Nanophase reinforced aluminum-based composite material and preparation method thereof

Abstract

The invention provides a preparation method of a nanophase reinforced aluminum matrix composite, and relates to the technical field of metal matrix composites.The preparation method comprises the following steps that nanophase powder and aluminum raw material powder are subjected to ball milling and mixing, and composite powder is obtained; sintering the composite material powder to obtain a billet; and the billet is sequentially subjected to thermal deformation treatment, warm deformation treatment and aftertreatment, and the nanophase reinforced aluminum matrix composite is obtained. Based on the method, the nanophase is pre-dispersed through ball-milling mixing, distortion energy is increased through thermal deformation treatment, so that grain boundary migration is excited, the high-proportion nanophase is promoted to enter the crystal, a large number of exogenous dislocations are introduced into the crystal through thermal deformation treatment, and therefore the defect that the number of intragranular movable dislocations excited by a reinforced phase (nanophase) is limited is overcome; the improvement of the plasticity and toughness of the composite material is promoted.

Description

Technical Field

[0001] The present invention belongs to the technical field of metal matrix composite materials, and in particular relates to a nano-phase reinforced aluminum matrix composite material and a preparation method thereof. Background Art

[0002] Nanophase-reinforced aluminum-matrix composites (AMCs) achieve a significant increase in strength with the addition of only a small amount of nanoparticles, and their machinability is significantly improved compared to AMCs reinforced with micron-particles. In recent years, AMCs, which combine high strength with good machinability, have become a popular candidate for future engineering applications.

[0003] However, nanophase reinforced aluminum matrix composites have the disadvantage of insufficient plasticity and toughness. This is mainly because the nanophase is easy to agglomerate at the grain boundaries, and the stress concentration during deformation can easily induce intergranular brittle fracture.

[0004] Some studies have used in-situ reactions or pre-high-energy ball milling to introduce nanophases into the crystals, triggering the proliferation of mobile dislocations within the crystals. This can, to a certain extent, improve the coordinated deformation between grain boundaries and within the crystals, thereby enhancing plasticity and toughness. However, the ability of intracrystalline nanophases to increase mobile dislocations is limited, so nanophase-reinforced aluminum-based composites still suffer from insufficient plasticity and toughness. Summary of the Invention

[0005] Therefore, the present invention provides a nano-phase reinforced aluminum-based composite material and a preparation method thereof, which can solve the problem of insufficient plasticity and toughness of the nano-phase reinforced aluminum-based composite material in the prior art.

[0006] In order to solve the above problems, the present invention provides a method for preparing a nanophase reinforced aluminum-based composite material, comprising the following steps:

[0007] Step 1): ball-milling the nanophase powder and the aluminum raw material powder to obtain a composite material powder;

[0008] Step 2): sintering the composite material powder to obtain an ingot;

[0009] Step 3): performing hot deformation treatment, warm deformation treatment and post-treatment on the ingot in sequence to obtain a nano-phase reinforced aluminum-based composite material;

[0010] The nanophase is caused to migrate into the crystal by the thermal deformation treatment; and exogenous dislocations are introduced into the crystal by the warm deformation treatment.

[0011] Furthermore, in step 1):

[0012] The average particle size of the nanophase powder is 10-100 nm; and / or

[0013] The average particle size of the aluminum raw material powder is 0.1-200 μm.

[0014] Furthermore, in step 1):

[0015] The aluminum raw material powder is pure aluminum powder and / or aluminum alloy powder;

[0016] Preferably, the aluminum content in the aluminum raw material powder is greater than 85wt%;

[0017] Preferably, the aluminum raw material powder is one or more of 2 series aluminum alloy powder, 5 series aluminum alloy powder, 6 series aluminum alloy powder, and 7 series aluminum alloy powder.

[0018] Furthermore, in step 1):

[0019] The mixture is ball-milled in an inert gas using a high-energy ball mill; preferably, the inert gas is argon; and the rotation speed of the high-energy ball mill is 200-400 rpm;

[0020] The ball-to-material weight ratio during ball milling is 5:1-30:1; and / or

[0021] The ball milling time is 6-20h; and / or

[0022] The total mass of the aluminum raw material powder and the nano-phase powder is a, and the mass of the nano-phase powder is b, wherein the mass fraction of b in a is 0.5-8.5 wt.%.

[0023] Furthermore, in step 2):

[0024] The sintering process adopts one of hot pressing sintering, hot isostatic pressing sintering and spark plasma sintering;

[0025] Preferably, the hot pressing sintering or hot isostatic pressing sintering adopts pressure sintering; wherein the sintering temperature is 350-630°C, the holding time is 1-4 hours, and the pressure is 20-100 MPa;

[0026] Preferably, the spark plasma sintering adopts pressureless sintering; wherein, the sintering temperature is 600-700° C., and the heat preservation time is 1-4 hours.

[0027] Furthermore, in step 3):

[0028] The temperature of the thermal deformation treatment is 350-550°C; and / or

[0029] The thermal deformation treatment method is one of extrusion, forging and rolling;

[0030] Preferably, when the thermal deformation treatment adopts extrusion, the nominal extrusion ratio is ≥7:1;

[0031] Preferably, when the thermal deformation treatment is performed by rolling, the nominal rolling ratio is ≥60%.

[0032] Furthermore, the volume of the nanophase in the crystal after the thermal deformation treatment in step 3) is a, and the volume of the nanophase powder in the composite material powder in step 1) is b, a / b.

[0033] Furthermore, in step 3):

[0034] The temperature of the warm deformation treatment is 200-300°C; and / or

[0035] The deformation amount of the warm deformation treatment is 5%-9%; and / or

[0036] The warm deformation treatment is performed by one of extrusion, forging and rolling;

[0037] Preferably, when the warm deformation treatment is performed by rolling, the nominal rolling ratio is ≤9%.

[0038] Furthermore, in step 3):

[0039] The post-treatment includes solution treatment and aging treatment;

[0040] Preferably, the temperature of the solution treatment is 450-550°C and the time is 1-4 hours;

[0041] Preferably, the aging treatment time is 5-120h;

[0042] Preferably, the aging treatment adopts natural aging or artificial aging; wherein, when artificial aging treatment is adopted, the temperature is 100-200°C.

[0043] In another aspect, the present invention provides a nano-phase reinforced aluminum-based composite material, wherein the dislocation density in the nano-phase reinforced aluminum-based composite material is ≥10 15 m -2 ;

[0044] Preferably, the nanophase reinforced aluminum-based composite material is prepared by any of the above preparation methods.

[0045] The nano-phase reinforced aluminum-based composite material and its preparation method provided by the present invention have the following beneficial effects:

[0046] 1. On the one hand, the present invention provides a method for preparing a nanophase reinforced aluminum-based composite material, which comprises the following steps: ball-milling and mixing nanophase powder and aluminum raw material powder to obtain composite material powder; sintering the composite material powder to obtain an ingot; and sequentially performing thermal deformation, warm deformation and post-treatment on the ingot to obtain a nanophase reinforced aluminum-based composite material; based on the above method, the nanophase is pre-dispersed by ball milling, and then the distortion energy is increased by thermal deformation, thereby stimulating grain boundary migration and promoting a high proportion of nanophase to enter the crystal; then, through warm deformation, after the nanophase is internalized, it presents a certain interface mismatch with the matrix; after the warm deformation, local plastic mismatch occurs, forming dislocations, prompting the introduction of a large number of exogenous dislocations into the crystal, thereby compensating for the deficiency of the limited number of mobile dislocations in the crystal stimulated by the reinforcing phase (nanophase), and promoting the improvement of the plastic toughness of the composite material.

[0047] 2. Furthermore, the present invention increases the ball milling efficiency by mixing the nanophase powder with the aluminum raw material powder in a high-energy ball mill and controlling the particle size of the nanophase powder, the particle size of the aluminum matrix powder, the ball-to-material ratio, and the proportion of the nanophase powder in the mixed powder, so that the nanophase powder can obtain a better pre-dispersion effect in the aluminum raw material powder.

[0048] 3. In another aspect, the present invention provides a nano-phase reinforced aluminum-based composite material prepared by any of the above-mentioned preparation methods, wherein the dislocation density in the nano-phase reinforced aluminum-based composite material is ≥10 15 m -2 . BRIEF DESCRIPTION OF THE DRAWINGS

[0049] To more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for the embodiments or the description of the prior art. The drawings described below are merely exemplary. Those skilled in the art can, without inventive effort, derive other implementation drawings based on the provided drawings.

[0050] Figure 1 Schematic diagram of the microstructure of the nano-phase reinforced aluminum-based composite material of the present invention;

[0051] Figure 2 middle: Figure 2 (a) is a schematic diagram of the microstructure of the nano-alumina reinforced aluminum-based composite material according to Example 1 of the present invention; Figure 2 (bc) is a schematic diagram of the microstructure of the nano-alumina reinforced aluminum matrix composite material of Comparative Example 1;

[0052] Figure 3 middle: Figure 3 (a) is a schematic diagram of the microstructure of the carbon nanotube-reinforced aluminum-based composite material according to Example 2 of the present invention; Figure 3 (bc) is a schematic diagram of the microstructure of the carbon nanotube reinforced aluminum matrix composite material of Example 3. DETAILED DESCRIPTION

[0053] The following will be combined with the accompanying drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the embodiments described are only part of the embodiments of the present invention, rather than all the embodiments. The following description of at least one exemplary embodiment is actually only illustrative and is in no way intended to limit the present invention and its application or use. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0054] The present invention provides a method for preparing a nano-phase reinforced aluminum-based composite material, comprising the following steps:

[0055] Step 1): In an inert gas atmosphere, the nanophase powder and the aluminum raw material powder are ball-milled and mixed using a high-energy ball mill to obtain a composite material powder;

[0056] Among them, the average particle size of the nanophase powder is 10-100nm; the average particle size of the aluminum raw material powder is 0.1-200μm; the aluminum raw material powder is pure aluminum powder and / or aluminum alloy powder; the aluminum content in the aluminum raw material powder is greater than 85wt%; the aluminum raw material powder is one or more of 2 series aluminum alloy powder, 5 series aluminum alloy powder, 6 series aluminum alloy powder, and 7 series aluminum alloy powder; argon is used as the inert gas; the ball-to-material weight ratio during ball milling mixing is 5:1-30:1; the ball milling mixing time is 6-20h; the speed of the high-energy ball mill is 200-400rpm; the total mass of the aluminum raw material powder and the nanophase powder is a, the mass of the nanophase powder is b, and the mass fraction of b in a is 0.5-8.5wt.%.

[0057] Step 2): sintering the composite material powder to obtain an ingot;

[0058] Among them, the sintering treatment adopts one of hot pressing sintering, hot isostatic pressing sintering, and spark plasma sintering; hot pressing sintering or hot isostatic pressing sintering adopts pressure sintering; among them, the sintering temperature is 350-630℃, the holding time is 1-4 hours, and the pressure is 20-100MPa; spark plasma sintering can adopt pressure sintering or pressureless sintering; among them, when using pressureless sintering, the sintering temperature is 600-700℃, and the holding time is 1-4 hours.

[0059] Step 3): performing hot deformation treatment, warm deformation treatment, solution treatment and aging treatment on the ingot in sequence to obtain a nanophase reinforced aluminum matrix composite material;

[0060] Among them, the temperature of hot deformation treatment is 350-550℃; the method of hot deformation treatment is one of extrusion, forging and rolling; when extrusion is adopted, the nominal extrusion ratio is ≥7:1; when rolling is adopted, the nominal rolling rate is ≥60%; the temperature of warm deformation treatment is 200-300℃; the deformation amount of warm deformation treatment is 5%-9%; the method of warm deformation treatment is one of extrusion, forging and rolling; when rolling is adopted, the nominal rolling rate is ≤9%; the temperature of solid solution treatment is 450-550℃, the time is 1-4h; the time of aging treatment is 5-120h; natural aging or artificial aging can be adopted; when artificial aging treatment is adopted, the temperature is 100-200℃, the temperature of aging treatment is 100-200℃, and the time is 5-120h. Among them, selecting this deformation range for warm deformation treatment can ensure that more exogenous dislocations are introduced without causing material structural defects; specifically, too small a deformation amount will lead to insufficient number of intracrystalline dislocations, and the effect of improving plasticity and toughness will not be significant; too large a deformation amount will cause structural defects and deteriorate the overall performance.

[0061] Based on the above method, the nanophase is pre-dispersed by ball milling and sintering to obtain an ingot. The nanophase in the ingot is mainly distributed near the grain boundaries. The distortion energy is increased by thermal deformation, thereby stimulating grain boundary migration and promoting a high proportion of nanophase to enter the crystal. Then, through warm deformation, a local plastic mismatch occurs between the intracrystalline nanophase and the matrix, thereby introducing a large number of exogenous dislocations into the crystal, thereby compensating for the limited number of mobile dislocations stimulated by the reinforcing phase (nanophase) within the crystal, and promoting the improvement of the plastic toughness of the composite material. In the present invention, the volume fraction of the intracrystalline nanophase after thermal deformation treatment accounts for ≥50% of the total added amount.

[0062] In the present invention, exogenous dislocations refer to dislocations introduced from outside the crystal by specific plastic deformation, as opposed to dislocations formed inside the crystal (intrinsic dislocations).

[0063] By mixing the nanophase powder with the aluminum raw material powder in a high-energy ball mill and controlling the particle size of the nanophase powder, the particle size of the aluminum matrix powder, the ball-to-material ratio, and the proportion of the nanophase powder in the mixed powder, the ball milling efficiency is increased, and the nanophase powder is better pre-dispersed in the aluminum raw material powder.

[0064] Pressure sintering can increase the density of the billet with the aid of pressure. The present invention can employ both pressure sintering and pressureless sintering in spark plasma sintering. Pressureless sintering relies entirely on thermal diffusion to achieve interfacial bonding between powders. While its degree of densification is slightly lower than that of pressure sintering, this method can produce multiple billets in a single sintering process, resulting in higher production efficiency in large-scale batch production. During pressure sintering, the holding time is controlled to 1-4 hours and the pressure is controlled to 20-100 MPa to prevent excessive grain growth during the sintering process.

[0065] In addition, by controlling the temperature of hot working (deformation) above the recrystallization temperature of the aluminum alloy and by controlling the deformation ratio, the internalization of some nanophases is promoted. By controlling the deformation ratio of warm deformation, a large number of exogenous dislocations are introduced while avoiding structural defects, making up for the limited number of mobile dislocations in the crystal that are purely stimulated by the reinforcement phase, increasing the degree of participation in the intracrystalline deformation, further improving the plasticity and toughness, and ultimately obtaining a nanophase-reinforced aluminum-based composite material with excellent comprehensive mechanical properties. Among them, if the deformation ratio of warm deformation is too small, the effect is not significant, and if the deformation ratio is too large, structural defects will be introduced, deteriorating the comprehensive mechanical properties of the composite material.

[0066] On the other hand, the present invention provides a nano-phase reinforced aluminum-based composite material, which is prepared by any of the above preparation methods, wherein the dislocation density in the nano-phase reinforced aluminum-based composite material is ≥10 15 m -2 .

[0067] The schematic diagram of the microstructure of the nano-phase reinforced aluminum-based composite material obtained by the present invention shows that a high proportion of nano-phase and exogenous dislocations are contained in the crystal.

[0068] The present invention is further described below with reference to specific examples and comparative examples.

[0069] Example 1

[0070] This embodiment provides a method for preparing a nanophase reinforced aluminum-based composite material, comprising the following steps:

[0071] Step 1): using a high-energy ball mill to mix nano-alumina powder with an average particle size of 10 nm and 2009Al powder with an average particle size of 13 μm to obtain a composite material powder;

[0072] During the ball milling process, argon was introduced as a protective gas, the ball-to-material weight ratio was 15:1, the ball milling time was 10 hours, and the speed of the high-energy ball mill was 350 rpm. The mass fraction of the nanophase powder in the mixed powder (2009Al powder and nanophase powder) was 4.25 wt.%.

[0073] Among them, the composition of 2009Al powder is as follows, in terms of mass percentage: Cu 3.0~5.0wt%, Mg0.5~1.5wt%, Mn0.3~1.0wt%, Zn<0.25wt.%, Cr<0.1wt.%, Ti<0.15wt.%, Si<0.5wt.%, Fe<0.5wt.%, and the balance is Al.

[0074] Step 2): hot pressing the composite material powder at 540° C. and 80 MPa and vacuum sintering for 1.5 hours to obtain an ingot;

[0075] Step 3) The billet is extruded at 380° C., then rolled at 250° C., and finally solutionized at 500° C. for 2 h and naturally aged for 96 h to obtain a nano-alumina reinforced aluminum-based composite material.

[0076] The extrusion ratio during extrusion is 16:1, and the deformation during rolling is 6%.

[0077] The microstructure of the nano-alumina reinforced aluminum matrix composite material obtained in this embodiment is as follows: Figure 2 As shown in (a), it can be seen that the nanophase is evenly distributed, the volume fraction of the nanophase in the crystal accounts for 55%, and the crystal contains exogenous dislocations with a dislocation density of 1.38×10 15 m -2 Tests have shown that the yield strength of the nano-alumina reinforced aluminum-based composite material reaches 660MPa, the tensile strength is 720MPa, and the elongation is 11%.

[0078] Example 2

[0079] This embodiment provides a method for preparing a nanophase reinforced aluminum-based composite material, comprising the following steps:

[0080] Step 1): using a high-energy ball mill to mix carbon nanotube powder with an average particle size of 15 nm and 2009Al powder with an average particle size of 13 μm to obtain a composite material powder;

[0081] During the ball milling process, argon was introduced as a protective gas, the ball-to-material weight ratio was 15:1, the ball milling time was 10 hours, and the speed of the high-energy ball mill was 350 rpm. The mass fraction of the nanophase powder in the mixed powder (2009Al powder and nanophase powder) was 1.5 wt.%.

[0082] Among them, the composition of 2009Al powder is as follows, in terms of mass percentage: Cu 3.0~5.0wt%, Mg0.5~1.5wt%, Mn0.3~1.0wt%, Zn<0.25wt.%, Cr<0.1wt.%, Ti<0.15wt.%, Si<0.5wt.%, Fe<0.5wt.%, and the balance is Al.

[0083] Step 2): hot pressing the composite material powder at 540° C. and 80 MPa and vacuum sintering for 1.5 hours to obtain an ingot;

[0084] Step 3) The billet is extruded at 380° C., then rolled at 250° C., and finally solutionized at 500° C. for 2 h and naturally aged for 96 h to obtain a carbon nanotube-reinforced aluminum-based composite material.

[0085] The extrusion ratio during extrusion is 16:1, and the deformation during rolling is 7%.

[0086] The microstructure of the carbon nanotube reinforced aluminum matrix composite material obtained in this embodiment is as follows: Figure 3 As shown in (a), it can be seen that the nanophase is evenly distributed, the volume fraction of the nanophase in the crystal accounts for 52%, and the crystal contains exogenous dislocations with a dislocation density of 1.43×10 15 m -2 Tests have shown that the carbon nanotube-reinforced aluminum matrix composite material has a yield strength of 670 MPa, a tensile strength of 740 MPa, and an elongation of 7%.

[0087] Comparative Example 1

[0088] This comparative example provides a method for preparing a nanophase reinforced aluminum-based composite material, comprising the following steps:

[0089] Step 1): using a high-energy ball mill to mix nano-alumina powder with an average particle size of 10 nm and 2009Al powder with an average particle size of 13 μm to obtain a composite material powder;

[0090] During the ball milling process, argon was introduced as a protective gas, the ball-to-material weight ratio was 15:1, the ball milling time was 10 hours, and the speed of the high-energy ball mill was 350 rpm. The mass fraction of the nanophase powder in the mixed powder (2009Al powder and nanophase powder) was 4.25 wt.%.

[0091] Among them, the composition of 2009Al powder is as follows, in terms of mass percentage: Cu 3.0~5.0wt%, Mg0.5~1.5wt%, Mn0.3~1.0wt%, Zn<0.25wt.%, Cr<0.1wt.%, Ti<0.15wt.%, Si<0.5wt.%, Fe<0.5wt.%, and the balance is Al.

[0092] Step 2): hot pressing the composite material powder at 540° C. and 80 MPa and vacuum sintering for 1.5 hours to obtain an ingot;

[0093] Step 3) The above-mentioned ingot is extruded at 380° C., then solutionized at 500° C. for 2 hours, and naturally aged for 96 hours to finally obtain a nano-alumina reinforced aluminum-based composite material.

[0094] The extrusion ratio during extrusion is 16:1.

[0095] The microstructure of the nano-alumina reinforced aluminum matrix composite material obtained in this comparative example is as follows: Figure 2 As shown in (b), the microstructure before thermal deformation is as follows Figure 2 As shown in (c), it can be seen that before thermal deformation, the nanophase is mainly distributed near the grain boundary; after thermal deformation, the nanophase is evenly distributed, the volume fraction of the nanophase in the grain is 52%, and the dislocation density is 3.23×10 14 m -2 . This comparative example 1 only adopts the hot extrusion method in the plastic deformation stage, the number of mobile dislocations in the crystal is insufficient, and the degree of participation in the intracrystalline deformation is low. After testing, the yield strength of the nano-alumina reinforced aluminum-based composite material is 650MPa, the tensile strength is 715MPa, and the elongation is 8%. It can be seen that the yield strength, tensile strength and elongation of the nano-alumina reinforced aluminum-based composite material of comparative example 1 are lower than those of embodiment 1, especially the elongation. This is because the nano-alumina reinforced aluminum-based composite material of embodiment 1 contains more dislocations, which can make up for the deficiency of the limited number of mobile dislocations in the crystal that are purely excited by the reinforcing phase when the material is loaded, increase the degree of participation in the intracrystalline deformation, further improve the plastic toughness, and effectively enhance the comprehensive strength and toughness properties of the material.

[0096] Comparative Example 2

[0097] This comparative example provides a method for preparing a nanophase reinforced aluminum-based composite material, comprising the following steps:

[0098] Step 1): using a high-energy ball mill to mix nano-alumina powder with an average particle size of 10 nm and 2009Al powder with an average particle size of 13 μm to obtain a composite material powder;

[0099] During the ball milling process, argon was introduced as a protective gas, the ball-to-material weight ratio was 15:1, the ball milling time was 10 hours, and the speed of the high-energy ball mill was 350 rpm. The mass fraction of the nanophase powder in the mixed powder (2009Al powder and nanophase powder) was 4.25 wt.%.

[0100] Among them, the composition of 2009Al powder is as follows, in terms of mass percentage: Cu 3.0~5.0wt%, Mg0.5~1.5wt%, Mn0.3~1.0wt%, Zn<0.25wt.%, Cr<0.1wt.%, Ti<0.15wt.%, Si<0.5wt.%, Fe<0.5wt.%, and the balance is Al.

[0101] Step 2): hot pressing the composite material powder at 540° C. and 80 MPa and vacuum sintering for 1.5 hours to obtain an ingot;

[0102] Step 3) The billet is extruded at 380° C., then rolled at 250° C., and finally solutionized at 500° C. for 2 h and naturally aged for 96 h to obtain a nano-alumina reinforced aluminum-based composite material.

[0103] The extrusion ratio during extrusion is 16:1, and the deformation during rolling is 11%.

[0104] In Comparative Example 2, the deformation ratio was increased during the warm deformation process, which caused internal structural defects in the material and deteriorated the overall performance. The obtained nano-alumina reinforced aluminum matrix composite material was tested to have a yield strength of 610 MPa, a tensile strength of 700 MPa, and an elongation of 7%.

[0105] Comparative Example 3

[0106] This comparative example provides a method for preparing a nanophase reinforced aluminum-based composite material, comprising the following steps:

[0107] Step 1): using a high-energy ball mill to mix carbon nanotube powder with an average particle size of 15 nm and 2009Al powder with an average particle size of 13 μm to obtain a composite material powder;

[0108] During the ball milling process, argon was introduced as a protective gas, the ball-to-material weight ratio was 15:1, the ball milling time was 10 hours, and the speed of the high-energy ball mill was 350 rpm. The mass fraction of the nanophase powder in the mixed powder (2009Al powder and nanophase powder) was 1.5 wt.%.

[0109] Among them, the composition of 2009Al powder is as follows, in terms of mass percentage: Cu 3.0~5.0wt%, Mg0.5~1.5wt%, Mn0.3~1.0wt%, Zn<0.25wt.%, Cr<0.1wt.%, Ti<0.15wt.%, Si<0.5wt.%, Fe<0.5wt.%, and the balance is Al.

[0110] Step 2): hot pressing the composite material powder at 540° C. and 80 MPa and vacuum sintering for 1.5 hours to obtain an ingot;

[0111] Step 3) The above-mentioned billet is extruded at 380° C., and then solutionized at 500° C. for 2 hours and naturally aged for 96 hours to finally obtain a carbon nanotube-reinforced aluminum-based composite material.

[0112] The extrusion ratio during extrusion is 16:1.

[0113] The microstructure of the carbon nanotube reinforced aluminum matrix composite material obtained in this comparative example is as follows: Figure 3 As shown in (b), the microstructure before thermal deformation is as follows Figure 3 As shown in (c), it can be seen that before thermal deformation, the nanophase is mainly distributed near the grain boundary; after thermal deformation, the nanophase is evenly distributed, the volume fraction of the nanophase in the grain is 51% of the total amount, and the dislocation density is 1.78×10 14 m -2 . This comparative example only uses hot extrusion in the plastic deformation stage, and the material has insufficient intracrystalline mobile dislocations, which reduces the degree of participation in intracrystalline deformation. After testing, the obtained carbon nanotube reinforced aluminum-based composite material has a yield strength of 670MPa, a tensile strength of 720MPa, and an elongation of 4.5%. Compared with Example 2, the yield strength, tensile strength, and elongation of the carbon nanotube reinforced aluminum-based composite material of Comparative Example 3 are lower than those of Example 2, especially the elongation. This is because the carbon nanotube reinforced aluminum-based composite material of Example 2 contains more dislocations, which can make up for the deficiency of the limited number of intracrystalline mobile dislocations excited by the reinforcing phase when loaded, thereby increasing the degree of participation in intracrystalline deformation, further improving plastic toughness, and effectively improving the comprehensive strength and toughness properties of the material.

[0114] Comparative Example 4

[0115] This comparative example provides a method for preparing a nanophase reinforced aluminum-based composite material, comprising the following steps:

[0116] Step 1): using a high-energy ball mill to mix carbon nanotube powder with an average particle size of 15 nm and 2009Al powder with an average particle size of 13 μm to obtain a composite material powder;

[0117] During the ball milling process, argon was introduced as a protective gas, the ball-to-material weight ratio was 15:1, the ball milling time was 10 hours, and the speed of the high-energy ball mill was 350 rpm. The mass fraction of the nanophase powder in the mixed powder (2009Al powder and nanophase powder) was 1.5 wt.%.

[0118] Among them, the composition of 2009Al powder is as follows, in terms of mass percentage: Cu 3.0~5.0wt%, Mg0.5~1.5wt%, Mn0.3~1.0wt%, Zn<0.25wt.%, Cr<0.1wt.%, Ti<0.15wt.%, Si<0.5wt.%, Fe<0.5wt.%, and the balance is Al.

[0119] Step 2): hot pressing the composite material powder at 540° C. and 80 MPa and vacuum sintering for 1.5 hours to obtain an ingot;

[0120] Step 3) The above-mentioned billet is extruded at 380° C., and then solutionized at 500° C. for 2 hours and naturally aged for 96 hours to finally obtain a carbon nanotube-reinforced aluminum-based composite material.

[0121] The extrusion ratio during extrusion is 4:1.

[0122] This comparative example used only hot extrusion during the plastic deformation stage, and the extrusion ratio was reduced. This resulted in insufficient intracrystalline nanophase content, with the volume fraction of the nanophase accounting for 30% of the total added mass. This excessively high content of nanophase at the grain boundaries easily induced stress concentration, deteriorating the material's overall mechanical properties. Testing of the resulting carbon nanotube-reinforced aluminum-based composite material revealed a yield strength of 650 MPa, a tensile strength of 710 MPa, and an elongation of 3.5%. Compared to Example 2, the yield strength, tensile strength, and elongation of the carbon nanotube-reinforced aluminum-based composite material in Comparative Example 3 were all lower than those in Example 2, particularly the elongation.

[0123] It is easy for those skilled in the art to understand that, under the premise of no conflict, the advantageous technical features of the above-mentioned methods can be freely combined and superimposed.

[0124] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention shall be included within the scope of protection of the present invention. The above description is merely a preferred embodiment of the present invention. It should be noted that those skilled in the art can make various improvements and variations without departing from the technical principles of the present invention, and such improvements and variations shall also be considered within the scope of protection of the present invention.

Claims

1. A method for preparing a nano-phase reinforced aluminum-based composite material, characterized in that: The following steps are involved: Step 1): ball-milling the nanophase powder and the aluminum raw material powder to obtain a composite material powder; Step 2): sintering the composite material powder to obtain an ingot; Step 3): performing hot deformation treatment, warm deformation treatment and post-treatment on the ingot in sequence to obtain a nano-phase reinforced aluminum-based composite material; The nanophase is caused to migrate into the crystal by the thermal deformation treatment; and exogenous dislocations are introduced into the crystal by the warm deformation treatment.

2. The method for preparing the nano-phase reinforced aluminum-based composite material according to claim 1, characterized in that: In said step 1): The average particle size of the nanophase powder is 10-100 nm; and / or The average particle size of the aluminum raw material powder is 0.1-200 μm.

3. The method for preparing the nano-phase reinforced aluminum-based composite material according to claim 1, characterized in that: In said step 1): The aluminum raw material powder is pure aluminum powder and / or aluminum alloy powder; Preferably, the aluminum content in the aluminum raw material powder is greater than 85wt%; Preferably, the aluminum raw material powder is one or more of 2 series aluminum alloy powder, 5 series aluminum alloy powder, 6 series aluminum alloy powder, and 7 series aluminum alloy powder.

4. The method for preparing the nano-phase reinforced aluminum-based composite material according to claim 1, characterized in that: In said step 1): The mixture is ball-milled in an inert gas using a high-energy ball mill; preferably, the inert gas is argon; and the rotation speed of the high-energy ball mill is 200-400 rpm; The ball-to-material weight ratio during ball milling is 5:1-30:1; and / or The ball milling time is 6-20h; and / or The total mass of the aluminum raw material powder and the nano-phase powder is a, and the mass of the nano-phase powder is b, wherein the mass fraction of b in a is 0.5-8.5 wt.%.

5. The method for preparing the nano-phase reinforced aluminum-based composite material according to claim 1, characterized in that: In the step 2): The sintering process adopts one of hot pressing sintering, hot isostatic pressing sintering and spark plasma sintering; Preferably, the hot pressing sintering or hot isostatic pressing sintering adopts pressure sintering; wherein the sintering temperature is 350-630°C, the holding time is 1-4 hours, and the pressure is 20-100 MPa; Preferably, the spark plasma sintering adopts pressureless sintering; wherein, the sintering temperature is 600-700° C., and the heat preservation time is 1-4 hours.

6. The method for preparing the nano-phase reinforced aluminum-based composite material according to claim 1, characterized in that: In the step 3): The temperature of the thermal deformation treatment is 350-550°C; and / or The thermal deformation treatment method is one of extrusion, forging and rolling; Preferably, when the thermal deformation treatment adopts extrusion, the nominal extrusion ratio is ≥7:1; Preferably, when the thermal deformation treatment is performed by rolling, the nominal rolling ratio is ≥60%.

7. The method for preparing the nano-phase reinforced aluminum-based composite material according to claim 1, characterized in that: The volume of the nanophase in the crystal after the thermal deformation treatment in step 3) is a, the volume of the nanophase powder in the composite material powder in step 1) is b, and a / b≥50%.

8. The method for preparing the nano-phase reinforced aluminum-based composite material according to claim 1, characterized in that: In the step 3): The temperature of the warm deformation treatment is 200-300°C; and / or The deformation amount of the warm deformation treatment is 5%-9%; and / or The warm deformation treatment is performed by one of extrusion, forging and rolling; Preferably, when the warm deformation treatment is performed by rolling, the nominal rolling ratio is ≤9%.

9. The method for preparing the nano-phase reinforced aluminum-based composite material according to claim 1, characterized in that: In the step 3): The post-treatment includes solution treatment and aging treatment; Preferably, the temperature of the solution treatment is 450-550°C and the time is 1-4 hours; Preferably, the aging treatment time is 5-120h; Preferably, the aging treatment adopts natural aging or artificial aging; wherein, when artificial aging treatment is adopted, the temperature is 100-200°C.

10. A nanophase reinforced aluminum matrix composite material, characterized in that: The dislocation density in the nanophase reinforced aluminum-based composite material is ≥10 15 m -2 ; Preferably, the nanophase reinforced aluminum-based composite material is prepared by the preparation method according to any one of claims 1 to 9 above.

Images