CN112899517B - A method for improving thermal deformation properties of titanium matrix composites - Google Patents

Abstract

The invention discloses a method for improving the thermal deformation performance of a titanium-based composite material, and belongs to the technical field of metal-based composite materials and preparation. The invention solves the technical problems such as high deformation resistance and many deformation defects of the existing titanium-based composite material thermal deformation. The present invention includes the following steps: 1) pretreating raw materials for preparing titanium-based composite materials, adding TiB ₂ powder, and placing it in a water-cooled copper crucible; 2) passing argon gas and hydrogen gas after vacuuming, and smelting, to obtain an improved thermal deformability Titanium matrix composites. The invention can significantly reduce the thermal deformation resistance of the titanium-based composite material, reduce the peak stress, and reduce the deformation temperature under the same peak stress, and there are almost no defects such as interface holes and deformation cracks after deformation, and the thermal deformation performance of the material is greatly improved. improve. In addition, the invention has the advantages of economy, safety, novelty, reliability, etc., and has a good application prospect.

Description

A method for improving thermal deformation properties of titanium matrix composites

technical field

The invention relates to a method for improving the thermal deformation performance of a titanium-based composite material, and belongs to the technical field of metal-based composite materials and preparation.

Background technique

With the continuous development of the aerospace field, the demand for various aerospace structural parts with excellent performance is increasing. At the same time, lightweight is also an important selection standard and development direction of engine materials. Traditional titanium alloys are under such a development trend. It has been difficult to apply, so the concept of titanium matrix composite material is proposed, that is, a metal matrix composite material formed by implanting some ceramic reinforcements into titanium alloys. This kind of composite material can inherit the ductility and toughness of titanium alloy, and has the properties of high strength and high modulus of ceramic reinforcement, so that the titanium matrix composite material has higher specific strength and specific modulus, and has excellent comprehensive performance.

The TiB whiskers in the TiB reinforced titanium matrix composites synthesized by in situ reaction are uniformly distributed, the interface with the titanium alloy matrix is clean, the reaction process is rapid, the production cost is low, and it has excellent specific strength and excellent high temperature performance. of aerospace materials. TiB reinforced titanium matrix composite ingots usually require hot deformation processing such as billet forging to meet the shape requirements of various parts, such as thin plates, profiles, pipelines, etc. Thermal deformation can not only improve the density of parts, but also deform and strengthen, and improve the strength and plasticity of materials. However, the ceramic reinforcement greatly increases the deformation resistance of the material, resulting in difficult deformation, causing holes in the interface between TiB and the substrate, and even leading to material cracking, increasing the scrap rate. Traditional methods such as increasing the deformation temperature and reducing the deformation rate can reduce the deformation resistance and reduce defects such as holes and cracks, but these methods are too expensive, time-consuming and energy-intensive, which greatly reduces production efficiency and increases production costs. Therefore, there is an urgent need for a method to solve the difficulties faced by the high temperature deformation process of TiB reinforced titanium matrix composites, so as to reduce deformation defects, improve yield, reduce costs and improve efficiency.

SUMMARY OF THE INVENTION

In order to solve the technical problems such as high deformation resistance and many deformation defects of the existing TiB-reinforced titanium-based composite materials, the present invention provides a method for improving the thermal deformation performance.

A method for improving the thermal deformation performance of a titanium-based composite material, the method comprising the steps of:

Step 1, pretreating the raw materials for preparing the titanium-based composite material, adding TiB ₂ powder, and placing it in a water-cooled copper crucible;

In step 2, after vacuuming, argon gas and hydrogen gas are introduced, and smelting is performed to obtain a titanium-based composite material with improved thermal deformability.

Further, the operation process of the pretreatment in step 1 is as follows: ultrasonic cleaning is performed sequentially with acetone and absolute ethanol, and after cleaning, it is placed in a drying oven, and dried at 100° C. for 4 hours.

Further, the raw material is sponge titanium, and elemental element or intermediate alloy corresponding to the type of alloying element to be added.

Further, the purity of argon and hydrogen in step 2 was 99.999%.

Further, the flow ratio of argon and hydrogen in step 2 is 2:3.

Further, the vacuum degree after vacuuming in step 2 is 3×10 ^-3 Pa.

Further, the operation process of smelting in step 2 is as follows: after the initial current 120A melts all the raw materials, the current rises to 500A, the current is kept unchanged, and the smelting is stopped after 10min; Smelting operation.

Further, the smelting operation was performed a total of 6 times.

Further, the smelting equipment is a vacuum non-consumable electric arc furnace.

The present invention has the following beneficial effects: the present invention smelts the titanium-based composite material in a mixed atmosphere of hydrogen and argon, and during the smelting process, hydrogen element is placed into the melt in the form of hydrogen atoms under the action of the plasma arc, and remains as the solidification process. For ingot casting, it plays the role of reducing deformation resistance and reducing deformation defects in the subsequent hot deformation process. The invention significantly reduces the thermal deformation resistance of the TiB reinforced titanium-based composite material, reduces the peak stress, and reduces the deformation temperature under the same peak stress, and there are almost no defects such as interface holes and deformation cracks after deformation, and the thermal deformation performance of the material is reduced. Greatly improve. In addition, the invention has the advantages of economy, safety, novelty, reliability, etc., and has a good application prospect.

Description of drawings

Figure 1 shows the thermal deformation stress-strain curves of composites B and A at 800°C;

Figure 2 shows the thermal deformation stress-strain curves of composites B and A at 900°C;

Figure 3a shows the thermal deformation microstructure of composite B under thermal deformation at 800 °C;

Figure 3b shows the thermal deformation microstructure of composite A under thermal deformation at 800 °C;

Figure 3c shows the thermal deformation microstructure of composite B under thermal deformation at 900 °C;

Figure 3d shows the thermal deformation microstructure of composite A under thermal deformation at 900 °C.

Detailed ways

The experimental methods used in the following examples are conventional methods unless otherwise specified. The used materials, reagents, methods and instruments, unless otherwise specified, are conventional materials, reagents, methods and instruments in the art, which can be obtained by those skilled in the art through commercial channels.

Example 1:

(1) Use acetone and anhydrous ethanol to ultrasonically clean industrial titanium sponge in turn, dry at 100°C for 4h in a drying oven, add TiB ₂ powder, the mass of TiB ₂ powder is 1.25% of the total mass of the composite material, placed in a vacuum for non-consumption in a water-cooled crucible in an electric arc furnace.

(2) After evacuating to a degree of vacuum of 3×10 ^-3 Pa, 99.999% argon and 99.999% pure hydrogen were introduced, and the flow ratio of hydrogen and argon was 2:3. After melting all the raw materials under the current of 150A, the current was increased to 500A, the current was kept unchanged, and the smelting stopped after 10 minutes. After the composite material was solidified and cooled, it was turned upside down and placed in a water-cooled copper crucible, and the smelting operation was repeated for a total of 6 times to obtain TiB Reinforced Ti-based composites.

Example 2:

The difference between this example and Example ₁ is that the mass of the raw material titanium sponge, pure Mo particles and TiB powder is 62.25%, 33%, 4.75% of the total mass of the composite material, and the rest of the operation steps are exactly the same as in Example 1, and the obtained TiB reinforced Ti-33Mo matrix composites.

Example 3:

The difference between this example and Example 1 is: the raw materials are sponge titanium, aluminum element and aluminum-vanadium master alloy; the quality of aluminum-vanadium master alloy is weighed according to the mass ratio of vanadium element in the prepared composite material; The mass ratio of the prepared composite material is 6%. If the quality of aluminum element in the aluminum-vanadium alloy does not meet the quality requirements of the composite material, use aluminum element to make up; the mass of the TiB ₂ powder added is 2.5% of the total mass of the composite material, and the rest of the operation steps are the same as that of the composite material. Example 1 is exactly the same, and a TiB-reinforced Ti-6Al-4V-based composite material is obtained, which is marked as composite material A.

Comparative Example 1:

The difference between this comparative example and Example 3 is that the raw materials are placed in a vacuum non-consumable electric arc furnace, and after the vacuum degree is 3×10 ^-3 Pa, only argon gas with a purity of 99.999% is introduced, and the rest The operation steps are exactly the same as in Example 3, and the composite material B is obtained.

The thermal deformation properties of Example 3 (composite material A) and comparative example 1 (composite material B) were investigated.

The thermal deformation process was simulated using a dynamic thermal simulation testing machine (model: Gleeble-1500D). The sample is a cylinder with a diameter of 6 mm and a height of 9 mm, taken from Example 3 (composite material A) and comparative example (composite material B), respectively. Graphite gaskets are used at both ends of the sample to ensure the lubricity of its contact with the indenter. The samples were protected by high-temperature silica gel, and the deformation temperature was measured by a thermocouple. The inert gas argon was used as the protective gas throughout the experiment. The experimental process is as follows: the heating rate is 10 °C/s, the set temperature of 800 °C and 900 °C is reached, the temperature is maintained for 5 min, and the loading is started at a strain rate of 0.01/s. The thermal compression stress-strain curve at 800 °C is shown in Figure 1, and the thermal compression stress-strain curve at 900 °C is shown in Figure 2. It can be seen from Figures 1 and 2 that the deformation resistance and peak flow stress of the composite material A during the thermal deformation process are both smaller than those of the composite material B, and the deformation temperature corresponding to the same deformation resistance applied to the composite material A is lower and lower, showing that The method of the invention can reduce the deformation resistance and improve the thermal deformation performance of the titanium-based composite material.

The thermal deformation structure of the composite materials of Example 3 (composite material A) and the comparative example (composite material B) was investigated.

Using a scanning electron microscope (model: Quanta 200FEG) to observe the surface morphology of the two materials after thermal deformation in the secondary electron mode. Samples were taken from Example 3 (Composite A) and Comparative Example (Composite B), respectively. After the above-mentioned thermal deformation experiments, the thermally deformed samples were immediately water quenched to retain the high-temperature microstructure. The observation sample was prepared as follows: the hot deformation sample that was quenched by water immediately after the heat deformation was cut into a cylinder with a diameter of 5 mm and a height of 3 mm, the upper and lower ends were ground flat, the surface oxide scale was removed by sanding with sandpaper, and polished with flannel, and anhydrous ethanol was used for polishing. After ultrasonic cleaning and polishing, the samples were air-dried and etched with hydrofluoric acid to obtain scanning microscope photos as shown in Fig. 3a, Fig. 3b, Fig. 3c and Fig. 3d. It can be seen from Figure 3a, Figure 3b, Figure 3c and Figure 3d that the composite material A has almost no defects such as interface holes and deformation cracks after thermal deformation, while the composite material B described in the comparative example has many holes and cracks after thermal deformation. It is shown that the method of the present invention has the effect of improving the thermal deformation structure and improving the thermal deformation performance of the titanium matrix composite material.

Claims (4)

1. A method for improving the thermal deformation properties of a titanium-based composite material, the method comprising the steps of:

step 1, pretreating raw materials for preparing titanium-based composite material, and adding TiB₂Powder, put into water-cooled copper crucible;

in the step 1, TiB₂After the powder is added, the mass proportion of the reinforcing body TiB in the titanium-based composite material obtained in the step 2 is 2.5-9.5%;

step 2, introducing argon and hydrogen after vacuumizing, and smelting to obtain the titanium-based composite material with improved thermal deformation;

the flow ratio of argon to hydrogen in the step 2 is 2: 3;

the purity of the argon and the hydrogen in the step 2 is 99.999 percent;

the vacuum degree after vacuum pumping in the step 2 is 3 multiplied by 10^-3Pa；

The smelting operation process in the step 2 specifically comprises the following steps: after all the raw materials are melted by the initial current 120A, the current is increased to 500A, the current is kept unchanged, and the melting is stopped after 10 min; after the material is solidified, the material is turned upside down and placed in a water-cooled copper crucible, and the smelting operation is repeated for 6 times.

2. The method for improving the thermal deformation performance of the titanium-based composite material as claimed in claim 1, wherein the pre-treatment in step 1 is carried out by: sequentially using acetone and absolute ethyl alcohol to carry out ultrasonic cleaning, placing the cleaned product in a drying oven, and drying the product for 4 hours at the temperature of 100 ℃.

3. The method of claim 1, wherein the raw material is sponge titanium, and the elemental substance or the intermediate alloy of the alloy element to be added is selected from the group consisting of elemental substances and intermediate alloys.

4. The method of claim 1, wherein the melting apparatus is a vacuum non-consumable arc furnace.

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