CN111519073A

CN111519073A - Nano reinforced metal matrix composite material with trimodal characteristics

Info

Publication number: CN111519073A
Application number: CN202010494039.9A
Authority: CN
Inventors: 申世军; 杨继彪
Original assignee: Shanghai Xinene Composite Material Engineering Technology Center Co ltd
Current assignee: Shanghai Xinene Composite Material Engineering Technology Center Co ltd
Priority date: 2020-06-03
Filing date: 2020-06-03
Publication date: 2020-08-11
Anticipated expiration: 2040-06-03
Also published as: CN111519073B

Abstract

The invention discloses a nano reinforced metal matrix composite material with a trimodal characteristic, which is characterized by comprising a nano carbon reinforcement and a metal matrix, wherein the grain size distribution of the metal matrix has an obvious trimodal distribution characteristic. Compared with the metal matrix with the grain structure in unimodal uniform distribution or bimodal distribution, the trimodal distribution provided by the invention can more effectively relieve stress-strain concentration and synchronously improve the strong plasticity of the material. Is favorable for promoting the engineering application of the nano reinforced metal matrix composite material.

Description

Nano reinforced metal matrix composite material with trimodal characteristics

Technical Field

The invention relates to a high-toughness nano reinforced metal matrix composite material, and belongs to the technical field of metal matrix composite materials.

Background

The nano-carbon reinforced metal matrix composite prepared by adding a small amount of nano-carbon, such as carbon nano-tube (CNT), graphene and the like, has the advantages of high modulus, high strength, high hardness, easiness in molding, easiness in processing and the like. However, the introduction of the nano carbon generally causes the plasticity and toughness of the metal matrix composite material to be obviously reduced, and typically, the tensile elongation is usually lower than 5%, which severely restricts the practical engineering application of the metal matrix composite material. How to improve the inversion relationship between strength and plasticity in the nanocarbon reinforced metal matrix composite becomes a key problem to be solved urgently in the field.

The reason for poor plasticity of the nano-carbon reinforced metal matrix composite is grain refinement and thermal stabilization caused by uniform dispersion distribution of nano-phase. Geometrically, when the nanocarbons are completely dispersed, the distance between two adjacent nanocarbons is only hundreds of nanometers, and the nanocarbons are mainly dispersed on the grain boundary, which inevitably leads to the refinement of the crystal grains to the size of ultra-fine grains/nanocrystals, and the ultra-fine grains/nanocrystals have poor plasticity and toughness, thus leading to poor plasticity of the metal matrix composite. In fact, various means have been developed to solve the problem of the inverse relationship of the strong plasticity of the ultrafine crystal/nanocrystal, wherein the most effective is the non-uniform design of the crystal grain structure, and therefore, various structures such as double peaks, layers, gradients, harmonics, heterogeneous laminations and the like are developed, and the structures can generate a large amount of geometrical necessary dislocation in the deformation process and bring extra strengthening and processing hardening in the plastic deformation process, thereby achieving the purpose of synchronously improving the strong plasticity.

Through the research of the prior art, in the research paper of Preparation and properties of dual-matrix carbon nano tube-reinforced aluminum Composites (Composites Part A99 (2017)) 84-93, a CNT/Al composite powder is obtained by adopting a high-energy ball milling method, and then the CNT/Al composite powder is mixed with non-ball milled pure aluminum powder to prepare a CNT/Al composite material with matrix grain size in bimodal distribution. A research paper, namely, enhanced soft structural-reduction correlation for Carbon nano tube/Al-Cu-Mgnano composites by material parameter optimization, also adopts a high-energy ball milling and powder metallurgy method to mix the CNT/2009Al composite powder subjected to high-energy ball milling with the powder of non-ball-milled 2009Al to prepare the CNT/2009Al composite material with the matrix grain size of a bimodal structure, and the plasticity is improved but the strength is also reduced compared with the uniform composite material through parameter optimization. The improvement effect of the bimodal structure on the strong plasticity of the nano-carbon reinforced metal matrix composite material is extremely limited, but the bottleneck of the existing strong plasticity inversion relation is difficult to break through.

Disclosure of Invention

The technical problems to be solved by the invention are as follows: the existing nanocarbon reinforced metal matrix composite material cannot improve the strength and the plasticity at the same time.

In order to solve the technical problems, the invention adopts the following technical scheme:

a nano reinforced metal-base composite material with trimodal characteristics is characterized by comprising a nano carbon reinforcement and a metal matrix, wherein the grain size distribution of the metal matrix has obvious trimodal distribution characteristics.

Preferably, the sizes of the crystal grains of the three peaks are respectively 50-500 nm, 0.5-3 μm and 3-30 μm, and the crystal grains of the three sizes are randomly distributed in space.

Preferably, the volume fraction of the nanocarbon reinforcements in the composite material is 0.1-10%.

Preferably, the nano carbon reinforcement is uniformly dispersed in the metal matrix without agglomeration.

Preferably, the nanocarbon reinforcement is any one or more of carbon nanotubes, graphene oxide, redox graphene, carbon nano onion spheres and carbon nanosheets.

Preferably, the carbon nanotubes are multi-walled or single-walled carbon nanotubes.

Preferably, the metal matrix is Al, Cu, Mg, Ti, Fe, Ni or an alloy of any two or more.

Preferably, the composite material is made by powder metallurgy, 3D printing, large plastic deformation or cold spray fabrication methods.

Compared with the prior art, the invention has the following beneficial effects:

in the prior art, a method for improving strong plasticity matching by adopting a bimodal size distribution crystal grain structure is adopted, coarse-grain metal is introduced into a fine grain structure of a uniform nano-carbon reinforced metal matrix composite, plasticity is provided by deformation of the coarse-grain metal, and a high strength and a high modulus are provided by a fine grain region of the uniform nano-carbon reinforced metal, but the method can not avoid reducing the strength of the composite; in the plastic deformation process, the difference between the strength and the modulus of the coarse-grain metal and the fine-grain nano-carbon reinforced metal is too large, so that stress concentration is easily generated at an interface, strain localization or interface debonding is caused, and the material is broken and fails in advance, so that the bottleneck of strong plastic inversion is difficult to break through by the method. Different from the double-peak size distribution crystal grain structure, the invention designs a three-peak size distribution crystal grain structure in order to avoid stress concentration at the interface between a coarse crystal area and a fine crystal area, and the structure adds a crystal grain structure with the middle primary size on the basis of double-peak size distribution, so that the stress-strain concentration of the whole material can be effectively relieved, and the strong plasticity inversion relation is broken through.

Drawings

FIG. 1 is a schematic diagram of a composite material with a matrix of a crystal grain structure with a trimodal size distribution according to the present invention;

FIG. 2 is a back-scattered electron diffraction inverse of the CNT/Al-Cu-Mg composite with a matrix of a trimodal size distribution grain structure prepared in example 1;

FIG. 3 is a graph of the grain size distribution of the CNT/Al-Cu-Mg composite with a matrix of a trimodal grain size distribution grain structure prepared in example 1.

Detailed Description

In order to make the invention more comprehensible, preferred embodiments are described in detail below with reference to the accompanying drawings.

The room-temperature tensile mechanical properties of the materials in all the following examples are carried out according to GB/T228.1-2010, and the tensile rate is 0.5 mm/min.

Example 1

In this example, a powder metallurgy method is adopted to prepare the CNT/Al-Cu-Mg composite material, in which the mass fraction of the carbon nanotube is 1.5%, the mass fraction of Cu is 4%, the mass fraction of Mg is 1.5%, and the balance is Al. Mixing pure Al powder with the medium particle size of 30 mu m with Cu powder, Mg powder and CNT powder in a mixer for 5 hours, and then ball-milling for 8 hours at the rotating speed of 200 r/min to obtain I-grade composite powder; and mixing the grade I composite powder with 30 mu m pure Al powder in a mixer for 1h to obtain grade II composite powder. The class II composite powder is subjected to pressing, vacuum sintering, hot extrusion and subsequent heat treatment to obtain the final compact CNT/Al-Cu-Mg composite material with a matrix of a trimodal size distribution grain structure, wherein the microstructure of the composite material is shown in figure 2, and figure 3 shows the distribution of the matrix grain size and has obvious trimodal size distribution characteristics. The mechanical properties are shown in Table 1.

Comparative example 1

In the comparative example, the same powder metallurgy method as that of example 1 is adopted, pure Al powder, 2024 powder, Cu powder, Mg powder and CNT which are the same as those in example 1 are respectively mixed in a mixer for 5 hours, then ball milling, densification and sintering, deformation processing and heat treatment are carried out according to the same process as that in example 1, and finally, the CNT/Al-Cu-Mg composite material with uniform and fine-grained matrix grain structure is obtained, and the mechanical properties of the CNT/Al-Cu-Mg composite material are shown in table 1.

Comparative example 2

This comparative example uses the same powder metallurgy method as example 1, pure Al powder as in example 1 was taken, mixed with Cu powder, Mg powder and CNT in a mixer for 5 hours, ball-milled using the same ball milling process as in example 1 to obtain CNT/Al composite powder, and then the composite powder and pure Al powder were mixed using the same mixing process as in example 1, followed by densification and sintering, deformation processing and heat treatment using the same process as in example 1 to finally obtain CNT/Al-Cu-Mg composite material with a matrix grain structure in bimodal distribution, and the mechanical properties thereof are listed in table 1.

Example 2

In this embodiment, a powder metallurgy method is adopted to prepare the CNT/Al-Zn-Cu-Mg composite material, wherein the mass fraction of the carbon nanotube is 1.5%, the mass fraction of Zn is 5%, the mass fraction of Cu is 2%, the mass fraction of Mg is 2%, and the balance is Al. Mixing pure Al powder and 7075Al powder with the medium particle size of 30 mu m with Zn powder, Mg powder, Cu powder and CNT in a mixer for 5 hours, then putting the mixture into a ball mill, and carrying out ball milling for 8 hours at the rotating speed of 200 r/min to obtain I-grade composite powder; and mixing the grade I composite powder and pure Al powder in a mixer for 1h to obtain grade II composite powder. The final compact CNT/Al-Zn-Cu-Mg composite material with a matrix of a trimodal size distribution grain structure was obtained by subjecting the above grade ii composite powder to pressing, vacuum sintering, hot extrusion and subsequent heat treatment, and the mechanical properties thereof are listed in table 1.

Example 3

In the embodiment, a powder metallurgy method is adopted to prepare the graphene/Al-Cu-Mg composite material, wherein the mass fraction of graphene is 0.5%, the mass fraction of Cu is 4%, the mass fraction of Mg is 1.5%, and the balance is Al.

Mixing pure Al powder and 2024Al powder with the medium particle size of 30 mu m with Cu powder, Mg powder and graphene in a mixer for 5 hours, then putting the mixture into a ball mill, and carrying out ball milling for 10 hours at the rotating speed of 200 r/min to obtain I-grade composite powder; and mixing the grade I composite powder and pure Al powder in a mixer for 1h to obtain grade II composite powder. The final compact graphene/Al-Cu-Mg composite material with a matrix of a trimodal size distribution grain structure was obtained by pressing, vacuum sintering, hot rolling and subsequent heat treatment of the above grade II composite powder, and the mechanical properties thereof are listed in Table 1.

TABLE 1 composition of composite materials, preparation method, texture and mechanical properties at room temperature

Note: the number before the element is the mass percent thereof

The high-toughness nano reinforced metal-based composite material can effectively relieve stress-strain concentration in the deformation process, prevent strain localization and premature crack initiation, can generate a large amount of geometric necessary dislocation in the deformation process, generates additional strengthening and work hardening, realizes synchronous promotion of strong plasticity, and breaks through the bottleneck of the existing strong plasticity inversion relation.

Claims

1. A nano reinforced metal-base composite material with trimodal characteristics is characterized by comprising a nano carbon reinforcement and a metal matrix, wherein the grain size distribution of the metal matrix has obvious trimodal distribution characteristics.

2. The nano-reinforced metal matrix composite according to claim 1, wherein the three peak crystal grain sizes are 50 to 500nm, 0.5 to 3 μm and 3 to 30 μm respectively, and the three crystal grains are randomly distributed in space.

3. The nanoreinforced metal matrix composite of claim 1, wherein the nanocarbon reinforcement comprises a volume fraction of 0.1 to 10% of the composite.

4. The nano-reinforced metal matrix composite of claim 1, wherein the nano-carbon reinforcement is uniformly dispersed within the metal matrix.

5. The nanoreinforced metal matrix composite of claim 1, wherein the nanocarbon reinforcement is any one or more of carbon nanotubes, graphene oxide, redox graphene, carbon nano onion spheres and carbon nano sheets.

6. The nanoreinforced metal matrix composite of claim 5, wherein the carbon nanotubes are multi-walled or single-walled carbon nanotubes.

7. The nano-reinforced metal matrix composite according to claim 1, wherein the metal matrix is Al, Cu, Mg, Ti, Fe, Ni or an alloy of any two or more thereof.

8. The nanoreinforced metal matrix composite of claim 1, wherein the composite is made by a powder metallurgy, 3D printing, large plastic deformation or cold spray fabrication method.