CN111500908A - Ultrahigh-strength ultrafine-grained TiB2Reinforced Al-Zn-Mg-Cu composite material and preparation - Google Patents

Abstract

Ultrahigh-strength ultrafine-grained TiB₂A reinforced Al-Zn-Mg-Cu composite material and a preparation method thereof belong to the field of composite materials. Using Al-Zn-Mg-Cu-Zr alloy as matrix and TiB with average size less than 1 μm₂In order to strengthen the particles, the composite material comprises the following components in percentage by mass: 8-12%, Mg: 1.0-2.0%, Cu: 1.0-1.5%, Zr: 0.05-0.15%, TiB₂: 1-5% and the balance of Al. Composite material prepared by adopting two-step methodAdjusting TiB₂The mass fraction of the particles, and the rapid solidification process, the crystal grains are refined, so that the matrix forms a large solid solution state, and the structure is more uniform.

Description

Ultrahigh-strength ultrafine-grained TiB2Reinforced Al-Zn-Mg-Cu composite material and preparation

Technical Field

The invention belongs to the field of composite materials, and particularly relates to component design and process optimization of an aluminum-based composite material.

Background

The Al-Zn-Mg-Cu series alloy is one of 7xxx series aluminum alloys, and is also called an ultra-high strength aluminum alloy. Based on the advantages of low density, high specific strength and hardness, easy processing and forming, better corrosion resistance, higher toughness and the like, the composite material is an important light structural material in the aerospace and military industries. Modern aircrafts and lightweight tanks are developing towards higher speed, more loads and higher trafficability, and the service life and the running safety are increasingly important, so that the materials used are required to have excellent comprehensive properties such as higher strength, better fatigue resistance and wear resistance.

Since the birth of 7075 alloy in 1943, Al-Zn-Mg-Cu aluminum alloy is subjected to researches on alloy composition optimization, melt purification, processing technology improvement, heat treatment optimization and the like. At present, the ultrahigh-strength aluminum alloy with the Zn content of 11 percent, the Zn/Mg value of 6 percent and the tensile strength of over 700MPa is developed. However, the alloy has serious stress corrosion cracking due to the excessively high Zn/Mg value, and the tensile strength is difficult to further improve after the Zn content of the alloy is increased to 11 percent. The strength of the alloy can be obviously improved by adding endogenous particles, the synthesis system mainly comprises stirring addition and in-situ synthesis, the research on preparing the composite material by taking the ultrahigh-strength Al-Zn-Mg-Cu alloy as a matrix is less, and SiC which has larger particle size and is not tightly bonded with the matrix interface is mostly taken as the matrixThe reinforced particles prepared in situ are directly carried out in the ultrahigh-strength aluminum alloy solution, and certainly cause certain loss to main component elements in the alloy. The invention starts from the design and control of microstructure and introduces TiB₂The particles are used for preparing the aluminum matrix composite material, and the strength of the alloy is obviously improved. The composite material is prepared by adopting a two-step method, so that the burning loss of alloy elements caused by high exothermic in-situ reaction directly carried out in an Al-Zn-Mg-Cu matrix is avoided, and TiB is reserved₂The cleanliness of the interface between the particles and the Al matrix. Forming superfine crystal grains by adopting a rapid solidification (single-roller melt-spun method) process, further carrying out T6 heat treatment on the material after cold press molding and hot extrusion deformation, and obtaining TiB in the composite material₂The particles are small in size and dispersed in distribution, and guarantee is provided for the performance of the aluminum matrix composite.

Disclosure of Invention

The invention aims to overcome the bottleneck that the strength of the ultrahigh-strength aluminum alloy is raised when the zinc content is too high. Introduction of TiB with smaller size into ultrahigh-strength aluminum alloy₂The particles are prepared into the composite material by a two-step method, and TiB is adjusted₂The mass fraction of the particles and the rapid solidification process refine the grains, so that the matrix forms a large solid solution state, the structure is more uniform, and the novel aluminum-based composite material with ultrahigh strength and ultrafine grain structure is prepared.

In order to achieve the purpose, the invention adopts the following design scheme:

ultrahigh-strength ultrafine-grained TiB₂The reinforced Al-Zn-Mg-Cu composite material and the preparation method are characterized in that: using Al-Zn-Mg-Cu-Zr alloy as matrix and TiB with average size less than 1 μm₂In order to strengthen the particles, the composite material comprises the following components in percentage by mass: 8-12%, Mg: 1.0-2.0%, Cu: 1.0-1.5%, Zr: 0.05-0.15%, TiB₂: 1-5% and the balance of Al.

In the preparation of the composite material, a rapid solidification process is adopted to form ultrafine grains, so that the matrix structure is more uniform. The method specifically comprises the following steps:

(1) using aluminum ingot, Al powder, Ti powder and TiO₂、H₃BO₃The raw materials are Ti powder, Ti powder and TiO powder, wherein the molar ratio of Ti to B is (1.0-2.2) to (3.1-4.0)₂The mass ratio of (1.5-2.7) to (0.2-2.5) to (0.5-3.1), and a melt self-propagating direct synthesis method is adopted to prepare the Al-TiB with lower mass fraction and average size of less than 1 mu m₂An intermediate alloy; TiB₂The interface of the particles and the matrix is clean, and the bonding degree is high; Al-TiB₂Intermediate alloy of TiB₂The mass percentage content of the active ingredients is 8-20%;

(2) taking high-purity aluminum ingot, pure magnesium, pure zinc, Al-Cu and Al-Zr intermediate alloy as raw materials, and taking the Al-TiB prepared in the step (1)₂Taking the intermediate alloy as a matrix, smelting the alloy at 780 ℃, and casting at 730-750 ℃;

(3) cutting the composite material ingot cast in the step (2) into blocks of (12-16) mm × (12-16) mm × (100-150) mm, spraying the molten composite material ingot onto a copper roller rotating at a high speed and throwing the molten composite material ingot out under the action of inert gas pressure through a rapid solidification process, and instantly condensing the molten composite material ingot to form an ultra-fine grain structure to prepare TiB₂Reinforcing the composite material thin strip;

(4) performing cold press molding on the thrown composite material thin strip, such as applying pressure of 700KN, loading for 2-5 min, and then performing hot extrusion deformation at the temperature of 400-410 ℃, wherein the extrusion ratio is (16-20): 1;

(5) carrying out T6 heat treatment on the composite material subjected to hot extrusion in the step (4) to obtain TiB₂The composite material is Al-Zn-Mg-Cu-Zr.

Reinforcing particles TiB in the composite material of the invention₂Fine and uniformly dispersed; the composite material has an ultrafine grain structure with uniform dispersion, the grain size range is 4-7 microns, and the average grain size is about 5 microns.

The invention prepares ultra-high strength and ultra-fine grain TiB₂The Al-Zn-Mg-Cu-Zr composite material is reinforced, the rapid solidification process and the hot extrusion process are optimized, and the segregation problem in the ingot casting of the endogenous particle reinforced aluminum matrix composite material is solved. TiB prepared by using ultrahigh-strength aluminum alloy as matrix₂In the/Al-Zn-Mg-Cu composite material, TiB₂The particles are dispersed and have small size, thereby providing guarantee for the performance of the ultra-high strength aluminum matrix composite material,compared with the base alloy, the strength is obviously improved. A

Drawings

FIG. 1 shows Al-TiB in example 1₂The microstructure of the master alloy.

FIG. 2 shows as-cast TiB in example 1₂The microstructure of the/Al-Zn-Mg-Cu composite material.

FIG. 3 shows TiB after Rapid solidification in example 1₂The microstructure of the/Al-Zn-Mg-Cu composite material.

FIG. 4 shows the rapid solidification of TiB in example 1₂And counting the grain size of the/Al-Zn-Mg-Cu composite material.

FIG. 5 shows TiB in hot-pressed state in example 1₂The microstructure of the/Al-Zn-Mg-Cu composite material.

Detailed Description

The present invention will be further illustrated with reference to the following examples, but the present invention is not limited to the following examples.

Example 1

Preparation of ultra-high strength and ultra-fine grain TiB₂The process of the/Al-Zn-Mg-Cu composite material is as follows:

(1) the proportion of the composite material is as follows: 5% of TiB₂10% Zn, 1.7% Mg, 1.0% Cu, 0.12% Zr, and the balance Al. Al-TiB₂The intermediate alloy consists of high-purity aluminum ingot, Al powder, Ti powder and TiO₂、H₃BO₃The preparation is carried out, wherein the molar ratio of Ti to B is 1:3.5, Al powder, Ti powder and TiO powder₂The mass ratio of the Al-Zn-Mg-Cu-Zr matrix is 2:2:3, and the Al-Zn-Mg-Cu-Zr matrix is prepared from pure aluminum ingots, pure zinc ingots, pure magnesium ingots, Al-50% of Cu and Al-4% of Zr intermediate alloy.

(2) Preparation of Al-TiB₂Intermediate alloy, weighing TiO according to the requirement₂、H₃BO₃Mixing the two powders, heating at 200 deg.C for 2 hr, and removing H₃BO₃Water content in (1). Heating the TiO₂And H₃BO₃Uniformly mixing the mixed powder with aluminum powder and titanium powder which are required to be weighed, placing the uniformly mixed powder into a die, and pressing to obtain the powder

The cylindrical powder cake of (1). And brushing a layer of coating on the mould and tools such as the slag spoon and the like to prevent Fe impurity element pollution. A graphite crucible is selected for smelting, and a graphite rod is used for stirring to prevent Si pollution. Heating the aluminum ingot to 800 ℃ by using a well-type resistance furnace, heating the melt to 900 ℃ after the aluminum ingot is completely melted, pressing a graphite bell jar into the block body in the step (3), uniformly stirring the graphite rod, and reacting for 10 min; standing for 5min after the reaction is finished, slagging off, and casting the aluminum melt into a mold to obtain Al-TiB₂Master alloy, as shown in fig. 1. Al-TiB₂Intermediate alloy of TiB₂The mass percentage of (B) is 10%.

(3) And (2) burdening the matrix components designed according to the step (1) by using pure aluminum ingots, pure zinc ingots, pure magnesium ingots, Al-50% of Cu and Al-4% of Zr intermediate alloy.

(4) Remelting the intermediate alloy obtained in the step (2) at 780 ℃, and adding a high-purity aluminum ingot, an Al-Cu intermediate alloy, an Al-Zr intermediate alloy and pure zinc in sequence. After the metal and the intermediate alloy are melted, removing floating slag on the surface of the melt, and adding pure magnesium when the temperature of the melt reaches 730 ℃. In order to uniformly distribute alloy elements, the melt is stirred and then refined, the refined melt is kept stand for 5min at 710 ℃, slag is removed, the melt is cast into a set mould, and a composite material ingot is obtained, wherein the microstructure of the composite material ingot is shown in figure 2.

(5) Cutting the composite material ingot obtained in the step (4) into blocks of 15mm × 15mm × 100mm, then adopting a rapid solidification (single-roller melt-spinning method) process, namely under the action of inert gas pressure, spraying the molten composite material ingot onto a 25m/s high-speed rotating copper roller, throwing the molten composite material ingot out, instantly condensing the molten composite material ingot to form an ultra-fine grain structure, and preparing TiB₂Reinforcing the composite material thin strip; as shown in fig. 3, the grain size statistics were performed thereon as shown in fig. 4. And (3) carrying out cold press molding on the spun composite material thin strip under the pressure of 700KN for 2min, carrying out hot extrusion deformation at the temperature of 410 ℃, wherein the extrusion ratio is 16:1, and the microstructure of the composite material thin strip is shown in figure 5.

(6) Carrying out T6 heat treatment (solid solution 460 ℃/2h, aging 120 ℃/24h) on the composite material subjected to hot extrusion in the step (5) to obtain 5% TiB₂The Al-Zn-Mg-Cu composite material.

Example 2

(1) The composite material comprises the following components in percentage by weight: 2% of TiB₂11% of Zn, 2.0% of Mg, 1.2% of Cu, 0.12% of Zr and the balance of Al. Al-TiB₂The intermediate alloy consists of high-purity aluminum ingot, Al powder, Ti powder and TiO₂、H₃BO₃The preparation is carried out, wherein the molar ratio of Ti to B is 1:3.5, Al powder, Ti powder and TiO powder₂The mass ratio of the aluminum ingot to the aluminum ingot is 2:2:3, and 2Kg of aluminum ingot. The Al-Zn-Mg-Cu-Zr matrix is prepared from pure aluminum ingots, pure zinc ingots, pure magnesium ingots, Al-50% Cu and Al-4% Zr intermediate alloy.

(2) Preparation of Al-TiB₂The master alloy was the same as in step (2) of example 1.

(3) And (2) mixing the matrix components designed in the step (1) by using pure aluminum ingots, pure zinc ingots, pure magnesium ingots, Al-50% of Cu and Al-4% of Zr intermediate alloy.

(4) Same as in step (4) in example 1.

(5) Same as in step (5) in example 1.

(6) Carrying out T6 heat treatment (solid solution 460 ℃/2h, aging 120 ℃/24h) on the composite material subjected to hot extrusion in the step (5) to obtain 2% TiB₂The Al-Zn-Mg-Cu composite material.

TiB prepared by the above method₂the/Al-Zn-Mg-Cu composite material has the advantages of ultrahigh strength, ultrafine crystal and the like.

Claims (3)

1. Ultrahigh-strength ultrafine-grained TiB₂The reinforced Al-Zn-Mg-Cu composite material is characterized in that: using Al-Zn-Mg-Cu-Zr alloy as matrix and TiB with average size less than 1 μm₂In order to strengthen the particles, the composite material comprises the following components in percentage by mass: 8-12%, Mg: 1.0-2.0%, Cu: 1.0-1.5%, Zr: 0.05-0.15%, TiB₂: 1-5% and the balance of Al.

2. The ultra-high strength ultra-fine grain TiB of claim 1₂The preparation method of the reinforced Al-Zn-Mg-Cu composite material is characterized in that a rapid solidification process is adopted to form ultra-fine grains, so that the matrix structure is more uniform; the method specifically comprises the following steps:

(1) with aluminiumIngot, Al powder, Ti powder, TiO₂、H₃BO₃The raw materials are Ti powder, Ti powder and TiO powder, wherein the molar ratio of Ti to B is (1.0-2.2) to (3.1-4.0)₂The mass ratio of (1.5-2.7) to (0.2-2.5) to (0.5-3.1), and a melt self-propagating direct synthesis method is adopted to prepare the Al-TiB with lower mass fraction and average size of less than 1 mu m₂An intermediate alloy; TiB₂The interface of the particles and the matrix is clean, and the bonding degree is high; Al-TiB₂Intermediate alloy of TiB₂The mass percentage content of the active ingredients is 8-20%;

(2) taking high-purity aluminum ingot, pure magnesium, pure zinc, Al-Cu and Al-Zr intermediate alloy as raw materials, and taking the Al-TiB prepared in the step (1)₂Taking the intermediate alloy as a matrix, smelting the alloy at 780 ℃, and casting at 730-750 ℃;

(3) cutting the composite material ingot cast in the step (2) into blocks of (12-16) mm × (12-16) mm × (100-150) mm, spraying the molten composite material ingot onto a copper roller rotating at a high speed and throwing the molten composite material ingot out under the action of inert gas pressure through a rapid solidification process, and instantly condensing the molten composite material ingot to form an ultra-fine grain structure to prepare TiB₂Reinforcing the composite material thin strip;

(4) performing cold press molding on the thrown composite material thin strip, such as applying pressure of 700KN, loading for 2-5 min, and then performing hot extrusion deformation at the temperature of 400-410 ℃, wherein the extrusion ratio is (16-20): 1;

(5) carrying out T6 heat treatment on the composite material subjected to hot extrusion in the step (4) to obtain TiB₂The composite material is Al-Zn-Mg-Cu-Zr.

3. The method of claim 2 wherein the composite material has a uniformly dispersed ultrafine grain structure with a grain size in the range of 4 to 7 microns and an average grain size of about 5 microns.

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