CN115505798A - A kind of spherical intermetallic compound particle reinforced aluminum matrix composite material and preparation method thereof - Google Patents

Abstract

The invention relates to the technical field of particle reinforced metal matrix composite materials, and discloses a spherical intermetallic compound particle reinforced aluminum matrix composite material and a preparation method thereof. Aiming at the difficulty of introducing ceramic particle reinforcement phase into the aluminum alloy melt by casting method and the problem of poor interfacial bonding, the present invention chooses the aluminum alloy matrix melt to be warmed to a low temperature range, and powders spherical or quasi-spherical copper particles of a certain size , quickly introduce the molten aluminum alloy slurry into the interior of the molten aluminum alloy slurry through one or more stirring rods, and quickly cast out after being uniformly dispersed in a short period of time. The high-melting-point metal particles wet well with the low-melting-point aluminum alloy matrix, and the AlCu intermetallic compound reinforcement phase with a spherical shape and a good bonding interface is formed in situ through the diffusion mechanism. The shape of the aluminum-copper intermetallic compound prepared by the method is controllable, and the hardness is high, the dispersion is uniform, and the interface metallurgical bonding is tight, so the comprehensive mechanical properties and heat resistance and wear resistance are significantly improved.

Description

A kind of spherical intermetallic compound particle reinforced aluminum matrix composite material and preparation method thereof

technical field

The invention relates to the technical field of particle-reinforced metal-based composite materials, in particular to a spherical intermetallic compound particle-reinforced aluminum-based composite material and a preparation method thereof.

Background technique

Particle-reinforced aluminum-based alloy is a material with strong vitality that emerges in response to the needs of modern scientific development. It integrates three characteristics: low expansion, high thermal conductivity, high strength and light weight. high-tech materials. Particle-reinforced aluminum alloys are widely selected for their matrix alloys, low cost, easy to prepare and process by traditional methods, can realize batch and large-scale production, and the prepared materials show good dimensional stability and isotropy. attention. Particle-reinforced aluminum alloys are used to manufacture parts such as cylinder blocks and cylinder heads of vehicle engines. While retaining the advantages of alloy materials, they can further improve the strength, wear resistance, heat resistance and fatigue resistance of engine parts. For example, SiCp/Al composite pistons are used in motorcycle and small car engines. Some developed countries have applied particle-reinforced aluminum-based composite materials to the ventral fins of military fighter jets. Compared with traditional aluminum alloy materials, it increases the stiffness of the material by 50%, and the service life is also increased from the original 400h to 6000h. In addition, the particle reinforced aluminum alloy prepared by precision casting, squeeze casting and powder metallurgy can reduce the deformation caused by stress release, improve the dimensional stability of the material, and also have high specific strength, damping and resonance frequency, reducing vibration amplification.

At present, the main methods for the preparation of particle-reinforced aluminum-based alloys include powder metallurgy and casting methods. Among them, the casting method has a simple process, low cost, and is suitable for mass production. It is an important research and development direction in this field. The reinforcing particles used in the existing particle-reinforced aluminum-based alloys are mainly ceramic particles (Al2O3, SiC, etc.), but the wettability between the ceramic particles and the metal melt is very poor, and the interface bonding is poor. How to introduce it into the melt well and disperse it uniformly is a technical difficulty in preparing particle-reinforced aluminum-based alloys by casting.

Contents of the invention

In view of the shortcomings in the use of the existing spherical intermetallic compound particle-reinforced aluminum matrix composite materials proposed in the background technology, the present invention provides a spherical intermetallic compound particle-reinforced aluminum matrix composite material and a preparation method thereof. It has the advantages of uniform dispersion of reinforcing particles in the matrix and a good combination of the two, and solves the problems raised in the above-mentioned background technology.

The present invention provides the following technical solutions: a spherical intermetallic compound particle reinforced aluminum matrix composite material, characterized in that its structural features are as follows:

(1) The metal matrix is aluminum alloy, and the solidification temperature range is 20°C to 50°C;

(2) The metal matrix contains 1%-30% particle reinforcement, and the diameter of the particle reinforcement is between 1 and 100 μm, and is uniformly dispersed in the matrix; based on the diffusion time, the particle reinforcement is from the particle interface to the core, Gradient distribution of all or part of the AlCu intermetallic compound layer, CuAl solid solution, pure copper structure.

(3) The particle reinforcement is in situ autogenous.

Preferably, the metal base is AlSi-based A356 cast aluminum alloy.

Preferably, the shape of the particle reinforcement is spherical.

Preferably, the gradient AlCu intermetallic compound layer refers to Al2Cu near the aluminum side, Al4Cu9 near the copper side, and AlCu three-layer intermetallic compound between them.

The method for preparing the above-mentioned spherical intermetallic compound particle reinforced aluminum matrix composite material comprises the following steps:

Step 1. Using aluminum alloy as the base material, heat it up to 680-720°C in a furnace to keep it melted;

Step 2. After the aluminum alloy matrix material is melted, sprinkle the slag remover into the furnace and keep it warm for 10-30 minutes;

Step 3, skimming off the scum on the surface of the aluminum alloy base material melt, adding an aluminum alloy modifier for modification treatment, the modifier being AlTiB or AlSr alloy;

Step 4, cooling the modified aluminum alloy matrix material melt to the range of 580°C-630°C and then keeping it warm to form a semi-solid slurry;

Step 5. Use the spiral stirring rod to go deep under the liquid surface formed in step 4, control the bottom of the rod to be 5-10cm away from the bottom surface of the melt, and stir at a speed of 200-800rpm to make the liquid surface form a vortex;

Step 6. Add copper powder in batches near the vortex of the liquid surface, and the adding time is 2-5 minutes. After the copper powder is added, continue to stir for 2-5 minutes, and let it stand to form a slurry;

Step 7. Take out the slurry formed in step 6 to make embryos for subsequent semi-solid casting or rapid casting after rapid heating of the slurry to 640-680°C.

Preferably, in step five, in order to speed up the rapid and thorough mixing between the copper powder and the molten aluminum, a plurality of screw rods should be evenly distributed and arranged in the transverse and longitudinal sections of the crucible melt space, leaving no or less dead spots for stirring.

Preferably, in step 6, the shape of the added copper powder particles is spherical, and the diameter is between 1-100 μm.

Preferably, during steps 4 to 6, an inert protective gas is simultaneously blown on the surface of the melt to reduce the oxygen content on the surface of the melt, reduce the surface oxidation of the aluminum liquid and copper powder and the inclusion of oxides into the melt.

Preferably, in the process of step 6 to step 7, the addition of copper powder, stirring, dispersion and standing time should be controlled within 10 minutes;

Preferably, in the process from step 3 to step 7, the time from adding the modificator to the casting process should be within 1 hour to prevent deterioration and decay.

The present invention has the following beneficial effects:

The copper reinforcement phase particles are made of metal during the addition and dispersion process, and there is no poor or difficult wetting with the aluminum alloy melt, so the upper limit of the ratio of reinforcement particles that can be added is relatively high.

1. In the present invention, the aluminum alloy matrix melt is selected from the low temperature range, and the spherical or quasi-spherical copper particle powder of a certain size is quickly introduced into the molten aluminum alloy slurry through one or more stirring rods. Quickly cast out after uniform dispersion. The high-melting-point metal particles wet well with the low-melting-point aluminum alloy matrix, and in situ self-generated AlCu intermetallic compound reinforcement phase with a spherical shape and a good bonding interface through the diffusion mechanism. The shape of the aluminum-copper intermetallic compound prepared by the method is controllable, and the hardness is high, the dispersion is uniform, and the interface metallurgical bonding is tight, so the comprehensive mechanical properties and heat resistance and wear resistance are significantly improved.

2. In the present invention, copper particles with low solidification temperature are added to the aluminum alloy matrix melt. When the aluminum alloy is still in the molten liquid-solid temperature range, the copper particles in the aluminum alloy slurry under multi-stirring rods and rapid stirring The dispersion speed is fast, and due to the short residence time of the copper particles in the high temperature zone, the copper particles can maintain a good initial shape and not be integrated into the aluminum matrix, but are self-generated in situ by the diffusion mechanism during the stirring and post-cooling process Part or even all of the AlCu metal compound is formed to increase the content of the AlCu metal compound, thereby further improving the performance of the composite material.

Description of drawings

Figure 1 is a low-magnification view of the structure of A356 aluminum alloy reinforced with 30wt% spherical AlCu particles;

Figure 2 is a high-magnification view of the structure of A356 aluminum alloy reinforced with 30wt% spherical AlCu particles;

Fig. 3 is 30wt% spherical AlCu particle reinforced A356 aluminum alloy energy spectrum surface scanning analysis diagram;

Figure 4 is a comparison of the hardness of 30wt% spherical AlCu particles reinforced A356 aluminum alloy and A356 aluminum alloy;

Figure 5 is a low-magnification view of the structure of A356 aluminum alloy reinforced with 10wt% spherical AlCu particles;

Fig. 6 is a hardness comparison between A356 aluminum alloy reinforced with 10wt% spherical AlCu particles and A356 aluminum alloy.

detailed description

The following will clearly and completely describe the technical solutions in the embodiments of the present invention with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only some, not all, embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by persons of ordinary skill in the art without making creative efforts belong to the protection scope of the present invention.

The chemical composition of the A356 aluminum alloy used in the examples of the present invention is shown in Table 1 below:

Table 1 Chemical composition of A356 aluminum alloy (wt.%)

Embodiment one:

An A356 aluminum alloy reinforced by in-situ spherical AlCu intermetallic compound particles, the mass percentage of AlCu particles is 30%, and the average particle diameter is 30 μm. As shown in Figure 1 and Figure 2, the particle sphericity is good, and the energy spectrum results As shown in Figure 3, the composition of the spherical black area is AlCu intermetallic compound. The Vickers hardness results are shown in Figure 4, which is significantly improved compared with the conventional A356 aluminum alloy.

The preparation process comprises the following steps:

Step 1. Using A356 aluminum alloy as the base material, heat it up to 720°C in a furnace to keep it melted;

Step 2. Sprinkle the slag remover after melting and keep it warm for 15 minutes;

Step 3, skimming the surface of the melt, adding AlTiB modifier;

Step 4, heat preservation after the melt is cooled to 630°C;

Step 5. Lower the three helical stirring rods in a character distribution and penetrate into the liquid surface, control the bottom of the rod to be 5cm away from the bottom of the crucible, and stir at a speed of 800rpm;

Step 6. Add copper powder in batches near the vortex of the stirring rod, and the adding time is controlled within 2 minutes; after the powder addition is completed, continue to stir for 2 minutes, and let it stand to form a slurry;

Step 7. The slurry formed in step 6 is directly taken out to make embryos for subsequent semi-solid casting.

Embodiment two,

An in-situ self-generated A356 aluminum alloy reinforced with spherical AlCu intermetallic compound particles, the difference from Example 1 is that the mass percentage of AlCu particles is 10%, and the average particle diameter is also 30 μm, as shown in Figure 5. The sphericity of the particles is good, and the Vickers hardness results are shown in Figure 6, which is significantly improved compared with the conventional A356 aluminum alloy.

The preparation process comprises the following steps:

Step 1. Using A356 aluminum alloy as the base material, heat it up to 680°C in a furnace to keep it melted;

Step 2. Sprinkle the slag remover after melting and keep it warm for 30 minutes;

Step 3, surface skimming, adding AlSe modifier;

Step 4, keep warm after cooling down to 590°C;

Step 5. Lower the single-helical stirring rod and penetrate into the liquid surface, and control the bottom of the rod to be 5cm away from the bottom of the crucible; the stirring speed is 200rpm;

Step 6. Add copper powder in batches near the vortex of the stirring rod, and the adding time is controlled within 5 minutes; after the powder addition is completed, continue to stir for 5 minutes, and let it stand to form a slurry;

Step 7. Rapidly raise the temperature of the slurry to 640-680° C. and then rapidly cast it into shape.

It should be noted that in this article, relational terms such as first and second are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply that there is a relationship between these entities or operations. There is no such actual relationship or order between them. Furthermore, the term "comprises", "comprises" or any other variation thereof is intended to cover a non-exclusive inclusion such that a process, method, article or apparatus comprising a set of elements includes not only those elements, but also includes elements not expressly listed. other elements of or also include elements inherent in such a process, method, article, or device.

Although the embodiments of the present invention have been shown and described, those skilled in the art can understand that various changes, modifications and substitutions can be made to these embodiments without departing from the principle and spirit of the present invention. and modifications, the scope of the invention is defined by the appended claims and their equivalents.

Claims (10)

1. A spherical intermetallic compound particle reinforced aluminum matrix composite material, characterized in that: its structural characteristics are as follows: (1) The metal matrix is aluminum alloy, and the solidification temperature range is 20°C to 50°C; (2) The metal matrix contains 1%-30% volume ratio of particle reinforcement, and the diameter of the particle reinforcement is between 1 and 100 μm, and is uniformly dispersed in the matrix; based on the length of diffusion time, the particle reinforcement from the particle interface to In the core, all or part of the AlCu intermetallic compound layer, CuAl solid solution, and pure copper structure are distributed in a gradient. (3) The particle reinforcement is self-generated in situ through the diffusion mechanism. 2. A spherical intermetallic compound particle-reinforced aluminum matrix composite material according to claim 1, characterized in that the metal matrix is preferably AlSi-based A356 cast aluminum alloy. 3. A spherical intermetallic compound particle-reinforced aluminum matrix composite material according to claim 1, characterized in that: the shape of the particle reinforcement is spherical. 4. A spherical intermetallic compound particle-reinforced aluminum matrix composite material according to claim 1, characterized in that: said gradient AlCu intermetallic compound layer refers to Al2Cu near the aluminum side, Al4Cu9 near the copper side, and between the two Between the AlCu three-layer intermetallic compound. 5. A method for preparing a spherical intermetallic compound particle-reinforced aluminum-based composite material according to any one of claims 1-4, characterized in that it comprises the following steps: Step 1. Using aluminum alloy as the base material, heat it up to 680-720°C in a furnace to keep it melted; Step 2. After the aluminum alloy matrix material is melted, sprinkle the slag remover into the furnace and keep it warm for 10-30 minutes; Step 3, skimming off the scum on the surface of the aluminum alloy base material melt, adding an aluminum alloy modifier for modification treatment, the modifier being AlTiB or AlSr alloy; Step 4, cooling the modified aluminum alloy matrix material melt to the range of 580°C-630°C and then keeping it warm to form a semi-solid slurry; Step 5. Use the spiral stirring rod to go deep under the liquid surface formed in step 4, control the bottom of the rod to be 5-10cm away from the bottom surface of the melt, and stir at a speed of 200-800rpm to make the liquid surface form a vortex; Step 6. Add copper powder in batches near the vortex of the liquid surface, and the adding time is 2-5 minutes. After the copper powder is added, continue to stir rapidly for 2-5 minutes, and let it stand to form a slurry; Step 7. Take out the slurry formed in step 6 to make embryos for subsequent semi-solid casting, or rapidly raise the temperature of the slurry to 640-680°C and then quickly cast it into shape. 6. the preparation method of a kind of spherical intermetallic compound particle reinforced aluminum matrix composite material according to claim 5, is characterized in that: in step 5, in order to speed up the rapid and sufficient mixing between copper powder and aluminum liquid, a plurality of screw rods The horizontal and vertical sections in the crucible melt space need to be evenly distributed and arranged. 7. The preparation method of a spherical intermetallic compound particle reinforced aluminum matrix composite material according to claim 5, characterized in that: in step 6, the shape of the added copper powder particles is spherical, and the diameter is between 1-100 μm . 8. A spherical intermetallic compound particle-reinforced aluminum matrix composite material and its preparation method according to claim 5, characterized in that: in the process from step 4 to step 6, an inert protective gas is simultaneously blown into the surface of the melt to reduce the melting temperature. The oxygen content on the surface of the body can be reduced to reduce the surface oxidation of aluminum liquid and copper powder and the inclusion of oxides into the melt. 9. The preparation method of a kind of spherical intermetallic compound particle reinforced aluminum matrix composite material according to claim 5, characterized in that: in the process of step 6 to step 7, the addition of copper powder, stirring and dispersion and standing time should be Control it within 10 minutes. 10. A method for preparing spherical intermetallic compound particle-reinforced aluminum matrix composites according to claim 5, characterized in that: in the process from step 3 to step 7, the time from adding the modificator to the casting process should be within Within 1 hour, prevent deterioration and decay.

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