Titanium diboride particle reinforced a356 aluminum matrix composite and method of making

Abstract

Titanium diboride particle reinforced A356 aluminum matrix composite material and preparation method thereof, belong to the technical field of aluminum alloy materials. The composite material is composed of the following components in percentage by mass: Si: 5.8~8.5%, Mg: 0.25~0.58%, Fe: 0.05~0.25%, Cu: 0.005~0.2%, Mn: 0.005~0.15%, V: 0.005~0.15%, Cr: 0.005~0.15%, Ti: 1.8~7.0%, B: 0.8~3.0%, C: 0.005~1.5%, Be: 0.005~0.05%, Sr: 0.01~0.025%, Sb: 0.015~0.15%, Te: 0.002~0.05%, Sc: 0.005~0.05%, La: 0.002~0.2%, inevitable impurities and the balance of Al. The composite material has the advantages of high strength, toughness and modulus, and the elongation is improved, and is especially suitable for the fields requiring lightweight and high-strength structural materials such as automobiles and aerospace.

Description

Technical Field

[0001] This invention belongs to the field of aluminum alloy materials technology, specifically relating to a high-strength, high-toughness, high-modulus titanium diboride particle-reinforced A356 aluminum matrix composite material and its preparation method. Background Technology

[0002] As a new generation of high-performance structural materials, particle-reinforced aluminum matrix composites significantly improve the strength, elastic modulus, wear resistance and high-temperature performance of aluminum alloys by introducing ceramic particles (such as SiC, TiB2, etc.), and have become an important material for high-end equipment such as aerospace, automotive industry and precision instruments.

[0003] However, these materials face technical bottlenecks in performance improvement. While the strength, hardness, and elastic modulus of the material are improved with the introduction of reinforcing particles, the plasticity, especially the elongation, often deteriorates simultaneously. The root cause of this bottleneck lies in the difficulty of controlling the distribution of reinforcing particles in the matrix: during traditional casting processes, particles tend to agglomerate at grain boundaries, forming stress concentration points, while also interfering with the distribution and morphology of second phases such as eutectic silicon, thereby significantly reducing the toughness and deformation capacity of the material.

[0004] In current manufacturing technologies, rapid solidification techniques such as powder metallurgy (including ball milling) and additive manufacturing (3D printing) can alleviate particle agglomeration to some extent due to their unique forming characteristics, improving distribution uniformity by inhibiting interfacial migration of reinforcing particles. However, these methods suffer from high equipment costs, complex processes, and limited production scale, making them difficult to meet the needs of large-scale industrial production. In contrast, traditional forming methods such as gravity casting, low-pressure casting, and high-pressure die casting have advantages such as low cost, high efficiency, and suitability for large-scale production of complex components, but they still lack effective solutions for addressing the problem of uniform particle distribution, resulting in unsatisfactory plasticity properties in the prepared composite materials.

[0005] Especially for in-situ self-generated titanium diboride (TiB2) particle-reinforced aluminum matrix composites, although the reinforcement and matrix interface have good bonding, the migration behavior of TiB2 particles during solidification is difficult to control, and they tend to accumulate at grain boundaries, deteriorating the material's ductility. Therefore, developing a technology suitable for traditional casting processes that can effectively control the distribution of reinforcing particles is of great significance for achieving a synergistic improvement in the strength and toughness of aluminum matrix composites. Summary of the Invention

[0006] This application further improves the formulation of the composite material to solve the aforementioned technical problems. One objective of this invention is to provide a titanium diboride particle-reinforced A356 aluminum-based composite material, and another objective is to provide a method for preparing this composite material.

[0007] The specific technical solution is explained below: Titanium diboride particle-reinforced A356 aluminum matrix composite material, by weight percentage, consists of the following components: Si: 5.8~8.5%, Mg: 0.25~0.58%, Fe: 0.05~0.25%, Cu: 0.005~0.2%, Mn: 0.005~0.15%, V: 0.005~0.15%, Cr: 0.005~0.15%, Ti: 1.8~7.0%, B: 0.8~3.0%, C: 0.005~1.5%, Be: 0.005~0.05%, Sr: 0.01~0.025%, Sb: 0.015~0.15%, Te: 0.002~0.05%, Sc: 0.005~0.05%, La: 0.002~0.2%, unavoidable impurities and balance Al.

[0008] In the above technical solution, the functions of each component are as follows: Si is the main strengthening element in A356 aluminum alloy, forming eutectic silicon and improving the material's casting fluidity and wear resistance. Too low a content leads to decreased strength, while too high a content reduces plasticity and forms coarse needle-like silicon particles, increasing the material's brittleness. Within the specified range, the morphology of Si remains around the hypoeutectic near-eutectic point, resulting in well-formed and moderately abundant silicon precipitates.

[0009] Mg and Si form the Mg2Si phase to improve the hardness and strength of the alloy. If the content is too low, the strengthening effect will not be significant, and if the content is too high, supersaturated precipitation will be formed, resulting in coarse second phase and a tendency for hot cracking. The above range takes into account both the strengthening performance and toughness of the material.

[0010] Ti and B react in situ to form fine TiB2 particles, which serve as a dispersed strengthening phase and refine the grain size.

[0011] Excessive Fe content leads to the formation of harmful impurities, including needle-like β-Fe phases, which reduce the toughness of the material.

[0012] Cu can be used for minor solid solution treatment to strengthen and improve corrosion resistance.

[0013] Mn can transform the harmful β-Fe phase into the relatively harmless α-Fe phase.

[0014] Sr is a casting modifier that can transform coarse needle-like silicon into fibrous silicon, improving toughness. However, if the Sr content is too high, it will react with TiB2 or produce needle-like Sr phase, which will disrupt the uniformity of the material structure.

[0015] Be is a purifying element that can reduce oxide film inclusions and improve the surface quality of materials; however, excessive Be will reduce the toughness of materials.

[0016] Sc and La, as rare earth elements, can further refine grains, purify metallic materials, and improve their high-temperature performance. The above range can avoid increased costs and brittleness.

[0017] V, Cr, Sb, Te and C: V and Cr can refine grains and improve corrosion resistance at a trace level; Sb and Te act as modifiers to improve the morphology of eutectic silicon; C can form Al4C3, which has a refining effect when the amount is appropriate, but excessive amount will introduce brittle phase.

[0018] In a preferred embodiment, the mass ratio of Si to Mg is (14~24):1. Within this ratio range, the material can obtain excellent strength properties while also taking into account toughness and achieving good elongation.

[0019] In a preferred embodiment, the mass ratio of Ti to B is (2~3):1. This ratio range ensures the generation of fine and uniformly distributed TiB2 particles, which helps to improve both the strength and toughness of the material. Exceeding this range may lead to embrittlement of the material.

[0020] In a preferred embodiment, the Fe content is ≤0.15%.

[0021] In a preferred embodiment, the composite material has an elastic modulus > 75 GPa, a yield strength > 300 MPa, and an elongation > 3.5%.

[0022] The preparation method of titanium diboride particle-reinforced A356 aluminum matrix composite material includes the following steps: Raw material preparation: Select alloy ingots, titanium source, boron source and refining agent according to the formula; Melting and heating: Place the alloy ingot in a graphite crucible and heat it to 750~780℃ until it is completely melted and the slag is removed; Salt formulation and addition: Mix the titanium source and boron source, add them to the molten alloy liquid at 780~800℃, stir at 200~300rpm for 8~12 minutes, and then cover the surface with refining agent; In-situ reaction: TiB2 particles are generated; Static refining: Maintain a temperature of 760~780℃ and let stand for 5~20 minutes, then refine under an inert atmosphere for 5~15 minutes; Casting: Cool to 720~740℃, pour into mold and cool to obtain casting; Post-treatment: The castings are subjected to solution treatment, water quenching, and aging strengthening.

[0023] In a preferred embodiment, the raw material components are added in the following manner: Si: elemental or Al-20Si (representing an alloy composed of aluminum and silicon, where the number "20" indicates the mass percentage content of silicon, the same below), Al-50Si master alloy; Mg: elemental or Al-20Mg master alloy; Fe: Al-20Fe, Al-50Fe master alloys; Cu: elemental or Al-50Cu master alloy; Mn: Al-10Mn / Al-20Mn master alloy; V: Al-5V, Al-10V intermediate alloy; Cr: Al-5Cr, Al-10Cr master alloy Ti: Potassium fluorotitanate or Al-10Ti master alloy; B: Potassium fluoroborate or Al-5B master alloy; C: Carbon nanotubes or AlTiC master alloy (an alloy composed of aluminum, titanium, and carbon). Be: Al-5Be master alloy; Sr: Al-10Sr master alloy; Sb: Elemental or Al-20Sb master alloy; Te: element; Sc: Al-2Sc master alloy; La: Al-10La master alloy.

[0024] In a preferred embodiment, the refining agent is a mixture of NaCl and KCl in a mass ratio of 1:1.

[0025] In a preferred embodiment, during the static refining step, the inert atmosphere is formed by argon gas being introduced at a flow rate of 3-5 L / min.

[0026] In a preferred embodiment, the post-treatment step involves solution treatment at 540±30℃ for 5~7h and aging strengthening treatment at 160±15℃ for 7~9h.

[0027] In summary, the technical solution described in this invention has the following main beneficial effects: Compared with existing technologies, the technical solution of this invention changes the interface state of in-situ self-generated TiB2 particles through the combined effect of elements such as La, Eu, Ce, Sc, Mn, Cr, V, and Y, thereby altering their migration behavior during solidification and making them uniformly distributed within the grains and at the grain boundaries. This eliminates the detrimental effect of particles on elongation and improves the overall performance of the material.

[0028] Further or more detailed beneficial effects will be described in conjunction with specific embodiments in the detailed implementation. Detailed Implementation

[0029] The present invention will be further explained in conjunction with the embodiments: The core technical problem faced by the technical solution of this application embodiment stems from the inventor's accurate understanding of the prior art. Therefore, how to improve the toughness and elongation of titanium diboride (TiB2) particle-reinforced A356 aluminum matrix composite material is a technical problem that the inventor urgently needs to solve.

[0030] It should be noted that the embodiments do not constitute a limitation on the scope of protection of the claims of this invention. All technical solutions that can be reasonably expected by those skilled in the art based on the technical concepts provided / proved by the embodiments should be covered within the scope of protection of the claims of this invention.

[0031] The specific implementation examples are detailed below: Example 1 This embodiment relates to a TiB2 particle-reinforced A356 aluminum matrix composite material, which, by mass percentage, consists of the following components: Si: 5.8%, Mg: 0.25%, Fe: 0.05%, Cu: 0.005%, Mn: 0.005%, V: 0.005%, Cr: 0.005%, Ti: 1.8%, B: 0.8%, C: 0.005%, Be: 0.005%, Sr: 0.01%, Sb: 0.005%, Te: 0.002%, Sc: 0.005%, La: 0.002%, unavoidable impurities and balance Al.

[0032] Example 2 This embodiment relates to a TiB2 particle-reinforced A356 aluminum matrix composite material, which, by mass percentage, consists of the following components: Si: 6.8%, Mg: 0.38%, Fe: 0.15%, Cu: 0.05%, Mn: 0.08%, V: 0.06%, Cr: 0.09%, Ti: 4.5%, B: 1.5%, C: 0.5%, Be: 0.02%, Sr: 0.015%, Sb: 0.08%, Te: 0.03%, Sc: 0.03%, La: 0.1%, unavoidable impurities and balance Al.

[0033] Example 3 This embodiment relates to a TiB2 particle-reinforced A356 aluminum matrix composite material, which, by mass percentage, consists of the following components: Si: 8.5%, Mg: 0.58%, Fe: 0.25%, Cu: 0.2%, Mn: 0.15%, V: 0.15%, Cr: 0.15%, Ti: 7.0%, B: 3.0%, C: 1.5%, Be: 0.05%, Sr: 0.025%, Sb: 0.15%, Te: 0.05%, Sc: 0.05%, La: 0.2%, unavoidable impurities and balance Al.

[0034] The preparation methods of TiB2 particle-reinforced A356 aluminum matrix composites in Examples 1-3 are as follows: Raw material preparation: Select Al-20Si, Al-20Mg, Al-20Fe, Al-5Be, Al-50Cu, Al-10Mn, Al-5V, Al-5Cr, AlTiC, Al-5B, Al-10Sr, Al-20Sb, elemental Te, Al-2Sc, and Al-10La according to the formula. The titanium source is K2TiF6 powder, the boron source is KBF4 powder, and the refining agent is a mixture of NaCl and KCl in a mass ratio of 1:1. The above raw materials are dried at 200℃ for 2 hours. Melting and heating: The above alloy ingot raw material is placed in a graphite crucible and heated to 765±15℃ to be completely melted and the slag is removed; Salt formulation and addition: Mix K2TiF6 and KBF4 at a mass ratio of 2.2:1, slowly add to the molten alloy liquid at 790±10℃, stir at 250rpm for 10 minutes, and cover the surface with refining agent; In-situ reaction continues until TiB2 particles are formed; Static refining: Maintain a temperature of 770±10℃ and let stand for 15 minutes, then refine for 10 minutes under an argon gas flow rate of 4 L / min. Casting: Cool to 730±10℃, pour into a mold preheated to 200℃ and cool to obtain the casting; Post-treatment: The castings were subjected to solution treatment at 540±30℃ for 6 hours, followed by water quenching. and Aging enhancement treatment at 160±15℃ for 8 hours.

[0035] Comparative Example 1: A TiB2 particle-reinforced A356 aluminum matrix composite material for casting produced by a domestic aluminum company. Formula: Si: 7.0%; Mg: 0.35%; TiB2: 3.0% (directly added powder particles, average particle size 2~5 μm); Fe: 0.15%; Cu: 0.02%; balance: Al and unavoidable impurities.

[0036] Comparative Example 2: TiB2 / A356 for powder composite casting developed by a domestic research institute. Formula: Si: 6.8%; Mg: 0.40%; TiB2: 2.5% (directly added as powder, particle size 1~3 μm); Fe: 0.12%; Mn: 0.05%; balance: Al and unavoidable impurities.

[0037] Comparative Example 3: Experimental TiB2-reinforced A356 prepared in the materials science laboratory of a university in China. Formula: Si: 7.2%; Mg: 0.33%; TiB2: 5.0% (average particle size 0.8~1 μm, directly added powder); Cu: 0.01%; Fe: 0.18%; balance: Al and unavoidable impurities.

[0038] The mechanical properties of the composite materials in Examples 1-3 and Comparative Examples 1-3 were tested and are shown in Table 1 below: Table 1 Mechanical property parameters of the composite materials corresponding to Examples 1-3 and Comparative Examples 1-3

[0039] In Table 1: the elastic modulus was tested using the standard "Dynamic Method for Testing Elastic Modulus of Particle-Reinforced Aluminum Matrix Composites"; the yield strength and elongation were tested using the static uniaxial tensile test specified in GB / T 228.1.

[0040] As shown in Table 1, the elastic modulus and yield strength of the composite materials corresponding to Examples 1 to 3 increase sequentially, while the elongation decreases sequentially. The elastic modulus can reach as low as 75 GPa or more, the yield strength is above 300 MPa, and the elongation is above 3.5%. Compared with Comparative Examples 1-3, the yield strength of Examples 1-3 is slightly improved, and the elongation is significantly improved while ensuring the elastic modulus. This is because the TiB2 particle-reinforced A356 aluminum matrix composites prepared in Examples 1-3 have the following improvements: In-situ generation of TiB2 particles: The particles generated by the reaction are small and uniformly distributed with a clean interface, and are firmly bonded to the matrix, reducing the phenomenon of easy agglomeration and interface weakening that is common with traditional powder addition. Grain refinement: The combined effect of TiB2 particles and a small amount of rare earth elements promotes the refinement of α-Al grains and improves the plasticity and toughness of the material; In the example, the mass ratio of Si to Mg was controlled at (14~24):1, while the mass ratio of Ti to B was controlled at (2~3):1, in order to balance the strength and toughness of the material; Harmful phase suppression: Strictly control impurities such as Fe and Cu, and improve phase morphology and reduce brittle fracture sources through elements such as Mn; Comprehensive strengthening: Particle strengthening, precipitation strengthening and grain refinement effects work together to improve yield strength while maintaining high elongation.

[0041] In the description of this specification, the references to terms such as "embodiment," "basic embodiment," "preferred embodiment," "other embodiment," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the present invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0042] Although preferred embodiments of the invention have been described, those skilled in the art, upon learning the basic inventive concept, can make other changes and modifications to these embodiments. Therefore, the appended claims are intended to be interpreted as including the preferred embodiments as well as all changes and modifications falling within the scope of the invention.

[0043] Obviously, those skilled in the art can make various modifications and variations to this invention without departing from its spirit and scope. Therefore, if these modifications and variations fall within the scope of the claims of this invention and their equivalents, this invention also intends to include these modifications and variations.

Claims

1. A titanium diboride particle-reinforced aluminum matrix composite material, characterized in that: It consists of the following components by mass percentage: Si: 5.8~8.5%, Mg: 0.25~0.58%, Fe: 0.05~0.25%, Cu: 0.005~0.2%, Mn: 0.005~0.15%, V: 0.005~0.15%, Cr: 0.005~0.15%, Ti: 1.8~7.0%, B: 0.8~3.0%, C: 0.005~1.5%, Be: 0.005~0.05%, Sr: 0.01~0.025%, Sb: 0.015~0.15%, Te: 0.002~0.05%, Sc: 0.005~0.05%, La: 0.002~0.2%, unavoidable impurities and balance Al; The mass ratio of Si to Mg is (14~24):1; The mass ratio of Ti to B is (2~3):1; Elastic modulus > 75 GPa, yield strength > 300 MPa, elongation > 3.5%.

2. The composite material according to claim 1, characterized in that: The Fe content is ≤0.15%.

3. The method for preparing the titanium diboride particle-reinforced aluminum matrix composite material according to claim 1 or 2, characterized in that: The steps include the following: Raw material preparation: Select alloy ingots, titanium source, boron source and refining agent according to the formula; Melting and heating: Place the alloy ingot in a graphite crucible and heat it to 750~780℃ until it is completely melted and the slag is removed; Salt formulation and addition: Mix the titanium source and boron source, add them to the molten alloy liquid at 780~800℃, stir at 200~300rpm for 8~12 minutes, and then cover the surface with refining agent; In-situ reaction: TiB2 particles are generated; Static refining: Maintain a temperature of 760~780℃ and let stand for 5~20 minutes, then refine under an inert atmosphere for 5~15 minutes; Casting: Cool to 720~740℃, pour into mold and cool to obtain casting; Post-treatment: The castings are subjected to solution treatment, water quenching, and aging strengthening.

4. The preparation method according to claim 3, characterized in that: The raw material components are added in the following ways: Si: elemental or Al-20Si, Al-50Si master alloy; Mg: elemental or Al-20Mg master alloy; Fe: Al-20Fe, Al-50Fe master alloys; Cu: elemental or Al-50Cu master alloy; Mn: Al-10Mn / Al-20Mn master alloy; V: Al-5V, Al-10V intermediate alloy; Cr: Al-5Cr, Al-10Cr master alloy Ti: Potassium fluorotitanate or Al-10Ti master alloy; B: Potassium fluoroborate or Al-5B master alloy; C: Carbon nanotubes or AlTiC master alloy; Be: Al-5Be master alloy; Sr: Al-10Sr master alloy; Sb: Elemental or Al-20Sb master alloy; Te: element; Sc: Al-2Sc master alloy; La: Al-10La master alloy.

5. The preparation method according to claim 3, characterized in that: The refining agent is a mixture of NaCl and KCl.

6. The preparation method according to claim 3, characterized in that: In the static refining step, the inert atmosphere is formed by argon gas being introduced at a flow rate of 3-5 L / min.

7. The preparation method according to claim 3, characterized in that: In the post-treatment step, the solution treatment is carried out at 540±30℃ for 5~7h; The aging process involves treating the product at 160±15℃ for 7~9 hours.

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