A method for preparing aluminum alloy single crystal

Abstract

The invention belongs to the technical field of aluminum alloy processing, and specifically relates to a method for preparing an aluminum alloy single crystal, wherein an aluminum alloy plate is subjected to multiple bending and annealing treatments to obtain an aluminum alloy single crystal; each bending and annealing treatment comprises bending the aluminum alloy plate, then high-temperature annealing, and then reverse bending to flatten the aluminum alloy plate and high-temperature annealing again; the aluminum alloy is an aluminum-copper-lithium alloy; the temperature of the high-temperature annealing is 450-510°C; the invention can increase the particle size of the single crystal.

Description

Technical Field

[0001] The invention belongs to the technical field of aluminum alloy processing, and in particular relates to a method for preparing an aluminum alloy single crystal. Background Art

[0002] Alloy properties are closely related to grain configuration. In order to study the properties of aluminum alloys, it is often necessary to study issues related to crystallographic orientation. Research on crystallographic orientation requires the use of single crystals, especially single crystals with large grain sizes.

[0003] The method for growing bulk metal single crystals is generally strain annealing, which is a method for growing crystals by plastic deformation and subsequent annealing. The specific steps include: Plastic deformation: First, the material is plastically deformed, usually by stretching or compression, so that the material produces a certain strain. Annealing: Then annealing is performed at an appropriate temperature, and the temperature change cannot be too drastic to increase the grain size. During the annealing process, the grains will gradually grow and eliminate the strain. CN104404614A discloses a method for preparing a single crystal of an aluminum-copper-magnesium aluminum alloy, wherein an Al-Cu-Mg aluminum alloy sample after homogenization annealing and hot working is subjected to a low-strain deformation treatment, followed by a recrystallization annealing, and the treatment is cyclically performed at least once; the low-strain deformation treatment is to give the sample a deformation close to the critical deformation degree. The low-strain deformation treatment is: the sample is stretched in the horizontal extension direction or compressed in the vertical thickness direction, and the deformation amount is 0.1-5% of the horizontal total length or 0.1-5% of the vertical total thickness. ‌

[0004] The third generation Al-Cu-Li alloy has the characteristics of low density, high specific stiffness and specific strength, and is regarded as an ideal aerospace structural material. In order to study the properties of Al-Cu-Li alloy, it is necessary to prepare single crystals of Al-Cu-Li alloy, but the composition of the third generation Al-Cu-Li alloy is relatively complex. The presence of multiple trace elements often makes recrystallization easily inhibited, and it is difficult to control the nucleation into large grains. The traditional strain annealing method is difficult to make the grains grow rapidly, so the traditional strain annealing method is very limited in the preparation of the third generation Al-Cu-Li alloy. Summary of the invention

[0005] The technical problem to be solved by the present invention is to provide a method for preparing aluminum alloy single crystals and to increase the particle size of the single crystals.

[0006] The embodiment of the present invention provides a method for preparing an aluminum alloy single crystal, wherein an aluminum alloy plate is subjected to multiple bending and annealing treatments to obtain an aluminum alloy single crystal; each bending and annealing treatment includes bending the aluminum alloy plate, then annealing at a high temperature, then bending in the reverse direction to make the aluminum alloy plate flat, and then annealing at a high temperature again;

[0007] The aluminum alloy is an aluminum-copper-lithium alloy; the temperature of the high-temperature annealing is 450-510°C, preferably 480-500°C.

[0008] Optionally, the bending annealing treatment is performed 3-10 times, preferably 3-5 times.

[0009] Optionally, when the aluminum alloy plate is bent, the bending deformation is 3-10% of the thickness of the aluminum alloy plate, preferably 4-7%.

[0010] Optionally, when the aluminum alloy plate is bent, the moving speed of the deformation column driving the aluminum alloy plate to bend is 0.5-2 mm / min, preferably 1 mm / min.

[0011] Optionally, the high temperature annealing has a holding time of 3 to 11 hours, preferably a holding time of 9 to 11 hours.

[0012] Optionally, the temperature when bending the aluminum alloy plate is room temperature.

[0013] Optionally, the device for bending the aluminum alloy plate is a device for preparing an aluminum alloy single crystal, the device for preparing the aluminum alloy single crystal comprising a base, a mounting frame and a support member are arranged on the base, the support member comprises support columns for supporting both ends of the aluminum alloy plate and a groove located below the aluminum alloy plate; a deformation assembly is arranged on the mounting frame, and a deformation column for bending the aluminum alloy plate is arranged on the deformation assembly;

[0014] The diameter of the deformable column is greater than 5 cm, and the width of the groove is greater than the diameter of the deformable column.

[0015] The deformation column of the present invention can be raised and lowered. The deformation column is located directly above the aluminum alloy plate. Both ends of the aluminum alloy plate are support columns. Therefore, when the deformation column is lowered, the aluminum alloy plate will bend.

[0016] The diameter of the deformation column is controlled to be greater than 5 cm, and the width of the groove is greater than the diameter of the deformation column, so that the degree of bending can be controlled. The single crystal grain size of the aluminum alloy plate obtained by bending this structure is larger.

[0017] Optionally, the diameter of the deformed column is 5-20 cm.

[0018] Optionally, the width of the groove is 1.5-2 times the diameter of the deformation column.

[0019] Optionally, it also includes a pad placed in the groove to control the bending degree of the aluminum alloy plate.

[0020] Optionally, the end of the deformation column of the present invention is hemispherical, and the diameter of the hemispherical shape is equal to the diameter of the deformation column.

[0021] The length of the deformation column of the present invention is greater than the width of the aluminum alloy plate.

[0022] The beneficial effect of the present invention is that the present invention improves the plane deformation mode used when preparing bulk aluminum alloy single crystals by conventional strain annealing method, adopts bending annealing method, improves the recrystallization effect by introducing a large amount of shear strain, improves the efficiency and effect of preparing aluminum alloy, especially Al-Cu-Li alloy single crystals, and increases the particle size of single crystals. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 It is a schematic structural diagram of the preparation device of the present invention.

[0024] Figure 2 The present invention is a schematic structural diagram of a cushion block.

[0025] Figure 3 This is a homogenized grain structure diagram of the Al-Cu-Li alloy of Example 2 of the present invention.

[0026] Figure 4 This is the single crystal structure diagram after processing in Example 2 of the present invention.

[0027] Figure 5 This is the single crystal organization diagram after being processed in comparative example 1 of the present invention.

[0028] Figure 6 This is the single crystal organization diagram after being processed in comparative example 2 of the present invention.

[0029] Figure 7 This is the single crystal organization diagram after being processed in comparative example 3 of the present invention.

[0030] Figure 8 This is the single crystal structure diagram after being processed in comparative example 4 of the present invention.

[0031] In the figure, 1 is a mounting frame, 2 is a deformation assembly, 21 is a deformation column, 3 is an aluminum alloy plate, 4 is a support member, 41 is a support column, 42 is a groove, 5 is a cushion block, and 6 is a base. DETAILED DESCRIPTION

[0032] The invention is applicable to all aluminum alloys, especially to Al-Cu-Li alloys, and has no special requirements on the specific composition and content of the alloys.

[0033] The present invention will be further described in detail below with reference to specific embodiments. Example 1

[0034] like Figure 1-2As shown, a preparation device of an aluminum alloy single crystal includes a base 6, on which a mounting frame 1 and a support member 4 are arranged, and the support member 4 includes support columns 41 for supporting both ends of an aluminum alloy plate 3 and a groove 42 located below the aluminum alloy plate 3; the mounting frame 1 is provided with a deformation component 2, and the deformation component 2 is provided with a deformation column 21 for bending the aluminum alloy plate 3;

[0035] The diameter of the deformation column 21 is greater than 5 cm, preferably 5-20 cm; the width of the groove 42 is greater than the diameter of the deformation column 21 , preferably, the width of the groove 42 is 1.5-2 times the diameter of the deformation column 21 .

[0036] It also includes a spacer block 5 placed in the groove 42 to control the bending degree of the aluminum alloy plate 3.

[0037] The method of use is to place the aluminum alloy plate 3 on the support 4, and the deformation column 21 moves downward under the action of the driving member. The deformation column 21 is located directly above the aluminum alloy plate 3, and the aluminum alloy plate 3 is bent. The degree to which the aluminum alloy plate 3 is bent is related to the descending height of the deformation column 21, the width of the groove 42, the diameter of the deformation column 21, and the shape of the end of the deformation column 21. Example 2

[0038] A method for preparing an aluminum alloy single crystal comprises the following steps:

[0039] An aluminum alloy is prepared, wherein the aluminum alloy is an aluminum-copper-lithium alloy, and the mass percentages of the alloy components used are: Si: 0.03, Fe: 0.04, Cu: 4.1, Li: 0.9, and the rest is Al.

[0040] The aluminum alloy was subjected to homogenization treatment, and the homogenization temperature was increased from 25°C to 500°C at a rate of 0.85°C / min and kept at this temperature for 24 hours. The grain morphology of the alloy after homogenization treatment is as follows: Figure 3 As shown. The average grain size is about 0.1mm.

[0041] The alloy after homogenization treatment is cut into strip samples of 5*15*3cm in size, i.e., aluminum alloy plate 3. The aluminum alloy plate 3 is subjected to multiple bending annealing treatments to obtain an aluminum alloy single crystal; each bending annealing treatment includes bending the aluminum alloy plate 3 using the preparation device described in Example 1, and then high-temperature annealing (the high-temperature annealing temperature is 500°C, and the holding time is 1h), and then reverse bending to flatten the aluminum alloy plate 3 and high-temperature annealing again (the high-temperature annealing temperature is 500°C, and the holding time is 1h).

[0042] The diameter of the deformation column 21 in the aluminum alloy single crystal preparation device of Example 1 is 8 cm; the width of the groove 42 is 1.5 times the diameter of the deformation column 21 .

[0043] The bending annealing treatment is performed 4 times. When the aluminum alloy plate 3 is bent, the bending deformation is 5% of the thickness of the aluminum alloy plate 3. When the aluminum alloy plate 3 is bent, the moving speed of the deformation column 21 driving the aluminum alloy plate 3 to bend is 1 mm / min. The specific deformation amount, number of times and grain size are shown in Table 1. The single crystal structure diagram after the treatment of Example 2 is shown in Figure 4 As shown. The maximum single crystal size is 3.5 cm. The deformation amount is calculated as the ratio of the pressure of the deformed component to the thickness of the sample.

[0044] Table 1 Deformation amount, number of times and grain size

[0045] . Comparative Example 1

[0046] The alloy composition, homogenization system and strip sample size used in Comparative Example 1 are the same as those in Example 2.

[0047] The strip sample was held by a uniaxial tensile die and subjected to uniaxial tensile treatment using a tensile machine. The deformation amount each time and the grain size after annealing are shown in Table 2.

[0048] Table 2 Deformation amount per time and average grain size after cyclic deformation-annealing

[0049] .

[0050] The final grains obtained are Figure 5 As shown, the largest single crystal size is 1.3 cm. Comparative Example 2

[0051] The material used in Comparative Example 2 is pure aluminum with a purity of 99.99%, and other systems are the same as Comparative Example 1.

[0052] The strip specimen was held by a uniaxial tensile die and subjected to uniaxial tensile treatment using a universal tensile machine. The deformation amount each time and the grain size after annealing are shown in Table 3.

[0053] Table 3 Deformation amount per time and average grain size after cyclic deformation-annealing

[0054] .

[0055] The final grains obtained are Figure 6 As shown, the largest single crystal size is 4.0 cm. Comparative Example 3

[0056] On the basis of Example 2, the diameter of the deformation column 21 in the aluminum alloy single crystal preparation device of Example 1 is set to 2 cm; the width of the groove 42 is 1.2 times the diameter of the deformation column 21, the sample size is 5*10*3 cm, and the others are the same as Example 2. The specific deformation amount, number of times and grain size are shown in Table 4.

[0057] Table 4 Deformation amount, number of times and grain size

[0058] .

[0059] The final grains obtained are Figure 7 As shown in the figure, the largest single crystal size is 1.9 cm. Comparative Example 4

[0060] On the basis of Example 2, the diameter of the deformation column 21 in the aluminum alloy single crystal preparation device of Example 1 is set to 25 cm; the width of the groove 42 is 2.5 times the diameter of the deformation column 21, the sample size is 5*50*3 cm, and the others are the same as Example 2. The specific deformation amount, number of times and grain size are shown in Table 5.

[0061] Table 5 Deformation amount, number of times and grain size

[0062] .

[0063] The final grains obtained are Figure 8 As shown in Figure 2, the largest single crystal size is 1.4 cm.

[0064] A person skilled in the art should understand that the discussion of any of the above embodiments is merely illustrative and is not intended to imply that the scope of protection of the present application is limited to these examples. In line with the concept of the present application, the technical features in the above embodiments or different embodiments may be combined, the steps may be implemented in any order, and there are many other variations of different aspects of one or more embodiments of the present application as described above, which are not provided in detail for the sake of simplicity.

[0065] One or more embodiments of the present application are intended to cover all such substitutions, modifications and variations that fall within the broad scope of the present application. Therefore, any omissions, modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of one or more embodiments of the present application should be included in the protection scope of the present application.

Claims

1. A method for preparing an aluminum alloy single crystal, characterized in that: The aluminum alloy plate (3) is subjected to multiple bending and annealing treatments to obtain an aluminum alloy single crystal; each bending and annealing treatment comprises bending the aluminum alloy plate (3), then annealing at high temperature, then bending in the opposite direction to make the aluminum alloy plate (3) flat, and annealing at high temperature again; The aluminum alloy is an aluminum-copper-lithium alloy; the temperature of the high temperature annealing is 450-510°C; The device for bending an aluminum alloy plate (3) is a device for preparing an aluminum alloy single crystal, comprising a base (6), wherein a mounting frame (1) and a support member (4) are arranged on the base (6), wherein the support member (4) comprises support columns (41) for supporting both ends of the aluminum alloy plate (3) and a groove (42) located below the aluminum alloy plate (3); a deformation component (2) is arranged on the mounting frame (1), and a deformation column (21) for bending the aluminum alloy plate (3) is arranged on the deformation component (2); The diameter of the deformable column (21) is 5-20 cm, and the width of the groove (42) is 1.5-2 times the diameter of the deformable column (21).

2. The preparation method according to claim 1, characterized in that: The bending annealing treatment is performed 3 to 10 times.

3. The preparation method according to claim 1, characterized in that: When the aluminum alloy plate (3) is bent, the bending deformation is 3 to 10% of the thickness of the aluminum alloy plate (3).

4. The preparation method according to claim 3, characterized in that: When the aluminum alloy plate (3) is bent, the bending deformation is 4-7% of the thickness of the aluminum alloy plate (3).

5. The preparation method according to claim 1, characterized in that: When the aluminum alloy plate (3) is bent, the moving speed of the deformation column (21) driving the aluminum alloy plate (3) to bend is 0.5-2 mm / min.

6. The preparation method according to claim 1, characterized in that: The high temperature annealing has a holding time of 3 to 11 hours.

7. The preparation method according to claim 1, characterized in that: It also includes a pad (5) placed in the groove (42) for controlling the bending degree of the aluminum alloy plate (3).

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