A method for preparing a tough-brittle bonded Ti-15Mo / TiCrNb / TiAl3 layered composite plate

Abstract

The application discloses a kind of Ti-15Mo / TiCrNb / TiAl3 layer composite plate preparation methods of ductile-brittle combination, comprising the following steps: one, preparation Ti-15Mo alloy plate, Ti4Cr4Nb alloy foil and aluminum foil raw material;Two, raw material surface treatment;Three, laminated design obtains laminated plate;Four, gradient vacuum hot-pressing sintering obtains sintered plate blank;Five, sintered plate blank vacuum annealing treatment obtains layer composite plate.The application adopts Ti4Cr4Nb alloy foil to isolate Ti-15Mo alloy plate and aluminum foil to ensure the plasticity and toughness of Ti-15Mo alloy, adopts hot-pressing sintering method to make Ti4Cr4Nb and aluminum interface in-situ generate TiAl3 intermetallic compound, and combines annealing regulation microstructure, obtains Ti-15Mo / TiCrNb / TiAl3 layer composite plate of ductile-brittle combination, applicable to impact protection material field.

Description

Technical Field

[0001] This invention belongs to the field of titanium-aluminum composite material technology, specifically relating to a method for preparing a ductile-brittle bonded Ti-15Mo / TiCrNb / TiAl3 layered composite plate. Background Technology

[0002] In recent years, the emergence of ductile-brittle layered composite materials has opened up a new avenue for the research of impact-resistant protective materials. A novel high-performance ductile-brittle layered composite material based on titanium / titanium aluminum (Ti / TiAl) lightweight metals has come into the researchers' view. Currently, Ti-TiAl3 layered composite plates have received considerable attention. However, due to the extremely low ductility and toughness of TiAl3, it is still not possible to directly composite TiAl3 alloy foil with Ti alloys through machining. The main method used is foil metallurgical composite method using Al and Ti foils to prepare layered composite plates. Due to the inherent brittleness of intermetallic compounds, it is difficult to significantly improve the overall mechanical properties of the material by relying solely on the layered structure and limited improvement of the properties of TiAl-based intermetallic compounds. However, in order to further improve the material's performance, it is proposed to use Ti-15Mo alloy, which has better ductility and toughness than Ti6Al4V (TC4), to composite with TiAl-based intermetallic compounds to improve the overall mechanical properties of this lightweight metal composite material. Therefore, how to achieve the composite of Ti-15Mo and TiAl intermetallic compounds, and ensure the ductility and toughness of Ti-15Mo and the formation of TiAl intermetallic compounds, is a problem that researchers must solve. Summary of the Invention

[0003] The technical problem to be solved by this invention is to provide a method for preparing a ductile-brittle combined Ti-15Mo / TiCrNb / TiAl3 layered composite plate, addressing the shortcomings of the prior art. This method uses Ti4Cr4Nb alloy foil to isolate the Ti-15Mo alloy sheet from the aluminum foil to ensure the ductility and toughness of the Ti-15Mo alloy. A hot-pressing sintering method is used to generate TiAl3 intermetallic compounds in situ at the Ti4Cr4Nb-aluminum interface. Combined with annealing treatment to control the microstructure, the ductile Ti-15Mo and the brittle TiAl3 intermetallic compounds are combined to form a ductile-brittle combined Ti-15Mo / TiCrNb / TiAl3 layered composite plate. This solves the problem of existing ductile-brittle laminated composite plates that need to both ensure the ductility and toughness of Ti-15Mo and promote the formation of TiAl-based intermetallic compounds.

[0004] To solve the above-mentioned technical problems, the technical solution adopted by the present invention is as follows: a method for preparing a ductile-brittle combined Ti-15Mo / TiCrNb / TiAl3 layered composite plate, characterized in that Ti-15Mo alloy plate, Ti4Cr4Nb alloy foil and aluminum foil are laminated and composited, and then the Ti-15Mo / TiCrNb / TiAl3 layered composite plate is prepared by hot pressing sintering composite method, specifically including the following steps:

[0005] Step 1: Prepare Ti-15Mo alloy plate, Ti4Cr4Nb alloy foil, and aluminum foil;

[0006] Step 2: Perform surface treatment on the Ti-15Mo alloy plate, Ti4Cr4Nb alloy foil and aluminum foil prepared in Step 1;

[0007] Step 3: The Ti-15Mo alloy plate, Ti4Cr4Nb alloy foil and aluminum foil after surface treatment in Step 2 are stacked. The Ti4Cr4Nb alloy foil is used to isolate the Ti-15Mo alloy plate from direct contact with the aluminum foil to obtain a stacked plate.

[0008] Step 4: Perform gradient vacuum hot pressing sintering on the laminated plate obtained in Step 3 to obtain a sintered plate blank;

[0009] Step 5: Vacuum annealing is performed on the sintered slab obtained in Step 4 to obtain Ti-15Mo / TiCrNb / TiAl3 layered composite plate.

[0010] The above-mentioned method for preparing a ductile-brittle combined Ti-15Mo / TiCrNb / TiAl3 layered composite plate is characterized in that the composition of the Ti-15Mo alloy plate, by mass percentage, is: Mo 15.8%, C 0.011%, Fe 0.01%, Si 0.01%, O 0.099%, N 0.013%, with the balance being titanium. The main component of this Ti-15Mo alloy plate is Mo, and the [Mo] equivalent is 15-16, ensuring that its plastic deformation mechanism is mainly based on the twin-induced plasticity (TWIP) effect. Simultaneously, by strictly controlling the content of impurity elements, excessive impurities are avoided from severely reducing the elongation of the Ti-15Mo alloy plate.

[0011] The above-mentioned method for preparing a ductile-brittle combined Ti-15Mo / TiCrNb / TiAl3 layered composite plate is characterized in that the composition of the Ti4Cr4Nb alloy foil, by mass percentage, is: Cr 4.16%, Fe 0.024%, Nb 7.50%, C 0.004%, O 0.043%, N 0.004%, with the balance being titanium. The composition of this Ti4Cr4Nb alloy foil is derived from Ti4822 alloy (γ-TiAl alloy). By removing the original Al element and strictly controlling the content of impurity elements, the plasticity of the Ti4Cr4Nb alloy foil is guaranteed.

[0012] The above-mentioned method for preparing a tough-brittle bonded Ti-15Mo / TiCrNb / TiAl3 layered composite plate is characterized in that the structure of the laminated plate in step three is a bottom layer Ti-15Mo and M combined units Ti-15Mo / Ti4Cr4Nb / Al / Ti4Cr4Nb located on the bottom layer Ti-15Mo, where M≥1, or a bottom layer Ti-15Mo, a top layer Ti-15Mo and N combined units Ti4Cr4Nb / Al / TiCrNb located between the bottom layer Ti-15Mo and the top layer Ti-15Mo, where N≥1.

[0013] The above-mentioned method for preparing a tough-brittle bonded Ti-15Mo / TiCrNb / TiAl3 layered composite plate is characterized in that the gradient vacuum hot pressing sintering process in step four is as follows: maintaining a vacuum degree of 1×10 -3 Pa ~ 1×10 -5 Pa, first heat from room temperature to 520℃ and hold for 2 hours, sintering pressure is 8t, then heat to 650℃ and hold for 6 hours, sintering pressure is 20t, then cool with the furnace to room temperature.

[0014] This invention employs a gradient vacuum hot-pressing sintering process. First, pre-sintering is performed at 520°C for 2 hours under low pressure. This activates the atomic activity between the laminated plates to promote interfacial reactions and releases residual stress from the lamination process. A sintering pressure of 8t is applied to ensure tight interfacial bonding. Then, the sintering temperature is increased to near the melting temperature of aluminum (650°C), and the pressure is increased to 20t. This facilitates the reaction of Al with Ti4Cr4Nb to form an interfacial TiAl3 intermetallic compound and avoids aluminum melting and leakage during sintering. It also reduces the risk of voids due to the Kirkendall effect during intermetallic compound formation, thus achieving densification of the intermetallic compound.

[0015] The above-described method for preparing a ductile-brittle bonded Ti-15Mo / TiCrNb / TiAl3 layered composite plate is characterized in that the thickness of the intermetallic compound layer at the interface in the sintered plate in step four reaches more than 20 μm. By controlling the sintering time, the thickness of the intermetallic compound layer at the interface (TiAl3) is ensured to reach more than 20 μm, thereby ensuring the dispersion of the effect of high-speed impact stress on the intermetallic compound.

[0016] The above-described method for preparing a ductile-brittle bonded Ti-15Mo / TiCrNb / TiAl3 layered composite plate is characterized by the following steps: the vacuum annealing treatment in step five is performed at a temperature of 850°C, with a holding time of 2-3 hours, a constant contact pressure, and air cooling. This invention, by controlling the annealing temperature to 850°C, can regulate the Ti-15Mo phase composition and grain size in the Ti-15Mo / TiCrNb / TiAl3 layered composite plate without altering the chemical composition of the intermetallic TiAl3 compounds. Typically, this vacuum annealing treatment increases the plasticity of the Ti-15Mo / TiCrNb / TiAl3 layered composite plate to over 38%.

[0017] The above-described method for preparing a ductile-brittle combined Ti-15Mo / TiCrNb / TiAl3 layered composite plate is characterized in that, in step five, the Ti-15Mo grain size in the Ti-15Mo / TiCrNb / TiAl3 layered composite plate is 60 μm. By controlling the Ti-15Mo grain size, the TWIP effect of Ti15Mo is ensured, allowing its plasticity to be maintained at over 35%, which is beneficial for improving the plasticity of the layered composite plate.

[0018] Compared with the prior art, the present invention has the following advantages:

[0019] 1. This invention involves hot-pressing and sintering a composite of Ti-15Mo alloy sheet, Ti4Cr4Nb alloy foil, and aluminum foil. By adding Ti4Cr4Nb alloy foil as an intermediate layer to prevent direct contact between the Ti-15Mo alloy sheet and the aluminum foil, Al atoms are effectively prevented from diffusing into the Ti-15Mo alloy. Thus, the composite and hot-pressing sintering process does not change the [Mo] equivalent of the Ti-15Mo alloy, effectively ensuring the intrinsic ductility and toughness of the Ti-15Mo alloy. At the same time, TiAl-based intermetallic compound TiAl3 is generated in situ at the interface between the Ti4Cr4Nb alloy foil and the aluminum foil. The ductility and toughness of the Ti-15Mo alloy sheet and the brittleness and hardness of the TiAl-based intermetallic compound are used to form a tough-brittle combined Ti-15Mo / TiCrNb / TiAl3 layered composite plate.

[0020] 2. This invention controls the phase composition and grain size of Ti-15Mo in the microstructure by vacuum annealing of sintered slabs. Without affecting the TiAl intermetallic compounds and Ti4Cr4Nb, it releases the residual stress of phase transformation in the intermetallic compound layer, thereby further improving the plasticity of Ti-15Mo / TiCrNb / TiAl3 layered composite plate.

[0021] 3. This invention designs a stacked structure of Ti-15Mo alloy plate, Ti4Cr4Nb alloy foil and aluminum foil to form different stacked structures, thereby obtaining layered composite plates with different properties to meet the needs of different applications.

[0022] The technical solution of the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. Attached Figure Description

[0023] Figure 1 The image shows the SEM morphology of the Ti-15Mo / TiCrNb / TiAl3 layered composite plate prepared in Example 1 of this invention.

[0024] Figure 2 The image shows the SEM morphology of the Ti-15Mo / TiCrNb / TiAl3 layered composite plate prepared in Example 2 of this invention.

[0025] Figure 3 This is a SEM image of the TiCrNb / TiAl3 layered composite plate prepared in Comparative Example 1 of this invention.

[0026] Figure 4 The image shows the SEM morphology of the TiCrNb / TiAl3 layered composite plate prepared in Comparative Example 2 of this invention. Detailed Implementation

[0027] Example 1

[0028] In this embodiment, Ti-15Mo alloy sheet, Ti4Cr4Nb alloy foil, and aluminum foil are laminated and then hot-pressed and sintered to prepare a Ti-15Mo / TiCrNb / TiAl3 layered composite plate. The composition of the Ti-15Mo alloy sheet by mass percentage is: Mo 15.8%, C 0.011%, Fe 0.01%, Si 0.01%, O 0.099%, N 0.013%, with the balance being titanium. The composition of the Ti4Cr4Nb alloy foil by mass percentage is: Cr 4.16%, Fe 0.024%, Nb 7.50%, C 0.004%, O 0.043%, N 0.004%, with the balance being titanium.

[0029] The method specifically includes the following steps:

[0030] Step 1: Prepare a Ti-15Mo alloy plate with a thickness of 1.5 mm, a Ti4Cr4Nb alloy foil with a thickness of 180 μm, and an aluminum foil with a thickness of 60 μm;

[0031] Step 2: Surface treatment of the Ti-15Mo alloy plate, Ti4Cr4Nb alloy foil and aluminum foil prepared in Step 1: First, remove the surface oxide film by pickling, and then place them in an ethanol solution to prevent oxidation;

[0032] Step 3: The Ti-15Mo alloy plate, Ti4Cr4Nb alloy foil, and aluminum foil after surface treatment in Step 2 are stacked. The Ti4Cr4Nb alloy foil is used to isolate the Ti-15Mo alloy plate from direct contact with the aluminum foil, resulting in a stacked plate with a total thickness of 11.1 mm. The structure of the stacked plate consists of a bottom Ti-15Mo layer and five combined units Ti-15Mo / Ti4Cr4Nb / Al / Ti4Cr4Nb located on the bottom Ti-15Mo layer.

[0033] Step 4: Perform gradient vacuum hot pressing sintering on the laminated plate obtained in Step 3 to obtain a sintered plate blank; the gradient vacuum hot pressing sintering process is as follows: maintain a vacuum degree of 1×10 -3 Pa ~ 1×10 -5 Pa, first heat from room temperature to 520℃ and hold for 2 hours, sintering pressure is 8t, then heat to 650℃ and hold for 6 hours, sintering pressure is 20t, then cool with the furnace to room temperature;

[0034] Step 5: Vacuum annealing is performed on the sintered slab obtained in Step 4 to obtain Ti-15Mo / TiCrNb / TiAl3 layered composite plate; the vacuum annealing temperature is 850℃, the holding time is 2h, and it is air-cooled to room temperature, with the constant pressure being the contact pressure.

[0035] Example 2

[0036] The difference between this embodiment and embodiment 1 is that: in step three, the structure of the laminate consists of a bottom Ti-15Mo, a top Ti-15Mo, and 15 combined units Ti4Cr4Nb / Al / Ti4Cr4Nb located between the bottom Ti-15Mo and the top Ti-15Mo, with a total thickness of 9.3mm; and in step five, the heat preservation time for vacuum annealing is 3h.

[0037] Comparative Example 1

[0038] The difference between this comparative example and Example 1 is as follows: In step three, Ti-15Mo alloy sheet was not used for the laminated design; the laminated plate structure consisted of 10 combined units of Ti4Cr4Nb / Al / Ti4Cr4Nb, with a total thickness of 4.2 mm. In step four, the gradient vacuum hot pressing sintering process was performed while maintaining a vacuum level of 1×10⁻⁶.-3 Pa ~ 1×10 -5 Pa, first heat from room temperature to 520℃ and hold for 2 hours, sintering pressure is 8t, then heat to 650℃ and hold for 3 hours, sintering pressure is 20t, then air cool to room temperature, without performing the vacuum annealing treatment in step five, directly use the sintered slab as TiCrNb / TiAl3 layered composite plate.

[0039] Comparative Example 2

[0040] The difference between this comparative example and Comparative Example 1 is that the gradient vacuum hot pressing sintering process in step four is as follows: the vacuum level is maintained at 1×10⁻⁶. -3 Pa ~ 1×10 -5 Pa, first heat from room temperature to 520℃ and hold for 2 hours, sintering pressure is 8t, then heat to 650℃ and hold for 6 hours, sintering pressure is 20t, then heat to 950℃ and hold for 16 hours, sintering pressure is 10t, then air cool to room temperature.

[0041] Figure 1 and Figure 2 The images show the SEM morphology of the Ti-15Mo / TiCrNb / TiAl3 layered composite plates prepared in Examples 1 and 2 of this invention, respectively. Figure 1 Figure (a) shows the SEM morphology of the Ti-15Mo / TiCrNb interface, Figure (b) shows the SEM morphology of the Ti-15Mo layer, and Figure (c) shows the SEM morphology of the composite plate. Figure 1 and Figure 2 It can be seen that the Ti-15Mo / TiCrNb / TiAl3 layered composite plate prepared by the present invention has good cross-section bonding. The aluminum in the laminate is completely consumed to form a dense TiAl3 intermetallic compound with a thickness of 20 μm. At the same time, the Ti-15Mo layer in the Ti-15Mo / TiCrNb / TiAl3 layered composite plate is mainly β phase with a grain size of 60 μm, and there is no obvious intermediate phase formed at the interface between Ti-15Mo and Ti4Cr4Nb layers.

[0042] The tensile properties of the Ti-15Mo layer in the Ti-15Mo / TiCrNb / TiAl3 layered composite plates prepared in Examples 1 and 2 of this invention were tested, and the results are shown in Table 1 below.

[0043] Table 1

[0044] Example 1 795 532 39.5 Example 2 798 528 38.0

[0045] As shown in Table 1, the elongation after fracture of the Ti-15Mo layer in the Ti-15Mo / TiCrNb / TiAl3 layered composite plate reached more than 38%, which meets the required characteristics of toughness layer material and ensures its intrinsic plasticity and toughness.

[0046] Figure 3 The image shows the SEM morphology of the TiCrNb / TiAl3 layered composite plate prepared in Comparative Example 1 of this invention. Figure 3 It can be seen that no intermetallic compounds were formed in the TiCrNb / TiAl3 layered composite plate, indicating that the 6-hour hot pressing sintering time is a necessary condition to ensure the effective consumption of aluminum layers and the formation of TiAl3 intermetallic compounds.

[0047] Figure 4 The image shows the SEM morphology of the TiCrNb / TiAl3 layered composite plate prepared in Comparative Example 2 of this invention. Figure 4 It can be seen that stable TiAl-based intermetallic compounds still do not appear at the interface of the TiCrNb / TiAl3 layered composite plate, indicating that further increasing the gradient vacuum hot pressing sintering temperature will promote the phase transformation of the TiAl3 layer. The diffusion couple formed by TiAl3 and Ti4Cr4Nb will promote the formation of intermetallic compounds such as TiAl2 and γ-TiAl, which will reduce the interface density, increase interface defects, and reduce the interface bonding strength.

[0048] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention in any way. Any simple modifications, alterations, and equivalent changes made to the above embodiments based on the inventive essence shall still fall within the protection scope of the present invention.

Claims

1. A method for preparing a tough-brittle bonded Ti-15Mo / TiCrNb / TiAl3 layered composite plate, characterized in that, Ti-15Mo alloy sheet, Ti4Cr4Nb alloy foil, and aluminum foil were laminated together, and then a Ti-15Mo / TiCrNb / TiAl3 layered composite plate was prepared by hot pressing and sintering. The specific steps included: Step 1: Prepare Ti-15Mo alloy plate, Ti4Cr4Nb alloy foil, and aluminum foil; Step 2: Perform surface treatment on the Ti-15Mo alloy plate, Ti4Cr4Nb alloy foil and aluminum foil prepared in Step 1; Step 3: The Ti-15Mo alloy plate, Ti4Cr4Nb alloy foil, and aluminum foil after surface treatment in Step 2 are stacked. The Ti4Cr4Nb alloy foil is used to isolate the Ti-15Mo alloy plate from direct contact with the aluminum foil, resulting in a stacked plate. The structure of the stacked plate is a bottom Ti-15Mo and M combined units Ti-15Mo / Ti4Cr4Nb / Al / Ti4Cr4Nb located on the bottom Ti-15Mo, where M≥1, or a bottom Ti-15Mo, a top Ti-15Mo, and N combined units Ti4Cr4Nb / Al / TiCrNb located between the bottom Ti-15Mo and the top Ti-15Mo, where N≥1. Step 4: Perform gradient vacuum hot pressing sintering on the laminated plate obtained in Step 3 to obtain a sintered plate blank; the gradient vacuum hot pressing sintering process is as follows: maintain a vacuum degree of 1×10 -3 Pa ~ 1×10 -5 Pa, first heat from room temperature to 520℃ and hold for 2 hours, sintering pressure is 8t, then heat to 650℃ and hold for 6 hours, sintering pressure is 20t, then cool with the furnace to room temperature; Step 5: Vacuum annealing is performed on the sintered slab obtained in Step 4 to obtain Ti-15Mo / TiCrNb / TiAl3 layered composite plate.

2. The method for preparing a tough-brittle bonded Ti-15Mo / TiCrNb / TiAl3 layered composite plate according to claim 1, characterized in that, The composition of the Ti-15Mo alloy plate, by mass percentage, is: Mo 15.8%, C 0.011%, Fe 0.01%, Si 0.01%, O 0.099%, N 0.013%, with the balance being titanium.

3. The method for preparing a tough-brittle bonded Ti-15Mo / TiCrNb / TiAl3 layered composite plate according to claim 1, characterized in that, The composition of the Ti4Cr4Nb alloy foil, by mass percentage, is: Cr 4.16%, Fe 0.024%, Nb 7.50%, C 0.004%, O 0.043%, N 0.004%, with the balance being titanium.

4. The method for preparing a tough-brittle bonded Ti-15Mo / TiCrNb / TiAl3 layered composite plate according to claim 1, characterized in that, In step four, the thickness of the intermetallic compound layer at the interface in the sintered slab reaches more than 20 μm.

5. The method for preparing a tough-brittle bonded Ti-15Mo / TiCrNb / TiAl3 layered composite plate according to claim 1, characterized in that, The vacuum annealing process described in step five is performed at a temperature of 850℃, with a holding time of 2-3 hours, a constant pressure of contact pressure, and air cooling.

6. The method for preparing a tough-brittle bonded Ti-15Mo / TiCrNb / TiAl3 layered composite plate according to claim 5, characterized in that, In step five, the Ti-15Mo grain size in the Ti-15Mo / TiCrNb / TiAl3 layered composite plate is 60μm.

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