CN116479281A - An aluminum alloy profile with mixed crystal heterostructure characteristics and its preparation method - Google Patents

Abstract

The invention relates to the technical field of metal material preparation, in particular to an aluminum alloy section bar with a mixed crystal heterostructure characteristic and a preparation method thereof. The preparation method of the aluminum alloy section with the mixed crystal heterostructure characteristics comprises the following steps: smelting with pureAl, tiB-containing ₂ And TiC particles, and aluminum intermediate alloy and pure metal which are added for manufacturing different series of aluminum alloy sections are smelted at the temperature of 800-850 ℃; casting, namely casting the smelted alloy at the temperature of 720-750 ℃. The beneficial effects of the invention are as follows: the preparation method comprises the steps of adding a small amount of TiB in the preparation of the aluminum alloy ₂ And TiC particles, after hot extrusion and solution heat treatment, mixed grains containing coarse grains and fine grains can be prepared, the proportion of the coarse grains and the fine grains is adjustable and controllable, and the alloy with the characteristics of the mixed crystal heterostructure can synchronously improve the strength performance and the elongation of the aluminum alloy section.

Description

An aluminum alloy profile with mixed crystal heterostructure characteristics and its preparation method

technical field

The invention relates to the technical field of metal material preparation, in particular to an aluminum alloy profile with mixed crystal heterostructure characteristics and a preparation method.

Background technique

Aluminum alloy has the advantages of good electrical and thermal conductivity, high strength-to-mass ratio, corrosion resistance and damage resistance. It is widely used in aerospace, rail transit, automobiles, ships, pressure vessels, electronic appliances, furniture and many other fields. It is one of the most widely used metal materials in industry. In general, metal materials have an inverse relationship of "strength-plasticity", that is, increasing the strength of the material will be accompanied by a decrease in the plasticity of the material. Therefore, it is difficult to simultaneously improve the comprehensive mechanical properties of alloys through conventional means. In recent years, scholars at home and abroad have broken the previous design concept of "homogeneous" grain structure, designed and prepared some "heterostructure" metal materials with different sizes or even cross-scale grains, breaking through the strong plasticity limit of existing metal materials.

So far, there are still many bottlenecks in the batch preparation of aluminum alloy heterostructure materials. How to prepare heterostructure aluminum alloy profiles and make full use of the advantages of heterostructure to improve the comprehensive mechanical properties of aluminum alloy profiles is the key to realize its industrial application. At present, the main methods for preparing heterostructured metal materials are: (1) surface treatment (such as surface mechanical grinding treatment (SMGT), surface mechanical abrasion treatment (SMAT), shot peening, etc.), which only forms heterostructures in micro-domains on the material surface; (2 powder metallurgy, which is a general method for fabricating heterogeneous thin sheet structures and harmonic structure materials. (3) Additive manufacturing (AM), this technology can prepare heterogeneous materials with controllable structures and customized properties; (4) Mechanical thermal processing, such as asymmetric rolling (ASR) , cumulative seam welding (ARB), friction stir processing (FSP), etc. It can be seen that the existing reported methods for preparing heterogeneous metal materials are not suitable for large-scale batch production, and are not suitable for the preparation of alloy profiles.

However, the present invention discloses an aluminum alloy profile with mixed-crystal heterostructure characteristics and a preparation method, which can be tried for batch and large-scale industrial preparation.

Contents of the invention

Aiming at the technical problems in the prior art, the present invention provides an aluminum alloy profile with mixed crystal heterostructure characteristics and a preparation method to solve the problem that the aluminum alloy with heterostructure cannot be produced in batches and on a large scale.

The technical solution of the present invention to solve the above-mentioned technical problems is as follows: a method for preparing an aluminum alloy profile with mixed crystal heterostructure characteristics, comprising:

Melting, using pure Al, aluminum master alloys containing TiB ₂ and TiC particles, aluminum master alloys and pure metals required for the manufacture of different series of aluminum alloy profiles for melting at a temperature of 800-850 ° C;

Casting, casting the smelted alloy at a temperature of 720°C to 750°C to form an ingot;

Uniform heat treatment, heating the ingot to 450°C-560°C for 8 hours to 24 hours;

Hot extrusion, the ingot after uniform heat treatment is extruded at a temperature of 400°C to 450°C, according to the extrusion ratio: 20 to 60 and the extrusion speed: 0.5m to 10m/min;

Solution heat treatment, heat preservation at a temperature of 460°C to 570°C for 0.5 hours to 10 hours.

The beneficial effects of the present invention are:

1), the preparation method adds a small amount of _TiB2 and TiC particles to the aluminum alloy, and after hot extrusion and solution heat treatment, a mixed grain structure containing coarse and fine grains can be prepared, and the ratio of coarse and fine grains is adjustable and controllable, and the alloy with the characteristics of the mixed crystal heterostructure can simultaneously improve the strength performance and elongation of the aluminum alloy profile. The preparation method is not only simple and convenient, but also easy to batch and large-scale preparation.

On the basis of the above technical solutions, the present invention can also be improved as follows.

Further, the melting step of the alloy comprises:

S1, choose to contain TiB₂Aluminum master alloy (10wt%-50wt%) with TiC particles, aluminum master alloy and pure metal (7wt%-21wt%) required for the manufacture of different series of aluminum alloy profiles, and smelting raw materials with pure Al as the balance, and TiB-containing₂The aluminum master alloy with TiC particles, the aluminum master alloy that needs to be added for the manufacture of different series of aluminum alloy profiles, and pure Al are put into the melting furnace, which contains TiB₂The composition of the aluminum master alloy with TiC particles is: TiB₂And TiC particles (3wt% ~ 6wt%) and the rest are pure Al, while TiB₂The respective proportions of TiC particles are 2:5~1:1;

S2. Add inert gas protection when the temperature in the melting furnace reaches above 780°C;

S3, heating the temperature in the melting furnace to 800°C-850°C;

S4. After the alloy in the smelting furnace is completely melted, at least one pure metal whose melting point is lower than Al is immersed in the alloy melt;

S5, using a mixer to stir the pure metal and the alloy melt evenly;

S6. Melt purification process, performing refining degassing and slag removal in the smelting furnace.

Further, the aluminum master alloys required for the manufacture of different series of aluminum alloy profiles include Al-20Si, Al-50Cu, and Al-10Mn, and the metal element in S4 and S5 is Mg.

Furthermore, the aluminum master alloys required for the manufacture of different series of aluminum alloy profiles include Al-50Cu and Al-10Mn, and the metal element in S4 and S5 is Mg.

Further, the aluminum master alloys required for the manufacture of different series of aluminum alloy profiles include Al-50Cu and Al-5Cr, and the metal elements in S4 and S5 are Mg and Zn.

Further, the casting step of the alloy comprises:

S1', first lower the temperature of the alloy in the smelting furnace to 720°C to 750°C;

S2', using casting or semi-continuous casting to cast the melted alloy to form a round ingot.

Further, the uniform heat treatment includes putting the ingot into a heating furnace and heating it at 530°C to 560°C for 8 hours to 16 hours. The hot extrusion includes extruding the ingot after the uniform heat treatment through an extruder at a temperature of 400°C to 450°C at an extrusion ratio of 30 to 60 and an extrusion speed of 5m to 10m/min. The solution heat treatment includes a temperature of 550°C to 570°C for 0.5 to 10 hours.

Further, the uniform heat treatment includes putting the ingot into a heating furnace and heating it at 480°C to 530°C for 16 hours to 24 hours. The hot extrusion includes extruding the ingot after the uniform heat treatment through an extruder at a temperature of 400°C to 450°C at an extrusion ratio of 20 to 50 and an extrusion speed of 0.8m to 4m/min. The solution heat treatment includes a temperature of 500°C to 530°C for 0.5 to 10 hours.

Further, the uniform heat treatment includes putting the ingot into a heating furnace and heating it at 450°C to 470°C for 18 hours to 24 hours. The hot extrusion includes extruding the ingot after the uniform heat treatment through an extruder at a temperature of 400°C to 450°C at an extrusion ratio of 20 to 40 and an extrusion speed of 0.5m to 2m/min. The solution heat treatment includes a temperature of 460°C to 475°C for 0.5 to 10 hours.

An aluminum alloy profile with mixed crystal heterostructure features, the aluminum alloy profile has grains mixed with coarse grains and fine grains, wherein the distribution ratios of coarse grains and fine grains in the grains are different.

Furthermore, different proportions of coarse grains and fine grains in the grains can be obtained by adjusting the time of solution heat treatment.

Description of drawings

Fig. 1 is a schematic diagram of the overall structure of the present invention;

Fig. 2 is the EBSD grain morphology diagram of extruded heterogeneous aluminum alloy profiles modified by adding TiB ₂ -TiC particles according to the present invention;

Fig. 3 is the EBSD grain morphology diagram of the extruded conventional aluminum alloy profile after modification without addition of TiB ₂ -TiC particles in the present invention;

Fig. 4 is a comparison diagram of the tensile mechanical properties of extruded alloy profiles modified by adding TiB ₂ -TiC particles and those modified without adding TiB ₂ -TiC particles in the present invention;

Fig. 5 is a diagram of tensile mechanical properties of conventional aluminum alloy profiles in solid solution state after modification without addition of TiB ₂ -TiC particles in the present invention;

Fig. 6 is a diagram of tensile mechanical properties of solid solution heterogeneous aluminum alloy profiles modified by adding TiB ₂ -TiC particles in the present invention;

Fig. 7 is an EBSD grain morphology diagram of a solid-solution heterogeneous aluminum alloy profile modified by adding TiB ₂ -TiC particles in the present invention at 560°C for 1 hour when the ratio of coarse grains to fine grains is 1:3;

Fig. 8 is an EBSD grain morphology diagram of a solid-solution heterogeneous aluminum alloy profile modified by adding TiB ₂ -TiC particles in the present invention at 560°C for 1.5 hours in solid solution with a ratio of coarse grain to fine grain of 1:1;

Fig. 9 is an EBSD grain morphology diagram of a solid-solution heterogeneous aluminum alloy profile modified by adding TiB ₂ -TiC particles in the present invention at 560°C for 3 hours in solid solution with a ratio of coarse grain to fine grain of 2:1;

Fig. 10 is the EBSD grain morphology diagram of the solid solution state heterogeneous aluminum alloy profiles modified by adding TiB ₂ -TiC particles in the solid solution at 560°C for 10 hours for 10 hours;

Fig. 11 is a schematic diagram of the evolution of the microstructure of the alloy profile of the present invention after extrusion and solid solution.

Detailed ways

The principles and features of the present invention are described below in conjunction with the accompanying drawings, and the examples given are only used to explain the present invention, and are not intended to limit the scope of the present invention.

There are still many bottlenecks in the batch preparation of aluminum alloy heterostructure materials. How to prepare heterogeneous aluminum alloy profiles and make full use of the advantages of heterogeneous structures to improve the comprehensive mechanical properties of aluminum alloy profiles is the key to realize its industrial application. At present, the main methods for preparing heterostructured metal materials are: (1) surface treatment (such as surface mechanical grinding treatment (SMGT), surface mechanical abrasion treatment (SMAT), shot peening, etc.), which only forms heterostructures in micro-domains on the material surface; (2 powder metallurgy, which is a general method for fabricating heterogeneous thin sheet structures and harmonic structure materials. (3) Additive manufacturing (AM), this technology can prepare heterogeneous materials with controllable structures and customized properties; (4) Mechanical thermal processing, such as asymmetric rolling (ASR) , accumulative roll welding (ARB), friction stir processing (FSP), etc. It can be seen that the methods for preparing heterogeneous structure metal materials in the existing reports are not suitable for large-scale batch production, and are also not suitable for the preparation of alloy profiles. To this end, the inventor has proposed a kind of aluminum alloy profile with mixed crystal heterostructure characteristics and a preparation method to solve the above problems.

The present invention provides the following preferred embodiments

Example 1

As shown in Figures 1 to 10, a method for preparing an aluminum alloy profile with mixed crystal heterostructure characteristics includes:

S1, choose to contain TiB₂Aluminum master alloy ingots (10wt%~50wt%) and TiC particles (10wt%~50wt%), Al-20Si (4wt%~7wt%), Al-50Cu (0wt%~1wt%), Al-10Mn (2wt%~8wt%), Mg ingots (1.3wt%~1.8wt%) and the rest are raw materials for melting pure Al ingots, and will contain TiB₂Aluminum master alloy ingots with TiC particles, Al-20Si, Al-50Cu, Al-10Mn and pure Al ingots are put into the melting furnace (and the TiB added in this step₂and TiC granular aluminum master alloy ingot can refer to this patent CN113373367A), wherein, containing TiB₂The composition of the aluminum master alloy ingot with TiC particles is: TiB₂And TiC particles (3wt% ~ 6wt%) and the rest are pure Al, while TiB₂The respective proportions of TiC particles are 2:5 to 1:1 (the configuration ratio can be but not limited to 2.2:1, 2.0:1 and 1.8:1, etc.), and TiB₂Particles adopt sub-micron scale, and TiC particles adopt nanoscale;

(It should also be noted here that Al-50Cu and Al-10Mn respectively represent the master alloy ingot containing 50wt% Cu and the balance being pure Al, and the master alloy ingot containing 10wt% Mn and the balance being pure Al. A similar format will appear below to explain here. This is a common term used by those skilled in the art, and will not be repeated here.)

S2. When the temperature in the melting furnace reaches above 780°C, add inert gas argon to the melting furnace for protection;

S3, heating the temperature in the smelting furnace to 800°C-850°C (the wettability between the TiB ₂ and TiC particles and the aluminum matrix can be increased through the high temperature of 800°C-850°C);

S4. After the alloy in the smelting furnace is completely melted, immerse the Mg ingot into the alloy melt;

S5, using a mixer to stir the Mg ingot and the alloy melt evenly;

S6. Melt purification process, refining degassing and slag removal in the smelting furnace, wherein the final composition of the remaining alloy after smelting is Mg: 1.2wt-1.8wt%, Si: 0.8wt-1.4wt%, Mn: 0.2wt-0.8wt%, Cu: 0wt-0.5wt%, and TiB ₂ +TiC particles: 0.5wt-2.5wt%, and the rest is pure aluminum ingot;

S7. Lower the temperature of the alloy in the melting furnace to 720°C to 750°C (the melting furnace can be closed, and the temperature in the furnace is naturally cooled to 720°C to 750°C);

S8. Casting the molten alloy into round ingots using casting or semi-continuous casting;

S9. Uniform heat treatment, putting the round ingot into a heating furnace and heating at 530°C to 560°C for 8 hours to 16 hours;

S10, hot extrusion, extruding the uniformly heat-treated ingot through an extruder at a temperature of 400°C to 450°C, according to an extrusion ratio of 30 to 60 and an extrusion speed of 5m to 10m/min;

S11, solution heat treatment, heat preservation at a temperature of 550° C. to 570° C. for 0.5 hours to 10 hours.

In this example, the submicron _TiB2 and nanoscale TiC particles added in S1 effectively refine the solidification structure of the Al-Mg-Si-Cu alloy, making the average grain size from 74.7 μm to 51.6 μm, inhibiting the recrystallization of the alloy during the hot extrusion process, preventing the abnormal growth of the grains, and improving the stability of the Al-Mg-Si-Cu alloy structure during the hot extrusion process.

Therefore, in order to highlight the submicron TiB₂and the criticality of nano-scale TiC particles in the process of preparing aluminum alloy profiles with mixed crystal heterogeneous structure characteristics, the applicant provided two sets of comparative examples and four sets of experiments; (the comparative examples and experiments used all used the preparation of 6000 series aluminum alloy profiles as an example, that is, the 6000 series Al-Mg-Si-Cu aluminum alloy prepared in Example 1, and in order to characterize the structure and performance characteristics of aluminum alloy profiles, an optical microscope (model: Lecia DFC, standard: JB/T 7946-2017) was used to observe For the microstructure of the profile, use a micro Vickers hardness tester (model: Zwick/Roell ZHVμ, standard: GB/T 4340) to measure the hardness value of the profile, and use an electronic universal material testing machine (model: CMT 5105, standard: GB/T228.1) to obtain the tensile curve)

Wherein, the parameters and steps used in comparative examples and experiments are as follows:

Step 1. Put the aluminum master alloy ingot (2200g) containing submicron _TiB2 and nanoscale TiC particles, the master alloy ingot of Al-20Si (325g), Al-50Cu (30g), Al-10Mn (200g) and pure Al ingot (2175g) into the melting furnace, _{wherein the composition of the aluminum master alloy ingot containing TiB2 and TiC particles is: TiB2 and TiC particles (11g) and pure Al (2090g), and TiB 2 and TiC} particles (110g) each account for a ratio of 2:1;

Step 2. When the temperature in the melting furnace reaches 780°C, add inert gas argon to the melting furnace for protection;

Step 3, heating the temperature in the melting furnace to 840°C;

Step 4, after the alloy in the smelting furnace is completely melted, the Mg ingot (70g) is immersed in the alloy melt;

Step 5, using a mixer to stir the Mg ingot and the alloy melt evenly;

Step 6, the melt purification process, refining and degassing and slag removal in the smelting furnace, wherein the final composition of the remaining alloy after smelting is Mg: 1.3wt%, Si: 1.3wt%, Mn: 0.4wt%, Cu: 0.3wt%, and TiB ₂ +TiC particles: 2.2wt%, and the rest is pure Al ingot;

Step 7, cooling the temperature of the alloy in the smelting furnace to 730°C;

Step 8, casting the melted alloy into a round ingot by casting;

Step 9, uniform heat treatment, put the round ingot into the heating furnace and heat at 550°C for 10 hours;

Step 10, hot extrusion, extruding the uniformly heat-treated ingot through an extruder at a temperature of 450° C. according to an extrusion ratio of 35 and an extrusion speed of 8 m/min;

Step 11, solution heat treatment, heat preservation at a temperature of 560° C. for 0.5 hours to 10 hours.

Comparative example 1

As shown in Figure 4, it is a comparison chart of the yield strength, tensile _strength and elongation of the alloy without adding TiB ₂ and TiC particles and the alloy with TiB ₂ and TiC particles in step 1 of the preparation of 6000 series Al-Mg-Si-Cu aluminum alloy profiles after step ₂ to step 10; Alloys, the conventional alloys and heterogeneous alloys that appear below are all described here, and will not be repeated here)

Among them, the yield strength of the conventional alloy without adding _TiB2 and TiC particles and after the above steps 1 to 10 (extruded conventional alloy profile) is 105 (±5) MPa, the tensile strength is 225 (±4) MPa, and the elongation is 30.7%;

However, the yield strength of the heterogeneous alloy with added _{TiB2 and} TiC particles after the above steps ₁ to 10 (extruded heterogeneous alloy profile) is 148 (±5) MPa, tensile strength is 255 (±4) MPa, and elongation is 12.7 (±0.5)%. The garment strength and tensile strength have been increased by 41% and 13% respectively, and the elongation after breaking has remained at a good 12.5%. (在此还需说明的是：挤压态异质合金型材为添加TiB ₂和TiC颗粒的异质合金经过步骤1～步骤10后所制成具有异质结构的6000系Al-Mg-Si-Cu铝合金型材，挤压态常规合金型材为没有添加TiB ₂和TiC颗粒的常规合金经过步骤1～步骤10后所制成常规的6000系Al-Mg-Si-Cu铝合金型材，而固溶态异质合金型材为添加TiB ₂和TiC颗粒的异质合金经过步骤1～步骤11后所制成具有异质结构的6000系Al-Mg-Si-Cu铝合金型材，固溶态常规合金型材为没有添加TiB ₂和TiC颗粒的常规合金后经过步骤1～步骤11后所制成常规的6000系Al-Mg-Si-Cu铝合金型材)

Comparative example 2

Using the same parameter steps as those used in Step 1 to Step 10 in Comparative Example 1, as shown in Figure 5, the 6000-series Al-Mg-Si-Cu aluminum alloy profile is prepared. In the process of Step 1, the conventional alloy without TiB ₂ and TiC particles has gone through Step 2 to Step 10, and in the solution heat treatment of Step 11, the holding temperature is set at 560 ° C, and the solution heat treatment time is respectively 1h, 1.5h, 3h, and 10h. The line chart of yield strength, tensile strength and elongation;

Among them, the yield strength of conventional alloys after solution heat for 1 hour: 104MPa, tensile strength: 232MPa, elongation: 25.2%;

Yield strength: 100MPa, tensile strength: 230MPa, elongation: 27.2% for conventional alloys after solution heat for 1.5h;

Yield strength: 101MPa, tensile strength: 232MPa, elongation: 22.2% for conventional alloys after solution heat for 3 hours;

Yield strength: 95MPa, tensile strength: 226MPa, elongation: 23.3% of conventional alloy after solution heat for 10h.

As shown in Figure 6, in the process of preparing 6000 series Al-Mg-Si-Cu aluminum alloy profiles in step 1, the heterogeneous alloy with TiB2 and TiC particles has gone through steps 2 to 10, and in step 11 during the solution heat treatment process, the holding temperature is set at 560 ° C, and the solution heat treatment time is 1h, 1.5h, 3h, and 10h respectively.

Among them, the yield strength of the heterogeneous alloy after solution heat for 1 hour: 174MPa, tensile strength: 293MPa, elongation: 13.5%;

Yield strength of heterogeneous alloy after solution heat for 1.5h: 180MPa, tensile strength: 303MPa, elongation: 15.0%;

Yield strength of heterogeneous alloys after solution heat for 3 hours: 227MPa, tensile strength: 345MPa, elongation: 12.0%;

Yield strength: 163MPa, tensile strength: 288MPa, elongation: 15.2% for heterogeneous alloy after solution heat for 10h;

Please refer to Figure 4 and Figure 6. After the heterogeneous alloys with added TiB ₂ and TiC particles have gone through steps 1 to 10 and steps 1 to 11 respectively, the structure of the alloy profile after step 11 has reached a specific heterogeneous structure feature, that is, the proportion distribution of coarse grains and fine grains in the grains is different, and when the heterogeneous alloy is solution heat treated for 3 hours. The profile is increased by 35% and 53% respectively without loss of elongation, and its performance is close to the peak aging strength of the conventional alloy profile with the same composition;

In addition, please refer to Figure 5 and Figure 6, the heterogeneous alloy with TiB ₂ and TiC particles after step 1 to step 11, compared with the conventional alloy without TiB ₂ and TiC particles after step 1 to 11, when the heat preservation temperature is set at 560°C in step 11, the solution heat treatment time is 1h, 1.5h, 3h, and 10h respectively, and its yield strength and tensile strength are increased by 67% and 26% respectively , 80% and 32%, 125% and 49%, 71% and 27%, and the elongation rate remained above 12% on average. (St in Figure 5 represents a conventional alloy without _TiB2 and TiC particles, CF in Figure 6 represents a heterogeneous alloy with _TiB2 and TiC particles added, and the following numbers represent the ratio of fine grains to coarse grains after solution heat treatment for different lengths of time)

In order to verify that the structure of the alloy profile achieves specific heterogeneous structure characteristics, that is, the influence of the different ratio distribution of coarse grains and fine grains in the grains on the yield strength, tensile strength, and elongation of the alloy profile, the applicant provided four sets of experiments;

Experiment 1

Please refer to Figure 6 and Figure 7. This experiment uses the same preparation steps and parameters as those in Comparative Example 2. After adding TiB ₂ and TiC particles, the heterogeneous alloy undergoes steps 1 to 10. The difference is that in this experiment, the set holding temperature of Step 11 is 560 ° C, and the solution heat treatment time is 1 hour. The ratio of coarse grains to fine grains in the alloy profile is 1:3 according to the EBSD grain morphology analysis, and the yield strength is 174 MPa, and the tensile strength is 293 MPa. Elongation: 13.5%;

Experiment 2

Please refer to Figure 6 and Figure 8. This experiment adopts the same preparation steps and parameters as in Comparative Example 2 after adding TiB ₂ and TiC particles, and the heterogeneous alloy undergoes steps 1 to 11. The difference is that in this experiment, the set holding temperature of S11 is 560°C, and the solution heat treatment time is 1.5h. The ratio of coarse grains to fine grains in the alloy profile is 1:1 according to the EBSD grain morphology analysis, and the yield strength is 180MPa, and the tensile strength is 303MPa a. Elongation: 15.0%;

Experiment 3

Please refer to Figure 6 and Figure 9. This experiment adopts the same preparation steps and parameters as in Comparative Example 2 after adding TiB ₂ and TiC particles, and the heterogeneous alloy undergoes steps 1 to 10. The difference is that in this experiment, the set holding temperature of S11 is 560 ° C, and the solution heat treatment time is 3 hours. The ratio of coarse grains to fine grains in the alloy profile is 2:1 according to the EBSD grain morphology analysis, and the yield strength is 227 MPa, and the tensile strength is 345 MPa. Elongation: 12.0%;

Experiment 4

Please refer to Figure 6 and Figure 10. This experiment adopts the same preparation steps and parameters as in Comparative Example 2 after adding TiB ₂ and TiC particles, and the heterogeneous alloy undergoes steps 1 to 10. The difference is that in this experiment, the set holding temperature of S11 is 560°C, and the solution heat treatment time is 10 hours. The ratio of coarse grains to fine grains in the alloy profile is 3:1 according to the EBSD grain morphology analysis, and the yield strength is 163MPa, and the tensile strength is 288MPa a. Elongation: 15.2%;

Please refer to Figure 11 (in Figure 11, under the same preparation steps and parameters as the experiment, A row is not added TiB₂The schematic diagram of the microstructure evolution of the conventional alloy with TiC particles after extrusion and solution heat for 1h, 3h and 10h respectively, and row B is the schematic diagram of the microstructure evolution of heterogeneous alloys with TiB2 and TiC particles after extrusion and solution heat for 1h, 3h and 10h respectively). Therefore, after the above comparative examples and experimental analysis: adding a small amount of TiB in the process of preparing aluminum alloy₂and TiC particles, making TiB₂TiC and TiC particles are distributed in a discontinuous layer in the matrix. Except for the particles in the matrix, most of the particles gather along the extrusion direction. This particle distribution leads to the formation of particle-enriched areas and particle-sparse areas. These non-uniformly distributed particles are the prerequisite for the heterogeneous grain crystallization of the aluminum alloy profile in subsequent heat treatment, and the particles lead to the uneven flow of the alloy during hot extrusion, so that most of the as-cast grains are broken into fine equiaxed grains. , the sliding and migration of grain boundaries are hindered, recrystallization is inhibited, and the growth of grains is effectively prevented. After solution heat treatment, the particles in the enriched area have a strong pinning effect, and the driving force of solution heat treatment is not enough to activate extensive recrystallization.

On the other hand, the grains undergoing severe plastic deformation have a higher tendency of abnormal grain growth at high temperature. During the solution heat treatment, the grains in the grain-sparse region experienced more severe extrusion deformation, and the grains grew abnormally, forming an alloy profile with a heterogeneous structure.

Combining with comparative examples and experiments, it is concluded that with the increase of solid solution time, the content of coarse grains in the heterogeneous structure increases and the content of fine grains decreases. Heterogeneous structures with different coarse/fine grain ratios can be obtained by adjusting the solution heat treatment time, so as to produce aluminum alloys with different properties and the same heterogeneous structure, which can be used in more fields and purposes, and has strong practicability, especially when adding TiB₂After steps 1 to 11 of the heterogeneous alloy with TiC particles, the solid solution heterogeneous alloy profile produced is set at 560°C in step 11, and the solution heat treatment time is 3 hours. When the ratio of coarse grains to fine grains in the alloy profile is 2:1 according to the EBSD grain morphology analysis, the yield strength increases by 125%, the tensile strength increases by 49%, and maintains good elongation. It has better comprehensive mechanical properties.

Example 2

Compared with Example 1, this Example 2 prepared a 2000-series Al-Cu-Mg aluminum alloy profile, and the specific preparation steps included:

S1', choose to contain TiB₂Aluminum master alloy ingots (10wt%-50wt%) and TiC particles, Al-50Cu (7.6wt%-9.8wt%), Al-10Mn (3wt%-9wt%), Mg ingots (1.3wt%-1.8wt%) and the balance are smelted raw materials for pure Al ingots, and will contain TiB₂Aluminum master alloy ingots with TiC particles, Al-50Cu, Al-10Mn and pure Al ingots are put into the melting furnace, which contains TiB₂The composition of the aluminum master alloy ingot with TiC particles is: TiB₂And TiC particles (3wt% ~ 6wt%) and the rest are pure Al, while TiB₂The respective proportions of TiC particles are 2:5 to 1:1 (the configuration ratio can be but not limited to 2.2:1, 2.0:1 and 1.8:1, etc.);

S2', when the temperature in the melting furnace reaches above 780°C, add inert gas argon for protection;

S3', heating the temperature in the smelting furnace to 800°C-850°C;

S4', after the alloy in the smelting furnace is completely melted, the Mg ingot is added to the melt;

S5', using a mixer to stir the Mg ingot and the alloy evenly;

S6', the melt purification process, refining degassing and slag removal in the smelting furnace, wherein the remaining alloy components after smelting are Mg: 1.2wt-1.8wt%, Mn: 0.3wt-0.9wt%, Cu: 3.8wt-4.9wt%, and TiB ₂ +TiC particles: 0.5wt-2.5wt%, and the rest is pure Al ingot;

S7', cooling the temperature of the alloy in the melting furnace to 720°C to 750°C (the melting furnace can be closed, and the temperature in the furnace is naturally cooled to 720°C to 750°C);

S8', using casting or semi-continuous casting to cast the molten alloy into a round ingot;

S9', uniform heat treatment, put the round ingot into a heating furnace and heat it at 480°C to 530°C for 16 hours to 24 hours;

S10', hot extrusion, extruding the uniformly heat-treated ingot through an extruder at a temperature of 400°C to 450°C according to an extrusion ratio of 20 to 50 and an extrusion speed of 0.8m to 4m/min;

S11', solution heat treatment, heat preservation at a temperature of 500°C to 530°C for 0.5 hours to 10 hours.

Example 3

Compared with Example 1, this Example 3 prepared a 7000 series Al-Zn-Mg-Cu aluminum alloy profile, and the specific preparation steps included:

S1", choose to contain TiB₂Aluminum master alloy ingots (10wt%-50wt%) and TiC particles, Al-50Cu (0wt%-4wt%), Al-5Cr (1wt%-5wt%), Mg ingots (2wt%-3wt%), Zn ingots (5wt%-7wt%) and the balance of pure Al ingots are put into the melting furnace, wherein TiB₂The composition of the aluminum master alloy ingot with TiC particles is: TiB₂And TiC particles (3wt% ~ 6wt%) and the rest are pure Al, while TiB₂The respective proportions of TiC particles are 2:5~1:1 (the configuration ratio can be but not limited to 2.2:1, 2.0:1 and 1.8:1, etc.);

S2", when the temperature in the melting furnace reaches above 780°C, add inert gas argon for protection;

S3", heating the temperature in the melting furnace to 800°C-850°C;

S4", after the alloy in the smelting furnace is completely melted, immerse the Mg ingot and the Zn ingot in the melt;

S5", using a mixer to stir the Mg ingot, Zn ingot and alloy evenly;

S6", melt purification process, refining degassing and slag removal in the smelting furnace, wherein the final composition of the remaining alloy after smelting is Mg: 2.0wt-3.0wt%, Zn: 5.0wt-7.0wt%, Cu: 0wt-2wt%, Cr: 0.05wt-0.25%, and TiB ₂ +TiC particles: 0.5wt-2.5wt%, and the rest is pure Al ingot;

S7", the temperature of the alloy in the melting furnace is lowered to 720°C-750°C (the melting furnace can be closed, and the temperature in the furnace is naturally cooled to 720°C-750°C);

S8", using casting or semi-continuous casting to cast the molten alloy into round ingots;

S9", uniform heat treatment, put the round ingot into the heating furnace and heat it at 450 ° C ~ 470 ° C for 18 hours to 24 hours;

S10", hot extrusion, the round ingot after uniform heat treatment is extruded through the extruder at a temperature of 400°C-450°C, according to the extrusion ratio: 20-40 and extrusion speed: 0.5m-2m/min;

S11", solution heat treatment, heat preservation at a temperature of 460°C to 475°C for 0.5 hours to 10 hours.

The above descriptions are only preferred embodiments of the present invention, and are not intended to limit the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present invention shall be included within the protection scope of the present invention.

Claims (11)

1. A method for preparing an aluminum alloy profile with mixed crystal heterostructure characteristics, characterized in that it comprises: Melting, using pure Al, aluminum master alloys containing TiB ₂ and TiC particles, aluminum master alloys and pure metals required for the manufacture of different series of aluminum alloy profiles for melting at a temperature of 800-850 ° C; Casting, casting the smelted alloy at a temperature of 720°C to 750°C to form an ingot; Uniform heat treatment, heating the ingot to 450°C-560°C for 8 hours to 24 hours; Hot extrusion, the ingot after uniform heat treatment is extruded at a temperature of 400°C to 450°C, according to the extrusion ratio: 20 to 60 and the extrusion speed: 0.5m to 10m/min; Solution heat treatment, heat preservation at a temperature of 460°C to 570°C for 0.5 hours to 10 hours. 2. A method for preparing an aluminum alloy profile with mixed crystal heterostructure characteristics according to claim 1, wherein the step of melting the alloy comprises: S1, choose to contain TiB₂Aluminum master alloy (10wt%-50wt%) with TiC particles, aluminum master alloy and pure metal (7wt%-21wt%) required for the manufacture of different series of aluminum alloy profiles, and smelting raw materials with pure Al as the balance, and TiB-containing₂The aluminum master alloy with TiC particles, the aluminum master alloy that needs to be added for the manufacture of different series of aluminum alloy profiles, and pure Al are put into the melting furnace, which contains TiB₂The composition of the aluminum master alloy with TiC particles is: TiB₂And TiC particles (3wt% ~ 6wt%) and the rest are pure Al, while TiB₂The respective proportions of TiC particles are 2:5~1:1; S2. Add inert gas protection when the temperature in the melting furnace reaches above 780°C; S3, heating the temperature in the melting furnace to 800°C-850°C; S4. After the alloy in the smelting furnace is completely melted, at least one pure metal whose melting point is lower than Al is immersed in the alloy melt; S5, using a mixer to stir the pure metal and the alloy melt evenly; S6. Melt purification process, performing refining degassing and slag removal in the smelting furnace. 3. A method for preparing aluminum alloy profiles with mixed crystal heterostructure characteristics according to claim 2, characterized in that, the aluminum master alloys to be added for the manufacture of different series of aluminum alloy profiles include Al-20Si, Al-50Cu, Al-10Mn, and the pure metal in S4 and S5 is Mg. 4. A method for preparing aluminum alloy profiles with mixed crystal heterostructure characteristics according to claim 2, characterized in that the aluminum master alloys added for the manufacture of different series of aluminum alloy profiles include Al-50Cu and Al-10Mn, and the pure metal in S4 and S5 is Mg. 5. A method for preparing aluminum alloy profiles with mixed crystal heterostructure characteristics according to claim 2, characterized in that the aluminum master alloys added for the manufacture of different series of aluminum alloy profiles include Al-50Cu and Al-5Cr, and the pure metals in S4 and S5 are Mg and Zn. 6. A method for preparing an aluminum alloy profile with mixed crystal heterostructure characteristics according to claim 1, wherein the casting step of the alloy comprises: S1', first lower the temperature of the alloy in the smelting furnace to 720°C to 750°C; S2', using casting or semi-continuous casting to cast the melted alloy to form a round ingot. 7. The method for preparing an aluminum alloy profile with mixed crystal heterogeneous structure according to claim 3, wherein the uniform heat treatment includes putting the ingot into a heating furnace and heating it at 530°C to 560°C for 8 hours to 16 hours, and the hot extrusion includes extruding the ingot after the uniform heat treatment through an extrusion machine at a temperature of 400°C to 450°C according to an extrusion ratio of 30 to 60 and an extrusion speed of 5m to 10m/min, and the solution heat treatment includes Continue at a temperature of 550° C. to 570° C. for 0.5 hours to 10 hours. 8. The method for preparing an aluminum alloy profile with mixed crystal heterogeneous structure according to claim 4, wherein the uniform heat treatment includes putting the ingot into a heating furnace and heating it at 480°C-530°C for 16 hours to 24 hours, and the hot extrusion includes extruding the uniformly heat-treated ingot through an extrusion machine at a temperature of 400°C-450°C according to an extrusion ratio: 20-50 and an extrusion speed: 0.8m-4m/min. The treatment includes a temperature of 500°C to 530°C for 0.5 hours to 10 hours. 9. A method for preparing an aluminum alloy profile with mixed crystal heterogeneous structure according to claim 5, wherein said uniform heat treatment includes putting the ingot into a heating furnace and heating it at 450°C-470°C for 18 hours to 24 hours, said hot extrusion includes extruding the uniformly heat-treated ingot through an extrusion machine at a temperature of 400°C-450°C according to an extrusion ratio: 20-40 and an extrusion speed: 0.5m-2m/min. The treatment includes a temperature of 460°C to 475°C for 0.5 hours to 10 hours. 10. An aluminum alloy profile with mixed crystal heterogeneous structure, made by the method according to any one of claims 1 to 9, characterized in that the aluminum alloy profile has grains mixed with coarse grains and fine grains. 11. An aluminum alloy profile with mixed crystal heterostructure characteristics according to claim 10, wherein different proportions of coarse grains and fine grains in grains can be obtained by adjusting the time of solution heat treatment.