthermore, the mass fraction of the core-shell reinforcement in the particle-reinforced aluminum matrix composite material is 10%;

[0011] In the core-shell reinforced body, the mass fraction of high-entropy alloy particles is 20%.

[0012] Furthermore, the core-shell reinforcing body also includes ceramic particles with a particle size of 5-15 μm, and the ceramic particles are selected from silicon carbide, alumina and boron carbide.

[0013] Furthermore, the preparation method of any of the above-described particle-reinforced aluminum matrix composites for reducing interfacial micro-defects includes the following steps:

[0014] S1: Ceramic particles and high-entropy alloy particles are mixed in a certain proportion and then ball-milled to form a core-shell-like reinforcement.

[0015] S2: The core-shell reinforced body obtained in S1 is filled into the surface of an aluminum plate with holes or grooves, and pre-stirred and friction processed with a needleless stirring head. The surface of the holes or grooves is then sealed to prepare a preform for stirring and friction processing.

[0016] S3: Fix the preform obtained in S2, perform stirring and friction processing using a needle-shaped stirring head, and simultaneously apply a high-energy pulsed current to the processing area;

[0017] S4: After processing in S3 is completed, cool to room temperature to obtain a particle-reinforced aluminum matrix composite material with reduced interfacial micro-defects.

[0018] Furthermore, in S1, the ball milling speed is 200~500 r / min, the ball milling time is 1~3 h, the ball-to-material ratio is 2:1, and the ball milling material is alumina ceramic.

[0019] Furthermore, in S2, the depth of the hole or groove on the aluminum plate surface is less than the length of the stirring needle, and the width of the hole or groove is less than the diameter of the stirring needle.

[0020] Furthermore, in S3, the friction stir processing parameters are: the rotational speed of the stirring head is 500~2000 r / min, and the moving speed is 30~800 mm / min.

[0021] Furthermore, in S3, the pulse frequency of the high-energy pulsed current is 1Hz~5kHz, and the current density is 1000~5000A / mm. 2 The duty cycle is 5-20%.

[0022] Furthermore, in S3, the local Joule heating effect of the pulsed current activates the high-entropy alloy, which can improve the wettability of the reinforcing particles and the aluminum matrix. The pulsed current and the high-entropy alloy work together to achieve in-situ healing of micro-defects at the interface of the composite material.

[0023] Furthermore, the above-described particle-reinforced aluminum matrix composites with reduced interfacial micro-defects are used in key load-bearing components in the aerospace and / or rail transportation fields.

[0024] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0025] (1) This invention improves the wettability of ceramic particles and aluminum matrix at heterogeneous interfaces by using pulsed current to localize high-entropy alloy particles, thereby filling and welding micropores and microcracks at the interface, fundamentally solving the problem that traditional friction stir processing is difficult to eliminate interface micro-defects, and greatly improving the interface bonding strength and density.

[0026] (2) The micron-sized ceramic particles of the present invention mainly bear the load transfer, while the nano-high-entropy alloy particles coordinate the interfacial stress, buffer the stress concentration, and pin dislocations. The core-shell structure formed by the two realizes multi-scale and multi-mechanism synergistic strengthening and toughening.

[0027] (3) The introduction of pulse current in this invention not only assists in defect healing, but its electroplastic effect also promotes the dynamic recrystallization of the matrix and obtains an ultrafine grain structure; at the same time, the current effectively reduces macroscopic residual stress and improves the fatigue performance of the material. Detailed Implementation

[0028] To make the above-mentioned objectives, features and advantages of the present invention more apparent and understandable, the specific embodiments of the present invention will be described in detail below with reference to specific examples.

[0029] Unless otherwise specified, all raw materials or reagents used in the following examples are commercially available products.

[0030] Among them, high-entropy alloy particles are alloy particles with equal or near-equal atomic ratios composed of at least four main elements, such as FeCoNiCrAl system and FeCoNiCrMn system; the particle size of high-entropy alloy particles is 100~500nm.

[0031] The ceramic particles have a particle size of 5~15μm and are selected from one of silicon carbide, alumina and boron carbide.

[0032] This invention discloses a method for preparing particle-reinforced aluminum matrix composites that reduce interfacial micro-defects, comprising the following steps:

[0033] (1) Micron-sized ceramic particles and nano-sized high-entropy alloy particles are mixed in a certain proportion and then ball-milled (ball milling parameters: rotation speed: 200~500 r / min, ball milling time: 1~3 h, ball-to-material ratio: 2:1, ball milling material: alumina ceramic) to form a core-shell-like reinforcement with a "hard core-soft shell" structure; the mass fraction of high-entropy alloy particles in the core-shell-like reinforcement is 5~30%;

[0034] (2) Fill the core-shell reinforced body obtained in step (1) into the surface of an aluminum plate with holes or grooves (the depth of the holes or grooves should be less than the length of the stirring pin, and the diameter of the holes or the width of the grooves should be less than the diameter of the stirring pin), perform pre-stirring friction processing with a needleless stirring head, seal the surface of the holes or grooves, and prepare a preform for stirring friction processing.

[0035] (3) A friction stir processing equipment with an integrated high-energy pulse current auxiliary device (the friction stir processing equipment with an integrated high-energy pulse current auxiliary device is: one end of the pulse current of the high-energy pulse current auxiliary device is connected to the stirring head of the friction stir processing equipment through a hollow conductive slip ring, and the other end of the high-energy pulse current auxiliary device is connected to the aluminum plate. At the same time, the stirring head and the aluminum plate are insulated from the friction stir processing equipment. The control of the pulse current parameter is integrated into the control system of the friction stir processing equipment to realize the simultaneous control of the friction stir processing parameters and the high-energy pulse current parameters) is used to fix the preform, and friction stir processing is performed using a needle-type stirring head (the friction stir processing process is: the rotation speed of the stirring head is 500~2000r / min, and the moving speed is 30~800mm / min; multiple passes of friction stir processing can be performed, and the moving direction during multiple passes can be the same as or opposite to the previous pass); while performing friction stir processing, a high-energy pulse current (pulse frequency is 1Hz~5kHz, current density is 1000~5000A / mm) is applied to the processing area. 2 (with a duty cycle of 5-20%), the local Joule heating effect of the pulsed current activates the high-entropy alloy, which can improve the wettability of the reinforcing particles and the aluminum matrix and promote the in-situ healing of micro-defects at the interface of the composite material.

[0036] (4) After processing, the material is naturally cooled to room temperature or controlled to room temperature to obtain a particle-reinforced aluminum matrix composite material with reduced interfacial micro-defects; the mass fraction of the core-shell reinforcement in the particle-reinforced aluminum matrix composite material with reduced interfacial micro-defects is 1~30%.

[0037] Example 1

[0038] A method for preparing a particle-reinforced aluminum matrix composite material with reduced interfacial micro-defects, comprising the following steps:

[0039] (1) Micron-sized silicon carbide particles and nano-sized high-entropy alloy particles were mixed in a certain proportion and then ball-milled (ball milling parameters: rotation speed: 200 r / min, ball milling time: 3 h, ball-to-material ratio: 2:1, ball milling material: alumina ceramic) to form a core-shell-like reinforcement with a "hard core-soft shell" structure; the mass fraction of high-entropy alloy particles in the core-shell-like reinforcement was 30%;

[0040] (2) Fill the core-shell reinforcement obtained in step (1) into the surface of an aluminum plate with holes or grooves (the aluminum plate is made of 6092 aluminum alloy, the depth of the hole or groove is less than the length of the stirring needle, and the diameter of the hole or the width of the groove is less than the diameter of the stirring needle), perform pre-stirring friction processing with a needleless stirring head, seal the surface of the hole or groove, and prepare a preform for stirring friction processing.

[0041] (3) The preform is fixed using a friction stir processing equipment with an integrated high-energy pulsed current auxiliary device, and friction stir processing is performed using a needle-shaped stirring head (the friction stir processing process is as follows: the rotation speed of the stirring head is 2000 r / min, and the moving speed is 600 mm / min; multiple passes of friction stir processing can be performed, and the moving direction during multiple passes can be the same as or opposite to the previous pass); while performing friction stir processing, a high-energy pulsed current (pulse frequency is 5 kHz, current density is 5000 A / mm) is applied to the processing area. 2 (with a duty cycle of 20%), the local Joule heating effect of the pulsed current activates the high-entropy alloy, which can improve the wettability of the reinforcing particles and the aluminum matrix. The pulsed current and the high-entropy alloy work together to achieve in-situ healing of micro-defects at the interface of the composite material.

[0042] (4) After processing, the material is naturally cooled to room temperature or controlled to room temperature to obtain a particle-reinforced aluminum matrix composite material with reduced interfacial micro-defects; the mass fraction of the core-shell reinforcement in the particle-reinforced aluminum matrix composite material with reduced interfacial micro-defects is 30%.

[0043] Example 2

[0044] A method for preparing a particle-reinforced aluminum matrix composite material with reduced interfacial micro-defects, comprising the following steps:

[0045] (1) Micron-sized silicon carbide particles and nano-sized high-entropy alloy particles were mixed in a certain proportion and then ball-milled (ball milling parameters: rotation speed: 300 r / min, ball milling time: 3 h, ball-to-material ratio: 2:1, ball milling material: alumina ceramic) to form a core-shell-like reinforcement with a "hard core-soft shell" structure; the mass fraction of high-entropy alloy particles in the core-shell-like reinforcement was 25%;

[0046] (2) Fill the core-shell reinforcement obtained in step (1) into the surface of an aluminum plate with holes or grooves (the aluminum plate is made of 6092 aluminum alloy, the depth of the hole or groove is less than the length of the stirring needle, and the diameter of the hole or the width of the groove is less than the diameter of the stirring needle), perform pre-stirring friction processing with a needleless stirring head, seal the surface of the hole or groove, and prepare a preform for stirring friction processing.

[0047] (3) The preform is fixed using a friction stir processing equipment with an integrated high-energy pulsed current auxiliary device, and friction stir processing is performed using a needle-type stirring head (the friction stir processing process is as follows: the rotation speed of the stirring head is 1500 r / min, and the moving speed is 800 mm / min; multiple passes of friction stir processing can be performed, and the moving direction during multiple passes can be the same as or opposite to the previous pass); while performing friction stir processing, a high-energy pulsed current (pulse frequency is 4 kHz, current density is 4000 A / mm) is applied to the processing area. 2 (with a duty cycle of 10%), the local Joule heating effect of the pulsed current activates the high-entropy alloy, which can improve the wettability of the reinforcing particles and the aluminum matrix. The pulsed current and the high-entropy alloy work together to achieve in-situ healing of micro-defects at the interface of the composite material.

[0048] (4) After processing, the material is naturally cooled to room temperature or controlled to room temperature to obtain a particle-reinforced aluminum matrix composite material with reduced interfacial micro-defects; the mass fraction of the core-shell reinforcement in the particle-reinforced aluminum matrix composite material with reduced interfacial micro-defects is 20%.

[0049] Example 3

[0050] A method for preparing a particle-reinforced aluminum matrix composite material with reduced interfacial micro-defects, comprising the following steps:

[0051] (1) Micron-sized ceramic particles and nano-sized high-entropy alloy particles were mixed in a certain proportion and then ball-milled (ball milling parameters: rotation speed: 350 r / min, ball milling time: 3 h, ball-to-material ratio: 2:1, grinding ball material: alumina ceramic) to form a core-shell-like reinforcement with a "hard core-soft shell" structure; the mass fraction of high-entropy alloy particles in the core-shell-like reinforcement was 20%;

[0052] (2) Fill the core-shell reinforcement obtained in step (1) into the surface of an aluminum plate with holes or grooves (the aluminum plate is made of 6092 aluminum alloy, the depth of the hole or groove is less than the length of the stirring needle, and the diameter of the hole or the width of the groove is less than the diameter of the stirring needle), perform pre-stirring friction processing with a needleless stirring head, seal the surface of the hole or groove, and prepare a preform for stirring friction processing.

[0053] (3) The preform is fixed using a friction stir processing equipment with an integrated high-energy pulsed current auxiliary device, and friction stir processing is performed using a needle-shaped stirring head (the friction stir processing process is as follows: the rotation speed of the stirring head is 1000 r / min, and the moving speed is 100 mm / min; multiple passes of friction stir processing can be performed, and the moving direction during multiple passes can be the same as or opposite to the previous pass); while performing friction stir processing, a high-energy pulsed current (pulse frequency is 3 kHz, current density is 3000 A / mm) is applied to the processing area. 2 (with a duty cycle of 15%), the local Joule heating effect of the pulsed current activates the high-entropy alloy, which can improve the wettability of the reinforcing particles and the aluminum matrix. The pulsed current and the high-entropy alloy work together to achieve in-situ healing of micro-defects at the interface of the composite material.

[0054] (4) After processing, the material is naturally cooled to room temperature or controlled to room temperature to obtain a particle-reinforced aluminum matrix composite material with reduced interfacial micro-defects; the mass fraction of the core-shell reinforcement in the particle-reinforced aluminum matrix composite material with reduced interfacial micro-defects is 10%.

[0055] Example 4

[0056] A method for preparing a particle-reinforced aluminum matrix composite material with reduced interfacial micro-defects, comprising the following steps:

[0057] (1) Micron-sized silicon carbide particles and nano-sized high-entropy alloy particles were mixed in a certain proportion and then ball-milled (ball milling parameters: rotation speed: 400 r / min, ball milling time: 3 h, ball-to-material ratio: 2:1, grinding ball material: alumina ceramic) to form a core-shell-like reinforcement with a "hard core-soft shell" structure; the mass fraction of high-entropy alloy particles in the core-shell-like reinforcement was 10%;

[0058] (2) Fill the core-shell reinforcement obtained in step (1) into the surface of an aluminum plate with holes or grooves (the aluminum plate is made of 6092 aluminum alloy, the depth of the hole or groove is less than the length of the stirring needle, and the diameter of the hole or the width of the groove is less than the diameter of the stirring needle), perform pre-stirring friction processing with a needleless stirring head, seal the surface of the hole or groove, and prepare a preform for stirring friction processing.

[0059] (3) The preform is fixed using a friction stir processing equipment with an integrated high-energy pulsed current auxiliary device, and friction stir processing is performed using a needle-type stirring head (the friction stir processing process is as follows: the rotation speed of the stirring head is 500 r / min, and the moving speed is 50 mm / min; multiple passes of friction stir processing can be performed, and the moving direction during multiple passes can be the same as or opposite to the previous pass); while performing friction stir processing, a high-energy pulsed current (pulse frequency is 2 kHz, current density is 2000 A / mm) is applied to the processing area. 2 (with a duty cycle of 5%), the local Joule heating effect of the pulsed current activates the high-entropy alloy, which can improve the wettability of the reinforcing particles and the aluminum matrix. The pulsed current and the high-entropy alloy work together to achieve in-situ healing of micro-defects at the interface of the composite material.

[0060] (4) After processing, the material is naturally cooled to room temperature or controlled to room temperature to obtain a particle-reinforced aluminum matrix composite material with reduced interfacial micro-defects; the mass fraction of the core-shell reinforcement in the particle-reinforced aluminum matrix composite material with reduced interfacial micro-defects is 5%.

[0061] Example 5

[0062] A method for preparing a particle-reinforced aluminum matrix composite material with reduced interfacial micro-defects, comprising the following steps:

[0063] (1) Micron-sized silicon carbide particles and nano-sized high-entropy alloy particles were mixed in a certain proportion and then ball-milled (ball milling parameters: rotation speed: 500 r / min, ball milling time: 1 h, ball-to-material ratio: 2:1, grinding ball material: alumina ceramic) to form a core-shell-like reinforcement with a "hard core-soft shell" structure; the mass fraction of high-entropy alloy particles in the core-shell-like reinforcement was 5%;

[0064] (2) Fill the core-shell reinforced body obtained in step (1) into the surface of an aluminum plate with holes or grooves (the depth of the holes or grooves should be less than the length of the stirring pin, and the diameter of the holes or the width of the grooves should be less than the diameter of the stirring pin), perform pre-stirring friction processing with a needleless stirring head, seal the surface of the holes or grooves, and prepare a preform for stirring friction processing.

[0065] (3) The preform is fixed using a friction stir processing equipment with an integrated high-energy pulsed current auxiliary device, and friction stir processing is performed using a needle-type stirring head (the friction stir processing process is as follows: the rotation speed of the stirring head is 2000 r / min, and the moving speed is 30 mm / min; multiple passes of friction stir processing can be performed, and the moving direction during multiple passes can be the same as or opposite to the previous pass); while performing friction stir processing, a high-energy pulsed current (pulse frequency is 1 kHz, current density is 1000 A / mm) is applied to the processing area. 2(with a duty cycle of 20%), the local Joule heating effect of the pulsed current activates the high-entropy alloy, which can improve the wettability of the reinforcing particles and the aluminum matrix. The pulsed current and the high-entropy alloy work together to achieve in-situ healing of micro-defects at the interface of the composite material.

[0066] (4) After processing, the material is naturally cooled to room temperature or controlled to room temperature to obtain a particle-reinforced aluminum matrix composite material with reduced interfacial micro-defects; the mass fraction of the core-shell reinforcement in the particle-reinforced aluminum matrix composite material with reduced interfacial micro-defects is 1%.

[0067] Comparative Example 1

[0068] A method for preparing a particle-reinforced aluminum matrix composite material, comprising the following steps:

[0069] (1) Fill the surface of an aluminum plate with holes or grooves into micron-sized silicon carbide particle reinforcement (the depth of the hole or groove should be less than the length of the stirring pin, and the diameter of the hole or the width of the groove should be less than the diameter of the stirring pin), perform pre-stirring friction processing with a needleless stirring head, seal the surface of the hole or groove, and prepare a preform for stirring friction processing. The aluminum plate grade is 6092 aluminum alloy.

[0070] (3) The preform is fixed by a traditional friction stir processing equipment and friction stir processing is performed by a needle-shaped stirring head (the friction stir processing process is as follows: the rotation speed of the stirring head is 2000 r / min and the moving speed is 600 mm / min; multiple passes of friction stir processing can be performed, and the moving direction can be the same as or opposite to the previous pass during multiple passes).

[0071] (4) After processing, the material is naturally cooled to room temperature or controlled to room temperature to obtain a particle-reinforced aluminum matrix composite material; the mass fraction of the core-shell reinforcement in the particle-reinforced aluminum matrix composite material that reduces interfacial micro-defects is 30%.

[0072] Comparative Example 2

[0073] Unlike Examples 1-5, only the mass fraction of high-entropy alloy particles in the core-shell reinforcement is changed; the other steps are the same as in Examples 1-5, as follows:

[0074] (1) Micron-sized silicon carbide particles and nano-sized high-entropy alloy particles were mixed in a certain proportion and then ball-milled (ball milling parameters: rotation speed: 300 r / min, ball milling time: 3 h, ball-to-material ratio: 2:1, grinding ball material: alumina ceramic) to form a core-shell-like reinforcement with a "hard core-soft shell" structure; the mass fraction of high-entropy alloy particles in the core-shell-like reinforcement was 2%;

[0075] (2) Fill the core-shell reinforcement obtained in step (1) into the surface of an aluminum plate with holes or grooves (the aluminum plate is made of 6092 aluminum alloy, the depth of the hole or groove is less than the length of the stirring needle, and the diameter of the hole or the width of the groove is less than the diameter of the stirring needle), perform pre-stirring friction processing with a needleless stirring head, seal the surface of the hole or groove, and prepare a preform for stirring friction processing.

[0076] (3) The preform is fixed using a friction stir processing equipment with an integrated high-energy pulsed current auxiliary device, and friction stir processing is performed using a needle-type stirring head (the friction stir processing process is as follows: the rotation speed of the stirring head is 1500 r / min, and the moving speed is 800 mm / min; multiple passes of friction stir processing can be performed, and the moving direction during multiple passes can be the same as or opposite to the previous pass); while performing friction stir processing, a high-energy pulsed current (pulse frequency is 4 kHz, current density is 4000 A / mm) is applied to the processing area. 2 (with a duty cycle of 10%), the local Joule heating effect of the pulsed current activates the high-entropy alloy, which can improve the wettability of the reinforcing particles and the aluminum matrix. The pulsed current and the high-entropy alloy work together to achieve in-situ healing of micro-defects at the interface of the composite material.

[0077] (4) After processing, the material is naturally cooled to room temperature or controlled to room temperature to obtain a particle-reinforced aluminum matrix composite material with reduced interfacial micro-defects; the mass fraction of the core-shell reinforcement in the particle-reinforced aluminum matrix composite material with reduced interfacial micro-defects is 20%.

[0078] Comparative Example 3

[0079] Unlike Examples 1-5, only the mass fraction of the core-shell reinforcement in the particle-reinforced aluminum matrix composite material for reducing interfacial micro-defects is changed; the other steps are the same as in Examples 1-5, as follows:

[0080] (1) Micron-sized silicon carbide particles and nano-sized high-entropy alloy particles were mixed in a certain proportion and then ball-milled (ball milling parameters: rotation speed: 350 r / min, ball milling time: 3 h, ball-to-material ratio: 2:1, grinding ball material: alumina ceramic) to form a core-shell-like reinforcement with a "hard core-soft shell" structure; the mass fraction of high-entropy alloy particles in the core-shell-like reinforcement was 20%;

[0081] (2) Fill the core-shell reinforcement obtained in step (1) into the surface of an aluminum plate with holes or grooves (the aluminum plate is made of 6092 aluminum alloy, the depth of the hole or groove is less than the length of the stirring needle, and the diameter of the hole or the width of the groove is less than the diameter of the stirring needle), perform pre-stirring friction processing with a needleless stirring head, seal the surface of the hole or groove, and prepare a preform for stirring friction processing.

[0082] (3) The preform is fixed using a friction stir processing equipment with an integrated high-energy pulsed current auxiliary device, and friction stir processing is performed using a needle-shaped stirring head (the friction stir processing process is as follows: the rotation speed of the stirring head is 1000 r / min, and the moving speed is 100 mm / min; multiple passes of friction stir processing can be performed, and the moving direction during multiple passes can be the same as or opposite to the previous pass); while performing friction stir processing, a high-energy pulsed current (pulse frequency is 3 kHz, current density is 3000 A / mm) is applied to the processing area. 2 (with a duty cycle of 15%), the local Joule heating effect of the pulsed current activates the high-entropy alloy, which can improve the wettability of the reinforcing particles and the aluminum matrix. The pulsed current and the high-entropy alloy work together to achieve in-situ healing of micro-defects at the interface of the composite material.

[0083] (4) After processing, the material is naturally cooled to room temperature or controlled to room temperature to obtain a particle-reinforced aluminum matrix composite material with reduced interfacial micro-defects; the mass fraction of the core-shell reinforcement in the particle-reinforced aluminum matrix composite material with reduced interfacial micro-defects is 45%.

[0084] The particulate reinforced aluminum matrix composites prepared in Examples 1-5 and Comparative Examples 1-3 were subjected to tensile and fatigue property tests, respectively. Tensile tests were conducted on an electronic universal testing machine with an initial strain rate of 1 x 10⁻⁶. -3 s -1 Tensile tests were conducted according to GB / T228-2010 "Metallic Materials - Tensile Testing at Room Temperature". Fatigue tests were performed on a fatigue testing machine, with the stress-time function curve being a sine wave, stress ratio R=0.1, and frequency 100Hz. Fatigue specimens were prepared according to GB / T3075-2008 "Metallic Materials - Fatigue Testing - Axial Force Control Method". The test results are shown in Table 1 below.

[0085] Table 1 Examples 1-5 and Comparative Examples 1-3

[0086] Comparison of properties of the prepared particle-reinforced aluminum matrix composites

[0087]

[0088] Analysis of Table 1 above shows that in Examples 1-5 of this invention, a core-shell reinforcement with a micron-sized reinforcement core and nano-high-entropy alloy particles as the shell was first prepared, and then it was fabricated with an aluminum plate to form a preform. Finally, an electric stirring friction processing technique was used, applying a high-density pulsed current while mechanically stirring. The local Joule heating effect of the pulsed current activated the high-entropy alloy. In addition, the high-entropy alloy can improve the wettability between the reinforcement particles and the aluminum matrix. Under the combined effect of the two, in-situ healing of interfacial micro-defects is achieved. The healing of interfacial micro-defects helps to improve the mechanical properties of the material, such as the tensile properties and fatigue properties described in Table 1.

[0089] As can be seen from the comparison between Examples 1-5 and Comparative Example 1, no high-entropy alloy particles were added in Comparative Example 1. The experiment was conducted on a conventional friction stir welding device without pulsed current assistance. The resulting composite material had a significant impact on fatigue performance. The main reason is that there are some micro-defects at the interface between silicon carbide particles and aluminum matrix. These micro-defects are the sites of fatigue crack initiation and propagation under cyclic loading, ultimately affecting fatigue performance.

[0090] As can be seen from the comparison between Examples 1-5 and Comparative Example 2, when the mass fraction of high-entropy alloy particles in the core-shell reinforcement is less than 5%, it has a significant impact on the fatigue life of the composite material. This is mainly related to the high-entropy alloy particles. When the mass fraction of high-entropy alloy particles is relatively low, the number of high-entropy alloy particles attached to the core-shell reinforcement will be greatly reduced. During the pulse current assisted stirring friction processing, the healing effect of high-entropy alloy on micro-defects will be greatly reduced, thereby affecting the mechanical properties of the sample.

[0091] As can be seen from the comparison between Examples 1-5 and Comparative Example 3, when the mass fraction of high-entropy alloy particles in the core-shell reinforcement is higher than 30%, it has a greater impact on the mechanical properties of the composite material. When the mass fraction of the core-shell reinforcement is 45%, the amount of added silicon carbide particles increases significantly. The increase in silicon carbide particles will greatly aggravate the wear of the stirring head, resulting in a decrease in the mixing degree of particles during friction stirring, which can easily lead to larger defects and reduce the performance of the composite material.

[0092] This invention solves the problems of weak interfacial bonding, easy defects, and inversion of strength and toughness in particle-reinforced aluminum matrix composites. The prepared composite material has strong interfacial bonding, fine structure, and excellent performance, and is suitable for key load-bearing components of high-end equipment such as aerospace and rail transportation.

Claims

1. A particle-reinforced aluminum matrix composite material for reducing interfacial micro-defects, characterized in that, Including aluminum matrix and core-shell-like reinforcement; The mass fraction of the core-shell reinforcement in the particle-reinforced aluminum matrix composite material is 1-30%. In the core-shell reinforced body, the mass fraction of high-entropy alloy particles is 5-30%; The high-entropy alloy particles are alloy particles with equal or near-equal atomic ratios composed of at least four main elements, and the particle size of the high-entropy alloy particles is 100~500nm.

2. The particle-reinforced aluminum matrix composite material for reducing interfacial micro-defects according to claim 1, characterized in that, The mass fraction of the core-shell reinforcement in the particle-reinforced aluminum matrix composite material is 10%. In the core-shell reinforced body, the mass fraction of high-entropy alloy particles is 20%.

3. The particle-reinforced aluminum matrix composite material for reducing interfacial micro-defects according to claim 1 or 2, characterized in that, The core-shell reinforcement also includes ceramic particles with a particle size of 5-15 μm, and the ceramic particles are selected from silicon carbide, alumina and boron carbide.

4. A method for preparing a particle-reinforced aluminum matrix composite material with reduced interfacial micro-defects as described in any one of claims 1 to 3, characterized in that, The steps are as follows: S1: Ceramic particles and high-entropy alloy particles are mixed in a certain proportion and then ball-milled to form a core-shell-like reinforcement. S2: The core-shell reinforced body obtained in S1 is filled into the surface of an aluminum plate with holes or grooves, and pre-stirred and friction processed with a needleless stirring head. The surface of the holes or grooves is then sealed to prepare a preform for stirring and friction processing. S3: Fix the preform obtained in S2, perform stirring and friction processing using a needle-shaped stirring head, and simultaneously apply a high-energy pulsed current to the processing area; S4: After processing in S3 is completed, cool to room temperature to obtain a particle-reinforced aluminum matrix composite material with reduced interfacial micro-defects.

5. The method for preparing particle-reinforced aluminum matrix composite material with reduced interfacial micro-defects according to claim 4, characterized in that, In S1, the ball milling speed is 200~500 r / min, the ball milling time is 1~3 h, the ball-to-material ratio is 2:1, and the ball milling material is alumina ceramic.

6. The method for preparing particle-reinforced aluminum matrix composite material with reduced interfacial micro-defects according to claim 4, characterized in that, In step S2, the depth of the hole or groove on the aluminum plate surface is less than the length of the stirring needle, and the width of the hole or groove is less than the diameter of the stirring needle.

7. The method for preparing particle-reinforced aluminum matrix composite material with reduced interfacial micro-defects according to claim 4, characterized in that, In S3, the stirring friction processing parameters are: the rotational speed of the stirring head is 500~2000 r / min, and the moving speed is 30~800 mm / min.

8. The method for preparing particle-reinforced aluminum matrix composite material with reduced interfacial micro-defects according to claim 4, characterized in that, In step S3, the pulse frequency of the high-energy pulsed current is 1Hz~5kHz, and the current density is 1000~5000A / mm. 2 The duty cycle is 5-20%.

9. The method for preparing particle-reinforced aluminum matrix composite material with reduced interfacial micro-defects according to claim 4, characterized in that, In S3, the local Joule heating effect of the pulsed current activates the high-entropy alloy. The activated high-entropy alloy can improve the wettability between the reinforcing particles and the aluminum matrix. The pulsed current and the high-entropy alloy work together to achieve in-situ healing of micro-defects at the interface of the composite material.

10. The application of the particle-reinforced aluminum matrix composite material with reduced interfacial micro-defects as described in any one of claims 1 to 3 in key load-bearing components in the aerospace and / or rail transportation fields.

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