Titanium-oxygen-iron alloy with strength and plasticity and preparation method of titanium-oxygen-iron alloy

Abstract

The invention belongs to the technical field of metal material preparation, and particularly relates to a titanium-oxygen-iron alloy with both strength and plasticity and a preparation method of the titanium-oxygen-iron alloy. The preparation method of the titanium-oxygen-iron alloy with both strength and plasticity comprises the following steps: S1, calculating the required addition amount of ferric oxide; s2, pure titanium powder and ferric oxide powder are mixed through an electrostatic self-assembly technology, and composite powder with uniform components is obtained; s3, the composite powder is cleaned, and the cleaned composite powder is subjected to drying treatment; and S4, the dried composite powder is placed in a forming cabin, a selective laser melting technology is adopted for forming machining, and the titanium-oxygen-iron alloy is obtained. According to the method, the high-performance, low-cost and non-toxic titanium oxide iron metal material is obtained through the SLM technology, accurate regulation and control and uniform distribution of oxygen elements in a titanium matrix are achieved, and a method and thought are provided for uniform mixing of nanoscale oxygen carrier powder in titanium.

Description

Technical Field

[0001] This invention belongs to the field of metal material preparation technology, and particularly relates to a titanium-iron alloy with both strength and ductility and its preparation method. Background Technology

[0002] Titanium alloys are widely used in aerospace, chemical, and medical implant fields due to their high strength, excellent corrosion resistance, and biocompatibility. Especially in the medical field, pure titanium (CP-Ti) and low-toxicity titanium alloys (such as Ti-6Al-4V) have become the mainstream choice for bone replacement materials and dental implants. However, traditional alloying elements (such as Al and V) have potential cytotoxicity, while low-toxicity alternatives (such as Ta and Nb) are expensive, further driving up the price of medical titanium alloys. On the other hand, some key areas have increasingly stringent requirements for the comprehensive mechanical properties of titanium alloys, demanding not only excellent strength levels but also good plasticity, posing a greater challenge to the performance of traditional titanium alloys. To obtain high-strength, low-cost, and non-toxic titanium alloys, recent research has focused on the development of oxygen-solution titanium alloys. The core of this approach lies in the fact that oxygen exists in titanium as an interstitial solid solution. When the oxygen content is precisely controlled within a suitable range (0.1-0.4 wt.%), the strength and hardness of the titanium alloy can be effectively improved through a solid solution strengthening mechanism. However, when the oxygen content exceeds a critical value (>0.5 wt.%), it leads to increased brittleness. Current research utilizes nanoscale oxygen carriers (… Uniform doping of titanium matrix introduces interstitial dissolved oxygen atoms to achieve a synergistic improvement in strength and ductility.

[0003] In addition, Ti powder and nano-scale oxygen carrier powder ( Uniform mixing is fundamental to the successful preparation of oxygen-solid-solution titanium alloys by SLM. However, the commonly used high-energy ball milling powder mixing method has the following inherent disadvantages: ① During mechanical ball milling, the metal elements of the milling jar itself will inevitably be introduced into the composite powder; ② To prevent powder agglomeration, process control agents are often used during ball milling, which leads to the uncontrollable addition of impurity elements; ③ Powder oxidation will also inevitably occur during ball milling, and the degree of this oxidation is difficult to control. This uncontrollable oxidation will directly lead to the inability to stably control the oxygen content of the titanium matrix within the target range, thus making it difficult to achieve precise control of oxygen content.

[0004] Therefore, there is an urgent need to develop a new powder mixing method to overcome the technical bottlenecks of traditional powder mixing processes and achieve uniform distribution of oxygen in the titanium matrix. Summary of the Invention

[0005] The main objective of this invention is to provide a titanium-oxygen-iron alloy with both strength and ductility, and a method for preparing the same, in order to overcome the shortcomings of the prior art.

[0006] To achieve the aforementioned objectives, the technical solution adopted by this invention includes: According to a first aspect of the present invention, a method for preparing a titanium-iron alloy possessing both strength and ductility is provided, comprising the following steps: S1. Based on the target oxygen element mass fraction of the mixed powder, the required amount of ferric oxide to be added is calculated in reverse according to the theoretical oxygen content of ferric oxide, where the oxygen element comes only from ferric oxide. S2. Pure titanium powder and the amount of ferric oxide powder calculated in step S1 are mixed by electrostatic self-assembly technology to obtain a composite powder with uniform composition. S3. The composite powder is cleaned with deionized water and then dried. S4. The dried composite powder is placed in a molding chamber, the oxygen content in the molding chamber is reduced to below 0.01% and a protective gas is continuously introduced, and selective laser melting technology is used for molding to obtain the titanium-oxygen-iron alloy. The composite powder contains 0.2-0.3% oxygen by mass and 0.4-0.6% iron by mass.

[0007] Furthermore, the pure titanium powder is a micron-sized commercial pure titanium spherical powder with a particle size of 15-53 μm and an oxygen content of less than 0.005%.

[0008] Furthermore, the electrostatic self-assembly technology includes the following steps: (1) Disperse pure titanium powder in an aqueous solution of polydiallyldimethylammonium chloride (PDDA), stir for 15-30 minutes, centrifuge and wash to remove excess polydiallyldimethylammonium chloride; obtain titanium powder with a positively charged surface; (2) Disperse the positively charged titanium powder in an aqueous solution of sodium polystyrene sulfonate (PSS), stir for 15-30 minutes, centrifuge and wash to obtain negatively charged titanium powder; (3) Soak and stir the negatively charged titanium powder and the amount of ferric oxide powder calculated in step S1 in a deionized water solution to obtain a composite powder with uniform composition.

[0009] Furthermore, the soaking time is 25-35 minutes, and the stirring speed is controlled within the range of 100-150 rpm.

[0010] Furthermore, the selective laser melting process parameters include: laser power of 220-300 W, scanning speed of 800-900 mm / s, scanning spacing of 0.1 mm, and single-layer powder thickness of 0.03 mm.

[0011] Furthermore, after selective laser melting and forming, the resulting workpiece is subjected to heat treatment, which includes heating to 700°C and holding at that temperature for 2 hours, followed by furnace cooling to room temperature.

[0012] Furthermore, the ferric oxide powder has a particle size range of 0.5-5 μm and a purity greater than 99.5%.

[0013] Furthermore, in step S3, the drying process includes a staged drying process at 70°C, which is carried out twice, with each drying session lasting 24 hours.

[0014] Furthermore, in step S3, the moisture content of the composite powder after drying is less than 0.02%.

[0015] According to a first aspect of the present invention, a titanium-oxygen-iron alloy with both strength and ductility is provided, wherein the titanium-oxygen-iron alloy has uniformly distributed oxygen and iron elements, and has a tensile strength of not less than 900 MPa and an elongation of not less than 20%.

[0016] Compared with the prior art, the advantages of the present invention include: This invention provides a titanium-iron oxide alloy with both strength and ductility, and its preparation method. This invention utilizes electrostatic self-assembly (SLM) technology to obtain a high-performance, low-cost, and non-toxic titanium-iron oxide metallic material, breaking through the technical bottleneck of traditional powder mixing processes. It achieves precise control and uniform distribution of oxygen in the titanium matrix, providing a method and approach for the uniform mixing of nanoscale oxygen carrier powder in titanium. Specifically, 1. This invention uses ferric oxide (Fe2O3) as the sole and calculable source of oxygen, and precisely calculates its addition amount based on the target oxygen content, fundamentally ensuring the stability and accuracy of the oxygen content in the final material (controlled within the ideal range of 0.2-0.3 wt.%), successfully solving the technical problem of oxygen content fluctuations caused by uncontrollable oxidation in traditional ball milling processes. 2. This invention uses electrostatic self-assembly technology to replace high-energy ball milling for powder mixing. This process eliminates the need for grinding media and process control agents, completely avoiding the introduction of foreign metallic and organic impurities, thereby preparing a highly uniform and pure titanium / ferric oxide composite powder, laying a solid foundation for the consistency of material properties. Attached Figure Description

[0017] Various other advantages and benefits will become apparent to those skilled in the art upon reading the following detailed description of preferred embodiments. The accompanying drawings are for illustrative purposes only and are not intended to limit the invention. Furthermore, the same reference numerals denote the same parts throughout the drawings. In the drawings: Figure 1a The image displayed is a scaled-down image of irregularly shaped particles; Figure 1b yes Figure 1a Enlarged image; Figure 1c This is a diagram of the spherical particles from the experimental example; Figure 1d yes Figure 1c Magnified view of medium-sized spherical particles; Figure 1e It is the EDS mapping of Fe; Figure 1f It is the EDS mapping of O; Figure 2 This is the XRD pattern of the experimental sample of this invention; Figure 3 This is a tensile stress-strain curve diagram of an experimental example of the present invention; Figure 4 This refers to the surface porosity of the experimental examples of this invention under a metallographic microscope; Figure 5a This is one of the metallographic micrographs of the experimental examples of this invention; Figure 5b This is the second metallographic micrograph of the experimental example of the present invention; Figure 6 These are SEM images of experimental examples of this invention. Detailed Implementation

[0018] In view of the shortcomings of the prior art, the inventors of this invention, through long-term research and extensive practice, have proposed the technical solution of this invention. The following will further explain and illustrate this technical solution, its implementation process, and its principles.

[0019] The present invention will now be described in further detail with reference to specific embodiments. The given embodiments are merely illustrative of the invention and not intended to limit its scope. The embodiments provided below can serve as a guide for further improvements by those skilled in the art and do not constitute a limitation on the invention in any way.

[0020] Unless otherwise specified, the experimental methods used in the following examples are conventional methods, performed according to the techniques or conditions described in the literature in this field or according to the product instructions. Unless otherwise specified, the materials and reagents used in the following examples are commercially available.

[0021] This invention provides a method for preparing a titanium-iron alloy that combines strength and ductility, comprising the following steps: S1. Based on the target oxygen element mass fraction of the mixed powder, the required amount of ferric oxide to be added is calculated in reverse according to the theoretical oxygen content of ferric oxide, wherein the oxygen element is solely derived from ferric oxide; the target oxygen element mass fraction is 0.2-0.3%; the particle size range of the ferric oxide powder is 0.5-5μm, and the purity is greater than 99.5%; S2. Pure titanium powder and the amount of ferric oxide powder calculated in step S1 are mixed by electrostatic self-assembly technology to obtain a composite powder with uniform composition; the pure titanium powder is micron-sized commercial pure titanium spherical powder with a particle size distribution of 15-53 μm and an oxygen content of less than 0.005%; the electrostatic self-assembly technology includes the following steps: (1) Disperse pure titanium powder in PDDA aqueous solution, stir for 15-30 minutes, centrifuge and wash to remove excess PDDA; obtain titanium powder with positive surface charge; (2) Disperse the titanium powder with positive surface charge in PSS aqueous solution, stir for 15-30 minutes, centrifuge and wash to obtain titanium powder with negative charge; (3) Soak and stir the titanium powder with the amount of ferric oxide powder calculated in step S1 in deionized aqueous solution to obtain a composite powder with uniform composition; the soaking time is 25-35 minutes, and the stirring speed is controlled at 100-150 rpm. Within the specified rpm range; the concentration of polydiallyl dimethyl ammonium chloride (PDDA) is 40 mg / ml, and the concentration of sodium polystyrene sulfonate (PSS) is 8 mg / ml. This invention first treats the surface with PDDA, then with PSS, constructing a bilayer structure. PDDA, as a cationic polyelectrolyte, can strongly adsorb onto the surface of almost any solid particle (regardless of its original charge), forming a robust, positively charged bottom film, thus solving the problem of uneven charge distribution on the surface of titanium powder. On this flat and positively charged PDDA bottom layer, negatively charged PSS can be uniformly and densely adsorbed through very strong electrostatic attraction, forming a stable and strongly negatively charged outer shell. The entire PSS / PDDA composite layer is very stable and not easily washed away or damaged.

[0022] S3. The composite powder is cleaned with deionized water, and the rinsing is performed 2-3 times. S4. The cleaned composite powder is subjected to a staged drying process at 70°C, performed twice, with each drying session lasting 24 hours. The drying process includes a staged drying process at 70°C, performed twice, with each drying session lasting 24 hours. The moisture content of the composite powder after the drying process is less than 0.02%. S5. The dried composite powder is placed in a molding chamber, the oxygen content in the molding chamber is reduced to below 0.01%, and argon gas is continuously introduced as a protective gas. Selective laser melting technology is used for molding processing, and the resulting workpiece is heat-treated. The heat treatment includes heating to 700°C and holding at that temperature for 2 hours, followed by furnace cooling to room temperature to obtain a titanium-oxygen-iron metal matrix composite material. The selective laser melting process parameters include: laser power of 220-300 W, scanning speed of 800-900 mm / s, scanning interval of 0.1 mm, and single-layer powder thickness of 0.03 mm. The composite powder contains 0.2-0.3% oxygen by mass and 0.4-0.6% iron by mass.

[0023] In some embodiments, a titanium-oxygen iron alloy prepared by any of the above methods is also provided, wherein the titanium-oxygen iron alloy has uniformly distributed oxygen and iron elements, and has a tensile strength of not less than 900 MPa and an elongation of not less than 20%.

[0024] This invention successfully prepared a titanium-oxygen alloy material with both high strength and high ductility by precisely controlling the content and distribution of dissolved oxygen and iron in the interstitial spaces. Its tensile strength is not less than 900 MPa, while its elongation is not less than 20%, achieving a good balance between strength and ductility and overcoming the common drawback of insufficient ductility in high-oxygen titanium alloys.

[0025] This invention has the advantages of good biocompatibility and low cost: the selected oxygen (O) and iron (Fe) elements are both inexpensive elements with good biocompatibility, avoiding the potential cytotoxicity problems of aluminum (Al) and vanadium (V) in traditional titanium alloys, and also avoiding the use of expensive alloying elements such as niobium (Nb) and tantalum (Ta), which significantly reduces material costs and is particularly suitable for the field of medical implants.

[0026] This invention boasts strong process compatibility, making it suitable for precision additive manufacturing: the entire preparation process (electrostatic self-assembly, cleaning, and drying) is highly compatible with subsequent selective laser melting (SLM) technology. The prepared powder exhibits good flowability and high purity, which is beneficial for the SLM process to form high-performance, high-density, precision, and complex parts, expanding the application prospects of this material in fields such as personalized medical implants. Example 1

[0027] This embodiment provides a method for preparing a titanium-iron alloy that combines strength and ductility, comprising the following steps: S1. Based on the target oxygen element mass fraction of the mixed powder, the required amount of ferric oxide to be added is calculated in reverse according to the theoretical oxygen content of ferric oxide, wherein the oxygen element is solely derived from ferric oxide; the target oxygen element mass fraction is 0.2%; the particle size of the ferric oxide powder is 0.5μm, and the purity is 99.6%; S2. Pure titanium powder and the amount of ferric oxide powder calculated in step S1 are mixed by electrostatic self-assembly technology to obtain a composite powder with uniform composition; the pure titanium powder is micron-sized commercial pure titanium spherical powder with a particle size distribution of 15μm and an oxygen content of less than 0.005%; the electrostatic self-assembly technology includes the following steps: (1) Disperse pure titanium powder in PDDA aqueous solution, stir for 15 minutes, centrifuge and wash to remove excess PDDA; obtain titanium powder with positive surface charge; (2) Disperse the titanium powder with positive surface charge in PSS aqueous solution, stir for 15 minutes, centrifuge and wash to obtain titanium powder with negative charge; (3) Soak and stir the titanium powder with the amount of ferric oxide powder calculated in step S1 in deionized aqueous solution to obtain a composite powder with uniform composition; the soaking time is 25 minutes, and the stirring speed is controlled within 100 rpm. S3. The composite powder is cleaned with deionized water, and the rinsing is performed twice. S4. The cleaned composite powder is subjected to a staged drying process at 70°C, performed twice, with each drying session lasting 24 hours. The drying process includes a staged drying process at 70°C, performed twice, with each drying session lasting 24 hours. The moisture content of the composite powder after the drying process is less than 0.02%. S5. The dried composite powder is placed in a molding chamber, the oxygen content in the molding chamber is reduced to below 0.01%, and argon gas is continuously introduced as a protective gas. Selective laser melting technology is used for molding processing, and the resulting workpiece is heat-treated. The heat treatment includes heating to 700°C and holding at that temperature for 2 hours, followed by furnace cooling to room temperature to obtain a titanium-oxygen-iron metal matrix composite material. The selective laser melting process parameters include: laser power of 220 W, scanning speed of 800 mm / s, scanning spacing of 0.1 mm, and single-layer powder thickness of 0.03 mm. The composite powder contains 0.2% oxygen by mass and 0.4% iron by mass.

[0028] In some embodiments, a titanium-oxygen iron alloy prepared by any of the above methods is also provided, the titanium-oxygen iron alloy having uniformly distributed oxygen and iron elements, having a tensile strength of 950 MPa and an elongation of 29.4%. Example 2

[0029] This embodiment provides a method for preparing a titanium-iron alloy that combines strength and ductility, comprising the following steps: S1. Based on the target oxygen element mass fraction of the mixed powder, the required amount of ferric oxide to be added is calculated in reverse according to the theoretical oxygen content of ferric oxide, wherein the oxygen element is solely derived from ferric oxide; the target oxygen element mass fraction is 0.2%; the particle size of the ferric oxide powder is 2.75μm, and the purity is 99.6%; S2. Pure titanium powder and the amount of ferric oxide powder calculated in step S1 are mixed by electrostatic self-assembly technology to obtain a composite powder with uniform composition; the pure titanium powder is micron-sized commercial pure titanium spherical powder with a particle size distribution of 34μm and an oxygen content of 0.004%; the electrostatic self-assembly technology includes the following steps: (1) dispersing pure titanium powder in PDDA aqueous solution, stirring for 22 minutes, centrifuging and washing to remove excess PDDA; obtaining titanium powder with a positively charged surface; (2) dispersing the titanium powder with a positively charged surface in PSS aqueous solution, stirring for 22 minutes, centrifuging and washing to obtain titanium powder with a negatively charged surface; (3) soaking and stirring the titanium powder with the amount of ferric oxide powder calculated in step S1 in deionized aqueous solution to obtain a composite powder with uniform composition; the soaking time is 30 minutes, and the stirring speed is controlled within the range of 125 rpm; S3. The composite powder is cleaned with deionized water, and the rinsing is performed twice. S4. The cleaned composite powder is subjected to a staged drying process at 70°C, which is carried out twice, with each drying session lasting 24 hours. The drying process includes a staged drying process at 70°C, which is carried out twice, with each drying session lasting 24 hours. The moisture content of the composite powder after the drying process is 0.018%. S5. The dried composite powder is placed in a molding chamber, the oxygen content in the molding chamber is reduced to below 0.01%, and argon gas is continuously introduced as a protective gas. Selective laser melting technology is used for molding processing, and the resulting workpiece is heat-treated. The heat treatment includes heating to 700°C and holding at that temperature for 2 hours, followed by furnace cooling to room temperature to obtain a titanium-oxygen-iron metal matrix composite material. The selective laser melting process parameters include: laser power of 220W, scanning speed of 800mm / s, scanning spacing of 0.1mm, and single-layer powder thickness of 0.03mm. The composite powder contains 0.25% oxygen and 0.5% iron by mass.

[0030] In some embodiments, a titanium-oxygen iron alloy prepared by any of the above methods is also provided, the titanium-oxygen iron alloy having uniformly distributed oxygen and iron elements, a tensile strength of 945 MPa, and an elongation of 27.1%. Example 3

[0031] This embodiment provides a method for preparing a titanium-iron alloy that combines strength and ductility, comprising the following steps: S1. Based on the target oxygen element mass fraction of the mixed powder, the required amount of ferric oxide to be added is calculated in reverse according to the theoretical oxygen content of ferric oxide, wherein the oxygen element is solely derived from ferric oxide; the target oxygen element mass fraction is 0.2%; the particle size of the ferric oxide powder is 5μm, and the purity is 99.7%; S2. Pure titanium powder and the amount of ferric oxide powder calculated in step S1 are mixed by electrostatic self-assembly technology to obtain a composite powder with uniform composition; the pure titanium powder is micron-sized commercial pure titanium spherical powder with a particle size distribution of 53 μm and an oxygen content of 0.004%; the electrostatic self-assembly technology includes the following steps: (1) dispersing pure titanium powder in PDDA aqueous solution, stirring for 30 minutes, centrifuging and washing to remove excess PDDA; obtaining titanium powder with a positively charged surface; (2) dispersing the titanium powder with a positively charged surface in PSS aqueous solution, stirring for 30 minutes, centrifuging and washing to obtain titanium powder with a negatively charged surface; (3) soaking and stirring the titanium powder with the amount of ferric oxide powder calculated in step S1 in deionized aqueous solution to obtain a composite powder with uniform composition; the soaking time is 35 minutes, and the stirring speed is controlled within the range of 150 rpm; S3. The composite powder is cleaned with deionized water, and the rinsing is performed 3 times. S4. The cleaned composite powder is subjected to a staged drying process at 70°C, performed twice, with each drying session lasting 24 hours. The drying process includes a staged drying process at 70°C, performed twice, with each drying session lasting 24 hours. The moisture content of the composite powder after the drying process is 0.018%. S5. The dried composite powder is placed in a molding chamber, the oxygen content in the molding chamber is reduced to below 0.01%, and argon gas is continuously introduced as a protective gas. Selective laser melting technology is used for molding processing, and the resulting workpiece is heat-treated. The heat treatment includes heating to 700°C and holding at that temperature for 2 hours, followed by furnace cooling to room temperature to obtain a titanium-oxygen-iron metal matrix composite material. The selective laser melting process parameters include: laser power of 300 W, scanning speed of 900 mm / s, scanning spacing of 0.1 mm, and single-layer powder thickness of 0.03 mm. The composite powder contains 0.3% oxygen and 0.6% iron by mass.

[0032] In some embodiments, a titanium-oxygen iron alloy prepared by any of the above methods is also provided, the titanium-oxygen iron alloy having uniformly distributed oxygen and iron elements, a tensile strength of 915 MPa, and an elongation of 20.7%.

[0033] To better understand the embodiments of the present invention, the following detailed discussion is provided in conjunction with specific experimental examples: Experimental Example Pure titanium powder and ferric oxide powder were uniformly mixed using electrostatic self-assembly technology to give the titanium powder a negatively charged surface. The treated titanium powder and ferric oxide were then mixed and stirred in a deionized aqueous solution for 30 minutes to allow the positively charged ferric oxide powder to be fully adsorbed onto the titanium powder surface. Since all the oxygen in the mixed powder comes from ferric oxide, the specific amount of ferric oxide to be added can be calculated and determined based on the target oxygen mass fraction (0.2-0.3 wt.%) in the mixed powder. The composite powder was then shaped using the SLM method, with laser powers of 220W, 250W, 280W, and 300W, scanning speeds of 800mm / s and 900mm / s, a scanning interval of 0.1mm, and a scanning layer thickness of 0.03mm. Annealing was then performed at 700℃ for 1 hour, followed by air cooling to obtain a titanium-iron alloy possessing both strength and ductility.

[0034] The electrostatic self-assembly technology includes two specific components: PDDA coating and PSS coating, which specifically include the following steps: Phase 1: Preparation of positively charged titanium powder (PDDA coating) Step 1: Pretreatment and dispersion of titanium powder 1. Weighing: Accurately weigh 1.0 gram of pure titanium powder into a beaker or conical flask.

[0035] 2. Dispersion: Add 100 ml of deionized water to the titanium powder.

[0036] 3. Ultrasonic dispersion: Place the beaker in an ultrasonic cleaner and ultrasonically treat for 15 minutes.

[0037] 4. Adjust pH: Adjust the pH of the dispersion to below the isoelectric point of titanium using dilute hydrochloric acid or sodium hydroxide solution, for example, to pH 3. This ensures that the titanium powder surface is protonated and positively charged, creating electrostatic repulsion with the subsequently added positively charged PDDA. This prevents the PDDA from causing rapid flocculation and sedimentation of the titanium powder, allowing PDDA molecules more time to rearrange and uniformly adsorb on the particle surface.

[0038] Step 2: Adsorption of PDDA solution 1. Prepare PDDA solution: Take 100 ml of deionized water, dissolve 40 mg of PDDA, and prepare a solution with a concentration of 0.4 mg / ml.

[0039] 2. Mixing: Pour the titanium powder dispersion prepared in step 1 into the PDDA solution. Stir gently and continuously with a magnetic stirrer.

[0040] 3. Adsorption reaction: Stir continuously at room temperature for at least 30 minutes. Ensure that all titanium powder particles have sufficient time to come into contact with PDDA molecules, so that PDDA is firmly adsorbed onto the titanium powder surface through electrostatic interaction and van der Waals forces.

[0041] Step 3: Centrifugation and washing 1. Centrifugation: Transfer the reaction mixture to centrifuge tubes and centrifuge to allow sedimentation (e.g., 5000 rpm, 5 minutes). The titanium powder will settle at the bottom of the tube.

[0042] 2. Washing: Carefully pour out or remove the supernatant using a pipette. This supernatant contains unadsorbed free PDDA molecules.

[0043] 3. Repeat washing: Add deionized water to the centrifuge tube, redisperse the titanium powder precipitate by vortexing or short-term sonication, and centrifuge again. Repeat this washing process at least 2-3 times until the supernatant is basically clear as determined by a conductivity meter or surface tension meter, ensuring that all free PDDA has been removed.

[0044] 4. Redispersing: After the final wash, redisperse the washed titanium powder with PDDA coating (at this time the surface is positively charged) in 100 ml of deionized water for later use.

[0045] Second stage: Preparation of negatively charged titanium powder (PSS coating) Step 4: Adsorption of PSS solution 1. Prepare PSS solution: Take 100 ml of deionized water, dissolve 80 mg of PSS, and prepare a solution with a concentration of 0.8 mg / ml.

[0046] 2. Mixing: Pour the positively charged titanium powder dispersion obtained in step 3 into the PSS solution.

[0047] 3. Adsorption reaction: Stir continuously at room temperature for at least 30 minutes. During this time, the negatively charged PSS will be firmly adsorbed onto the positively charged PDDA layer through strong electrostatic attraction, forming a stable PSS / PDDA bilayer structure.

[0048] Step 5: Centrifugation and Washing 1. Centrifugation: Centrifuge the mixture after the reaction (under the same conditions as step 3).

[0049] 2. Washing: Carefully remove the supernatant and wash with water by centrifugation 2-3 times to thoroughly remove unadsorbed PSS molecules.

[0050] 3. Final dispersion: The negatively charged titanium powder on the surface of the final product is redispersed in an appropriate amount of deionized water (e.g., 50 ml), which can then be used for the next step of electrostatic self-assembly experiment with ferric oxide.

[0051] In practice, after PDDA coating and PSS coating, a small amount of sample was dispersed in deionized water, and its Zeta potential was measured. After PDDA coating, the Zeta potential was significantly positive (e.g., above +30 mV). After PSS coating, the Zeta potential was significantly negative (e.g., below -30 mV).

[0052] Comparative Example The powder was mixed by ball milling. Specifically, steel balls with a diameter of 2 mm were used to ball mill the powder at a frequency of 300 Hz with a ball-to-powder ratio of 5:1 for 3 hours. The mass ratio of the powder was the same as in the experimental example.

[0053] SEM analysis was performed on the powders from the experimental and comparative examples after mixing. The results are as follows: Figures 1a-1f As shown, in Figures 1a-1f It was found that in ball milling, residual stress accumulates inside the powder, damaging its sphericity and affecting its flowability. In contrast, the powder obtained through electrostatic self-assembly maintained excellent sphericity, and energy dispersive spectroscopy revealed that ferric oxide powder was uniformly distributed on the surface of the titanium powder, achieving a uniform distribution of oxygen within the titanium matrix. Figure 1a This displays particles of irregular shape and varying sizes in proportion to a certain ratio. Figure 1b : Figure 1a When magnified, the surface of the particles appears even rougher. Figure 1c : These are spherical particles from the experiment, and Figure 1a The irregularity creates a contrast. Figure 1d :yes Figure 1c A magnified view of medium-sized spherical particles; the particle surface is smooth. Figure 1e and Figure 1f This is EDS mapping, used to display elemental distribution. 1e indicates Fe, and 1f indicates O, indicating that the sample mainly contains Fe and O elements. 1e shows the distribution of Fe, and 1f shows the distribution of O. These two graphs show that Fe and O are evenly distributed within the spherical particles.

[0054] Figure 2 The XRD patterns of the experimental powder and the molded sample (220w-800mm / s) are shown in Figures A and B, respectively. Due to the low content of ferric oxide powder, no obvious corresponding diffraction peaks were found in the XRD patterns. However, the pattern of titanium in the molded sample showed a slight angular shift compared to the original powder, indicating that oxygen atoms were dissolved in the titanium matrix through SLM.

[0055] Figure 3 This is a tensile stress-strain diagram of the sample after SLM forming in the experimental example. The diagram shows that the material exhibits significant yielding and plastic deformation before fracture. Compared to Ti-6Al-4V, the experimental sample demonstrates better plasticity. Furthermore, its performance is far superior to that of traditional pure titanium after SLM forming, and its experimental results also surpass those in other literature.

[0056] Table 1 Mechanical properties of samples with different printing parameters

[0057] Figure 4 This figure presents the porosity analysis results of the surface microstructure of samples prepared under eight different combinations of process parameters. As shown in the figure, the number of pores on the sample surface increases significantly with increasing laser power. The sample obtained with the laser power set to 220W exhibits the lowest surface porosity. This result indicates that the material has the highest density under these process parameters, and its overall mechanical and service performance is therefore superior to samples prepared under other parameter conditions.

[0058] Figure 5a and Figure 5b The two images are metallographic micrographs of experimental examples at different locations. Figure 5a and Figure 5b The metallographic microscope has a magnification of 100x. Under these observation conditions, the overall morphology of columnar crystals dominated by directional heat flow can be clearly seen. During the laser melting printing process, the heat in the molten pool is conducted from top to bottom. This heat flow characteristic causes the grains to preferentially complete nucleation and growth along the heat flow direction during the solidification stage, eventually forming directional columnar crystals. The growth direction of the columnar crystals is consistent with the printing direction. Figure 6 The image is an experimental SEM image. The SEM image is magnified 3000 times and shows a large number of uniform needle-like α-titanium. The formation of this morphology is mainly attributed to the rapid solidification characteristics of SLM, which ultimately promotes the formation of fine needle-like single crystals.

[0059] Traditionally, oxygen is considered a harmful element in titanium alloys. This is because excessive oxygen, when it accumulates in stress concentration areas such as dislocations and grain boundaries, not only induces the precipitation of brittle phases but also interacts strongly with dislocations during deformation, leading to microstructural degradation and macroscopic brittle fracture, severely impacting the material's service safety. However, this experiment, through precise control of the oxygen content (0.2-0.3 wt.%), achieved positive regulation of the properties of titanium-iron oxy-oxide alloys, significantly improving material strength while maintaining excellent ductility. Analysis suggests that, on the one hand, 0.2-0.3 wt.% oxygen can exert a significant strengthening effect through interstitial solid solution; that is, oxygen atoms occupying interstitial spaces in the titanium lattice induce lattice distortion, effectively hindering dislocation movement and thus improving material strength. On the other hand, this oxygen content is far below the critical threshold (<0.5%) where excessive oxygen leads to a sharp decrease in plasticity, therefore it does not significantly damage the material's plasticity.

[0060] The above descriptions are merely some embodiments of the present invention. It should be noted that those skilled in the art can make other modifications and improvements without departing from the inventive concept of the present invention, and these all fall within the protection scope of the present invention.

Claims

1. A method for preparing a titanium-oxygen iron alloy possessing both strength and ductility, characterized in that, Includes the following steps: S1. Based on the target oxygen element mass fraction of the mixed powder, the required amount of ferric oxide to be added is calculated in reverse according to the theoretical oxygen content of ferric oxide, where the oxygen element comes only from ferric oxide. S2. Pure titanium powder and the amount of ferric oxide powder calculated in step S1 are mixed by electrostatic self-assembly technology to obtain a composite powder with uniform composition. S3. The composite powder is cleaned with deionized water and then dried. S4. The dried composite powder is placed in a molding chamber, the oxygen content in the molding chamber is reduced to below 0.01% and a protective gas is continuously introduced, and selective laser melting technology is used for molding to obtain the titanium-oxygen-iron alloy. The composite powder contains 0.2-0.3% oxygen by mass and 0.4-0.6% iron by mass.

2. The method for preparing the titanium-iron alloy possessing both strength and ductility according to claim 1, characterized in that, The pure titanium powder is a micron-sized commercial pure titanium spherical powder with a particle size of 15-53 μm and an oxygen content of less than 0.005%.

3. The method for preparing the titanium-iron alloy possessing both strength and ductility according to claim 1, characterized in that, The electrostatic self-assembly technology includes the following steps: (1) Disperse pure titanium powder in PDDA aqueous solution, stir for 15-30 minutes, centrifuge and wash to remove excess PDDA; obtain titanium powder with positive surface charge; (2) Disperse the positively charged titanium powder in PSS aqueous solution, stir for 15-30 minutes, centrifuge and wash to obtain negatively charged titanium powder; (3) Soak and stir the negatively charged titanium powder and the amount of ferric oxide powder calculated in step S1 in a deionized aqueous solution.

4. The method for preparing the titanium-iron alloy possessing both strength and ductility according to claim 3, characterized in that, The soaking time is 25-35 minutes, and the stirring speed is controlled within the range of 100-150 rpm.

5. The method for preparing the titanium-iron alloy possessing both strength and ductility according to claim 1, characterized in that, The selective laser melting process parameters include: laser power of 220-300W, scanning speed of 800-900mm / s, scanning interval of 0.1mm, and single-layer powder thickness of 0.03mm.

6. The method for preparing the titanium-iron alloy possessing both strength and ductility according to claim 1, characterized in that, After selective laser melting and forming, the resulting workpiece is subjected to heat treatment, which includes heating to 700°C and holding at that temperature for 2 hours, followed by furnace cooling to room temperature.

7. The method for preparing the titanium-iron alloy possessing both strength and ductility according to claim 1, characterized in that, The ferric oxide powder has a particle size range of 0.5-5 μm and a purity greater than 99.5%.

8. The method for preparing the titanium-iron alloy possessing both strength and ductility according to claim 1, characterized in that, In step S3, the moisture content of the composite powder after drying is less than 0.02%.

9. A titanium-iron alloy prepared by the method for preparing a titanium-iron alloy possessing both strength and ductility as described in any one of claims 1-8, characterized in that, The titanium-oxygen-iron alloy has uniformly distributed oxygen and iron elements, and its tensile strength is not less than 900 MPa and its elongation is not less than 20%.

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