CN107012354B - A kind of preparation method of Al-Si9Cu1 particulate reinforced composite - Google Patents

Abstract

The invention relates to the technical field of preparation of particle-reinforced aluminum-based composite materials, in particular to a method for preparing in-situ (TiB ₂ +ZrB ₂ ) particle-reinforced Al-Si-Cu-based composite materials. The present invention puts a certain proportion of Al18Si, pure Al, and Al50Cu alloy into a graphite crucible at a certain temperature to melt, and then adds a certain proportion of potassium fluorotitanate, potassium fluorozirconate and borax mixed powder at a certain temperature. After the powder is completely added , Turn on the mechanical stirring and the electromagnetic stirrer to stir for a certain period of time. After the stirring is completed, lower the temperature in the furnace to a certain temperature and carry out slag removal. After slag removal, perform casting in a certain way to obtain the required composite material. The as-cast structure grain of the obtained composite material is smaller and rounder than that of the Al-Si-Cu alloy, and has the advantages of high strength and good shape.

Description

A kind of preparation method of Al-Si9Cu1 particle reinforced composite material

technical field

The invention relates to a preparation method in the technical field of composite materials, in particular, the in-situ (TiB ₂ +ZrB ₂ ) particle-reinforced Al-Si-Cu matrix composite is prepared by using a melt reaction method combining mechanical stirring and electromagnetic stirring. Material.

Background technique

Particle-reinforced aluminum matrix composites have the advantages of high specific strength and high elastic modulus, and have broad prospects in the fields of aerospace, advanced manufacturing, and national defense. Compared with the traditional aluminum-matrix composites with particles, the in-situ particle-reinforced aluminum-matrix composites have good wettability between the particles and the matrix, and the interface is firmly bonded. It is not suitable to introduce impurities during the reaction process. The prepared materials are purer and have better performance. excellent. Al-Si-Cu alloy is an important Al-Si alloy, and the addition of Cu element can improve the performance of the alloy. First of all, the larger Cu atoms dissolve into the Al-Si alloy, causing serious lattice distortion in the Al solid solution, hindering the movement of dislocations, increasing the shear stress of the slip movement, forming solid solution strengthening, and improving the alloy’s strength. strength. Thirdly, Cu forms θ(CuAl ₂ ) phase in Al-Si alloy. During solution treatment, CuAl ₂ dissolves into α solid solution, and precipitates θ′, θ″(CuAl ₂ ) metastable phase or CuAl ₂ stable phase, these strengthening phases can hinder the movement of dislocations, improve tensile strength, hardness, fatigue strength and high temperature strength. The Al-Si-Cu alloy with excellent performance is used as the matrix to prepare (TiB ₂ +ZrB ₂ ) particles The reinforced aluminum-based composite material is a combination of a matrix with excellent performance and ceramic particles with excellent performance. It is an excellent combination, and the performance of the prepared composite material is better than that of Al-Si-Cu alloy.

The melt direct reaction method is to directly melt the aluminum alloy matrix, add reactants to it, and then cast after fully reacting. This method can directly obtain the cast composite material. The process is simple in operation, low in production cost, and short in cycle. production. However, the melt direct reaction method also has disadvantages. The composite material particles prepared under this process are agglomerated, which affects the material properties. The combination of mechanical stirring and electromagnetic stirring is applied in the melt reaction process, and the agglomerated particles are continuously broken during the stirring process to make the particle distribution more uniform. Since the particle TiB ₂ has the effect of refining the grain, it is prepared by this method. The matrix grains of the composite material are finer, which greatly improves the performance of the material.

After exploring the existing technical literature, it was found that the Chinese patent number is: 2015107658685, and the name is: a preparation method of particle-reinforced aluminum-based composite materials. The prefabricated block is put into the sprue and poured with molten aluminum. In this method, a ball mill is required to grind the composite particles, which takes a long time. Since the particles have been made into prefabricated blocks before, the particle dispersion is not good, and the particle coating and rolling increase. The preparation process steps are not as simple and cost-saving as the preparation method of this patent. At the same time, the particles in this patent are added from outside, and the degree of combination between the particles and the matrix material is not as good as the composite material prepared in situ in this patent. The Chinese patent number is: 2015100957741, and the title is: A preparation method of in-situ Al ₃ Ti particle reinforced Al-Si-Cu composite material semi-solid slurry, which uses K ₂ TiF ₆ in Al-Si-Cu molten alloy The powder is stirred by electromagnetic stirring, and the temperature is gradually lowered during the stirring process. The cooling process in the preparation process of this method is not easy to control, and the cooling rate will also affect the material properties, and the patent is prepared with Al ₃ Ti particle reinforcement, which is not as fine as TiB ₂ particles, and does not have the effect of TiB ₂ particles to refine the grain , so the material prepared by this patent preparation method is not as controllable as the material prepared by this patent, nor is it as fine as the matrix structure of the composite material prepared by this patent.

Contents of the invention

The invention uses a melt reaction preparation method combining mechanical stirring and electromagnetic stirring to prepare in-situ (TiB ₂ +ZrB ₂ ) particle-reinforced Al-Si-Cu-based composite materials.

Preparation process of the present invention is:

(1) Put potassium fluorotitanate (molecular formula K ₂ TiF ₆ ), potassium fluorozirconate (molecular formula K2ZrF ₆ ), and borax powder into a drying oven for drying (temperature 175°C, time 5 hours). After drying, weigh and mix uniformly according to a certain mass ratio for future use.

(2) Calculate and weigh the mass of pure Al, Al18Si and Al50Cu required to prepare a certain amount of Al-Si-Cu alloy, and then put the weighed pure Al and Al18Si into a preheated crucible at 400-450°C After melting, wait for the temperature to rise to 720°C, add Al50Cu and stir with a graphite rod. (3) After the Al50Cu is completely melted, raise the temperature to 810°C-860°C, add the mixed potassium fluorotitanate, potassium fluorozirconate and borax powder in 3 batches, and stir with a graphite rod during the addition process. (4) After the powder is completely added, turn on the external electromagnetic stirrer and mechanical stirrer at the same time for stirring. The direction of mechanical stirring is opposite to that of electromagnetic stirring, and the stirring time is 15 minutes. The stirring method is: stirring together for 5 minutes, standing still for 5 minutes, stirring in 3 times, and the whole stirring process is 25 minutes. During the stirring process, the temperature is kept between 810°C and 860°C. (5) After the stirring is completed, cool the melt to 705°C to 745°C, and add a slag removal agent to carry out slag removal. (6) Cast immediately after removing the slag, and use copper molds for casting molds. (7) The obtained composite material is subjected to heat treatment.

The mass percentage of Si in the Al-Si-Cu alloy matrix is 9%, the mass percentage of Cu is 1%, and the balance is Al.

The stirring voltage of the electromagnetic stirrer is 250V-380V, and the stirring frequency is 10.1HZ.

The rotational speed of the mechanical stirring is 200 rpm.

The amount of the mixed powder of the reinforcing particle reaction raw material accounts for 10% to 30% of the mass of the alloy raw material, preferably 20%; the generated reinforcing particles are TiB ₂ and ZrB ₂ with a mass ratio of 1:1.

The in-situ (TiB ₂ +ZrB ₂ ) particle-reinforced Al-Si-Cu-based composite material prepared by the method of electromagnetic stirring and mechanical stirring in the present invention has fine matrix grains and a relatively pure structure, and the obtained TiB ₂ and ZrB ₂ Particles are more evenly dispersed. Compared with the Al-Si-Cu alloy, the mechanical properties of the prepared material are greatly improved, and the tensile strength is also improved.

Description of drawings

Fig.1 Metallographic diagram of (TiB ₂ +ZrB ₂ ) particle reinforced AlSi9Cu1 composite material with 1.5% particle weight without heat treatment

Fig. 2. Metallographic diagram of (TiB ₂ +ZrB ₂ ) particle-reinforced AlSi9Cu1 composite material with 3% particle mass without heat treatment

Fig. 3. Metallographic diagram of (TiB ₂ +ZrB ₂ ) particle-reinforced AlSi9Cu1 composite material with a particle mass of 6% without heat treatment

Fig. 4. Metallographic diagrams of (TiB ₂ +ZrB ₂ ) particle-reinforced AlSi9Cu1 composites after heat treatment and without heat treatment

Detailed ways

The embodiments of the present invention are described in detail below: the present embodiment is implemented under the premise of the technical solution of the present invention, and detailed implementation and specific operation process are provided, but the protection scope of the present invention is not limited to the following implementation case.

Implementation Case 1 Preparation of AlSi9Cu1 Composite Material with Particle Mass Fraction of 1.5%

The material components and mass ratio of the present invention are: Si 9%, Cu 1%, (TiB ₂ +ZrB ₂ ) particles 1.5%, and the balance is pure Al.

The preparation process is as follows:

(1) Al18Si, pure Al and Al50Cu are prepared according to the mass ratio of 0.48:0.50:0.02 to prepare 500g alloy, put the prepared materials into the crucible in the electromagnetic stirring furnace and melt them, and after they are completely melted, heat up at 810℃～ Between 860°C, then add dry mixed powder of potassium fluozirconate, potassium fluotitanate and borax, the powder mass accounts for 10% of the melt mass, and the uniformly mixed reaction powder is added in 3 batches, and is used during the addition process Graphite rod stirring.

(2) After the powder is completely added, turn on the electromagnetic stirring device, the stirring voltage is 250V-380V, and the stirring frequency is 10.1HZ. While turning on the electromagnetic stirring device, turn on the mechanical stirrer above the crucible for stirring. The stirring direction is opposite to the electromagnetic stirring direction. Repeat 3 times.

(3) After the stirring is completed, lower the furnace temperature to 705°C to 745°C, add slagging agent, stir with a graphite rod, and remove slag.

(4) Immediately cast after slag removal, the casting temperature is 705°C-745°C, and the casting mold is a copper mold.

(5) The obtained composite material is successively subjected to heat treatment of solid solution at 500° C. for 5 hours and aging at 150° C. for 10 hours. The mechanical properties of the material obtained after the heat treatment are: σb=230MPa, E=4.21GPa, and the elongation is : 5.1%

(6) The mechanical properties of composite materials without heat treatment are: σb=210MPa, E=3.71GPa, elongation: 4.2%

It can be seen from Figure 1 that the composite material matrix with a particle mass fraction of 1.5% contains a large number of needle-like structures, and the distance between dendrites is large, and the grains are relatively coarse. Figure 4 shows that the composite material without heat treatment is compared with the composite material after heat treatment. The Si phase in the composite material after heat treatment changes from needle-like to short rod-like or rod-like, and the sharp corners disappear, and are more uniformly dispersed on the grain boundaries of the grains.

Implementation Case 2 Preparation of AlSi9Cu1 Composite Material with Particle Mass Fraction of 3%

The material composition and mass ratio of the present invention are: Si 9%, Cu 1%, (TiB ₂ +ZrB ₂ ) particles 3%, and the balance is pure Al.

The preparation process is as follows:

(1) Al18Si, pure Al and Al50Cu are prepared according to the mass ratio of 0.48:0.50:0.02 to prepare 500g of alloy, put the prepared materials into the crucible in the electromagnetic stirring furnace and melt them, after they are completely melted, heat up at 810℃～ Between 860°C, then add dry mixed powder of potassium fluozirconate, potassium fluotitanate and borax, the powder mass accounts for 20% of the melt mass, and the uniformly mixed reaction powder is added in 3 batches, and used during the addition process Graphite rod stirring for 2min.

(2) After the powder is completely added, turn on the electromagnetic stirring device, the stirring voltage is 250V-380V, and the stirring frequency is 10.1HZ. While turning on the electromagnetic stirring device, turn on the mechanical stirrer above the crucible for stirring. The stirring direction is opposite to the electromagnetic stirring direction. Repeat 3 times.

(3) After the stirring is completed, lower the furnace temperature to 705°C to 745°C, add slagging agent, stir with a graphite rod, and remove slag.

(4) Immediately cast after slag removal, the casting temperature is 705°C-745°C, and the casting mold is a copper mold.

(5) The obtained composite material is successively subjected to heat treatment of solid solution at 500° C. for 5 hours and aging at 150° C. for 10 hours. The mechanical properties of the material obtained after the heat treatment are: σb=290MPa, E=11.2GPa, elongation : 7.8%

(6) The mechanical properties of the composite material without heat treatment are: σb=250MPa, E=10.98GPa, elongation: 6.0%.

It can be seen from Figure 2 that the needle-like structure in the matrix of the composite material with a particle mass fraction of 3% is reduced, and the distance between dendrites is greatly reduced, and the crystal grains are also smaller and round. Figure 4 shows that the composite material without heat treatment is compared with the composite material after heat treatment. The Si phase in the composite material after heat treatment changes from needle-like to short rod-like or rod-like, and the sharp corners disappear, and are more uniformly dispersed on the grain boundaries of the grains.

Implementation Case 3 Preparation of AlSi9Cu1 Composite Material with Particle Mass Fraction of 6%

The material components and mass ratio of the present invention are: Si 9%, Cu 1%, (TiB ₂ +ZrB ₂ ) particles 6%, and the balance is pure Al.

The preparation process is as follows:

(1) Al18Si, pure Al and Al50Cu are prepared according to the mass ratio of 0.48:0.50:0.02 to prepare 500g of alloy, put the prepared materials into the crucible in the electromagnetic stirring furnace and melt them, after they are completely melted, heat up at 810℃～ Between 860°C, then add dry mixed powder of potassium fluozirconate, potassium fluotitanate and borax, the powder mass accounts for 30% of the melt mass, and the uniformly mixed reaction powder is added in 3 batches, and is used during the addition process Graphite rod stirring for 2min.

(2) After the powder is completely added, turn on the electromagnetic stirring device, the stirring voltage is 250V-380V, and the stirring frequency is 10.1HZ. While turning on the electromagnetic stirring device, turn on the mechanical stirrer above the crucible for stirring. The stirring direction is opposite to the electromagnetic stirring direction. Repeat 3 times.

(3) After the stirring is completed, lower the furnace temperature to 705°C to 745°C, add slagging agent, stir with a graphite rod, and remove slag.

(4) Immediately cast after slag removal, the casting temperature is 705°C-745°C, and the casting mold is a copper mold.

(5) The obtained composite material is successively subjected to heat treatment of solid solution at 500° C. for 5 hours and aging at 150° C. for 10 hours. The mechanical properties of the material obtained after the heat treatment are: σb=275MPa, E=9.16GPa, and the elongation is : 6.8%

(6) The mechanical properties of the composite material without heat treatment are: σb=235MPa, E=6.06GPa, and the elongation is 4.1%

It can be seen from Figure 3 that the composite material matrix with a particle mass fraction of 6% contains a large number of needle-like structures, and the distance between the dendrites is smaller, and the grains become smaller, but there are more particles between the grains. The particle agglomeration is also more powerful. Figure 4 shows that the composite material without heat treatment is compared with the composite material after heat treatment. The Si phase in the composite material after heat treatment changes from needle-like to short rod-like or rod-like, and the sharp corners disappear, and are more uniformly dispersed on the grain boundaries of the grains. The following table is the performance table of composite materials and matrix materials.

Table 1. Composite materials and their matrix properties

It can be seen from the table that (TiB ₂ +ZrB ₂ ) particle reinforced AlSi9Cu1 composite material has better performance than its corresponding matrix material, and the performance of the composite material after heat treatment is greatly improved compared with that of the material without heat treatment.

Claims (9)

1. a kind of preparation method of Al-Si9Cu1 particulate reinforced composite, which is characterized in that, will in situ in reaction process After the mixed-powder of enhancing particle reaction raw material is added in the alloy raw material for preparing matrix alloy Al-Si9Cu1 of melting, together When open additional electromagnetic stirring device and mechanical agitator and be stirred, mechanical stirring is contrary with electromagnetic agitation, mixing time For 15min；Stirring means are as follows: be first stirred together for 5min, then stand 5min, then be stirred together for 5min, then stand 5min, finally again It is stirred together for 5min, entire whipping process is 25min；The specific steps of preparation method are as follows:

(1) pure Al needed for calculating and weighing good a certain amount of Al-Si9Cu1 alloy of preparation, the quality of Al18Si and Al50Cu, Later by load weighted pure Al, Al18Si, which is put into the crucible of preheating, to be melted, and is warming up to 720 DEG C of additions to temperature after thawing Al50Cu is simultaneously stirred with graphite rod；

(2) it after Al50Cu melts completely, heats up 810 DEG C~860 DEG C, the potassium fluotitanate that point 3 batches of additions mix, potassium fluorozirconate And the mixed-powder of the enhancing particle reaction raw material of borax, it is stirred during the addition process and with graphite rod；

(3) after being added completely into powder, open simultaneously additional electromagnetic stirring device and mechanical agitator be stirred, mechanical stirring with Electromagnetic agitation is contrary, and in whipping process, temperature is maintained between 810 DEG C~860 DEG C；

(4) to be mixed to finish, 705 DEG C~745 DEG C are cooled the melt to, agent of skimming is added and skims；

(5) it casts immediately after having taken off slag, casting die selects copper mold；

(6) obtained composite material is heat-treated.

2. a kind of preparation method of Al-Si9Cu1 particulate reinforced composite as described in claim 1, which is characterized in that institute Stating the voltage that magnetic stirrer is stirred is 250V~380V, stirring frequency 10.1Hz.

3. a kind of preparation method of Al-Si9Cu1 particulate reinforced composite as described in claim 1, which is characterized in that institute Stating churned mechanically revolving speed is 200rpm.

4. a kind of preparation method of Al-Si9Cu1 particulate reinforced composite as described in claim 1, which is characterized in that The mass ratio of Al18Si, pure Al and Al50Cu are 0.48:0.50:0.02；The temperature of crucible preheating is 400~450 DEG C.

5. a kind of preparation method of Al-Si9Cu1 particulate reinforced composite as described in claim 1, which is characterized in that increase The amount that the mixed-powder of strong particle reaction raw material is added accounts for the 10%~30% of alloy raw material quality；The enhancing particle of generation is TiB₂And ZrB₂, mass ratio 1:1.

6. a kind of preparation method of Al-Si9Cu1 particulate reinforced composite as claimed in claim 5, which is characterized in that increase The amount that the mixed-powder of strong particle reaction raw material is added accounts for the 20% of alloy raw material quality.

7. a kind of preparation method of Al-Si9Cu1 particulate reinforced composite as described in claim 1, which is characterized in that will Obtained composite material carry out heat treatment refer to: obtained composite material successively carry out 500 DEG C of 5h solid solution and 150 DEG C of 10h Timeliness heat treatment.

8. a kind of preparation method of Al-Si9Cu1 particulate reinforced composite as described in claim 1, which is characterized in that institute State the mixed-powder of enhancing particle reaction raw material the preparation method is as follows: first by potassium fluotitanate, potassium fluorozirconate, borax powder is put into After drying box drying, example is weighed and is uniformly mixed according to a certain mass ratio, with spare.

9. a kind of preparation method of Al-Si9Cu1 particulate reinforced composite as claimed in claim 8, which is characterized in that institute Stating drying temperature is 175 DEG C, drying time 5h.