PREPARATION METHOD OF IN-SITU TERNARY NANOPARTICLE-REINFORCED ALUMINUM MATRIX COMPOSITE

Abstract

The present invention provides a method for preparing an in-situ ternary nanoparticle-reinforced aluminum matrix composite (AMC). In this method, an in-situ reaction generation technique is used, and with a powder containing formation elements for producing reinforcing particles as a reactant, in conjunction with a low-frequency rotating magnetic field/ultrasonic field regulation technique, an aluminum-based composite material is prepared using nanoparticle intermediate alloy re-melting. An AA6016-based composite material reinforced by ternary nanoparticles has an average particle size of 65 nm, and has an obvious refinement phenomenon compared with unitary and dual-phase nanoparticles.

Claims

1. A preparation method of an in-situ ternary nanoparticle-reinforced aluminum matrix composite, comprising a two-step method: step I: adding a reaction mixed salt with elements for forming TiB.sub.2 reinforcement particles to a molten pure aluminum melt, while applying an acousto-magneto coupling field to prepare an aluminum matrix composite with the TiB.sub.2 reinforcement particles, the aluminum matrix composite being used as a TiB.sub.2 reinforcement particle-containing intermediate alloy; and step II: adding a weighed reaction mixed salt to an AA6111 melt according to required different volume fractions of reinforcement particles (ZrB.sub.2+Al.sub.2O.sub.3) for a reaction, and applying the acousto-magneto coupling field during the reaction; after the reaction is completed, adding the TiB.sub.2 nanoparticle-containing intermediate alloy to obtain a resulting mixture, and subjecting the resulting mixture to incubation, standing, refining, slag removal, and casting to obtain an AA6111-based composite ingot, and subjecting the AA6111-based composite ingot to a T6 heat treatment to obtain the ternary (ZrB.sub.2+Al.sub.2O.sub.3+TiB.sub.2) nanoparticle-reinforced aluminum matrix composite with a high strength and a high modulus wherein the preparation method specifically comprises the following steps: step 1: weighing borax, KBF.sub.4K.sub.2ZrF.sub.6 and K.sub.2TiF.sub.6 as reaction salts, and weighing an industrial pure aluminum and an AA6111 aluminum alloy as matrices, wherein powders of the reaction salts are dried, the KBF.sub.4 reaction salt and the K.sub.2TiF.sub.6 reaction salt are weighed at an amount enough to form a 5 wt. % TiB.sub.2 reinforcement particle-containing intermediate alloy and thoroughly mixed to obtain a KBF.sub.4/K.sub.2TiF.sub.6 mixed reaction salt powder, the K.sub.2ZrF.sub.6 reaction salt and the borax reaction salt are weighed at an amount of 1% to 3% of a volume fraction of (ZrB.sub.2+Al.sub.2O.sub.3) in the finally-formed in-situ (ZrB.sub.2+Al.sub.2O.sub.3+TiB.sub.2) nanoparticle-reinforced AA6111-based composite and thoroughly mixed to obtain a K.sub.2ZrF.sub.6/borax mixed reaction salt powder, and the KBF.sub.4/K.sub.2TiF.sub.6 mixed reaction salt powder and the K.sub.2ZrF.sub.6/borax mixed reaction salt powder are each wrapped with an aluminum foil for a later use; step 2: preparation of the TiB.sub.2 reinforcement particle-containing intermediate alloy: placing the weighed industrial pure aluminum in a preheated crucible for melting by heating to 830° C. to 870° C., to obtain a resulting aluminum melt; adding the weighed KBF.sub.4/K.sub.2TiF.sub.6 mixed reaction salt powder to the resulting aluminum melt, and after the weighed KBF.sub.4/K.sub.2TiF.sub.6 mixed reaction salt powder is completely added, applying the acousto-magneto coupling field for a reaction; and after the reaction is conducted at 850° C. for 30 min to obtain a first melt, cooling the first melt to 730° C. to 750° C., subjecting the first melt to refining and slag removal, and casting with a copper mold to obtain a wedge-shaped ingot for a later use, which is the TiB.sub.2 reinforcement particle-containing intermediate alloy; step 3: preparation of the (ZrB.sub.2+Al.sub.2O.sub.3+TiB.sub.2) nanoparticle-reinforced AA6111-based composite: placing the weighed AA6111 aluminum alloy in a preheated graphite crucible for melting by heating to 830° C. to 870° C., to obtain a resulting AA6111 aluminum alloy melt; adding the weighed K.sub.2ZrF.sub.6/borax mixed reaction salt powder to the resulting AA6111 aluminum alloy melt, and after the weighed K.sub.2ZrF.sub.6/borax mixed reaction salt powder is completely added, applying the acousto-magneto coupling field for a reaction; after the reaction is conducted at 850° C. for 15 min to obtain a second melt, subjecting the second melt to refining and slag removal; after the second melt is cooled to 750° C., adding the pre-weighed TiB.sub.2 reinforcement particle-containing intermediate alloy to the second melt, wherein the TiB.sub.2 reinforcement particle-containing intermediate alloy is weighed at an amount that allows a weight percentage of the TiB.sub.2 in the (ZrB.sub.2+Al.sub.2O.sub.3+TiB.sub.2) nanoparticle-reinforced AA6111-based composite to be 1 wt. % to 3 wt. %; after the TiB.sub.2 reinforcement particle-containing intermediate alloy is completely melted, applying the acousto-magneto coupling field, followed by incubating for 15 min to 20 min to obtain a third melt; subjecting the third melt to refining and slag removal, and then casting with a copper mold to obtain the (ZrB.sub.2+Al.sub.2O.sub.3+TiB.sub.2) nanoparticle-reinforced AA6111-based composite; and step 4: subjecting the obtained composite to the T6 heat treatment, wherein the T6 heat treatment comprises a solid solution treatment and an aging treatment, wherein parameters of the acousto-magneto coupling field comprise: an excitation current of 200 A to 250 A; a magnetic field frequency of 15 Hz to 20 Hz; an ultrasonic power of 1.5 Kw to 2 Kw; and an ultrasonic frequency of 20 KHz to 30 KHz.

2. (canceled)

3. The preparation method of the in-situ ternary nanoparticle-reinforced aluminum matrix composite according to claim 1, wherein in the step 1, the powders of the reaction salts are dried at 200° C. to 250° C. for 2 h to 3 h.

4. The preparation method of the in-situ ternary nanoparticle-reinforced aluminum matrix composite according to claim 1, wherein in the step 2, in the TiB.sub.2 reinforcement particle-containing intermediate alloy obtained after the casting, a proportion of the TiB.sub.2 reinforcement particles is 5wt %, with the balance being Al.

5. (canceled)

6. The preparation method of the in-situ ternary nanoparticle-reinforced aluminum matrix composite according to claim 1, wherein in the step 4, the solid solution treatment is conducted as follows: heating from a room temperature to a temperature of 545° C.-550° C., keeping at the temperature for 2.5 h to 3 h, and then quenching in a water bath at a temperature not higher than 30° C., with a quenching transfer time of less than 10 s; and the aging treatment is conducted as follows: heating from a room temperature to a temperature of 160° C.-180° C., keeping at the temperature for 6 h to 8 h, and then furnace-cooling.

7. (canceled)

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0019] In order to explain the technical solutions of the present invention more clearly, accompanying drawings that need to be used will be briefly introduced below. Apparently, the accompanying drawings in the following description show merely some examples of the present invention, and other drawings may be derived from these accompanying drawings by a person of ordinary skill in the art without creative efforts.

[0020] (a) of FIG. 1 shows optical microscopy (OM) images of the matrix, and (b) of FIG. 1 shows optical microscopy images of the 1 vol % ZrB.sub.2+1 vol % Al.sub.2O.sub.3+1 wt % TiB.sub.2.

[0021] FIG. 2 is a scanning electron microscopy (SEM) image of the 2 vol. % ZrB.sub.2+2 vol. % Al.sub.2O.sub.3+2 wt. % TiB.sub.2 ternary nanoparticles obtained in the present invention.

[0022] FIG. 3 is an SEM image of the 2 vol. % ZrB.sub.2+2 vol. % Al.sub.2O.sub.3 binary nanoparticles prepared through an in-situ reaction.

[0023] FIG. 4 is an SEM image of the 1 vol. % ZrB.sub.2+1 vol. % Al.sub.2O.sub.3+1 wt. % TiB.sub.2 ternary particles prepared in the present invention.

DESCRIPTION OF THE EMBODIMENTS

[0024] The present invention can be implemented according to the following examples, but is not limited to the following examples. Unless otherwise specified, the terms used in the present invention generally have the meanings commonly understood by those of ordinary skill in the art. It should be understood that these examples are used merely to illustrate the present invention rather than limit the scope of the present invention in any way. In the following examples, various processes and methods that are not described in detail are conventional methods known in the art.

EXAMPLE 1

[0025] Preparation of a 1 vol. % ZrB.sub.2+1 vol. % Al.sub.2O.sub.3+1 wt. % TiB.sub.2 nanoparticle-reinforced AMC

[0026] A two-step melt reaction method was adopted. Step 1: Preparation of a 5 wt. % TiB.sub.2 particle-reinforced AMC: K.sub.2BF.sub.6 and K.sub.2TiF.sub.6 powders were used as reactants, and dried at 200° C. for 120 min in a drying box to remove crystal water. Then the composition design was conducted according to a TiB.sub.2 nanoparticle mass fraction of 5%. 254.91 g of dried potassium fluoroborate and 246.10 g of potassium fluorotitanate were weighed, thoroughly mixed, and wrapped with aluminum foil for later use. 886.25 g of industrial pure aluminum was weighed and heated to 850° C. in a high-frequency induction heating furnace, then the mixed reaction salt was pressed into the resulting melt using a graphite bell jar, and an acousto-magneto coupling field was applied at an excitation current of 200 A, a magnetic field frequency of 15 Hz, an ultrasonic power of 1.8 Kw, and an ultrasonic frequency of 20 KHz to allow a reaction. After the reaction was conducted for 30 min at the temperature, the melt was cooled to 750° C., and then subjected to refining, slag removal, and casting at 720° C. to obtain a wedge-shaped ingot, which was the TiB.sub.2 reinforcement particle-containing intermediate alloy. Step 2: Preparation of a (ZrB.sub.2+Al.sub.2O.sub.3) nanoparticle-reinforced AA6111-based composite: The composition design was conducted according to a nanoparticle (ZrB.sub.2+Al.sub.2O.sub.3) volume fraction of 1%. 1,328.64 g of an AA6111 aluminum alloy, 48.77 g of borax (Na.sub.2B.sub.4O.sub.7.10H.sub.2O), and 113.88 g of potassium fluorozirconate (K.sub.2ZrF.sub.6) were weighed. The weighed AA6111 aluminum alloy was heated to 850° C. in a high-frequency induction heating furnace for melting, then the weighed K.sub.2ZrF.sub.6 and borax were added to the resulting aluminum melt in multiple batches, and after the reaction salt powder was completely added, an acousto-magneto coupling field was applied to allow a reaction for 15 min. The resulting melt was subjected to refining and slag removal. After the melt was cooled to 750° C., the pre-weighed (245.6 g) TiB.sub.2-containing intermediate alloy was added to the melt, and an acousto-magneto coupling field was applied to allow a reaction for 15 min. The resulting melt was subjected to refining, slag removal, and casting at 720° C. to obtain the 1 vol. % ZrB.sub.2+1 vol. % Al.sub.2O.sub.3+1 wt. % TiB.sub.2 nanoparticle-reinforced AMC.

[0027] The obtained composite ingot was processed into a standard tensile specimen, and then the tensile specimen was subjected to a T6 heat treatment, where the solid solution treatment was conducted as follows: heating from room temperature to 550° C. and keeping at the temperature for 3 h, and the aging treatment was conducted as follows: heating from room temperature to 160° C., keeping at the temperature for 8 h, and furnace-cooling.

[0028] It can be seen from FIG. 1 and FIG. 4 that, compared with the matrix grains, a grain structure of the composite is refined and has a relatively uniform size, the particles have a small size and are uniformly distributed, and there is no obvious particle agglomeration, which improves the strength and plasticity of the material. Results of the room-temperature mechanical performance test show that the composite prepared by the method of the present invention has a tensile strength of 343.6 MPa and an elongation at break of 22.87%.

EXAMPLE 2

[0029] Preparation of a 2 vol. % ZrB.sub.2+2 vol. % Al.sub.2O.sub.3+2 wt. % TiB.sub.2 nanoparticle-reinforced AMC

[0030] A two-step melt reaction method was adopted: Step 1: An AMC with 5 wt. % TiB.sub.2 reinforcement particles was prepared, and the composition design was conducted according to a TiB.sub.2 nanoparticle mass fraction of 5%. The composite was used as a nanoparticle-containing intermediate alloy. Step 2: Preparation of a (ZrB.sub.2+Al.sub.2O.sub.3) nanoparticle-reinforced AA6111-based composite: The composition design was conducted according to a nanoparticle (ZrB.sub.2+Al.sub.2O.sub.3) volume fraction of 2%. 1,218.64 g of an AA6111 aluminum alloy, 96.31 g of borax (Na.sub.2B.sub.4O.sub.7.10H.sub.2O), and 224.89 g of potassium fluorozirconate (K.sub.2ZrF.sub.6) were weighed. The weighed AA6111 aluminum alloy was heated to 850° C. in a high-frequency induction heating furnace for melting, then the weighed K.sub.2ZrF.sub.6 and borax were added to the resulting aluminum melt in multiple batches, and after the reaction salt powder was completely added, an acousto-magneto coupling field was applied to allow a reaction for 15 min. The resulting melt was subjected to refining and slag removal. After the melt was cooled to 750° C., the pre-weighed (487.46 g) TiB.sub.2-containing intermediate alloy was added to the melt, and an acousto-magneto coupling field was applied to allow a reaction for 15 min. The resulting melt was subjected to refining, slag removal, and casting at 720° C. to obtain the 2 vol. % ZrB.sub.2+2 vol. % Al.sub.2O.sub.3+2 wt. % TiB.sub.2 nanoparticle-reinforced AMC.

[0031] The obtained composite ingot was processed into a standard tensile specimen, and then the tensile specimen was subjected to a T6 heat treatment, where the solid solution treatment was conducted as follows: heating from room temperature to 550° C. and keeping at the temperature for 3 h, and the aging treatment was conducted as follows: heating from room temperature to 160° C., keeping at the temperature for 8 h, and furnace-cooling.

[0032] It can be seen from FIG. 2 and FIG. 3 that, compared with binary particles, the ternary particle-reinforced AMC prepared by the present invention has a high particle yield, and because TiB.sub.2 particles are added as an intermediate alloy, the IBS between the particles and the matrix is high, the surface of the material is clean, and the strength and plasticity of the composite are significantly improved. Results of the room-temperature mechanical performance test show that the composite prepared by the method of the present invention has a tensile strength of 368.41 MPa and an elongation at break of 24.6%.

EXAMPLE 3

[0033] Preparation of a 3 vol % ZrB.sub.2+3 vol % Al.sub.2O.sub.3+2 wt % TiB.sub.2 nanoparticle-reinforced AMC

[0034] A two-step melt reaction method was adopted. Step 1: An AMC with 5 wt. % TiB.sub.2 reinforcement particles was prepared, and the composition design was conducted according to a TiB.sub.2 nanoparticle mass fraction of 5%. The composite was used as a nanoparticle-containing intermediate alloy. Step 2: Preparation of a (ZrB.sub.2+Al.sub.2O.sub.3) nanoparticle-reinforced AA6111-based composite: The composition design was conducted according to a nanoparticle (ZrB.sub.2+Al.sub.2O.sub.3) volume fraction of 3%. 1,354.62 g of an AA6111 aluminum alloy, 159.87 g of borax (Na.sub.2B.sub.4O.sub.7.10H.sub.2O), and 373.30 g of potassium fluorozirconate (K.sub.2ZrF.sub.6) were weighed. The weighed AA6111 aluminum alloy was heated to 850° C. in a high-frequency induction heating furnace for melting, then the weighed K.sub.2ZrF.sub.6 and borax were added to the resulting aluminum melt in multiple batches, and after the reaction salt powder was completely added, an acousto-magneto coupling field was applied to allow a reaction for 15 min. The resulting melt was subjected to refining and slag removal. After the melt was cooled to 750° C., the pre-weighed (541.84 g) nano TiB.sub.2-containing intermediate alloy was added to the melt, and an acousto-magneto coupling field was applied to allow a reaction for 15 min. The resulting melt was subjected to refining, slag removal, and casting at 720° C. to obtain the 3 vol. % ZrB.sub.2+3 vol. % Al.sub.2O.sub.3+2 wt. % TiB.sub.2 nanoparticle-reinforced AMC.

[0035] The obtained composite ingot was processed into a standard tensile specimen, and then the tensile specimen was subjected to a T6 heat treatment, where the solid solution treatment was conducted as follows: heating from room temperature to 550° C. and keeping at the temperature for 3 h, and the aging treatment was conducted as follows: heating from room temperature to 160° C., keeping at the temperature for 8 h, and furnace-cooling.

[0036] The tensile properties were determined in accordance with an ASTM E8M-09 experimental standard test at a tensile rate of 1 mm/min and room temperature. Results of the room-temperature mechanical performance test show that the composite prepared by the method of the present invention has a tensile strength of 352.84 MPa and an elongation at break of 21.3%.