CN113967746A - 3D printing method of high-corrosion-resistance high-strength low-elasticity-modulus titanium alloy powder and titanium alloy - Google Patents
3D printing method of high-corrosion-resistance high-strength low-elasticity-modulus titanium alloy powder and titanium alloy Download PDFInfo
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B22—CASTING; POWDER METALLURGY
- B22F—WORKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; MAKING METALLIC POWDER; APPARATUS OR DEVICES SPECIALLY ADAPTED FOR METALLIC POWDER
- B22F10/00—Additive manufacturing of workpieces or articles from metallic powder
- B22F10/20—Direct sintering or melting
- B22F10/28—Powder bed fusion, e.g. selective laser melting [SLM] or electron beam melting [EBM]
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B22—CASTING; POWDER METALLURGY
- B22F—WORKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; MAKING METALLIC POWDER; APPARATUS OR DEVICES SPECIALLY ADAPTED FOR METALLIC POWDER
- B22F10/00—Additive manufacturing of workpieces or articles from metallic powder
- B22F10/30—Process control
- B22F10/32—Process control of the atmosphere, e.g. composition or pressure in a building chamber
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B33—ADDITIVE MANUFACTURING TECHNOLOGY
- B33Y—ADDITIVE MANUFACTURING, i.e. MANUFACTURING OF THREE-DIMENSIONAL [3-D] OBJECTS BY ADDITIVE DEPOSITION, ADDITIVE AGGLOMERATION OR ADDITIVE LAYERING, e.g. BY 3-D PRINTING, STEREOLITHOGRAPHY OR SELECTIVE LASER SINTERING
- B33Y10/00—Processes of additive manufacturing
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B33—ADDITIVE MANUFACTURING TECHNOLOGY
- B33Y—ADDITIVE MANUFACTURING, i.e. MANUFACTURING OF THREE-DIMENSIONAL [3-D] OBJECTS BY ADDITIVE DEPOSITION, ADDITIVE AGGLOMERATION OR ADDITIVE LAYERING, e.g. BY 3-D PRINTING, STEREOLITHOGRAPHY OR SELECTIVE LASER SINTERING
- B33Y70/00—Materials specially adapted for additive manufacturing
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- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C14/00—Alloys based on titanium
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B22—CASTING; POWDER METALLURGY
- B22F—WORKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; MAKING METALLIC POWDER; APPARATUS OR DEVICES SPECIALLY ADAPTED FOR METALLIC POWDER
- B22F2201/00—Treatment under specific atmosphere
- B22F2201/10—Inert gases
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
- Y02P10/00—Technologies related to metal processing
- Y02P10/25—Process efficiency
Abstract
The invention discloses a 3D printing method of high-corrosion-resistance high-strength low-elasticity-modulus titanium alloy powder and a titanium alloy, and the method comprises the steps of selective laser melting forming; powder paving, namely placing titanium alloy powder into a powder feeding cylinder of selective laser melting equipment; leveling a base material, namely adjusting the distance between the base material on a forming cylinder and a powder spreading scraper to be 0.02-0.03 mu m, and uniformly spreading titanium alloy powder on the base material; heating the base material, namely heating the base material on the forming cylinder; inflating, closing the cabin door, and inflating inert gas; printing, namely performing 3D printing according to a set model; the titanium alloy powder is mixed powder of Ti-13Nb-13Zr alloy powder and Ta powder, and the mass fraction of the Ta powder is 2-8%. The invention solves the technical bottleneck of contradiction between high strength and low elastic modulus of biomedical materials, and the obtained alloy has high biocompatibility, high corrosion resistance, high strength, lower elastic modulus and better popularization value.
Description
Technical Field
The invention belongs to the technical field of titanium alloy materials, and particularly relates to a 3D printing method of high-corrosion-resistance high-strength low-elasticity-modulus titanium alloy powder and a titanium alloy.
Background
Titanium alloys have been widely used in the biomedical field because of their high specific strength, excellent biocompatibility and high corrosion resistance. Pure titanium and TiAl-based alloys, which are most widely used, have some problems, such as low strength and narrow service range of pure titanium components; the TiAl-based alloy has high elastic modulus, so that the biological stress is difficult to transfer to bone tissues to cause stress shielding, and meanwhile, the release of Al ions is continuously reported to cause certain influence on the health of human bodies in recent years. Therefore, the development of a titanium alloy which has high strength and low elastic modulus and does not contain any toxic element has important significance in the field of biomedicine.
The TiNb-based alloy is a novel beta-type titanium alloy, has higher biocompatibility and lower elastic modulus, and is a biomedical material with development prospect. Current research on TiNb-based alloys has focused primarily on traditional manufacturing techniques such as casting, forging, extrusion, and the like. The main challenges of the above process for forming TiNb-based alloys are: (1) component segregation exists in the forming process, so that the mechanical property of the final sample is poor; (2) the TiNb-based alloy has poor hot processing performance, and the subsequent processing process of a formed workpiece is difficult; (3) the process flow is complex, the material utilization rate is low, and the cost of a formed sample is overhigh; (4) the forming of workpieces with complex structures is difficult, and parts of the workpieces with complex structures can not be formed even by the traditional process.
However, in recent years, with the continuous update of biomedical components, more complex and high-performance titanium alloy workpieces are required to be designed in a light weight manner, and hollow parts are required to reduce weight, so that a severe test is provided for the forming process. The 3D printing technology is becoming an effective way for solving the forming problem of the biomedical titanium alloy precision complex structure lightweight component.
Therefore, the development of a titanium alloy which has high corrosion resistance, high strength and low elastic modulus and does not contain any toxic element and a 3D printing method thereof have important significance in the field of biomedicine. However, how to obtain high strength and reasonably reduce the elastic modulus of the material is a great key problem in the development of biomedical materials, and particularly, no relevant report exists on the research of high-corrosion-resistance, high-strength and low-elastic-modulus titanium alloy and 3D printing thereof.
Disclosure of Invention
This section is for the purpose of summarizing some aspects of embodiments of the invention and to briefly introduce some preferred embodiments. In this section, as well as in the abstract and the title of the invention of this application, simplifications or omissions may be made to avoid obscuring the purpose of the section, the abstract and the title, and such simplifications or omissions are not intended to limit the scope of the invention.
In view of the above and/or the deficiencies in the prior art, an object of the present invention is to provide a 3D printing method for high corrosion resistance, high strength and low elastic modulus titanium alloy powder, by which the formation of high elastic modulus phase α phase in titanium alloy can be effectively inhibited, an all β phase structure with almost low elastic modulus can be obtained, and at the same time, grains can be significantly refined, the elastic modulus of titanium alloy can be reduced while maintaining high strength, and finally, a novel non-toxic titanium alloy with strength > 1000MPa and elastic modulus < 75GPa can be obtained.
In order to solve the technical problems, the invention provides the following technical scheme: A3D printing method of high-corrosion-resistance high-strength low-elasticity-modulus titanium alloy powder comprises selective laser melting forming;
powder paving, namely placing titanium alloy powder into a powder feeding cylinder of selective laser melting equipment;
leveling a base material, namely adjusting the distance between the base material on a forming cylinder and a powder spreading scraper to be 0.02-0.03 mu m, and uniformly spreading titanium alloy powder on the base material;
heating the base material, namely heating the base material on the forming cylinder;
inflating, closing the cabin door, and inflating inert gas;
printing, namely performing 3D printing according to a set model;
the titanium alloy powder is mixed powder of Ti-13Nb-13Zr alloy powder and Ta powder, and the mass fraction of the Ta powder is 2-8%.
As a preferable scheme of the 3D printing method of the titanium alloy powder with high corrosion resistance, high strength and low elastic modulus of the invention, wherein: the preparation method of the titanium alloy powder comprises the following steps,
drying, namely respectively drying Ti-13Nb-13Zr alloy powder and metal Ta powder;
ball-milling and mixing the two kinds of dry powder according to a certain proportion;
and (4) screening, namely screening the powder after ball milling and powder mixing, and taking the screened powder.
As a preferable scheme of the 3D printing method of the titanium alloy powder with high corrosion resistance, high strength and low elastic modulus of the invention, wherein: the Ti-13Nb-13Zr alloy powder is pre-alloy powder, the medium particle size is 30-40 mu m, and the metal Ta powder is hydrogenated and dehydrogenated powder, and the particle size is 1-4 mu m.
As a preferable scheme of the 3D printing method of the titanium alloy powder with high corrosion resistance, high strength and low elastic modulus of the invention, wherein: the drying is vacuum drying oven drying, the drying temperature is 323-353K, and the drying time is 10-14 h.
As a preferable scheme of the 3D printing method of the titanium alloy powder with high corrosion resistance, high strength and low elastic modulus of the invention, wherein: the ball milling is a planetary ball mill, the ball milling atmosphere is argon protection, and the ball-to-material ratio is 1-3: 1, ball milling speed is 50-200 r/min, and ball milling time is 1-3 h.
As a preferable scheme of the 3D printing method of the titanium alloy powder with high corrosion resistance, high strength and low elastic modulus of the invention, wherein: the screenThe method comprises air-bag type air flow classification screening, wherein the material of a screen is 316L, the mesh number of the screen is 270-400 meshes, and the air flow is 800-1200 m3/h。
As a preferable scheme of the 3D printing method of the titanium alloy powder with high corrosion resistance, high strength and low elastic modulus of the invention, wherein: the base material is a Ti-6Al-4V base material, and the scraper is a high-speed steel scraper;
wherein, the base material on the forming cylinder is heated, and the heating temperature is 100 ℃.
As a preferable scheme of the 3D printing method of the titanium alloy powder with high corrosion resistance, high strength and low elastic modulus of the invention, wherein: and filling inert gas to ensure that the oxygen content in the chamber is lower than 100ppm, wherein the inert gas is argon.
As a preferable scheme of the 3D printing method of the titanium alloy powder with high corrosion resistance, high strength and low elastic modulus of the invention, wherein: the 3D printing is carried out, the laser power is 325W, the laser scanning speed is 1000mm/s, the laser scanning interval is 0.13mm, the scanning layer thickness is 0.03mm, and the scanning mode adopts a Z-shaped scanning mode which rotates 67 degrees layer by layer.
Another object of the present invention is to provide a titanium alloy obtained by the 3D printing method of the titanium alloy powder with high corrosion resistance, high strength and low elastic modulus, wherein the titanium alloy comprises Ti, Nb, Zr and Ta, and the atomic ratio of each element is as follows: ti: 64-74%, Nb: 8-13%, Zr: 8-13%, Ta: 0 to 10 percent.
Compared with the prior art, the invention has the following beneficial effects:
the metallic tantalum is added into the pre-alloyed Ti-13Nb-13Zr alloy, so that the biocompatibility and the corrosion resistance of the alloy are enhanced, meanwhile, the metallic tantalum is a beta-phase stable element with the same crystal form, the formation of a high elastic modulus alpha phase in the alloy can be inhibited, the elastic modulus of the alloy is reduced, meanwhile, the high-melting-point metallic tantalum is used as a heterogeneous nucleation point in the solidification process, the formation of fine grains can be promoted in the 3D printing process, and the high strength of the alloy is maintained.
Aiming at the problem that the high melting point difference between titanium alloy and metal tantalum cannot be formed by adopting a traditional processing mode, and serious composition segregation is easily caused to cause the alloy performance to be deteriorated, the invention provides a 3D printing technology which comprises selective laser melting and provides optimized process parameters, and the process parameters provided by the invention can realize high-density forming, have no obvious composition segregation, have the tensile strength of more than 1000MPa and have the elastic modulus of less than 75 GPa.
Drawings
In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings needed to be used in the description of the embodiments will be briefly introduced below, and it is obvious that the drawings in the following description are only some embodiments of the present invention, and it is obvious for those skilled in the art to obtain other drawings based on these drawings without inventive exercise. Wherein:
FIG. 1 is SEM pictures of Ti-13Nb-13Zr prealloyed powder, metal tantalum powder and powder of Ti-13Nb-13Zr prealloyed powder mixed with metal tantalum uniformly in accordance with the present invention;
FIG. 2 is a composition of phases with different tantalum contents after 3D printing and forming in the invention;
FIG. 3 shows a fine grain structure obtained after 3D printing and forming according to the present invention;
FIG. 4 is a stress-strain curve of the high-strength low-elasticity titanium alloy with the strength of over 1000MPa and the elastic modulus of less than 75GPa, which is obtained by 3D printing in the invention.
Detailed Description
In order to make the aforementioned objects, features and advantages of the present invention more comprehensible, specific embodiments thereof are described in detail below with reference to examples of the specification.
In the following description, numerous specific details are set forth in order to provide a thorough understanding of the present invention, but the present invention may be practiced in other ways than those specifically described and will be readily apparent to those of ordinary skill in the art without departing from the spirit of the present invention, and therefore the present invention is not limited to the specific embodiments disclosed below.
Furthermore, reference herein to "one embodiment" or "an embodiment" means that a particular feature, structure, or characteristic described in connection with the embodiment is included in at least one implementation of the invention. The appearances of the phrase "in one embodiment" in various places in the specification are not necessarily all referring to the same embodiment, nor are separate or alternative embodiments mutually exclusive of other embodiments.
Through CALPHAD calculation, the solidification interval and phase precipitation characteristics of Nb, Zr and Ta to Ti from a high-temperature solution to a solid phase are researched, a TiNb, TiZr, TiTa, TiNbZr, TiNbTa and TiZrTa multi-phase diagram is obtained, phase evolution of TiNbZrTa series alloy and phase composition after solid phase solidification under different Ta contents are researched from the phase diagram, and the optimal component ratio is obtained and is Nb: 9.32-12.13%, Zr: 8.41-10.72%, Ta: 3.15-8.17%, Ti: and (4) the balance.
Example 1
(1) Taking Ti-13Nb-13Zr prealloyed spherical powder with the medium grain size of 30 μm, as shown in figure 1(a), and hydrogenated and dehydrogenated metal tantalum powder with the grain size of 1 μm, as shown in figure 1(b), wherein the components are Ti-13Nb-13 Zr: 92% of tantalum metal, 8% of tantalum metal, and weighing the two materials by using an electronic scale;
(2) and respectively placing the two kinds of powder into a vacuum drying oven for drying at 323K for 10h, placing the two kinds of dried powder into a planetary ball mill for ball milling, wherein the ball milling atmosphere is argon, and the ball-to-material ratio is 1: 3, the ball milling time is 3 hours, and the ball milling speed is 100 r/min;
(3) drying the ball-milled powder in a vacuum drying oven again at 323K for 10h, screening the dried powder by using a wind bag type airflow classifying screen machine, wherein the material of the screen is 316L, the mesh number of the screen is 270 meshes, and the airflow is 1000m3And h, obtaining the mixed powder of the Ti-13Nb-13Zr alloy and the metal tantalum with uniform grain diameter, as shown in the figure 1 (c).
(4) Adjusting BLT-S210 equipment, pouring mixed powder into a powder feeding cylinder of the equipment, installing a forming cylinder Ti-6Al-V base material, adjusting the height of the base material to enable the distance between the base material and a high-speed steel scraper to be 0.02-0.03 mu m, starting to heat the base material after the adjustment is finished, heating the base material to 373K, starting to pre-spread the powder to enable the powder to be uniformly spread on the base material, then closing a cabin door, and starting to flush argon gas to enable the oxygen content in the equipment to be lower than 100 ppm.
(5)3D printing, forming according to a set three-dimensional model, wherein the forming process parameters are as follows: the laser power is 325W, the laser scanning speed is 1000mm/s, the laser scanning interval is about 0.13mm, the scanning layer thickness is about 0.03mm, and the scanning mode adopts a zigzag scanning mode of rotating 67 degrees layer by layer to obtain the 3D printed titanium alloy.
The titanium alloy obtained by the 3D printing and forming process has high compactness and no obvious defects, and the alloy has high corrosion resistance, high strength and low elastic modulus, wherein the strength is more than 1000MPa, and the elastic modulus is lower than 75GPa, as shown in figure 4.
EPMA analysis of the formed sample revealed that the titanium alloy obtained had the following composition: 67.92% of Ti, 11.94% of Nb, 11.93% of Zr, 7.92% of Ta and 0.29% of O.
In the method, the addition of the metal tantalum obviously improves the biocompatibility of the alloy and the corrosion resistance of the alloy, and the metal tantalum is used as a beta-phase stable element of the same crystal form, inhibits the formation of an alpha phase and improves the content of a low elastic modulus beta phase, as shown in figure 2(8Ta), so that the alloy has a lower elastic modulus and reduces the stress shielding effect. Meanwhile, due to the addition of the metal tantalum, the metal tantalum is used as a heterogeneous nucleation point in the material, the nucleation rate of the alloy is increased, the grain size is reduced, the obtained grains are fine, and the average grain size is 0.071 mu m measured by ImageJ, as shown in figures 3(d) and (d'), so that the alloy has higher strength.
Example 2
This example 2 differs from example 1 in the content of Ti-13Nb-13Zr prealloy and the content of the hydrogenated dehydrogenated metallic tantalum powder: in this example, Ti-13Nb-13 Zr: 94%, metallic tantalum: 6 percent. EPMA analysis of the formed sample revealed that the obtained titanium alloy had a composition of 69.48% Ti, 12.19% Nb, 12.17% Zr, 5.91% Ta and 0.25% O.
Compared with example 1, the content of metallic tantalum is slightly reduced, the content of beta-phase stabilizing elements is reduced, the content of low-elastic-modulus beta-phase is reduced, and the phase composition after 3D printing is shown in figure 2(6 Ta). Meanwhile, the metallic tantalum content was decreased, the heterogeneous nucleation point was decreased, and the alloy nucleation rate was decreased, and thus, the crystal grains were increased as compared with those obtained in example 1, and the average grain size was 0.112 μm as measured by ImageJ, as shown in fig. 3(c) and (c'). The alloy finally obtained has strength of 960MPa and elastic modulus of 78 GPa.
Example 3
This example 3 differs from example 1 in the content of Ti-13Nb-13Zr prealloy and the content of the hydrogenated dehydrogenated metallic tantalum powder: in this example, Ti-13Nb-13 Zr: 96%, metallic tantalum: 4 percent. EPMA analysis of the formed sample revealed that the obtained titanium alloy had a composition of 70.97% Ti, 12.45% Nb, 12.43% Zr, 3.93% Ta and 0.22% O.
Compared with examples 1 and 2, the content of the metallic tantalum is continuously reduced, the content of the beta-phase stabilizing element is reduced, the content of the low-elasticity-modulus beta-phase is reduced, and the phase composition after 3D printing is shown in figure 2(4 Ta). The metallic tantalum content was further reduced, the heterogeneous nucleation point was further reduced, and the alloy nucleation rate was further reduced, compared to examples 1 and 2, and thus, the crystal grains were increased, compared to those obtained in examples 1 and 2, and the average grain size was 0.134 μm as measured by ImageJ, as shown in fig. 3(b) and (b'). The alloy finally obtained has the strength of 900MPa and the elastic modulus of 82 GPa.
Example 4
This example 4 differs from example 1 in the content of Ti-13Nb-13Zr prealloy and the content of the hydrogenated dehydrogenated metallic tantalum powder: in this example, Ti-13Nb-13 Zr: 98%, metallic tantalum: 2 percent. EPMA analysis of the formed sample revealed that the obtained titanium alloy had Ti 72.45%, Nb 12.68%, Zr 12.66%, Ta 1.99%, and O0.22%.
Compared with examples 1, 2 and 3, the content of the metallic tantalum is continuously reduced, the content of the beta-phase stabilizing element is reduced, the content of the low-elasticity-modulus beta-phase is reduced, and the phase composition after 3D printing is shown in figure 2(2 Ta). The metallic tantalum content was further reduced, the heterogeneous nucleation point was further reduced, and the alloy nucleation rate was further reduced, compared to examples 1, 2 and 3, and thus, the crystal grains were increased, compared to those obtained in examples 1, 2 and 3, and the average grain size was 0.185 μm as measured by ImageJ, as shown in fig. 3(a) and (a'). The alloy finally obtained had a strength of 870MPa and an elastic modulus of 87 GPa.
Example 5
This example 5 differs from example 1 in the content of Ti-13Nb-13Zr prealloy and the content of the hydrogenated dehydrogenated metallic tantalum powder: in this example, Ti-13Nb-13 Zr: 90%, metallic tantalum: 10 percent. EPMA analysis of the formed sample revealed that the obtained titanium alloy had a composition of 66.47% Ti, 11.51% Nb, 11.48% Zr, 9.87% Ta and 0.64% O.
In comparison with example 1, the increase in metallic tantalum content beyond the highest boundary value of metallic tantalum calculated for CALPHAD is likely to cause a hard brittle phase w in the formed alloy, resulting in a sharp increase in the elastic modulus of the alloy. The alloy finally obtained has the strength of 1180MPa and the elastic modulus of 100 GPa.
Example 6
This example 6 differs from example 1 in the content of Ti-13Nb-13Zr prealloy and the content of the hydrogenated dehydrogenated metallic tantalum powder: in this example, Ti-13Nb-13 Zr: 100%, metallic tantalum: 0 percent. EPMA analysis of the formed sample revealed that the obtained titanium alloy had a composition of 73.93% Ti, 12.95% Nb, 12.92% Zr and 0.20% O.
Compared with the examples 1 to 4, the alloy in the embodiment has no metal tantalum added, no beta phase stabilizing element, low elastic modulus beta phase content reduced, and high elastic modulus alpha martensite content remarkably improved, and the composition of the phase after 3D printing and forming is as shown in figure 2(Ti-3Nb-13Zr), compared with the examples 1 to 4, the alloy nucleation rate is further reduced, and the crystal grain is obviously increased, but due to the precipitation of the high strength alpha martensite phase, the finally obtained alloy strength is 1100MPa, and the elastic modulus is increased to more than 100 GPa.
The 3D printed titanium alloys obtained in examples 1-6 were tested for biocompatibility and corrosion resistance. Biocompatibility test method: growing and proliferating cells on the surface of the alloy material, and carrying out cell statistics after a certain time; the corrosion resistance test method comprises the following steps: electrochemical corrosion-voltammetry curve. The results are shown in Table 1.
TABLE 1
As can be seen from the data in Table 1, the titanium alloy prepared in the embodiments 1-5 has better biocompatibility and corrosion resistance; the biocompatibility and corrosion resistance of the titanium alloy prepared in example 6 are obviously reduced.
Meanwhile, the corrosion resistance and the biocompatibility of the alloy are gradually enhanced along with the increase of the content of the metal tantalum, so that the corrosion resistance and the biocompatibility of the alloy can be improved while the high strength and the low elastic modulus of the alloy can be realized by reasonably increasing the content of the metal tantalum within the boundary condition range of the metal tantalum.
Example 7
The present embodiment 7 differs from embodiment 1 in the process conditions for 3D printing: no substrate heat treatment was performed during the BLT-S210 equipment adjustment. Compared with example 1, the substrate of the present example is not heated, the cooling rate is further increased, the hard brittle phase w phase is formed in the alloy, the strength (1000-1100MPa) and the elastic modulus (more than 110GPa) of the alloy are obviously improved, the elongation is obviously reduced (less than 2%), and the alloy has almost no processability.
Example 8
The present embodiment 8 is different from embodiment 1 in the process conditions of 3D printing: in the 3D printing process, the forming process parameters are as follows: the laser power is 275W, the laser scanning speed is 1200mm/s, the laser scanning interval is about 0.13mm, the scanning layer thickness is about 0.03mm, and the scanning mode adopts a zigzag scanning mode of rotating by 67 degrees layer by layer. EPMA analysis shows that the incomplete melting of the niobium element and the tantalum element in the obtained alloy is obvious, the segregation of alloy components is serious, and the finally obtained titanium alloy has the properties that the strength is less than 500MPa and the elongation is less than 3%.
Compared with embodiment 1, the laser power is reduced, the laser scanning speed is increased, the laser energy density is reduced, the alloy strength is obviously reduced, and the service environment of the alloy is limited.
Example 9
The present embodiment 9 is different from embodiment 1 in the process conditions of 3D printing: in the 3D printing process, the forming process parameters are as follows: the laser power is 400W, the laser scanning speed is 1200mm/s, the laser scanning interval is about 0.13mm, the scanning layer thickness is about 0.03mm, and the scanning mode adopts a zigzag scanning mode of rotating 67 degrees layer by layer. EPMA analysis of the formed sample shows that the obtained alloy has a titanium element content reduced by about 5% compared with the preset content, a zirconium element content reduced by about 3% compared with the preset content, and the finally obtained titanium alloy has the properties of strength less than 650MPa and elongation less than 4%.
Compared with the embodiment 1, the laser power is higher, the laser energy density is increased, the over-burning phenomenon, the keyhole and other metallurgical defects appear in a molten pool, the density of the formed alloy is reduced, the alloy strength and the elongation are reduced, and meanwhile, the element is easily gasified and deviates from the preset alloy composition due to the increase of the laser energy density.
Comparative example 1
The difference between the comparative example 1 and the example 1 is that according to the proportion of 68.08% of Ti, 11.96% of Nb, 11.96% of Zr and 8% of Ta, gas atomized spherical pure Ti, Nb and Zr metal powder and hydrogenated dehydrogenated Ta metal powder are respectively adopted for ball milling and powder mixing, the hardness of the pure Ti powder is low, the damage to the sphericity in the ball milling process is serious, meanwhile, four kinds of powder are ball milled, a large amount of powder is still single powder particles, the mixing is not uniform, and the 3D printing technological parameters which are the same as those of the example 1 are adopted for printing and forming. EPMA analysis is carried out on the formed sample, and the result shows that the obtained titanium alloy has serious component segregation, the finally obtained titanium alloy has the performance that the strength is less than 700MPa, and the elongation is less than 5%. Meanwhile, as the melting points of pure titanium, pure zirconium, pure niobium and pure tantalum are greatly different, pure metal powder is adopted for mixing, the 3D printing forming process parameters are difficult to regulate, and the forming process is easy to cause the gasification of low-melting-point elements, so that the formed alloy deviates from the preset alloy components.
Comparative example 2
The difference between this comparative example 2 and example 1 is that a spherical tibb pre-alloy, spherical pure Zr and hydrogenated dehydrogenated polygonal pure Ta powder were ball milled and mixed in the proportions of 68.08% Ti, 11.96% Nb, 11.96% Zr, and 8% Ta, and the resulting powder was printed and formed using the same 3D printing process parameters as in example 1. The high melting point difference between zirconium and tantalum is liable to cause incomplete melting of tantalum or gasification of zirconium. EPMA analysis is carried out on the formed sample, and the result shows that the obtained titanium alloy has serious component segregation, the finally obtained titanium alloy has the performance that the strength is less than 730MPa, and the elongation is less than 5%.
Comparative example 3
The difference between the comparative example 3 and the example 1 is that prealloy powder is prepared by plasma atomization according to the proportion of 68.08% of Ti, 11.96% of Nb, 11.96% of Zr and 8% of Ta, the 3D printing process parameters same as those of the example 1 are adopted for printing and forming, the forming effect is good, the elastic modulus of the alloy is less than 75GPa, but the alloy strength is not high, and the finally obtained alloy strength is less than 800 MPa. This is due to the lack of heterogeneous nucleation sites during solidification, the resulting alloy grains being coarser compared to example 1, the lack of fine grain strengthening and dispersion strengthening, resulting in lower alloy strength.
Aiming at the problem that the high melting point difference between titanium alloy and metal tantalum cannot be formed by adopting a traditional processing mode, and serious composition segregation is easily caused to cause the alloy performance to be deteriorated, the invention provides a 3D printing technology which comprises selective laser melting and provides optimized process parameters, and the process parameters provided by the invention can realize high-density forming, have no obvious composition segregation, have the tensile strength of more than 1000MPa and have the elastic modulus of less than 75 GPa.
The metallic tantalum is added into the pre-alloyed Ti-13Nb-13Zr alloy, so that the biocompatibility and the corrosion resistance of the alloy are enhanced, meanwhile, the metallic tantalum is a beta-phase stable element with the same crystal form, the formation of a high elastic modulus alpha phase in the alloy can be inhibited, the elastic modulus of the alloy is reduced, meanwhile, the high-melting-point metallic tantalum is used as a heterogeneous nucleation point in the solidification process, the formation of fine grains can be promoted in the 3D printing process, and the high strength of the alloy is maintained.
It should be noted that the above-mentioned embodiments are only for illustrating the technical solutions of the present invention and not for limiting, and although the present invention has been described in detail with reference to the preferred embodiments, it should be understood by those skilled in the art that modifications or equivalent substitutions may be made on the technical solutions of the present invention without departing from the spirit and scope of the technical solutions of the present invention, which should be covered by the claims of the present invention.
Claims (10)
1. A3D printing method of high-corrosion-resistance high-strength low-elasticity-modulus titanium alloy powder is characterized by comprising the following steps of: comprises selective laser melting forming;
powder paving, namely placing titanium alloy powder into a powder feeding cylinder of selective laser melting equipment;
leveling a base material, namely adjusting the distance between the base material on a forming cylinder and a powder spreading scraper to be 0.02-0.03 mu m, and uniformly spreading titanium alloy powder on the base material;
heating the base material, namely heating the base material on the forming cylinder;
inflating, closing the cabin door, and inflating inert gas;
printing, namely performing 3D printing according to a set model;
the titanium alloy powder is mixed powder of Ti-13Nb-13Zr alloy powder and Ta powder, and the mass fraction of the Ta powder is 2-8%.
2. The 3D printing method of high corrosion resistance, high strength, low elastic modulus titanium alloy powder according to claim 1, wherein: the preparation method of the titanium alloy powder comprises the following steps,
drying, namely respectively drying Ti-13Nb-13Zr alloy powder and metal Ta powder;
ball-milling and mixing the two kinds of dry powder according to a certain proportion;
and (4) screening, namely screening the powder after ball milling and powder mixing, and taking the screened powder.
3. The 3D printing method of high corrosion resistance, high strength, low elastic modulus titanium alloy powder according to claim 1, wherein: the Ti-13Nb-13Zr alloy powder is pre-alloy powder, the medium particle size is 30-40 mu m, and the metal Ta powder is hydrogenated and dehydrogenated powder, and the particle size is 1-4 mu m.
4. The 3D printing method of high corrosion resistance, high strength, low elastic modulus titanium alloy powder according to claim 1, wherein: the drying is vacuum drying oven drying, the drying temperature is 323-353K, and the drying time is 10-14 h.
5. The 3D printing method of high corrosion resistance, high strength, low elastic modulus titanium alloy powder according to claim 1, wherein: the ball milling is a planetary ball mill, the ball milling atmosphere is argon protection, and the ball-to-material ratio is 1-3: 1, ball milling speed is 50-200 r/min, and ball milling time is 1-3 h.
6. The 3D printing method of high corrosion resistance, high strength, low elastic modulus titanium alloy powder according to claim 1, wherein: the screening is air-bag type air flow grading screening, the material of the screen is 316L, the mesh number of the screen is 270-400 meshes, and the air flow is 800-1200 m3/h。
7. 3D printing method of high corrosion resistance high strength low elastic modulus titanium alloy powder according to claim 1 or 2 characterized by: the base material is a Ti-6Al-4V base material, and the scraper is a high-speed steel scraper;
wherein, the base material on the forming cylinder is heated, and the heating temperature is 100 ℃.
8. The 3D printing method of high corrosion resistance, high strength, low elastic modulus titanium alloy powder according to claim 3 or 4, characterized by: and filling inert gas to ensure that the oxygen content in the chamber is lower than 100ppm, wherein the inert gas is argon.
9. The 3D printing method of high corrosion resistance, high strength and low elastic modulus titanium alloy powder according to any one of claims 1 to 5, wherein: the 3D printing is carried out, the laser power is 325W, the laser scanning speed is 1000mm/s, the laser scanning interval is 0.13mm, the scanning layer thickness is 0.03mm, and the scanning mode adopts a Z-shaped scanning mode which rotates 67 degrees layer by layer.
10. The titanium alloy obtained by the 3D printing method of the high-corrosion-resistance high-strength low-elastic-modulus titanium alloy powder according to any one of claims 1 to 6, wherein the titanium alloy is prepared by the following steps: the titanium alloy comprises Ti, Nb, Zr and Ta, wherein the atomic ratio of each element is as follows: ti: 64-74%, Nb: 8-13%, Zr: 8-13%, Ta: 0 to 10 percent.
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