A method for preparing a high-density high-elongation injection-molded titanium alloy

Abstract

This invention relates to the field of metal powder injection molding technology, specifically to a method for preparing high-density, high-elongation injection-molded titanium alloys. The method includes selecting spherical titanium alloy powder with a particle size distribution of D10: 5-8 μm, D50: 10-14 μm, and D90: 18-23 μm; mixing the titanium alloy powder with a polymer binder to obtain a feedstock; injection molding to obtain a blank; catalytic debinding; and sintering to obtain the titanium alloy component. This invention improves the powder bulk density and sintering activity by optimizing the particle size distribution and morphology of the titanium alloy powder; by optimizing the feedstock system and mixing process, the titanium alloy powder and binder are fully mixed, improving the uniformity and stability of the feedstock; and by employing optimized debinding and sintering processes, the heating rate, sintering temperature, and holding time are synergistically controlled, shortening the sintering cycle while promoting densification and effectively reducing porosity.

Description

Technical Field

[0001] This invention relates to the field of powder injection molding materials technology, and in particular to a method for preparing high-density, high-elongation injection-molded titanium alloys. Background Technology

[0002] Titanium alloys possess high specific strength, excellent corrosion resistance, good biocompatibility, and excellent high-temperature resistance, making them widely used in aerospace, medical devices, automotive industry, consumer electronics, and precision machinery. With the increasing demand for complex structures, miniaturized and lightweight components, traditional forging, casting, and machining processes are no longer sufficient to meet the large-scale manufacturing needs of precision titanium alloy parts due to low material utilization, high processing costs, and difficulties in forming complex structures.

[0003] Metal injection molding (MIM) technology combines the advantages of plastic injection molding and powder metallurgy, enabling the one-step molding of complex three-dimensional structural parts. It boasts advantages such as high dimensional accuracy, high material utilization, and suitability for mass production, making it a crucial technological route for manufacturing complex and precision titanium alloy parts. Currently, titanium alloy MIM processes typically include titanium alloy powder selection, feedstock preparation, injection molding, debinding, and high-temperature sintering. Among these, powder properties, the feedstock system, and the sintering process are key factors affecting the final product's density, mechanical properties, and production efficiency.

[0004] However, existing titanium alloy injection molding processes still have many shortcomings. On the one hand, to obtain high sintering density, fine-particle spherical powders are usually used. However, fine powders have a large specific surface area, easily leading to increased oxygen content, increased feed viscosity, and decreased injection flowability, which can easily cause incomplete filling, delamination, and defects, and also affect the final elongation. On the other hand, to improve sintering density, existing technologies often require higher sintering temperatures, longer holding times, or hot isostatic pressing (HIP) post-treatment processes, which not only increase production cycles and manufacturing costs but also reduce production efficiency. In addition, existing feed systems are prone to problems such as uneven mixing, powder agglomeration, debinding cracking, and sintering deformation, limiting further improvements in product density and dimensional stability.

[0005] For example, Chinese invention patent CN114226731A discloses a low-cost injection molding method for preparing fully dense titanium alloy parts. The method uses an injection molding process with irregular hydrogenated and dehydrogenated titanium alloy powder with a particle size distribution of 35μm≤D90≤75μm as raw material. Although the cost is low, the residual porosity is high due to the coarser powder.

[0006] Chinese invention patent CN108555278A discloses a binder for titanium alloy powder injection molding and a method for injection molding titanium alloy parts. Although its relative density can reach 98.3%, its elongation is only 9.5%, making it difficult to apply to industries with high elongation requirements. Chinese invention patent CN110947971A discloses a method for preparing TC4 titanium alloy parts by powder injection molding, which also suffers from the problem of low elongation.

[0007] Chinese invention patent CN110935878A discloses an injection molding method for titanium alloy parts with a relative density of ≥99%. However, it uses the HIP sintering process. Although it achieves good density and elongation, conventional injection molding sintering equipment cannot meet the requirements. Furthermore, after HIP, the grain size will grow excessively, and the pressure and temperature need to be strictly controlled, resulting in unstable shrinkage.

[0008] Therefore, how to improve injection molding efficiency, shorten the sintering cycle, and reduce manufacturing costs while ensuring the high density and excellent mechanical properties of sintered products, and thus achieve the injection molding preparation of high-density, high-performance titanium alloys, has become a technical problem that urgently needs to be solved in this field. Summary of the Invention

[0009] In view of this, the purpose of this invention is to propose a method for preparing high-density, high-elongation injection-molded titanium alloys, in order to solve the problem of improving injection molding efficiency, shortening the sintering cycle, and reducing manufacturing costs while ensuring the high density and excellent mechanical properties of sintered products, thereby achieving the injection molding preparation of high-density, high-performance titanium alloys.

[0010] This invention proposes a method for preparing high-density, high-elongation injection-molded titanium alloys, comprising the following steps:

[0011] Step 1, Powder selection: Spherical titanium alloy powder is selected, and the particle size distribution of the spherical titanium alloy powder is: D10: 5-8μm, D50: 10-14μm, D90: 18-23μm;

[0012] Step 2, Feed preparation: The titanium alloy powder and polymer binder are put into a mixing equipment for mixing, and after a certain period of time, they are extruded and granulated to obtain a uniform injection molding feed.

[0013] Step 3, Injection Molding: The feed material is injected into the mold cavity through injection molding equipment to obtain a smooth injection blank;

[0014] Step 4, Catalytic Degreasing: The injection preform is placed in an oxalic acid degreasing furnace to remove some of the binder from the preform, obtaining a degreased preform;

[0015] Step 5, Sintering: The degreased blank is placed in a special injection molding sintering furnace for hot degreasing and sintering. By controlling the heating rate, sintering temperature and holding time, a high-density titanium alloy part with high elongation is obtained.

[0016] Optionally, the elemental composition of the titanium alloy powder, calculated by mass percentage, includes the following components: C: ≤0.1%, O: ≤0.2%, Al: 5.5-6.5%, V: 3.5-4.5%, Fe: ≤0.3%, with the remainder being Ti.

[0017] Optionally, the tap density of the titanium alloy powder is 2.5-3.0 g / cm³. 3 .

[0018] Optionally, the feed comprises, by weight percentage: 80%-90% titanium alloy powder and 10%-20% binder; the binder comprises, by weight percentage: 70%-80% polyoxymethylene, 10%-20% polyethylene, 1%-5% stearic acid, 0.5%-2% antioxidant, and 1%-3% ethylene-vinyl acetate copolymer.

[0019] Optionally, the titanium alloy powder and the polymer binder are placed together in a mixing equipment for mixing, and then extruded and granulated after a certain period of time to obtain a uniform injection molding feed. Specifically, this includes: placing the polymer binder and titanium alloy powder into the mixing equipment in sequence, with a temperature of 170℃-220℃, a screw speed of 10-30 r / min, and a mixing time of 30-60 min; during the granulation process, the extrusion temperature is 140-180℃, the screw speed is 10-30 r / min, and the pelletizing speed is 100-200 r / min.

[0020] Optionally, the injection molding conditions in step three are: mold temperature 120℃-140℃, injection temperature 170℃-190℃, injection pressure 220-270Mpa, and holding pressure 150~190Mpa.

[0021] Optionally, the catalytic degreasing process in step four involves heating to 100-120°C at a rate of 2°C / min, purging the furnace with nitrogen atmosphere for 60-120 min, then maintaining the temperature for 6-12 h in an environment where oxalic acid is involved in catalysis, and then cooling naturally.

[0022] Optionally, the sintering process in step five involves heating to 600-800℃ at a rate of 5℃ / min, holding at that temperature for 2-6 hours, heating to 1000-1100℃ at a rate of 5℃ / min, holding at that temperature for 2-6 hours, and then cooling to room temperature.

[0023] The beneficial effects of this invention are:

[0024] This invention improves the bulk density and sintering activity of titanium alloy powder by optimizing its particle size distribution and morphology, thereby enhancing the sintering driving force. By optimizing the feeding system and mixing process, the titanium alloy powder and binder are thoroughly mixed, improving feeding uniformity and stability, reducing the probability of powder-binder separation and molding defects during injection molding, and improving the quality of the blank. Optimized debinding and sintering processes, with coordinated control of heating rate, sintering temperature, and holding time, shorten the sintering cycle while promoting densification, effectively reducing porosity and improving the relative density and comprehensive mechanical properties of the sintered product. This invention can meet the appearance and performance requirements of titanium alloys in aerospace, medical devices, and consumer electronics fields. Attached Figure Description

[0025] To more clearly illustrate the technical solutions in this invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only for this invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0026] Figure 1 Metallographic image of the product prepared in Example 1;

[0027] Figure 2 Metallographic image of the product obtained in Example 2;

[0028] Figure 3 Metallographic image of the product obtained in Example 3;

[0029] Figure 4 Metallographic image of the product obtained in Example 4;

[0030] Figure 5 Metallographic image of the product obtained in Example 5;

[0031] Figure 6 Metallographic image of the product prepared for Comparative Example 1;

[0032] Figure 7 Metallographic image of the product obtained in Example 2;

[0033] Figure 8 The image shows the metallographic image of the product obtained in Example 3. Detailed Implementation

[0034] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to specific embodiments.

[0035] It should be noted that, unless otherwise defined, the technical or scientific terms used in this invention should have the ordinary meaning understood by one of ordinary skill in the art to which this invention pertains. Terms such as "comprising" or "including" mean that the element or object preceding the word encompasses the elements or objects listed following the word and their equivalents, without excluding other elements or objects.

[0036] Example 1:

[0037] A method for preparing a high-density, high-elongation injection-molded titanium alloy includes the following steps:

[0038] Powder selection: Spherical TC4 (Ti-6Al-4V) titanium alloy powder was selected, with the following chemical composition (mass percentage): C: 0.03%, O: 0.12%, Al: 6.05%, V: 4.02%, Fe: 0.18%, and the balance being Ti; the powder particle size distribution was: D10=5.1μm; D50=11.8μm; D90=19.8μm, and the tap density was 2.72g / cm³.

[0039] Feed preparation: By mass percentage, titanium alloy powder 85%, binder 15%, binder composition: polyoxymethylene 75%, polyethylene 15%, stearic acid 3%, antioxidant 1%, ethylene-vinyl acetate copolymer 3%, mixed at 190℃ for 45 min, screw speed 20 r / min. Subsequently, twin-screw granulation was carried out at 160℃, screw speed 20 r / min, and pelletizing speed 150 r / min.

[0040] Injection molding: mold temperature 130℃, injection temperature 190℃, injection pressure 250MPa, holding pressure 170MPa, to obtain injection blanks with smooth surfaces and no cracks.

[0041] Catalytic degreasing: Heat to 110℃ at 2℃ / min, purge with nitrogen for 90min, catalyze with oxalic acid and keep warm for 8h, then cool naturally.

[0042] Sintering: The temperature was increased to 700℃ at a rate of 5℃ / min and held for 4 hours, then increased to 1050℃ and held for 4 hours. The product was then cooled to room temperature. The properties of the resulting product are as follows: density 4.41 g / cm³, porosity 0.14%, tensile strength 1075 MPa, yield strength 962 MPa, elongation 18.5%, oxygen content 0.27%, and its metallographic structure is as follows. Figure 1 As shown.

[0043] Example 2:

[0044] A method for preparing a high-density, high-elongation injection-molded titanium alloy includes the following steps:

[0045] Powder selection: Spherical TC4 (Ti-6Al-4V) titanium alloy powder was selected, with the following chemical composition (mass percentage): C: 0.03%, O: 0.15%, Al: 5.90%, V: 3.95%, Fe: 0.18%, and the balance being Ti; the powder particle size distribution was: D10=5.7μm; D50=10.7μm; D90=18.5μm, and the tap density was 2.61g / cm³.

[0046] Feed preparation: By mass percentage, titanium alloy powder 84%, binder 16%, binder composition: polyoxymethylene 78%, polyethylene 12%, stearic acid 3%, antioxidant 1%, ethylene-vinyl acetate copolymer 3%, mixed at 180℃ for 40min, screw speed 20r / min, then granulated by twin screw at 160℃, screw speed 20r / min, pelletizing speed 150r / min.

[0047] Injection molding: mold temperature 125℃, injection temperature 175℃, injection pressure 235MPa, holding pressure 160MPa, to obtain injection blanks with smooth surfaces and no cracks.

[0048] Catalytic degreasing: Heat to 115℃ at 2℃ / min, purge with nitrogen for 90min, catalyze with oxalic acid and keep warm for 10h, then cool naturally.

[0049] Sintering: The temperature was increased to 650℃ at a rate of 5℃ / min and held for 5 hours, then increased to 1000℃ and held for 5 hours. The product was then cooled to room temperature. The properties of the resulting product are as follows: density 4.38 g / cm³, porosity 0.29%, tensile strength 1024 MPa, yield strength 932 MPa, elongation 15.7%, oxygen content 0.29%, and its metallographic structure is as follows. Figure 2 As shown.

[0050] Example 3:

[0051] A method for preparing a high-density, high-elongation injection-molded titanium alloy includes the following steps:

[0052] Powder selection: Spherical TC4 (Ti-6Al-4V) titanium alloy powder was selected, with the following chemical composition (mass percentage): C: 0.02%, O: 0.15%, Al: 5.90%, V: 3.95%, Fe: 0.18%, and the balance being Ti; the powder particle size distribution was: D10=6.8μm; D50=12.5μm; D90=20.8μm, and the tap density was 2.81g / cm³.

[0053] Feed preparation: By mass percentage, titanium alloy powder 86%, binder 14%, binder composition: polyoxymethylene 75%, polyethylene 15%, stearic acid 4%, antioxidant 0.5%, ethylene-vinyl acetate copolymer 2.5%, mixed at 195℃ for 50 min, screw speed 25 r / min, then granulated by twin screw at 170℃, screw speed 25 r / min, pelletizing speed 170 r / min.

[0054] Injection molding: mold temperature 135℃, injection temperature 185℃, injection pressure 260MPa, holding pressure 180MPa, to obtain injection blanks with smooth surfaces and no cracks.

[0055] Catalytic degreasing: Heat to 105℃ at 2℃ / min, purge with nitrogen for 120min, catalyze with oxalic acid and keep warm for 6h, then cool naturally.

[0056] Sintering: The temperature was increased to 750℃ at a rate of 5℃ / min and held for 3 hours, then increased to 1080℃ and held for 3 hours. The product was then cooled to room temperature. The properties of the resulting product are as follows: density 4.34 g / cm³, porosity 0.32%, tensile strength 1012 MPa, yield strength 909 MPa, elongation 13.7%, oxygen content 0.24%, and its metallographic structure is as follows. Figure 3 As shown.

[0057] Example 4:

[0058] A method for preparing a high-density, high-elongation injection-molded titanium alloy includes the following steps:

[0059] Powder selection: Spherical TC4 (Ti-6Al-4V) titanium alloy powder was selected, with the following chemical composition (mass percentage): C: 0.02%, O: 0.13%, Al: 5.76%, V: 4.11%, Fe: 0.20%, and the balance being Ti. The powder particle size distribution was: D10=7.2μm; D50=13.4μm; D90=22.5μm, and the tap density was 2.95g / cm³.

[0060] Feed preparation: By mass percentage, titanium alloy powder 88%, binder 12%. The binder composition is: polyoxymethylene 75%, polyethylene 15%, stearic acid 4%, antioxidant 0.5%, ethylene-vinyl acetate copolymer 2.5%. Mixing is carried out at 210℃ for 60 min with screw speed of 30 r / min, followed by twin-screw granulation at 180℃ with screw speed of 30 r / min and pelletizing speed of 180 r / min.

[0061] Injection molding: mold temperature 140℃, injection temperature 190℃, injection pressure 270MPa, holding pressure 190MPa, to obtain injection blanks with smooth surfaces and no cracks.

[0062] Catalytic degreasing: Heat to 120℃ at 2℃ / min, purge with nitrogen for 120min, catalyze with oxalic acid and keep warm for 10h, then cool naturally.

[0063] Sintering: The temperature was increased to 800℃ at a rate of 5℃ / min and held for 2 hours, then increased to 1100℃ and held for 2 hours. The product was then cooled to room temperature. The properties of the resulting product are as follows: density 4.35 g / cm³, porosity 0.33%, tensile strength 1086 MPa, yield strength 991 MPa, elongation 15.2%, oxygen content 0.29%. Its metallographic structure is as follows: Figure 4 As shown.

[0064] Example 5:

[0065] A method for preparing a high-density, high-elongation injection-molded titanium alloy includes the following steps:

[0066] Powder selection: Spherical TC4 (Ti-6Al-4V) titanium alloy powder was selected, with the following chemical composition (mass percentage): C: 0.01%, O: 0.14%, Al: 6.1%, V: 4.15%, Fe: 0.20%, and the balance being Ti; the powder particle size distribution was: D10=6.3μm; D50=12.1μm; D90=20.3μm, and the tap density was 2.78g / cm³.

[0067] Feed preparation: By mass percentage, titanium alloy powder 87% and binder 13%. The binder composition is: polyoxymethylene 72%, polyethylene 18%, stearic acid 3%, antioxidant 0.5%, ethylene-vinyl acetate copolymer 1.5%. The mixture is mixed at 195℃ for 55 min with a screw speed of 22 r / min, followed by twin-screw granulation at 165℃ with a screw speed of 22 r / min and a pelletizing speed of 160 r / min.

[0068] Injection molding: mold temperature 132℃, injection temperature 182℃, injection pressure 255MPa, holding pressure 175MPa, to obtain injection blanks with smooth surfaces and no cracks.

[0069] Catalytic degreasing: Heat to 110℃ at 2℃ / min, purge with nitrogen for 120min, catalyze with oxalic acid and keep warm for 8h, then cool naturally.

[0070] Sintering: The temperature was increased to 720℃ at a rate of 5℃ / min and held for 4 hours, then increased to 1060℃ and held for 4 hours. The product was then cooled to room temperature. The properties of the resulting product are as follows: density 4.40 g / cm³, porosity 0.17%, tensile strength 1062 MPa, yield strength 952 MPa, elongation 18.8%, oxygen content 0.26%, and its metallographic structure is as follows. Figure 5 As shown.

[0071] Comparative Example 1:

[0072] Powder selection: Spherical TC4 (Ti-6Al-4V) titanium alloy powder was selected, with the following chemical composition (mass percentage): C: 0.02%, O: 0.11%, Al: 5.76%, V: 4.11%, Fe: 0.20%, and the balance being Ti; the powder particle size distribution was: D10=9.2μm; D50=22.3μm; D90=38.8μm, and the tap density was 2.91g / cm³.

[0073] Feed preparation: By mass percentage, titanium alloy powder 85%, binder 15%, binder composition: polyoxymethylene 75%, polyethylene 15%, stearic acid 3%, antioxidant 1%, ethylene-vinyl acetate copolymer 6%, mixed at 190℃ for 45min, screw speed 20r / min, then granulated by twin screw at 160℃, screw speed 20r / min, pelletizing speed 150r / min.

[0074] Injection molding: mold temperature 130℃, injection temperature 190℃, injection pressure 250MPa, holding pressure 170MPa, to obtain injection blanks with smooth surfaces and no cracks.

[0075] Catalytic degreasing: Heat to 110℃ at 2℃ / min, purge with nitrogen for 90min, catalyze with oxalic acid and keep warm for 8h, then cool naturally.

[0076] Sintering: The temperature was increased to 700℃ at a rate of 5℃ / min and held for 4 hours, then increased to 1050℃ and held for 4 hours. The product was then cooled to room temperature. The properties of the resulting product are as follows: density 4.30 g / cm³, porosity 0.62%, tensile strength 1015 MPa, yield strength 902 MPa, elongation 11.5%, oxygen content 0.24%, and its metallographic structure is as follows. Figure 6 As shown.

[0077] Comparative Example 2:

[0078] Powder selection: Spherical TC4 (Ti-6Al-4V) titanium alloy powder was selected, with the following chemical composition (mass percentage): C: 0.03%, O: 0.12%, Al: 6.05%, V: 4.02%, Fe: 0.18%, and the balance being Ti. The powder particle size distribution was: D10=5.1μm; D50=11.8μm; D90=19.8μm, and the tap density was 2.72g / cm³.

[0079] Feed preparation: By mass percentage, titanium alloy powder 85%, binder 15%, binder composition: polyoxymethylene 80%, polyethylene 10%, stearic acid 8%, antioxidant 2%, ethylene-vinyl acetate copolymer 0%, mixed at 190℃ for 45min, screw speed 20r / min, then granulated by twin screw at 160℃, screw speed 20r / min, pelletizing speed 150r / min.

[0080] Injection molding: mold temperature 130℃, injection temperature 190℃, injection pressure 250MPa, holding pressure 170MPa, to obtain injection blanks with smooth surfaces and no cracks.

[0081] Catalytic degreasing: Heat to 110℃ at 2℃ / min, purge with nitrogen for 90min, catalyze with oxalic acid and keep warm for 8h, then cool naturally.

[0082] Sintering: The temperature was increased to 700℃ at 5℃ / min and held for 4 hours, then increased to 1050℃ and held for 4 hours. The product was cooled to room temperature. The properties of the product were as follows: density 4.24 g / cm³, porosity 1.1%, tensile strength 905 MPa, yield strength 810 MPa, elongation 8.2%, and oxygen content 0.31%.

[0083] During injection testing of this comparative sample, poor flowability was observed, leading to frequent short injections, localized powder-gel separation, severe flow lines, and certain defects. The metallographic structure of the sample was as follows: Figure 7 As shown.

[0084] Comparative Example 3:

[0085] Powder selection: Spherical TC4 (Ti-6Al-4V) titanium alloy powder was selected, with the following chemical composition (mass percentage): C: 0.03%, O: 0.12%, Al: 6.05%, V: 4.02%, Fe: 0.18%, and the balance being Ti. The powder particle size distribution was: D10=5.1μm; D50=11.8μm; D90=19.8μm, and the tap density was 2.72g / cm³.

[0086] Feed preparation: by mass percentage, titanium alloy powder 85%, binder 15%, binder composition: polyoxymethylene 75%, polyethylene 15%, stearic acid 3%, antioxidant 1%, ethylene-vinyl acetate copolymer 6%; mix at 190℃ for 45 min, screw speed 20 r / min, then granulate with twin screws at 160℃, screw speed 20 r / min, pelletizing speed 150 r / min.

[0087] Injection molding: mold temperature 130℃, injection temperature 190℃, injection pressure 250MPa, holding pressure 170MPa, to obtain injection blanks with smooth surfaces and no cracks.

[0088] Catalytic degreasing: Heat to 110℃ at 2℃ / min, purge with nitrogen for 90min, catalyze with oxalic acid and keep warm for 8h, then cool naturally.

[0089] Sintering: The temperature was increased to 700℃ at a rate of 5℃ / min and held for 4 hours, then increased to 980℃ and held for 4 hours, before cooling to room temperature. The properties of the resulting product are as follows: density 4.20 g / cm³, porosity 1.3%, tensile strength 880 MPa, yield strength 779 MPa, elongation 8.9%, oxygen content 0.28%, and its metallographic structure is as follows. Figure 8 As shown.

[0090] The detection results of Examples 1-5 and Comparative Examples 1-3 are shown in Table 1:

[0091] Table 1

[0092]

[0093] According to the data in Table 1, the titanium alloy products prepared in this embodiment have a density of 4.33-4.42 g / cm3, a porosity of 0.1%-0.4%, a tensile strength of 1000-1100 MPa, a yield strength of 900-1000 MPa, an elongation of 10%-20%, and an oxygen content of 0.2%-0.4%. The product quality and performance parameters are superior to those of the titanium alloy products prepared in Comparative Examples 1-3.

[0094] Those skilled in the art should understand that the discussion of any of the above embodiments is merely exemplary and is not intended to imply that the scope of the invention (including the claims) is limited to these examples; within the framework of the invention, the technical features of the above embodiments or different embodiments can also be combined, the steps can be implemented in any order, and there are many other variations of the different aspects of the invention as described above, which are not provided in the details for the sake of brevity.

[0095] This invention is intended to cover all such substitutions, modifications, and variations that fall within the broad scope of the appended claims. Therefore, any omissions, modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this invention should be included within the scope of protection of this invention.

Claims

1. A method for preparing a high-density, high-elongation injection-molded titanium alloy, characterized in that, Includes the following steps: Step 1, Powder selection: Spherical titanium alloy powder is selected, and the particle size distribution of the spherical titanium alloy powder is: D10: 5-8μm, D50: 10-14μm, D90: 18-23μm; Step 2, Feed preparation: The titanium alloy powder and polymer binder are put into a mixing equipment for mixing, and after a certain period of time, they are extruded and granulated to obtain a uniform injection molding feed. Step 3, Injection Molding: The feed material is injected into the mold cavity through injection molding equipment to obtain a smooth injection blank; Step 4, Catalytic Degreasing: The injection preform is placed in an oxalic acid degreasing furnace to remove some of the binder from the preform, obtaining a degreased preform; Step 5, Sintering: The degreased blank is placed in a special injection molding sintering furnace for hot degreasing and sintering. By controlling the heating rate, sintering temperature and holding time, a high-density titanium alloy part with high elongation is obtained.

2. The method for preparing high-density, high-elongation injection-molded titanium alloy according to claim 1, characterized in that, The elemental composition of the titanium alloy powder, calculated by mass percentage, includes the following components: C: ≤0.1%, O: ≤0.2%, Al: 5.5-6.5%, V: 3.5-4.5%, Fe: ≤0.3%, with the remainder being Ti.

3. The method for preparing high-density, high-elongation injection-molded titanium alloy according to claim 1, characterized in that, The tap density of the titanium alloy powder is 2.5-3.0 g / cm³. 3 .

4. The method for preparing high-density, high-elongation injection-molded titanium alloy according to claim 1, characterized in that, The feed consists of the following components by weight percentage: 80%-90% titanium alloy powder and 10%-20% binder; the binder by weight percentage is: 70%-80% polyoxymethylene, 10%-20% polyethylene, 1%-5% stearic acid, 0.5%-2% antioxidant, and 1%-3% ethylene-vinyl acetate copolymer.

5. The method for preparing high-density, high-elongation injection-molded titanium alloy according to claim 1, characterized in that, The second step of feeding preparation specifically includes: placing the polymer binder and titanium alloy powder into the mixing equipment in sequence, with a temperature of 170℃-220℃, a screw speed of 10-30 r / min, and a mixing time of 30-60 min; during the granulation process, the extrusion temperature is 140-180℃, the screw speed is 10-30 r / min, and the pelletizing speed is 100-200 r / min.

6. The method for preparing high-density, high-elongation injection-molded titanium alloy according to claim 1, characterized in that, The injection molding conditions for step three are: mold temperature 120℃-140℃, injection temperature 170℃-190℃, injection pressure 220-270Mpa, and holding pressure 150~190Mpa.

7. The method for preparing high-density, high-elongation injection-molded titanium alloy according to claim 1, characterized in that, The fourth step, catalytic degreasing, involves heating to 100-120°C at a rate of 2°C / min, purging the furnace with nitrogen atmosphere for 60-120 min, then maintaining the temperature for 6-12 h in an environment where oxalic acid is involved in catalysis, and then allowing it to cool naturally.

8. The method for preparing high-density, high-elongation injection-molded titanium alloy according to claim 1, characterized in that, The fifth step of the sintering process involves heating to 600-800℃ at a rate of 5℃ / min, holding at that temperature for 2-6 hours, heating to 1000-1100℃ at a rate of 5℃ / min, holding at that temperature for 2-6 hours, and then cooling down to room temperature.

Images