RU2751401C2 - Method for producing aluminium-based nanostructural composite material - Google Patents

Abstract

FIELD: composite materials.SUBSTANCE: invention relates to a method for producing a nanostructural composite material based on aluminium modified with C60fullerene and can be used in mechanical engineering and the aerospace industry. The method for producing an aluminium-based nanostructural composite material includes processing an aluminuim alloy and C60fullerene in a planetary mill, wherein the mixture of aluminium alloy shavings with 6% wt. magnesium and a C60fullerene powder in an amount of 0.1 to 0.5% wt. is divided into two parts, the first part is processed in a planetary mill at 1600 rpm for 15 minutes and the second one at 1800 rpm for 45 minutes, the parts are combined in a 1:1 ratio, processed in a planetary mill at 900 rpm for 25 minutes, the workpiece is pressed at 550 MPa and direct extrusion is performed with a deformation degree of 5 to 7 at a pressure of 1 to 1.5 GPa and a temperature of 280±°C.EFFECT: increased plasticity of the material and increased mechanical properties with a density maintained at the level of the initial matrix alloy, expanding the possibility of using the material in the engineering and aerospace industries due to high specific strength values.1 cl, 3 dwg, 4 tbl, 3 ex

Description

The invention relates to a method for producing a nanostructured composite material based on aluminum modified with C ₆₀ fullerene, with improved physical and mechanical properties, for use in mechanical engineering and aerospace.

Aluminum-based nanostructured composite materials modified with C ₆₀ fullerene demonstrate an increased level of mechanical properties. For this kind of nanostructured composites, it is known that with a decrease in the average crystallite size of the matrix, the strength properties increase, while at the initial stages there is a laminar decrease in plasticity proportional to a decrease in the average crystallite size, and then, when the critical value of the average crystallite size is reached, there is a sharp decrease in plasticity almost to zero values. Therefore, the control of the properties of bulk nanostructured composite materials only by reducing the structural elements of the material is severely limited.

The low plasticity of nanostructured composite materials does not allow their full use as structural materials. The solution to this problem can be the creation of a material that is a mechanical mixture of particles similar in phase, but different in structural state, i.e. creation of a nanostructured composite material, whose structure is formed from a mixture of strong and less plastic particles with less strong, but more plastic (article Martin P. Harmer, Helen M. Chan, Gary A. Miller. Unique Opportunities for Microstructural Engineering with Duplex and Laminar Ceramic Composite // Journal of the American Ceramic Society. Vol 75 (7), P1715-1728, 2005).

The main task in the development of a nanostructured composite material based on aluminum with a duplex structure is the need to select the ratio of the content of strong and less plastic particles to less strong particles with higher plasticity. The final material will have a higher ductility with minimal losses in strength properties.

Analogs of this invention are the following patents describing the production of hardened aluminum alloys with a duplex structure.

RU 2485196 (20.06.2013, С22С 1/05) proposes to form products in a liquid or semi-liquid state from a powder material in special forms under pressure, as a powder material, granules of a composite material with a metal matrix and with nanosized strengthening particles, which are obtained by the method of mechanical alloying from the initial particles of the matrix material and powders of strengthening nanoparticles with the duration of treatment determined by the empirical formula. The volume fraction of the strengthening particles is from 0.1% to 50%, and the size of the strengthening nanoparticles is from 0.7 nm to 100 nm. The method of obtaining provides for the production of finely dispersed nanostructured powders of various granulometric composition by grinding the initial components in high-energy ball mills. The material can be used either in the form of a powder - for modifying various polymer compositions, or it can be subjected to subsequent thermobaric treatment to obtain bulk workpieces and products. The processing mode is selected empirically to obtain the optimum material properties. The concentration of modifying particles is from 0.1 to 5 wt.%.

US 20100189995 (29.07.2010, В32В 9/00), where a nanostructured composite material based on aluminum with a duplex structure consists of two phases: granules of pure aluminum and granules of aluminum-carbon nanotubes, which are either fused or sprayed. This material with a duplex structure consists of homogeneously distributed grains of a nanostructured composite material with a complex hierarchical structure. The components of the nanostructured composite material are mixed not only at the level of powder particles (aggregates), but also at a lower level - individual agglomerates and crystallites, which makes it possible to effectively use the advantages of each of the NCM components with a duplex structure.

The closest technical solution to the proposed one (analogue of the invention) is RU 2440433 (22.10.2010, C22C 21/00), which describes a method for producing a nanostructured composite based on aluminum, including, in particular, mixing an Al-Li aluminum alloy of grades 1420, 1430 or Al-Sc grade 1570 with carbon nanoclusters in a ball mill and sintering of the resulting mixture under pressure. The optimal parameters of mechanical activation in the prototype are: accelerations developed by grinding balls - from 500 to 800 m / s ² ; processing time for 12-15 minutes. The grain size of particles of aluminum alloys is in the range from 5 to 150 nm. _{Fullerene C 60 is} used as strengthening nanoparticles in an amount of 0.5 ÷ 12 wt.% In molecular form. Sintering takes place in a cell of a high-pressure chamber of the "piston-cylinder" type at 280-380 ° C under a pressure of 0.5-1.5 GPa. Due to the arrangement of C ₆₀ molecules on the surface of aluminum alloy grains and the formation of strong covalent bonds between structural elements, this composite with a C ₆₀ fullerene concentration of 0.5 ÷ 12 wt.% Has a density of 2470-2650 kg / m ³ , and also has an increased hardness and specific strength in comparison with analogues.

The disadvantage of this invention is the use of thermally hardened alloys of the Al-Li and Al-Sc system, which, when nanostructuring, turn out to be too brittle, and their heat treatment in a nanostructured state is not possible due to accelerated recrystallization processes, which is emphasized in the specified patent: consolidation temperature 280- 380 ° C; deformation at destruction does not exceed 0.1%. In addition, the method of obtaining in a chamber of the "piston-cylinder" type has a number of disadvantages, the main one of which in this case is the impossibility of obtaining extended or sufficiently large samples due to a strong gradient of pressure distribution over the volume of the reaction zone of the chamber. And the samples made according to the prototype have no isotropy of physical properties. In addition, due to the low rate of diffusion processes at a sintering temperature below 0.75 _{Tm of the} matrix, an excessively long exposure is required to ensure a satisfactory strength of bonds between the composite particles.

As a result, the resulting material with a concentration of C ₆₀ fullerene of 0.5 wt% has the following characteristics shown in the table:

The problem to be solved by this invention is aimed at creating a nanostructured composite material with a duplex structure based on aluminum modified with C ₆₀ fullerene, with improved physical and mechanical properties for use in mechanical engineering and the aerospace industry.

The task is solved due to precise control of the chemical and phase composition of the powders, ensuring the average size of aluminum crystallites ≤70 nm in fine-crystalline powder and in the range of 70-150 nm in coarse-crystalline, due to strict adherence to the 1: 1 ratio of two types of powders in the final material, as well as due to their mixing at the level of individual crystallites. _{Fullerene C 60} powder in crystalline form in an amount of 0.1-5-0.5 wt.% Is used as a modifying carbon phase.

According to the proposed technical solution, a nanostructured composite material based on aluminum with a duplex structure has a frame of strong particles with a small crystallite size, between which are located larger plastic particles, in which deformation stresses will be localized. To increase the bond strength between aluminum crystallites and more efficiently redistribute the load perceived by the material, in the process of mechanoactivation treatment, favorable thermodynamic conditions are created for the formation of strong aluminum-fullerene complexes, which additionally fasten individual crystallites.

The technical result is an increase in the plasticity of a nanostructured composite material with a duplex structure based on aluminum modified with C ₆₀ fullerene, with insignificant losses in strength characteristics.

A method for producing a nanostructured composite material with a duplex structure based on aluminum includes several stages of component preparation: 1 - preparation of coarse-crystalline powders; 2 - preparation of fine crystalline powders; 3 - mixing coarse and fine-crystalline powders; 4 - consolidation of the obtained powder mixture by the method of severe plastic deformation - direct hot extrusion.

To obtain coarse-grained powders of a nanostructured composite material based on aluminum (70-150 nm) in an argon atmosphere, 400 grams of the original AMg6 alloy shavings (GOST 4784-97) and fullerene C ₆₀ (0.1 ÷ 0.5 wt.% ). Further, in a planetary ball mill, the said mixture is mechanically activated for 15 minutes at a carrier operating frequency of 1600 rpm.

To obtain fine-crystalline powders of a nanostructured composite material based on aluminum (less than 70 nm) in an argon atmosphere, 400 grams of the original AMg6 alloy shavings (GOST 4784-97) and fullerene C ₆₀ (0.1 ÷ 0.5 wt.%) Are placed in grinding containers ... Further, in a planetary ball mill, mechanoactivation processing of the specified mixture is carried out for 45 minutes at an operating frequency of the carrier of 1800 rpm.

To obtain a powder of a nanostructured composite material with a duplex structure based on aluminum in a 1: 1 ratio, coarse and fine-crystalline powders are mixed (200 grams of each type of powder). Further, in a planetary ball mill, mechanoactivation processing of the specified mixture is carried out for 25 minutes at an operating frequency of the carrier of 900 rpm.

The resulting powder mixture is compacted into a cylindrical briquette with a diameter of 50 mm under a pressure of 400-600 MPa and subjected to direct hot extrusion with a degree of deformation of 5-7.

To characterize the mechanical properties of a nanostructured composite material with a duplex structure based on aluminum, tensile, compression and bending tests are carried out, and the microhardness and density of the obtained materials are also determined. Tests are carried out in accordance with GOST 25.503-97, GOST 14019-2003, GOST 1497-84, GOST 9450-76, GOST 20018-74.

X-ray structural studies are carried out on a universal X-ray diffractometer PANalytical Empyrean, studies by Raman spectroscopy on a TRIAX-552 and iHR550 spectrometer, studies by transmission microscopy on a JEM-2010 microscope, and studies of physical and mechanical properties on a universal testing machine Instron 5982, a PMT hardness tester 3, and laboratory electronic scales KERN-770-60, with an attachment for measuring density Sartorius YDK 01 LP.

BRIEF DESCRIPTION OF FIG. 1, 2, 3

FIG. 1 shows the diffraction patterns of a coarse-crystalline and fine-crystalline powder of a nanostructured composite material based on aluminum and a nanostructured composite material with a duplex structure based on aluminum modified with C ₆₀ fullerene after extrusion.

FIG. Figure 2 shows a JEM-2010 transmission electron microscope (TEM) image of grains of a nanostructured composite material with a duplex structure based on aluminum in an extruded sample.

FIG. 3 shows the Raman spectra of an extruded sample of a nanostructured composite material with a duplex structure based on aluminum.

The following examples illustrate the invention:

Example 1. Obtaining a nanostructured composite material based on aluminum modified with C ₆₀ fullerene.

In an inert atmosphere, 400 grams of the original AMg6 alloy shavings and 0.4 wt% of C ₆₀ fullerene powder in crystalline form are mixed. The resulting mixture is poured into grinding containers and mechanoactivation processing is carried out in a planetary ball mill with the following parameters:

To obtain coarse-crystalline NKM powders, the said mixture is mechanically activated for 15 minutes at a carrier operating frequency of 1600 rpm.

To obtain fine-crystalline NKM powders, the said mixture is mechanically activated for 45 minutes at a carrier operating frequency of 1800 rpm.

To obtain an NCM powder with a duplex structure in a 1: 1 ratio in an inert atmosphere, coarse and fine-crystalline powders obtained according to the parameters indicated above are mixed. Further, in a planetary ball mill, mechanoactivation processing of the specified mixture is carried out for 25 minutes at an operating frequency of the carrier of 900 rpm.

Then the resulting powder mixture in an amount of 200 g is loaded into a piston-cylinder chamber and pressed at a pressure of 550 MPa. Then the resulting briquette is placed in the extruder pressing unit and direct extrusion is performed with a deformation degree of 5-7 at a pressure of 1-1.5 GPa and a temperature of 280 ± 5 ° C. After the extrusion process is completed, the structure and mechanical properties of the samples are examined.

FIG. 1 shows the diffraction patterns of a coarse-crystalline and fine-crystalline powder of a nanostructured composite material based on aluminum and a nanostructured composite material with a duplex structure based on aluminum modified with C ₆₀ fullerene after extrusion.

FIG. Figure 2 shows a JEM-2010 transmission electron microscope (TEM) image of grains of a nanostructured composite material with a duplex structure based on aluminum in an extruded sample. FIG. 3 shows the Raman spectra of an extruded sample of a nanostructured composite material with a duplex structure based on aluminum.

X-ray phase analysis and TEM studies show that the average crystallite size in a nanostructured composite material based on aluminum with a duplex structure modified with C ₆₀ fullerene is 95 nm. Crystallites are covered with a ~ 1 nm carbon layer formed from fullerene C ₆₀ . It is rather difficult to obtain a direct TEM image of such layers, and no accumulations of carbon material larger than 1 nm, which could have been detected in the sample if present, were not found. The layers covering the crystals can be identified using Raman spectra. During mechanoactivation processing and extrusion, fullerene formed covalent chemical bonds with the matrix material (aluminum) and metal-carbon complexes were transformed: the Raman spectra show a wide halo in the region of 700 cm ^-1 (Fig. 3).

As a result, the resulting material has the following characteristics shown in the table:

Example 2. Obtaining a nanostructured composite material based on aluminum modified with C ₆₀ fullerene at fullerene concentrations that differ from the optimal one given in example 1.

In an inert atmosphere, 400 grams of the original AMg6 alloy shavings and 5 wt% of C ₆₀ fullerene powder in crystalline form are mixed. Further operations are carried out analogously to example 1.

As a result, the resulting material has the following characteristics shown in the table:

Example 3. Obtaining a nanostructured composite material based on aluminum, modified with fullerene C ₆₀ , with a ratio of fine and coarse-crystalline powders different from the optimal one given in example 1.

Coarsely and finely crystalline powders of a nanostructured composite material based on aluminum are prepared according to example 1. To obtain a powder of a nanostructured composite material with a duplex structure based on aluminum in a ratio of 1: 2, coarsely and finely crystalline powders are mixed in an inert atmosphere. Further operations are carried out analogously to example 1. As a result, the resulting material has the following characteristics shown in the table:

Claims (1)

A method for producing a nanostructured composite material based on aluminum, including the processing of an aluminum alloy and fullerene C ₆₀ in a planetary mill and subsequent thermobaric treatment, characterized in that a mixture of aluminum alloy shavings with 6 wt.% Magnesium and fullerene C ₆₀ powder is divided into two portions, the first portion is processed in a planetary mill at 1600 rpm for 15 minutes, and the second at 1800 rpm for 45 minutes, the portions are combined in a 1: 1 ratio, processed in a planetary mill at 900 rpm for 25 minutes, the workpiece is pressed at 550 MPa, carried out direct extrusion with a degree of deformation of 5-7 at a pressure of 1-1.5 GPa and a temperature of 280 ± 5 ° C, while fullerene C _{60 is} taken in an amount of 0.1-0.5 wt.%.

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