Low-cost as-cast high-toughness Ti-Al-Mo-Fe-Zr series titanium alloy and preparation method thereof

Abstract

The invention discloses a low-cost as-cast high-toughness Ti-Al-Mo-Fe-Zr series titanium alloy and a preparation method thereof, and relates to a Ti-Al-Mo-Fe-Zr series titanium alloy and a preparation method thereof. The invention aims to solve the problem that the cost cannot be reduced while the good mechanical property of the existing titanium alloy is maintained. The alloy has the chemical general formula of Ti (87.2-x) Mo (6.8) Fe (4.5) Al (1.5) Zr (x) in percentage by mass, and x is more than or equal to 0.5 and less than or equal to 4. The preparation method comprises the following steps: 1, weighing raw materials; secondly, the Mo powder and the Zr powder are wrapped with aluminum foil, and wrapped powder is obtained; the Fe blocks and the Al blocks are cleaned and dried, and cleaned block materials are obtained; the titanium sponge, the wrapped powder and the cleaned blocks are placed in a copper crucible in a non-self-consumption vacuum arc furnace; and 3, smelting, and solidifying under the assistance of ultrasonic vibration. The invention is used for the low-cost as-cast high-toughness Ti-Al-Mo-Fe-Zr series titanium alloy and the preparation method thereof.

Description

Technical Field

[0001] The invention relates to a Ti-Al-Mo-Fe-Zr series titanium alloy and a preparation method thereof. Background Art

[0002] With excellent properties such as high specific strength, low density and high corrosion resistance, titanium alloys have been successfully used in aerospace, petrochemical, energy and power generation. In addition, the excellent biocompatibility of titanium alloys also makes it occupy an important position in the biomedical field.

[0003] Pure titanium has an allotropic transformation. Above the transformation temperature, it is in the β phase with a body-centered cubic structure, high strength, and strong plastic deformation ability. At room temperature, it is mainly in the α phase with a close-packed hexagonal structure, good heat resistance and creep resistance, but relatively poor plasticity. By adding β-stabilizing elements, the β transformation temperature can be lowered, the β stability can be improved, and the β structure at room temperature can be obtained. Commonly used stabilizing elements include V, Mo, Nb, Cr, etc. Among them, although Al is not a β-stabilizing element, it is often added to titanium alloys because of its ability to improve thermal stability, elastic modulus and solid solution strengthening effects.

[0004] Although it has various excellent properties, the high cost has always restricted the development and promotion of titanium alloys. On the one hand, the titanium alloy itself and the added elements have high costs, such as V, Mo, etc.; on the other hand, the titanium alloy processing and subsequent treatment processes are relatively complicated and require a large amount of energy. Therefore, titanium alloys have not yet been widely used in the civilian field. Therefore, reducing costs while maintaining their good mechanical properties is one of the future development directions of titanium alloys. Summary of the invention

[0005] The present invention aims to solve the problem that the existing titanium alloys cannot reduce the cost while maintaining good mechanical properties, and further provide a low-cost cast high-toughness Ti-Al-Mo-Fe-Zr titanium alloy and a preparation method thereof.

[0006] A low-cost cast high-toughness Ti-Al-Mo-Fe-Zr titanium alloy, based on mass percentage, its chemical formula is Ti (87.2-x) Mo 6.8 Fe 4.5 Al 1.5 Zr x , where 0.5≤x≤4.

[0007] A method for preparing a low-cost cast high-toughness Ti-Al-Mo-Fe-Zr titanium alloy is carried out according to the following steps:

[0008] 1. Weigh titanium sponge, Mo powder, Fe block, Al block, Zr powder and aluminum foil according to the ratio of (87.2-x)% Ti, 6.8% Mo, 4.5% Fe, 1.5% Al and x% Zr by mass to obtain weighed raw materials; wherein 0.5≤x≤4;

[0009] 2. Wrapping Mo powder and Zr powder with aluminum foil to obtain wrapped powder; washing and drying Fe blocks and Al blocks to obtain washed blocks; placing titanium sponge, the wrapped powder and the washed blocks in a copper crucible in a non-consumable vacuum arc furnace, starting a condensed water cycle, and then sequentially evacuating and passing argon gas, and repeating the evacuation and passing argon gas multiple times;

[0010] 3. Use an arc gun to melt the weighed raw materials in turn, cool them naturally and turn them over, and repeat the melting, cooling and turning over 6 to 9 times to obtain a metal ingot. Melt the metal ingot again, start the ultrasonic vibration device after melting, and solidify it with the assistance of ultrasonic vibration to obtain a cast high-toughness Ti-Al-Mo-Fe-Zr titanium alloy.

[0011] The beneficial effects of the present invention are:

[0012] 1. The low-cost cast high-toughness Ti-Al-Mo-Fe-Zr titanium alloy of the present invention utilizes the low-cost element Fe to replace the element V, thereby effectively reducing the cost of raw materials.

[0013] 2. The main component phase of the low-cost cast high-toughness Ti-Al-Mo-Fe-Zr titanium alloy of the present invention is β phase, which improves the mechanical properties of the alloy.

[0014] 3. The present invention utilizes ultrasonic vibration to reduce casting defects during the casting process, while promoting metal melt nucleation, thereby improving the crack propagation process, increasing metal toughness and tensile properties, and strengthening alloy mechanical properties. This method can effectively reduce defects in cast alloys and improve product quality.

[0015] 4. The low-cost cast high-toughness Ti-Al-Mo-Fe-Zr titanium alloy of the present invention has a tensile strength of ≥890MPa and a fracture toughness of ≥65MPa / m 1 / 2 , elongation at break ≥12%.

[0016] 5. The low-cost cast high-toughness Ti-Al-Mo-Fe-Zr titanium alloy of the present invention has a short preparation process and a simple preparation method, which simplifies the titanium alloy processing process, reduces the processing cost, and ensures high-toughness mechanical properties.

[0017] The invention is used for a low-cost cast high-toughness Ti-Al-Mo-Fe-Zr series titanium alloy and a preparation method thereof. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 The XRD pattern of the as-cast high-toughness Ti-Al-Mo-Fe-Zr titanium alloy prepared in Example 1;

[0019] Figure 2 The tensile engineering stress-strain curve of the as-cast high-toughness Ti-Al-Mo-Fe-Zr titanium alloy prepared in Example 1;

[0020] Figure 3 The three-point bending engineering stress-strain curve of the cast high-toughness Ti-Al-Mo-Fe-Zr titanium alloy prepared in Example 1;

[0021] Figure 4 The tensile engineering stress-strain curve of the as-cast high-toughness Ti-Al-Mo-Fe-Zr titanium alloy prepared in Example 2;

[0022] Figure 5 The three-point bending engineering stress-strain curve of the as-cast high-toughness Ti-Al-Mo-Fe-Zr titanium alloy prepared in Example 2;

[0023] Figure 6 The tensile fracture diagrams of the cast high-toughness Ti-Al-Mo-Fe-Zr titanium alloy prepared in Example 2 and the comparative experiment, the scale is 2μm, a is the comparative experiment, and b is Example 2. DETAILED DESCRIPTION

[0024] Specific implementation method 1: This implementation method is a low-cost cast high-toughness Ti-Al-Mo-Fe-Zr titanium alloy, and its chemical formula is Ti in terms of mass percentage. (87.2-x) Mo 6.8 Fe 4.5 Al 1.5 Zr x , where 0.5≤x≤4.

[0025] The beneficial effects of this embodiment are:

[0026] 1. The low-cost cast high-toughness Ti-Al-Mo-Fe-Zr titanium alloy of the present invention utilizes the low-cost element Fe to replace the element V, thereby effectively reducing the cost of raw materials.

[0027] 2. The main component phase of the low-cost cast high-toughness Ti-Al-Mo-Fe-Zr titanium alloy of the present invention is β phase, which improves the mechanical properties of the alloy.

[0028] 3. The present invention utilizes ultrasonic vibration to reduce casting defects during the casting process, while promoting metal melt nucleation, thereby improving the crack propagation process, increasing metal toughness and tensile properties, and strengthening alloy mechanical properties. This method can effectively reduce defects in cast alloys and improve product quality.

[0029] 4. The low-cost cast high-toughness Ti-Al-Mo-Fe-Zr titanium alloy of the present invention has a tensile strength of ≥890MPa and a fracture toughness of ≥65MPa / m 1 / 2 , elongation at break ≥12%.

[0030] 5. The low-cost cast high-toughness Ti-Al-Mo-Fe-Zr titanium alloy of the present invention has a short preparation process and a simple preparation method, which simplifies the titanium alloy processing process, reduces the processing cost, and ensures high-toughness mechanical properties.

[0031] Specific implementation method 2: This implementation method is a method for preparing a low-cost cast high-toughness Ti-Al-Mo-Fe-Zr titanium alloy, which is carried out according to the following steps:

[0032] 1. Weigh titanium sponge, Mo powder, Fe block, Al block, Zr powder and aluminum foil according to the ratio of (87.2-x)% Ti, 6.8% Mo, 4.5% Fe, 1.5% Al and x% Zr by mass to obtain weighed raw materials; wherein 0.5≤x≤4;

[0033] 2. Wrapping Mo powder and Zr powder with aluminum foil to obtain wrapped powder; washing and drying Fe blocks and Al blocks to obtain washed blocks; placing titanium sponge, the wrapped powder and the washed blocks in a copper crucible in a non-consumable vacuum arc furnace, starting a condensed water cycle, and then sequentially evacuating and passing argon gas, and repeating the evacuation and passing argon gas multiple times;

[0034] 3. Use an arc gun to melt the weighed raw materials in turn, cool them naturally and turn them over, and repeat the melting, cooling and turning over 6 to 9 times to obtain a metal ingot. Melt the metal ingot again, start the ultrasonic vibration device after melting, and solidify it with the assistance of ultrasonic vibration to obtain a cast high-toughness Ti-Al-Mo-Fe-Zr titanium alloy.

[0035] Specific implementation method 3: This implementation method is different from specific implementation method 2 in that the purity of the titanium sponge, Mo powder, Fe block, Al block, Zr powder and aluminum foil in step 1 is greater than 99.95%. Other aspects are the same as specific implementation method 2.

[0036] Specific implementation method 4: This implementation method is different from specific implementation method 2 or 3 in that: in step 2, vacuum is first evacuated to a vacuum degree of 10 in the furnace. -4 MPa~10 -3 MPa, and then fill with argon gas to a pressure of 400Pa-600Pa, and repeat the vacuuming and argon gas flow 2-3 times. The rest is the same as the second or third embodiment.

[0037] Specific implementation mode 5: This implementation mode is different from specific implementation modes 2 to 4 in that the smelting described in step 3 is specifically carried out under the conditions of argon atmosphere and current of 400A to 600A. The rest is the same as specific implementation modes 2 to 4.

[0038] Specific embodiment 6: This embodiment is different from specific embodiments 2 to 5 in that the solidification under the assistance of ultrasonic vibration described in step 3 is to gradually reduce the current of the arc gun from 400A to 600A to 40A to 60A at a speed of 4A / s to 6A / s under the assistance of ultrasonic vibration, and then return the current to zero, thereby achieving solidification. Others are the same as specific embodiments 2 to 5.

[0039] Specific embodiment 7: This embodiment is different from specific embodiments 2 to 6 in that the solidification under the assistance of ultrasonic vibration described in step 3 is to gradually reduce the current of the arc gun from 500A to 50A at a speed of 5A / s under the assistance of ultrasonic vibration, and then return the current to zero, thereby achieving solidification. Other aspects are the same as specific embodiments 2 to 6.

[0040] Specific embodiment 8: This embodiment differs from specific embodiments 2 to 7 in that the ultrasonic vibration assistance described in step 3 is performed under the conditions of a vibration frequency of 40 Hz to 60 Hz and an ultrasonic processing power of 1 kW to 2 kW. The rest is the same as specific embodiments 2 to 7.

[0041] Specific embodiment 9: This embodiment differs from specific embodiments 2 to 8 in that the ultrasonic vibration assistance described in step 3 is specifically performed under the conditions of a vibration frequency of 50 Hz and an ultrasonic processing power of 1 kW. The rest is the same as specific embodiments 2 to 8.

[0042] Specific implementation example 10: This implementation example is different from specific implementation examples 2 to 9 in that: in step 1, 2≤x≤4. The rest is the same as specific implementation examples 2 to 9.

[0043] The following examples are used to verify the beneficial effects of the present invention:

[0044] Embodiment 1:

[0045] A low-cost cast high-toughness Ti-Al-Mo-Fe-Zr titanium alloy, based on mass percentage, its chemical formula is Ti 85.2 Mo 6.8 Fe 4.5 Al 1.5 Zr2.

[0046] A method for preparing a low-cost cast high-toughness Ti-Al-Mo-Fe-Zr titanium alloy is carried out according to the following steps:

[0047] 1. Weigh titanium sponge, Mo powder, Fe block, Al block, Zr powder and aluminum foil according to the ratio of 85.2% Ti, 6.8% Mo, 4.5% Fe, 1.5% Al and 2% Zr by mass to obtain weighed raw materials;

[0048] 2. Wrapping Mo powder and Zr powder with aluminum foil to obtain wrapped powder; washing Fe block and Al block with acetone and then drying to obtain washed block; placing titanium sponge, wrapped powder and washed block in a copper crucible in a non-consumable vacuum arc furnace, starting condensed water circulation, and first evacuating the furnace to a vacuum degree of 10 -4 MPa, then fill with argon gas to a pressure of 500Pa, and repeat the vacuum and argon gas flow 3 times;

[0049] 3. Use an arc gun to melt the weighed raw materials in turn, cool them naturally and turn them over, and repeat the melting, cooling and turning over 7 times to obtain a metal ingot. Melt the metal ingot again, start the ultrasonic vibration device after melting, and solidify it with the assistance of ultrasonic vibration to obtain a cast high-toughness Ti-Al-Mo-Fe-Zr titanium alloy.

[0050] The purity of the titanium sponge, Mo powder, Fe block, Al block, Zr powder and aluminum foil described in step 1 is greater than 99.95%.

[0051] The smelting described in step 3 is specifically carried out under the conditions of argon atmosphere and a current of 500A.

[0052] The ultrasonic vibration assisted solidification described in step three is specifically to gradually reduce the current of the arc gun from 500A to 50A at a speed of 5A / s under the assistance of ultrasonic vibration, and then return the current to zero, thereby achieving solidification.

[0053] The ultrasonic vibration assistance described in step three is specifically carried out under the conditions of a vibration frequency of 50 Hz and an ultrasonic processing power of 1 kW.

[0054] Embodiment 2: This embodiment is different from Embodiment 1 in that the ultrasonic vibration assistance described in step 3 is specifically performed under the conditions of a vibration frequency of 50 Hz and an ultrasonic processing power of 2 kW. The rest is the same as Embodiment 1.

[0055] Comparative experiment: The difference between this comparative experiment and Example 2 is that the ultrasonic vibration assistance is omitted in step 3. The rest is the same as Example 2.

[0056] Figure 1 This is the XRD diagram of the cast high-toughness Ti-Al-Mo-Fe-Zr titanium alloy prepared in Example 1; it can be seen from the figure that the main component phase of the Ti-Al-Mo-Fe-Zr titanium alloy is β phase.

[0057] Figure 2 This is the tensile engineering stress-strain curve of the cast high-toughness Ti-Al-Mo-Fe-Zr titanium alloy prepared in Example 1; as can be seen from the figure, the alloy exhibits high tensile strength and elongation at break, with its tensile strength reaching 900 MPa and its elongation at break reaching 12.8%.

[0058] Figure 3 The three-point bending engineering stress-strain curve of the cast high-toughness Ti-Al-Mo-Fe-Zr titanium alloy prepared in Example 1; the fracture toughness of the alloy is calculated to be 70MPa / m 1 / 2 .

[0059] Figure 4 This is the tensile engineering stress-strain curve of the cast high-toughness Ti-Al-Mo-Fe-Zr titanium alloy prepared in Example 2; as can be seen from the figure, the alloy exhibits high tensile strength and elongation at break, with its tensile strength reaching 890 MPa and its elongation at break reaching 19.2%.

[0060] Figure 5 The three-point bending engineering stress-strain curve of the cast high-toughness Ti-Al-Mo-Fe-Zr titanium alloy prepared in Example 2; the fracture toughness of the alloy is calculated to be 65MPa / m 1 / 2 .

[0061] Figure 6 The tensile fracture diagrams of the cast high-toughness Ti-Al-Mo-Fe-Zr titanium alloy prepared in Example 2 and the comparative experiment, the scale is 2μm, a is the comparative experiment, and b is Example 2. By comparison, it is found that the dimples at the fracture of the cast high-toughness Ti-Al-Mo-Fe-Zr titanium alloy prepared in Example 1 become shallow and uniform, indicating that adding ultrasonic assistance is beneficial to improving the fracture process of the material.

Claims

1. A low-cost cast high-toughness Ti-Al-Mo-Fe-Zr titanium alloy, characterized in that In terms of mass percentage, its general chemical formula is Ti (87.2-x) Mo 6.8 Fe 4.5 Al 1.5 Zr x , where 0.5≤x≤4.

2. A method for preparing a low-cost cast high-toughness Ti-Al-Mo-Fe-Zr titanium alloy as claimed in claim 1, characterized in that It is carried out in the following steps:

1. Weigh titanium sponge, Mo powder, Fe block, Al block, Zr powder and aluminum foil according to the ratio of (87.2-x)% Ti, 6.8% Mo, 4.5% Fe, 1.5% Al and x% Zr by mass to obtain weighed raw materials; wherein 0.5≤x≤4; 2. Wrapping Mo powder and Zr powder with aluminum foil to obtain wrapped powder; washing and drying Fe blocks and Al blocks to obtain washed blocks; placing titanium sponge, the wrapped powder and the washed blocks in a copper crucible in a non-consumable vacuum arc furnace, starting a condensed water cycle, and then sequentially evacuating and passing argon gas, and repeating the evacuation and passing argon gas multiple times; 3. Use an arc gun to melt the weighed raw materials in turn, cool them naturally and turn them over, and repeat the melting, cooling and turning over 6 to 9 times to obtain a metal ingot. Melt the metal ingot again, start the ultrasonic vibration device after melting, and solidify it with the assistance of ultrasonic vibration to obtain a cast high-toughness Ti-Al-Mo-Fe-Zr titanium alloy.

3. The method for preparing a low-cost cast high-toughness Ti-Al-Mo-Fe-Zr titanium alloy according to claim 2, characterized in that The purity of the titanium sponge, Mo powder, Fe block, Al block, Zr powder and aluminum foil described in step 1 is greater than 99.95%.

4. The method for preparing a low-cost cast high-toughness Ti-Al-Mo-Fe-Zr titanium alloy according to claim 2, characterized in that In step 2, first evacuate the furnace until the vacuum degree is 10 -4 MPa~10 -3 MPa, and then fill it with argon to a pressure of 400Pa~600Pa, and repeat the vacuum and argon flow 2~3 times.

5. The method for preparing a low-cost cast high-toughness Ti-Al-Mo-Fe-Zr titanium alloy according to claim 2, characterized in that The smelting described in step 3 is specifically carried out under the conditions of argon atmosphere and current of 400A to 600A.

6. The method for preparing a low-cost cast high-toughness Ti-Al-Mo-Fe-Zr titanium alloy according to claim 2, characterized in that The ultrasonic vibration assisted solidification described in step three is specifically to gradually reduce the current of the arc gun from 400A to 600A to 40A to 60A at a speed of 4A / s to 6A / s under the assistance of ultrasonic vibration, and then return the current to zero to achieve solidification.

7. The method for preparing a low-cost cast high-toughness Ti-Al-Mo-Fe-Zr titanium alloy according to claim 6, characterized in that The ultrasonic vibration assisted solidification described in step three is specifically to gradually reduce the current of the arc gun from 500A to 50A at a speed of 5A / s under the assistance of ultrasonic vibration, and then return the current to zero, thereby achieving solidification.

8. The method for preparing a low-cost cast high-toughness Ti-Al-Mo-Fe-Zr titanium alloy according to claim 7, characterized in that The ultrasonic vibration assistance described in step three is specifically carried out under the conditions of a vibration frequency of 40 Hz to 60 Hz and an ultrasonic processing power of 1 kW to 2 kW.

9. A method for preparing a low-cost cast high-toughness Ti-Al-Mo-Fe-Zr titanium alloy according to claim 8, characterized in that The ultrasonic vibration assistance described in step three is specifically carried out under the conditions of a vibration frequency of 50 Hz and an ultrasonic processing power of 1 kW.

10. The method for preparing a low-cost cast high-toughness Ti-Al-Mo-Fe-Zr titanium alloy according to claim 2, characterized in that In step 1, 2≤x≤4.

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