Fuse wire additive manufacturing method for regulating and controlling strength of titanium alloy by adding rare earth oxide

Abstract

The invention discloses a fuse wire additive manufacturing method for regulating and controlling the strength of titanium alloy by adding rare earth oxide, which comprises the following steps of: 1, ultrasonically stirring and mixing rare earth oxide nano powder and ethanol solution to obtain turbid liquid; 2, polishing the surface of the titanium or titanium alloy substrate until the roughness is not greater than Ra1.6; thirdly, the surface of a substrate is evenly coated with the turbid liquid, after drying, fuse wire additive manufacturing of titanium or titanium alloy wires is carried out under inert atmosphere protection, and the titanium alloy with the improved strength is obtained; the fuse wire additive manufacturing process comprises the steps that layer-by-layer deposition is conducted, and after each layer is deposited and completely solidified and cooled, the surface of the deposited layer is coated with turbid liquid and dried. According to the method, coating of the turbid liquid containing the rare earth oxide and the fuse wire additive manufacturing process are combined, the titanium or titanium alloy containing the rare earth oxide and uniform in component is prepared, metallurgical bonding of the rare earth oxide and the titanium or titanium alloy wire is achieved, and the method is suitable for the technical field of metal additive manufacturing.

Description

Technical Field

[0001] The present invention belongs to the technical field of metal additive manufacturing, and in particular relates to a fused filament additive manufacturing method for adjusting the strength of titanium alloy by adding rare earth oxides. Background Art

[0002] Titanium and its alloys are widely used in aerospace, biomedical, and high-end equipment manufacturing due to their excellent specific strength, corrosion resistance, heat resistance, and biocompatibility, becoming important strategic metal materials. As an emerging metal additive manufacturing technology, fused filament additive manufacturing (FAM) offers advantages such as low equipment cost, short forming cycles, high component performance, and energy conservation and environmental protection, making it a particularly advantageous option for future large-scale industrial applications. Consequently, FAM of titanium alloys has garnered widespread attention from the global academic community. With the rapid development of lightweight and high-performance materials technologies, the iterative upgrades in aerospace, medical, and energy equipment are placing higher standards on the strength of titanium alloys. However, adjusting FAM process parameters has limited impact on the strength of titanium alloys. Furthermore, FAM of high-strength titanium alloys suffers from a narrow process window and difficulties in controlling microstructure and mechanical properties. Therefore, there is an urgent need to develop a method for improving the strength of FAM-manufactured titanium alloys.

[0003] Rare earth oxides are considered ideal reinforcements for improving the microstructure of titanium alloys due to their high melting point, excellent chemical stability, and low interfacial energy with the titanium matrix. At the same time, rare earth oxides have a strong adsorption capacity for oxygen and nitrogen impurities in titanium alloys, which can purify grain boundaries and promote structural uniformity. In addition, the addition of rare earth oxides can optimize the molten pool metallurgical process and reduce the tendency of thermal cracking. Based on these advantages, the addition of rare earth oxides has become an effective method to improve the strength of titanium alloy fused wire additive manufacturing. Compared with micron particles, nano rare earth oxides can reduce their lattice mismatch with titanium and titanium alloys, promote the formation of coherent / semi-coherent interfaces, and significantly improve the strength of titanium alloys. Only a small amount of rare earth oxides is required to achieve the effect of improving strength, and the cost is lower.

[0004] In the fused filament additive manufacturing process, metal wire is usually used as the raw material. In order to introduce nano rare earth oxides into titanium alloys, composite wires of titanium or titanium alloys and rare earth oxides need to be prepared in advance. However, nano powders have a large specific surface area and high surface energy, and are very prone to agglomeration, resulting in uneven mixing and affecting the composition uniformity of the composite wires. In addition, the preparation of composite wires requires special equipment and processes. When the composition or content changes, not only does the composite wire need to be re-prepared, but the process also needs to be optimized for the new composition. This customized production method increases production costs and increases technical difficulty. Summary of the Invention

[0005] The present invention aims to overcome the shortcomings of the prior art by providing a fused filament additive manufacturing method that modulates the strength of titanium alloys by adding rare earth oxides. This method combines a suspension prepared by mixing rare earth oxides with an ethanol solution and then uses the suspension coating combined with fused filament additive manufacturing to modulate the strength of the titanium alloy. This method addresses the uneven composition of rare earth oxides introduced into the filaments by prior art techniques.

[0006] To achieve the above-mentioned object, the technical solution adopted by the present invention is: a fused filament additive manufacturing method for adjusting the strength of titanium alloy by adding rare earth oxides, characterized in that the method comprises the following steps: Step 1: mixing rare earth oxide nanopowder and ethanol solution by ultrasonic stirring to obtain a suspension; Step 2: Grind the surface of the titanium or titanium alloy substrate to a roughness not greater than Ra1.6; Step 3: Evenly coat the suspension obtained in step 1 on the surface of the polished substrate in step 2, and after drying, perform fused additive manufacturing of titanium or titanium alloy wire under the protection of an inert atmosphere to obtain a titanium alloy with enhanced strength; the fused additive manufacturing process is as follows: layer-by-layer deposition, after each layer is deposited and completely solidified and cooled, the surface of the deposited layer is coated with the suspension and dried.

[0007] The present invention polishes the substrate surface to a roughness of no more than Ra1.6 to enhance the adhesion and uniformity of the suspension; by mixing rare earth oxide nanopowder with ethanol and then coating it on the substrate surface, the complicated process of preparing composite wires is avoided and the preparation cost is reduced; at the same time, the volatility of ethanol is utilized to have no effect on the composition of the titanium alloy; in addition, the type and content of rare earth oxides can be flexibly adjusted to effectively improve and adjust the strength of the titanium alloy.

[0008] The above-mentioned fused filament additive manufacturing method for adjusting the strength of titanium alloy by adding rare earth oxides is characterized in that the rare earth oxide nanopowder in step one is selected from Y2O3, La2O3, CeO2, and Nd2O3, and the particle size of the rare earth oxide nanopowder is not greater than 300nm.

[0009] The present invention adopts the above-mentioned rare earth oxides to form a coherent / semi-coherent interface with titanium or titanium alloy during the solidification process of fused filament additive manufacturing. The nanoparticles can reduce the lattice mismatch and promote the formation of coherent / semi-coherent interfaces, thereby improving the strength of titanium and titanium alloys by pinning grain boundaries and dislocations and forming nanoparticles.

[0010] The above-mentioned fused filament additive manufacturing method for adjusting the strength of titanium alloy by adding rare earth oxides is characterized in that the concentration of the suspension in step 1 is less than 5%.

[0011] The present invention prevents rare earth oxides from agglomerating by controlling the concentration of the suspension to be less than 5%.

[0012] The above-mentioned fused filament additive manufacturing method for adjusting the strength of titanium alloy by adding rare earth oxides is characterized in that the ultrasonic stirring time in step 1 is 20 minutes to 60 minutes.

[0013] The above-mentioned fused filament additive manufacturing method for adjusting the strength of titanium alloy by adding rare earth oxides is characterized in that the drying in step three is natural drying or low-temperature drying under an inert protective atmosphere.

[0014] The above-mentioned fused filament additive manufacturing method for adjusting the strength of titanium alloy by adding rare earth oxides is characterized in that the temperature of the low-temperature drying is 40°C~60°C.

[0015] The present invention controls the low-temperature drying temperature to 40°C to 60°C, thereby accelerating the volatilization rate of the ethanol solvent and reducing the temperature difference between the newly coated suspension and the adjacent deposited layer. This reduction in temperature difference effectively suppresses the agglomeration and uneven distribution of rare earth oxide particles caused by thermal stress during the drying process. The low-temperature drying is achieved through arc scanning preheating in fused filament additive manufacturing.

[0016] The above-mentioned fused wire additive manufacturing method for adding rare earth oxides to regulate the strength of titanium alloy is characterized in that the parameters of the fused wire additive manufacturing in step three are: pulse current 80A~200A, shielding gas flow rate 20L / min~30L / min, wire feeding speed 3m / min~8m / min, and voltage 18V~25V.

[0017] The present invention can take into account both the stability of rare earth oxide nanopowder and the quality of titanium alloy additive forming by reducing heat input.

[0018] Compared with the prior art, the present invention has the following advantages: 1. This invention utilizes rare earth oxide nanopowders as modifiers to enhance the strength of titanium alloy fused wire additive components. By coating the substrate with rare earth oxides, the type and content of the rare earth oxides can be flexibly adjusted, facilitating rapid manufacturing of titanium alloy fused wire additive components. This approach avoids the limitations of optimizing fused wire additive manufacturing process parameters to enhance strength and eliminates the need for pre-preparing composite wires.

[0019] 2. The present invention can refine the grain size of titanium alloy by using rare earth oxides for fused additive manufacturing of titanium alloy, thereby avoiding the coarse grains of titanium alloy manufactured by fused additive manufacturing.

[0020] 3. By adding rare earth oxides, the present invention can reduce the heat input of the additive manufacturing process, reduce energy consumption, and reduce residual stress.

[0021] The technical solution of the present invention is further described in detail below through the accompanying drawings and embodiments. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 This is the particle morphology of Y2O3 used in Example 1 of the present invention.

[0023] Figure 2 The microstructure of the Y2O3-added TC4 titanium alloy prepared in Example 1 of the present invention.

[0024] Figure 3 This is a mechanical property test diagram of the TC4 titanium alloy with Y2O3 added prepared in Example 1 of the present invention and the TC4 titanium alloy prepared in Comparative Example 1.

[0025] Figure 4 This is a mechanical property test diagram of the TC4 titanium alloy with La2O3 added prepared in Example 2 of the present invention and the TC4 titanium alloy prepared in Comparative Example 1. DETAILED DESCRIPTION

[0026] Example 1 The method of this embodiment includes the following steps: Step 1: Y2O3 powder with a particle size of 300 nm was mixed with ethanol solution and ultrasonically stirred for 20 min to obtain a suspension with a concentration of 5%; Step 2: polishing and cleaning the surface of the TC4 titanium alloy substrate, wherein the surface roughness of the polished TC4 titanium alloy substrate is Ra1.6; Step 3. Evenly spray the suspension obtained in step 1 onto the surface of the TC4 titanium alloy substrate cleaned in step 2. After natural drying under an argon atmosphere, TC4 titanium alloy wire is used for fused additive manufacturing under an argon atmosphere to obtain a TC4 titanium alloy with improved strength. The fused additive manufacturing parameters are: pulse current 80A, shielding gas flow rate 20L / min, wire feeding speed 3m / min, and voltage 18V. The fused additive manufacturing process is: layer-by-layer deposition, and each time a layer is deposited, the surface of the deposited layer is coated with the suspension and naturally dried under an argon atmosphere.

[0027] The morphology of the Y2O3 powder used in step 1 of this embodiment is as follows Figure 1 As shown, Y2O3 powder can also be replaced by CeO2 or Nd2O3.

[0028] The Y2O3-added TC4 titanium alloy prepared in this embodiment was subjected to microscopic analysis. Figure 2 As shown, the dispersed phase is uniformly distributed in the tissue in the form of tiny particles.

[0029] Comparative Example 1 The preparation method of this comparative example is: TC4 titanium alloy is prepared by adopting the same fused additive manufacturing parameters as Example 1.

[0030] The mechanical properties of the TC4 titanium alloy prepared in this comparative example (denoted as TC4) and the TC4 titanium alloy with Y2O3 added (denoted as TC4+Y2O3) prepared in Example 1 were tested. Figure 3 Compared with the high-strength TC4 titanium alloy with Y2O3 added in Example 1, the strength of the TC4 titanium alloy is significantly lower.

[0031] In summary, the Y2O3-added TC4 titanium alloy prepared in Example 1 has uniform structure and significantly improved mechanical properties.

[0032] Example 2 The difference between this embodiment and embodiment 1 is that the rare earth oxide nanopowder used in step 1 is La2O3.

[0033] The mechanical properties of the TC4 titanium alloy with La2O3 added (denoted as TC4+La2O3) prepared in this embodiment were tested. The results are as follows: Figure 4 Compared with the TC4 titanium alloy prepared in Comparative Example 1, the strength of the TC4 titanium alloy with La2O3 added in this embodiment is significantly improved, indicating that the preparation method of this embodiment can improve the strength of the TC4 titanium alloy.

[0034] Example 3 The difference between this embodiment and embodiment 1 is that the ultrasonic stirring time in step 1 is 60 minutes.

[0035] The strength of the Y2O3-added TC4 titanium alloy prepared in this embodiment is 1125 MPa, which is significantly higher than that of the TC4 titanium alloy.

[0036] Example 4 The difference between this embodiment and embodiment 1 is that the substrate used in step 2 and the wire material used in step 3 are both pure titanium with a titanium content greater than 99%; the drying in step 3 is performed at a low temperature of 60°C under the protection of an inert atmosphere, and the low-temperature drying is achieved by arc scanning preheating of fused filament additive manufacturing.

[0037] The strength of the titanium alloy with Y2O3 added prepared in this embodiment is 650 MPa, and the strength of pure titanium without Y2O3 added is 536 MPa.

[0038] Example 5 The difference between this embodiment and embodiment 1 is that: in step 3, each layer of the suspension is coated by spraying twice, and in step 3, the drying is performed at a low temperature of 40°C under the protection of an inert atmosphere, and the low-temperature drying is achieved by arc scanning preheating of fused filament additive manufacturing.

[0039] The strength of the Y2O3-added TC4 titanium alloy prepared in this embodiment is 1176 MPa, which is significantly higher than that of the TC4 titanium alloy.

[0040] Example 6 The difference between this embodiment and embodiment 1 is that the drying in step 3 is performed at a low temperature of 50° C. under the protection of an inert atmosphere, and the low temperature drying is achieved by arc scanning preheating of fused filament additive manufacturing.

[0041] The high-strength TC4 titanium alloy with Y2O3 added prepared in this embodiment has a strength of 1163 MPa, which is significantly higher than that of TC4 titanium alloy.

[0042] Example 7 The difference between this embodiment and embodiment 1 is that the fused wire additive manufacturing parameters in step three are: pulse current 200A, shielding gas flow rate 30L / min, wire feeding speed 8m / min, and voltage 25V.

[0043] The strength of the Y2O3-added TC4 titanium alloy prepared in this embodiment is 1168 MPa, which is significantly higher than that of the TC4 titanium alloy.

[0044] Example 8 The difference between this embodiment and embodiment 1 is that the fused wire additive manufacturing parameters in step 3 are: pulse current 100A, shielding gas flow rate 25L / min, wire feeding speed 6m / min, and voltage 20V.

[0045] The strength of the Y2O3-added TC4 titanium alloy prepared in this embodiment is 1183 MPa, which is significantly higher than that of the TC4 titanium alloy.

[0046] The above description is only a preferred embodiment of the present invention and does not limit the present invention in any way. Any simple modification, change and equivalent structural transformation made to the above embodiment based on the technical essence of the present invention shall still fall within the scope of protection of the technical solution of the present invention.

Claims

1. A fused filament additive manufacturing method for adjusting the strength of titanium alloy by adding rare earth oxides, characterized in that: The method comprises the following steps: Step 1: mixing rare earth oxide nanopowder and ethanol solution by ultrasonic stirring to obtain a suspension; Step 2: Grind the surface of the titanium or titanium alloy substrate to a roughness not greater than Ra1.6; Step 3: Evenly coat the suspension obtained in step 1 on the surface of the polished substrate in step 2, and after drying, perform fused additive manufacturing of titanium or titanium alloy wire under the protection of an inert atmosphere to obtain a titanium alloy with enhanced strength; the process of the fused additive manufacturing is: layer-by-layer deposition, and after each layer is deposited and completely solidified and cooled, the surface of the deposited layer is coated with the suspension and dried.

2. The method for fused filament additive manufacturing by adding rare earth oxides to control the strength of titanium alloy according to claim 1, characterized in that: The rare earth oxide nanopowder in step 1 is selected from Y2O3, La2O3, CeO2, and Nd2O3, and the particle size of the rare earth oxide nanopowder is not greater than 300 nm.

3. The method for fused filament additive manufacturing by adding rare earth oxides to control the strength of titanium alloy according to claim 1, characterized in that: The concentration of the suspension in step 1 is less than 5%.

4. The method for fused filament additive manufacturing by adding rare earth oxides to control the strength of titanium alloy according to claim 1, characterized in that: The ultrasonic stirring time in step 1 is 20 min to 60 min.

5. The method for fused filament additive manufacturing by adding rare earth oxides to control the strength of titanium alloy according to claim 1, characterized in that: The drying in step 3 is natural drying or low-temperature drying under an inert protective atmosphere.

6. The method for fused filament additive manufacturing by adding rare earth oxides to control the strength of titanium alloy according to claim 5, characterized in that: The temperature of the low-temperature drying is 40°C to 60°C.

7. The method for fused filament additive manufacturing by adding rare earth oxides to control the strength of titanium alloy according to claim 1, characterized in that: The parameters of the fused filament additive manufacturing described in step 3 are: pulse current 80A~200A, shielding gas flow rate 20L / min~30L / min, wire feeding speed 3m / min~8m / min, and voltage 18V~25V.

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