A nanocrystalline toughened titanium-based amorphous composite material and its preparation process

Abstract

The present invention belongs to the technical field of metallic materials, and relates to a nanocrystalline toughened titanium-based amorphous composite material and a preparation process thereof. The copper mold suction casting method + high-pressure torsion process is adopted, and the morphology and size of dendrites in the composite material are regulated by a large plastic deformation method, so as to realize the evolution of micron-scale dendrites in the composite material into nanoscale ones, thereby obtaining a nanocrystalline toughened titanium-based amorphous composite material. The size of the nanocrystals is 20-300 nm, the nanoindentation hardness is ≥4.05 GPa, and the uniform plastic deformation strain is ≥4%. The formation of nanocrystals avoids the softening caused by highly localized shear in the amorphous matrix and improves the work hardening ability of the titanium-based amorphous composite material.

Description

Technical Field

[0001] The present invention relates to the technical field of metallic materials, and particularly to a nano-crystalline toughened titanium-based amorphous composite material and a preparation process thereof. Background Art

[0002] Due to its excellent mechanical properties such as high strength, high toughness, excellent corrosion resistance and large elastic limit, amorphous composite materials have a large application demand in fields such as the aviation industry, precision instrument components, and the mobile phone industry. Among them, the addition of crystalline toughening phases is an important factor in realizing the plastic deformation ability of amorphous alloys. Therefore, the regulation of crystalline toughening phases is one of the key technologies restricting the development and application of amorphous composite materials. Titanium-based amorphous composite materials consist of two parts: an amorphous matrix and crystalline toughening phases. The plastic deformation carrier of the amorphous matrix is highly localized shear bands, resulting in brittle failure of the amorphous matrix. The addition of crystalline toughening phases can effectively prevent the expansion of localized shear bands and improve the plastic deformation ability of amorphous composite materials. However, because the work hardening ability of the crystalline phase during the deformation process is difficult to exceed the shear softening of the amorphous matrix, most titanium-based amorphous composite materials exhibit non-uniform deformation under the loading state, that is, they show work softening, and this phenomenon is another stumbling block restricting the engineering application of titanium-based amorphous composite materials.

[0003] From the currently disclosed research, methods such as laser additive manufacturing and composition regulation can regulate the size and distribution of crystalline phases in titanium-based amorphous composite materials and improve the plastic deformation ability of the composite materials. However, regulating the morphology and distribution of crystalline phases in titanium-based amorphous composite materials in terms of preparation processes and raw material ratios is at a disadvantage in terms of operation means and cost control, and requires a large number of experimental verifications with a long experimental period. Summary of the Invention

[0004] The main object of the present invention is to propose a nano-crystalline toughened titanium-based amorphous composite material and a preparation process thereof, and to regulate the size of crystalline toughening phases in the titanium-based amorphous composite material by means of large plastic deformation, thereby improving the performance of the titanium-based amorphous composite material.

[0005] To solve the above technical problems, according to one aspect of the present invention, the following technical solutions are provided:

[0006] A preparation process of a nano-crystalline toughened titanium-based amorphous composite material, comprising the following steps:

[0007] S1. Prepare a titanium-based amorphous composite material by a vacuum copper mold suction casting process;

[0008] S2. Take cylindrical specimens from the titanium-based amorphous composite material and perform high-pressure torsion to obtain a nano-crystalline toughened titanium-based amorphous composite material.

[0009] As a preferred embodiment of the preparation process of the nanocrystalline toughened titanium-based amorphous composite material of the present invention, in step S1, the titanium-based amorphous composite material, in atomic percentage, includes: Ti 41%, Zr 32%, Ni 6%, Ta 7%, Be 14%.

[0010] As a preferred embodiment of the preparation process of the nanocrystalline toughened titanium-based amorphous composite material of the present invention, in step S1, the mold for the vacuum copper mold suction casting process is a cylindrical mold with a diameter of 6 mm and a length of 80 mm.

[0011] As a preferred embodiment of the preparation process of the nanocrystalline toughened titanium-based amorphous composite material of the present invention, in step S2, the cylindrical specimen is a cylindrical specimen with a diameter of 6 mm and a height of 3 mm.

[0012] As a preferred embodiment of the preparation process of the nanocrystalline toughened titanium-based amorphous composite material of the present invention, in step S2, the pressure for high-pressure torsion is 3 - 5 GPa, the number of revolutions is 30 - 50 r, and the high-pressure torsion is carried out at room temperature.

[0013] As a preferred embodiment of the preparation process of the nanocrystalline toughened titanium-based amorphous composite material of the present invention, in step S2, the dimensional deformation amount of the high-pressure torsion specimen along the height direction is ≥50%.

[0014] To solve the above technical problems, according to another aspect of the present invention, the present invention provides the following technical solution:

[0015] A nanocrystalline toughened titanium-based amorphous composite material is prepared by using the above-mentioned preparation process of the nanocrystalline toughened titanium-based amorphous composite material.

[0016] As a preferred embodiment of the nanocrystalline toughened titanium-based amorphous composite material of the present invention, the nanocrystals in the titanium-based amorphous composite material are β-Ti with a BCC structure, and the nanocrystals are in the shape of dendritic stretching or agglomerated particles, and their size is 20 - 300 nm.

[0017] The beneficial effects of the present invention are as follows:

[0018] The present invention provides a nanocrystalline toughened titanium-based amorphous composite material and its preparation process. The copper mold suction casting method + high-pressure torsion process is adopted, and the morphology and size of dendrites in the composite material are regulated by the method of large plastic deformation, realizing the evolution of micron-scale dendrites in the composite material into nano-scale ones, so as to obtain a nanocrystalline toughened titanium-based amorphous composite material, with the size of its nanocrystals being 20 - 300 nm, the nanoindentation hardness ≥ 4.05 GPa, and the uniform plastic deformation strain ≥ 4%. The formation of nanocrystals avoids the softening caused by highly localized shear in the amorphous matrix, and improves the work hardening ability of the titanium-based amorphous composite material. Brief Description of the Drawings

[0019] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required for use in the description of the embodiments or the prior art. Obviously, the drawings in the following description are only some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on the structures shown in these drawings.

[0020] Figure 1 It is the microstructure diagram of the titanium-based amorphous composite material of Embodiment 1 of the present invention;

[0021] Figure 2 It is the microstructure diagram of the titanium-based amorphous composite material of Comparative Example 1 of the present invention.

[0022] The realization, functional features and advantages of the object of the present invention will be further described in conjunction with the embodiments with reference to the drawings. Detailed Embodiments

[0023] The following will clearly and completely describe the technical solutions in the embodiments. Obviously, the described embodiments are only some embodiments of the present invention, rather than all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts belong to the scope of protection of the present invention.

[0024] The present invention provides a nanocrystalline toughened titanium-based amorphous composite material and its preparation process, regulates the shape and size of the crystal toughening phase therein, adopts the copper mold suction casting method + high-pressure torsion process, and regulates the morphology and size of dendrites in the composite material by the method of large plastic deformation, realizing the evolution of micron-scale dendrites in the composite material into nano-scale ones, so as to obtain a nanocrystalline toughened titanium-based amorphous composite material, with the size of its nanocrystals being 20 - 300 nm, the nanoindentation hardness ≥ 4.05 GPa, and the uniform plastic deformation strain ≥ 4%. It solves the defects of strain softening and hardness decrease caused by highly localized shear in the amorphous matrix of the titanium-based amorphous composite material, and improves the performance of the titanium-based amorphous composite material.

[0025] According to one aspect of the present invention, the present invention provides the following technical solution:

[0026] A preparation process of a nanocrystalline toughened titanium-based amorphous composite material, comprising the following steps:

[0027] S1. Prepare a titanium-based amorphous composite material by a vacuum copper mold suction casting process;

[0028] S2. Take a cylindrical sample from the titanium-based amorphous composite material for high-pressure torsion to obtain a nanocrystalline toughened titanium-based amorphous composite material.

[0029] Preferably, in the step S1, the titanium-based amorphous composite material, in atomic percentage, comprises: Ti 41%, Zr 32%, Ni 6%, Ta 7%, Be 14%.

[0030] Preferably, in the step S1, the base metal alloy is melted in a vacuum state and a cylindrical alloy is obtained by suction casting; the mold of the vacuum copper mold suction casting process is a cylindrical mold with a diameter of 6 mm and a length of 80 mm.

[0031] Preferably, in the step S2, the cylindrical sample is a cylindrical sample with a diameter of 6 mm and a height of 3 mm.

[0032] Preferably, in the step S2, the pressure of the high-pressure torsion is 3-5 GPa, the number of revolutions is 30-50 r, and the high-pressure torsion is carried out at room temperature. Specifically, the pressure of the high-pressure torsion can be any one of, for example, 3 GPa, 4 GPa, 5 GPa or the range between any two of them; the number of revolutions can be any one of, for example, 30 r, 40 r, 50 r or the range between any two of them. The formation of nanocrystals is closely related to the large plastic deformation caused by high-pressure torsion. There are two kinds of nanocrystallization phenomena during the plastic deformation process: one is that the micron-sized dendrites are stretched and separated due to torsion, and the size gradually decreases to the nanoscale; the other is that agglomerated particle nanocrystals appear inside the dendrites due to the bearing of torsion pressure and the strong interaction with the amorphous matrix.

[0033] Preferably, in the step S2, the dimensional deformation amount of the high-pressure torsion sample along the height direction is ≥50%. The dimensional deformation amount of the high-pressure torsion sample along the height direction is related to the torsion pressure and the number of turns in the high-pressure torsion process. The dimensional deformation amount of the high-pressure torsion sample along the height direction is preferably 50-75%; specifically, the deformation amount of the sample after high-pressure torsion can be any one of, for example, 50%, 55%, 60%, 65%, 70%, 75% or the range between any two of them.

[0034] According to another aspect of the present invention, the present invention provides the following technical solution:

[0035] A nanocrystalline toughened titanium-based amorphous composite material is prepared by using the preparation process of the above-mentioned nanocrystalline toughened titanium-based amorphous composite material. The nanocrystals are β-Ti with a BCC structure, and the nanocrystals are in the shape of dendritic stretching or agglomerated particles, and their size is 20-300 nm.

[0036] The technical solution of the present invention will be specifically described below in conjunction with specific embodiments.

[0037] Using a vacuum melting furnace, a titanium-based amorphous composite as-cast specimen is prepared by the method of copper mold suction casting. The mold for the vacuum copper mold suction casting process is a cylindrical mold with a diameter of 6 mm and a length of 80 mm. A cylindrical specimen of 6 mm (diameter) × 3 mm (height) is intercepted from the as-cast specimen as a high-pressure torsion specimen for standby.

[0038] Table 1 Detection composition of titanium-based amorphous composite material (at.%)

[0039]

[0040] Example 1

[0041] A preparation process of a nanocrystalline toughened titanium-based amorphous composite material includes the following steps:

[0042] S1. Prepare a titanium-based amorphous composite material by a vacuum copper mold suction casting process;

[0043] S2. Take a cylindrical specimen from the titanium-based amorphous composite material and conduct a high-pressure torsion test. Control the pressure of the high-pressure torsion to be 5 GPa and the number of revolutions to be 50 r (H-50), and conduct it at room temperature;

[0044] In Example 1, the height of the deformed specimen becomes 0.75 mm, and the deformation amount is (3 - 0.75) / 3 = 75%; the microstructural morphology diagram is as Figure 1 shown ( Figure 1 The upper left side in is the TEM diagram, the lower left side is the SAED diagram, and the right side is the SEM diagram). It can be seen that the micron-sized dendrites are deformed by high-pressure torsion, and severe plastic deformation occurs inside the dendrites and at the positions of forced torsional stretching to form nanocrystals (such as the area pointed by the arrow in the SEM diagram). The size of the nanocrystals is 20-150 nm. By means of the high-pressure torsion process, the size of the crystal phase in the titanium-based amorphous composite material is refined and evolved into nanoscale crystals; the nanoindentation hardness of the as-cast specimen of the titanium-based amorphous composite material is 4.03 GPa, and the nanoindentation hardness of the H-50 specimen is 4.47 GPa, and the uniform plastic deformation strain is 4%.

[0045] Example 2

[0046] A preparation process of a nanocrystalline toughened titanium-based amorphous composite material includes the following steps:

[0047] S1. Prepare a titanium-based amorphous composite material by the vacuum copper mold suction casting process;

[0048] S2. Take cylindrical specimens from the titanium-based amorphous composite material and conduct a high-pressure torsion test. Control the pressure of the high-pressure torsion to be 5 GPa and the number of revolutions to be 30 r (H-30), and conduct it at room temperature;

[0049] In Example 2, the height of the deformed specimen becomes 1.38 mm, and the deformation amount is (3 - 1.38) / 3 = 54%; the nanoscale crystal size is 50 - 300 nm. By means of the high-pressure torsion process, the size of the crystal phase in the titanium-based amorphous composite material is refined and evolved into nanoscale crystals; the nanoindentation hardness of the as-cast specimen of the titanium-based amorphous composite material is 4.03 GPa, the nanoindentation hardness of the H-30 specimen is 4.05 GPa, and the uniform plastic deformation strain is 5%.

[0050] Comparative Example 1

[0051] The difference from Example 1 is that step S2 is not carried out.

[0052] In this comparative example, a titanium-based amorphous composite material is prepared by the vacuum copper mold suction casting method, Figure 2 Fig. is the microstructure diagram of the titanium-based amorphous composite material in Comparative Example 1, where the size of the dendritic β-Ti crystal toughening phase is 1 - 2 μm. The nano-hardness of the titanium-based amorphous composite material is 4.03 GPa, and the uniform plastic deformation strain is 2%.

[0053] Comparative Example 2

[0054] The difference from Example 1 is that in step S2, the number of revolutions of the high-pressure torsion is controlled to be 10 r (H-10).

[0055] In the H-10 specimen of Comparative Example 2, the nanocrystal size is 350 - 400 nm, which is larger than the nanocrystal sizes in Examples 1 and 2, which is due to insufficient deformation. In Comparative Example 2, the height of the deformed specimen becomes 2 mm, the deformation amount is (3 - 2) / 3 = 33.3%, the nano-hardness is 4.02 GPa, and the uniform plastic deformation is 2.3%.

[0056] It can be seen from the above examples and comparative examples that the present invention adopts the copper mold suction casting method + high-pressure torsion process, and regulates the morphology and size of the dendritic crystals in the composite material by the method of large plastic deformation, realizing the evolution of micron-scale dendritic crystals in the composite material into nanoscale ones, thereby obtaining a titanium-based amorphous composite material toughened by nanocrystals, with the nanocrystal size of 20 - 300 nm, the nanoindentation hardness ≥ 4.05 GPa, and the uniform plastic deformation strain ≥ 4%.

[0057] The above are only the preferred embodiments of the present invention, and do not limit the patent scope of the present invention accordingly. Any equivalent structural transformation made by using the content of the specification of the present invention under the inventive concept of the present invention, or any direct / indirect application in other related technical fields is included in the patent protection scope of the present invention.

Claims

1. A process for preparing a nanocrystalline toughened titanium-based amorphous composite material, characterized in that: The steps include: S1. A titanium-based amorphous composite material is prepared by vacuum copper mold suction casting process, wherein the titanium-based amorphous composite material comprises, in atomic percentage, 41% Ti, 32% Zr, 6% Ni, 7% Ta, and 14% Be; S2. Take a cylindrical sample from the titanium-based amorphous composite material and perform high-pressure torsion. The pressure of the high-pressure torsion is 3-5GPa, the number of revolutions is 30-50r, the high-pressure torsion is performed at room temperature, and the dimensional deformation of the high-pressure torsion sample along the height direction is ≥50%; obtain a nanocrystal-toughened titanium-based amorphous composite material, and realize the regulation of the size of the crystal toughening phase in the titanium-based amorphous composite material by a large plastic deformation method. The nanocrystals of the titanium-based amorphous composite material are β-Ti with a BCC structure, and the nanocrystals are in a dendrite-like stretched or agglomerated granular shape, and the size is 20-300nm; the nanoindentation hardness of the nanocrystal-toughened titanium-based amorphous composite material is ≥4.05GPa, and the uniform plastic deformation strain is ≥4%.

2. The process for preparing the nanocrystalline toughened titanium-based amorphous composite material according to claim 1, characterized in that: In the step S1, the mold for the vacuum copper mold suction casting process is a cylindrical mold with a diameter of 6 mm and a length of 80 mm.

3. The process for preparing the nanocrystalline toughened titanium-based amorphous composite material according to claim 1, characterized in that: In step S2, the cylindrical sample is a cylindrical sample with a diameter of 6 mm and a height of 3 mm.

4. A nanocrystal-toughened titanium-based amorphous composite material, characterized in that: The nanocrystalline toughened titanium-based amorphous composite material is prepared by the preparation process of any one of claims 1 to 3.

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