CN114836650B - Titanium alloy with complete equiaxed crystal structure and ultrahigh yield strength - Google Patents
Titanium alloy with complete equiaxed crystal structure and ultrahigh yield strength Download PDFInfo
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Abstract
The invention discloses a titanium alloy with a complete equiaxed crystal structure and ultrahigh yield strength, wherein the Md value of the titanium alloy is 2.35-2.37, and the Bo value is 2.77-2.79; the titanium alloy comprises the following components: 1-3wt% Mo,2.5-4.5wt% Co,2.5-4.5wt% Fe, the balance Ti and unavoidable impurities; the structure of the titanium alloy is an equiaxed crystal structure, and the yield strength is greater than 1100MPa. According to the invention, by combining the alloy component design with the preparation method of additive manufacturing, solid solution treatment and water quenching, a completely fine equiaxial crystal structure is obtained, the titanium alloy manufactured by additive manufacturing is prevented from forming mechanical property anisotropy, and meanwhile, the microstructure and component distribution characteristics of the alloy ensure that the alloy has high beta stability, dislocation slip deformation is promoted, and effective precipitation strengthening, solid solution strengthening and grain boundary strengthening are promoted to obtain the material, so that the alloy has ultrahigh yield strength and good plasticity.
Description
Technical Field
The invention relates to the technical field of titanium alloy materials, in particular to a metastable beta titanium alloy with complete equiaxed crystal structure, ultrahigh yield strength and high plasticity, which is expected to be applied to key parts with light weight, high specific strength and corrosion resistance in the fields of aviation, aerospace, biomedical, national defense, military industry and the like.
Background
Metastable beta titanium alloys are of great interest because of their high tensile strength, high plasticity, excellent corrosion resistance, low density, low modulus of elasticity, and good biocompatibility. Metastable beta titanium alloys developed in recent years, such as Ti-12Mo and Ti-9Mo-6W, exhibit high tensile strength, high strain hardening rates (up to 2 GPa), and excellent plasticity (elongation up to 35%). Such alloys primarily take stress-induced martensitic Transformation (TRIP) and mechanical twinning deformation (TWIP) as the primary plastic deformation mechanisms, where the β → α "deformation-induced martensitic transformation occurs in the stress range of 190-360MPa depending on the strain rate, which results in such titanium alloys exhibiting very low yield strengths (< 500 MPa), limiting their applications. Recently, a plurality of metastable beta titanium alloys which take twinning deformation as a main deformation mechanism are designed and developed by using a d-electron alloy design method, wherein the metastable beta titanium alloys comprise Ti-10Cr, ti-15Mo, ti-10Mo-1Fe, ti-7Mo-3Cr, ti-13Mo-18Zr, ti-6Cr-4Mo-2Al-2Sn-1Zr and the like, and the metastable beta titanium alloys show higher yield strength (up to 870 MPa). In addition, metastable beta titanium alloys, which individually have dislocation glide as the main deformation mechanism, such as Ti-7Mo-3Cr-1Fe and Ti-6Mo-5.5Cr-1Co-0.1C, have been developed, and the yield strength of these metastable beta titanium alloys exceeds 1GPa. Basically, with the improvement of the beta stability, the main deformation mechanism of the metastable beta titanium alloy is changed from stress induced martensite phase transformation to mechanical twinning deformation, and then the alloy slips in place, so that the yield strength of the alloy is improved. In general, the metastable beta titanium alloy with high yield strength is still too few to be further explored and developed so as to widen the application prospect of the material as a structural material.
In addition, it is worth noting that the development of the current metastable beta titanium alloy is based on the traditional manufacturing process such as alloy smelting, casting, forging or rolling, solution treatment and water quenching. The preparation process has the advantages of multiple working procedures, complex flow and long period for determining each process parameter, and the development of the novel metastable beta titanium alloy by using the process has the advantages of long development period, high cost, large energy consumption and serious pollution, and is difficult to quickly discover and develop the novel high-performance metastable beta titanium alloy. Moreover, even if a great deal of process optimization is carried out by using the traditional process method, the obtained grain size is usually large (ranging from dozens of micrometers to hundreds of micrometers), which is not beneficial to further improving the yield strength of the alloy. Laser additive manufacturing, and in particular selective laser melting, is a near-net-shape forming technique based on a tiny molten pool (several hundred microns in size), and due to extremely fast solidification and cooling rates, the width of the formed grains is usually several microns to tens of microns, which is an order of magnitude smaller than the grain size of metastable beta titanium alloy prepared by traditional methods. Also, many metallic materials produced by selective laser melting (including metastable beta titanium alloys) can also form nano-or sub-micron scale cellular structures due to extremely fast solidification and cooling rates. The cell boundaries of the cellular structure are often enriched with a large number of dislocations and some solute elements, and during the deformation process, the cell boundaries can effectively block the movement of the dislocations, but do not completely prevent the penetration of the dislocations, so that the material is facilitated to obtain high plasticity while obtaining high strength. Because of the relatively fine microstructure, the metastable beta titanium alloy of selective laser melting generally has higher yield strength. These unique process features allow selective laser melting to exhibit great potential and advantages in developing new high performance titanium alloys. However, it is worth mentioning that a very large thermal gradient usually exists in a tiny molten pool formed by melting the titanium alloy by the laser in the selected area, which results in the formation of columnar crystals and strong texture, resulting in anisotropy of mechanical properties, and limiting the popularization and application of the technology. In addition to process considerations, most titanium alloys are currently designed and developed based on conventional manufacturing processes, which also makes these alloys susceptible to columnar grain formation during laser additive manufacturing. For example, most of the commonly used alloying elements of the titanium alloy at present comprise Al, V, mo, cr, nb, sn and the like which have small grain growth restriction factors, which are not beneficial to the rapid formation of high-component supercooling degree at the solidification solid-liquid front edge of the alloy to promote nucleation and are not beneficial to the transformation of columnar crystal to isometric crystal. Therefore, there is a great need to develop the design and development of new high-performance metastable beta titanium alloy based on selective laser melting. The metastable beta-titanium alloy which not only can form a complete equiaxial crystal structure in the laser additive manufacturing process, but also has high yield strength and high plasticity is obtained through the advanced alloy component design.
In summary, the metastable beta titanium alloy, which uses stress-induced martensitic Transformation (TRIP) and mechanical twinning deformation (TWIP) as the main plastic deformation mechanisms, generally has low yield strength because the beta → alpha ″ deformation-induced martensitic transformation occurs in a low stress range. The metastable beta titanium alloy taking twin deformation as a main deformation mechanism has higher yield strength, but is usually lower than 900MPa, and is not enough to be used as a high-strength structural material for large-scale popularization and application. The recently developed metastable beta titanium alloys, such as Ti-7Mo-3Cr-1Fe and Ti-6Mo-5.5Cr-1Co-0.1C, which individually take dislocation glide as the main deformation mechanism, show yield strength higher than 1GPa, and show a certain application prospect, but the alloys are relatively few in total. Laser additive manufacturing, especially selective laser melting can form a microstructure which is finer than that of the traditional process due to extremely high solidification and cooling rates, is expected to further improve the mechanical property of the titanium alloy, and provides a brand new path for the research and development of novel high-strength metastable beta titanium alloy. However, a steep thermal gradient usually exists in a small molten pool formed by melting titanium alloy by selective laser, which causes formation of columnar crystals and strong texture, resulting in anisotropy of mechanical properties, and limits popularization and application of the technology. Moreover, most of the titanium alloys are developed based on the traditional manufacturing process design, wherein the used alloy elements such as Al, V, mo, cr, nb, sn and the like have small grain growth restriction factors, which are not beneficial to the rapid formation of high-component supercooling degree at the solidification solid-liquid front edge of the alloy to promote nucleation and forming of isometric crystal structures. Therefore, there is a great need to develop the design and development of new high performance metastable beta titanium alloy based on selective laser melting. The metastable beta titanium alloy which not only can form a complete equiaxial crystal structure in the laser additive manufacturing process, but also has high yield strength and high plasticity is obtained through advanced alloy component design.
Disclosure of Invention
Aiming at the problem that the yield strength of the conventional metastable beta titanium alloy is generally low, the invention aims to improve the yield strength of the metastable beta titanium alloy through advanced alloy component design, develop a novel metastable beta titanium alloy with ultrahigh yield strength and good plasticity and promote the metastable beta titanium alloy to be widely popularized and applied in the fields of aerospace, biomedicine, national defense war industry and the like as a light high-strength structural material.
The invention also aims to solve the problem that the titanium alloy obtains a complete and fine isometric crystal structure by further combining advanced alloy component design with selective laser melting, so that the titanium alloy manufactured by additive manufacturing is prevented from forming anisotropy of mechanical properties.
The invention also aims to solve the problems that the research and development speed of the novel high-performance metastable beta titanium alloy is accelerated by utilizing the selective laser melting technology, the research and development period is shortened, the research and development efficiency is improved, the research and development cost is saved, and the defects of the traditional metastable beta titanium alloy research and development process approach are overcome.
Titanium alloy with complete equiaxed grain structure and ultrahigh yield strength
The value is 2.35 to 2.37,
a value of 2.77-2.79; the titanium alloy comprises the following components: 1-3wt% Mo,2.5-4.5wt% Co,2.5-4.5wt% Fe, the balance Ti and unavoidable impurities; the structure of the titanium alloy is an equiaxed crystal structure, and the yield strength is greater than 1100MPa.
Preferably, the titanium alloy comprises the following components: 2wt% Mo,3.6wt% Co,3.4wt% Fe, the balance being Ti and unavoidable impurities.
Preferably, the titanium alloy is prepared by smelting, casting, forging or rolling, the equiaxed crystal grain size range of the titanium alloy is 10-150 mu m, and the yield strength is more than 1100MPa.
Preferably, the titanium alloy is prepared by additive manufacturing, the equiaxed crystal grain size of the titanium alloy ranges from 1 to 70 microns, and the yield strength is greater than 1200MPa.
A preparation method of the titanium alloy with the complete equiaxed crystal structure and the ultrahigh yield strength comprises the following steps:
(1) Preparing a block sample by carrying out raw material proportioning according to alloy components and carrying out smelting, casting, forging or rolling;
(2) And carrying out solid solution heat treatment and water quenching on the massive sample.
A preparation method of the titanium alloy with the complete equiaxed crystal structure and the ultrahigh yield strength comprises the following steps:
(1) Mixing spherical pure Ti powder, pure Fe powder and pure Co powder by using a three-dimensional swinging powder mixer to obtain mixed powder;
(2) Adding high-melting-point pure Mo powder particles into the mixed powder, and performing ball milling by using a horizontal high-energy ball mill;
(3) Melting and sampling the mixed powder after ball milling by using any one of selective laser melting, selective electron beam melting and laser direct deposition to obtain a block sample;
(4) And carrying out solid solution heat treatment and water quenching on the massive sample.
Preferably, in the step (1), the particle sizes of the spherical pure Ti powder, the pure Fe powder and the pure Co powder are 15-53 microns, and the technological parameters of the powder mixing are as follows: mixing for 6 hours at the rotating speed of 28 rpm; in the step (2), the grain diameter of the high-melting-point pure Mo powder is 1-3 microns, and the technological parameters of ball milling are as follows: and (3) carrying out ball milling and mixing for 20 minutes under the conditions of a ball powder ratio of 4.
A preparation method of the titanium alloy with the complete equiaxed crystal structure and the ultrahigh yield strength comprises the following steps:
(1) Proportioning raw materials according to alloy components, preparing a pre-alloyed bar through smelting and casting, and preparing pre-alloyed powder by using any one of an inert gas atomization method, a plasma atomization method or a rotary electrode powder preparation method;
(2) Melting and sampling the mixed powder after ball milling by using any one of selective laser melting, selective electron beam melting and laser direct deposition to obtain a block sample;
(3) And carrying out solid solution heat treatment and water quenching on the massive sample.
A preparation method of the titanium alloy with the complete equiaxed crystal structure and the ultrahigh yield strength comprises the following steps:
(1) The preparation method comprises the following steps of (1) carrying out raw material proportioning according to alloy components, preparing a pre-alloyed bar through smelting and casting, and preparing the alloyed bar into a metal wire;
(2) Melting and sampling the wire material by using laser direct deposition equipment to obtain a block sample;
(3) And carrying out solid solution heat treatment and water quenching on the massive sample.
Preferably, the process parameters of the solution heat treatment are as follows: the heating rate is 5-15 ℃/min, the solid solution temperature is 750-850 ℃, and the solid solution heat preservation time is 30-120 min.
Preferably, the water quenching process parameters are as follows: immediately putting the solution into clear water or saline water for cooling until the temperature reaches room temperature, wherein the quenching cooling rate is 500-800 ℃/s.
Compared with the prior art, the invention has the following beneficial effects:
aiming at the problems that the yield strength of the metastable beta titanium alloy is low and the columnar crystal structure is easy to form after additive manufacturing to cause anisotropy of mechanical properties, the invention provides an integrated design approach for developing the metastable beta titanium alloy with complete equiaxial crystal structure and ultrahigh yield strength based on additive manufacturing based on theoretical models such as a component supercooling solidification theory, a d-electron theory, a thermodynamic phase diagram and the like. The metastable beta titanium alloy with complete fine equiaxed crystal structure and ultrahigh yield strength is prepared by additive manufacturing, solid solution and quenching treatment, the yield strength reaches over 1200MPa, the yield strength is improved by 400-700MPa compared with that of most of the current metastable beta titanium alloys, and the application prospect of the metastable beta titanium alloy as a high-performance structural material is greatly widened. The formed complete fine equiaxed crystal structure (the grain size range is 1-70 microns, more than 80 percent of the grain size is less than 30 microns) ensures that the titanium alloy manufactured by the additive has isotropic performance, and overcomes the bottleneck problem that the titanium alloy manufactured by the additive is easy to form columnar crystals and causes anisotropic mechanical property for a long time. After solution heat treatment and water quenching treatment, a high-density dispersion distribution omega phase (about 2 nm) is formed in the alloy, dispersion distribution nano-scale Mo atom agglomeration exists in the alloy (as shown in figure 3 d), and Co and Fe atoms are completely dissolved in a beta matrix. The microstructure and the component distribution characteristics not only ensure that the alloy has high beta stability, prevent the beta → alpha' martensite phase transformation in the deformation process, promote the dislocation sliding deformation, but also promote the material to obtain effective precipitation strengthening, solid solution strengthening, grain boundary strengthening and the like, thereby leading the alloy to have ultrahigh yield strength and good plasticity.
Meanwhile, the high-performance metastable beta titanium alloy can be efficiently prepared by using an extremely simple additive manufacturing, solid solution and quenching way, compared with the traditional preparation process, the research and development and preparation period of the alloy are greatly shortened, and the preparation process is greatly simplified. In addition, the invention successfully adds a large amount of Co and Fe elements into the titanium and ensures that the Co and Fe elements are uniformly distributed on an alloy matrix by utilizing the characteristics of a micro molten pool and ultra-fast cooling speed of laser/electron beam additive manufacturing, and does not form serious Co/Fe segregation and thick beta' or beta plaques as in the traditional casting process, so that the solute elements of the titanium alloy are diversified. In addition, the powder mixing technology combining the three-dimensional swing powder mixer and the horizontal ball mill is utilized, simple substance powder with different particle sizes and densities can be rapidly mixed according to needs and proportions, uniform distribution of various kinds of powder is guaranteed, tiny particles are guaranteed to be uniformly assembled on the surface of large particles, and the total amount of powder required for preparing a block sample is small (less than or equal to 4 kilograms). Therefore, the material consumption of the novel high-performance metastable beta titanium alloy in the development process can be greatly saved, and the development cost of the novel alloy is saved. The development and preparation route is environment-friendly because the laser/electron beam additive manufacturing process does not generate any carbon dioxide and other harmful gases, and a large number of thermal mechanical processing and machining procedures are not needed subsequently.
Drawings
FIG. 1 is a scanning electron microscope micrograph showing the morphology and distribution of powder particles (a) after mixing Ti, fe and Co powders with particle sizes of 15-53 μm for 6 hours by using a three-dimensional swinging powder mixing device and mixing Mo particles with low particle sizes (1-3 μm) and high melting point for 20 minutes by using a horizontal ball mill; (b) Mo particles are uniformly distributed and assembled on the surface of the large particles; (c) An energy scattering X-ray spectrogram (EDS) shows that Fe and Co powder are uniformly dispersed among titanium powder particles, and Mo particles are uniformly distributed in large particles;
FIG. 2 is a selected area laser melting optical micrograph of a novel metastable beta titanium alloy grain structure and a back-scattered electron diffraction inverse polarization map beta grain reconstruction map;
FIG. 3 illustrates the composition and matrix composition distribution of a novel metastable beta titanium alloy phase for selective laser melting and solution treatment;
FIG. 4 is a plot of tensile engineering stress-strain curves for a selected-zone laser melting and solution treatment of a novel metastable beta titanium alloy;
FIG. 5 is a transmission electron microscope image of a novel metastable beta titanium alloy fine sliding band and dislocation structure by selective laser melting and solution treatment.
Detailed Description
Aiming at the problems that the yield strength of the metastable beta titanium alloy is low and the columnar crystal structure is easy to form after laser additive manufacturing, so that the mechanical property is anisotropic, the invention provides an integrated design approach for developing a novel metastable beta titanium alloy which has high strength and high plasticity and complete equiaxial crystal structure and is manufactured based on laser additive manufacturing on the basis of a plurality of theoretical models such as a component supercooling solidification theory, a d-electron theory, a thermodynamic phase diagram and the like. Firstly, according to the principle of component supercooling, elements with high growth restriction factors and beta-phase stability such as Fe and Co are selected as main alloy elements of titanium, and high beta stability of the alloy is ensured while promoting solid-liquid front component supercooling degree and isometric crystal structure formation in the additive manufacturing process. According to the definition of molybdenum equivalent (MoE =1.0 (Mo) +0.67 (V) +0.44 (W) +0.28 (Nb) +0.22 (Ta) +2.9 (Fe) +1.6 (Cr) +1.25 (Ni) +1.70 (Mn) +1.70 (Co) -1.0 (Al), wt%), it can be seen that the molybdenum equivalents of Fe and Co are also the highest among the numerous alloying elements, thus being effective in ensuring high β stability of the alloy. According to Ti-Fe and Ti-Co phase diagrams, eutectic reaction platforms exist in Ti-Fe/Co, so that the content of Fe and Co needs to be controlled to avoid forming eutectic structures in the solidification process to cause alloy embrittlement. The specific selection of the contents of the alloying elements is based on the d-electron theory
And selecting components which can avoid the beta → alpha' martensite phase transformation region and are positioned at a sliding/twin junction or a pure twin deformation region to ensure that the deformation mechanism of the developed metastable beta titanium alloy is mainly based on sliding or twin so as to obtain high yield strength and good plasticity. Based on the integrated design method, elements capable of meeting the above conditions are obtainedMo in the elemental composition interval, i.e., 1-3wt%, co in the amount of 2.5-4.5wt%, fe in the amount of 2.5-4.5wt%, and Ti and unavoidable impurities as the balance. The titanium alloy has the molybdenum equivalent of 16-20 and has higher beta stability.
The value is 2.35 to 2.37,
a value of 2.77 to 2.79 in
Slip/twin junctions are shown.
Preferably, one of the typical component formulations, ti-3.4Fe-3.6Co-2Mo (wt.%), was screened out.
The titanium alloy with complete equiaxed crystal structure and ultrahigh yield strength is prepared by the following method:
preparing prealloying powder or prealloying wire materials according to the designed alloy components; and then, preparing a sample by using selective laser melting, selective electron beam melting or laser direct deposition equipment to prepare a block sample. Because the metal material manufactured by the additive is usually subjected to rapid solidification and cooling, a high-density dislocation structure and large residual stress are easily formed in the material, and solution heat treatment and water quenching are carried out on the alloy after the additive manufacturing in order to eliminate internal stress and dislocation.
Optionally, the spherical pure Ti powder, the pure Fe powder and the pure Co powder with the particle size ranges of 15-53 microns are mixed by using a three-dimensional swing powder mixer, and are mixed for 6 hours at the rotating speed of 28rpm, so as to obtain a uniform powder particle distribution state. Then, high-melting point pure Mo powder particles with irregular shapes and particle sizes ranging from 1 to 3 microns are added into the powder, a horizontal high-energy ball mill is used for ball milling and mixing for 20 minutes under the conditions of a ball powder ratio of 4.
Optionally, raw material proportioning is carried out according to designed alloy components, a pre-alloy bar is prepared by smelting and casting, and then pre-alloy powder is prepared by using an inert gas atomization method, a plasma atomization method or a rotary electrode powder preparation method;
optionally, the raw materials are proportioned according to the designed alloy components, a pre-alloy bar is prepared by smelting and casting, and then the pre-alloy bar is prepared into a pre-alloy wire.
The additive-produced titanium alloy having a fully equiaxed grain structure and an ultra-high yield strength and the method for producing the same according to the present invention will be further explained with specific examples.
Example one
The raw material proportioning is carried out according to the designed alloy components, and the preparation method comprises the following steps: adding simple substance metal Ti powder, fe powder and Co powder with similar melting points into a three-dimensional swinging powder mixing device in the same particle size range of 15-53 mu m for preferential mixing (without adding steel balls), and mixing for 6 hours at the rotating speed of 28 rpm. And then, carrying out short-time high-efficiency mixing on the high-melting-point metal powder particles Mo and the high-particle-diameter simple substance powder particles in a small-particle-diameter 1-3 μm form by using a horizontal high-energy ball mill, wherein the ball-powder ratio is 4. After the powder is well mixed, melting and sample preparation are carried out on the powder by utilizing selective laser melting or selective electron beam melting or laser direct deposition equipment, and then solid solution treatment and water quenching are carried out. The technological parameters of the solution heat treatment are as follows: the heating rate is 5-15 ℃/min, the solid solution temperature is 750-850 ℃, and the solid solution heat preservation time is 30-120 min; the technological parameters of water quenching are as follows: immediately putting the solution into clear water or saline water for cooling until the temperature is room temperature, wherein the quenching cooling rate is 500-800 ℃/s.
Example two
The preparation method comprises the steps of proportioning raw materials according to designed alloy components, preparing a pre-alloy bar through smelting and casting, preparing pre-alloy powder through an inert gas atomization method, a plasma atomization method or a rotating electrode powder preparation method, melting the powder through selective laser melting or selective electron beam melting or laser direct deposition equipment to prepare a sample, and finally performing solution treatment and water quenching. The technological parameters of the solution heat treatment are as follows: the heating rate is 5-15 ℃/min, the solid solution temperature is 750-850 ℃, and the solid solution heat preservation time is 30-120 min; the technological parameters of water quenching are as follows: after the solid solution treatment, the material is immediately put into clean water or saline water for cooling until the temperature reaches room temperature, and the quenching cooling rate is 500-800 ℃/s.
EXAMPLE III
The preparation method comprises the steps of proportioning raw materials according to designed alloy components, preparing a pre-alloyed bar through smelting and casting, preparing the alloyed bar into a metal wire, melting and sampling the wire by using laser direct deposition equipment, and finally performing solid solution treatment and water quenching. The technological parameters of the solution heat treatment are as follows: the heating rate is 5-15 ℃/min, the solid solution temperature is 750-850 ℃, and the solid solution heat preservation time is 30-120 min; the technological parameters of water quenching are as follows: after the solution treatment, the material is immediately put into clean water or saline water for cooling until the temperature reaches room temperature, and the quenching cooling rate is 500-800 ℃/s.
Example four
The titanium alloy designed by the invention can also be prepared by using the traditional manufacturing method, and the titanium alloy is prepared by carrying out raw material proportioning according to the designed alloy components, smelting, casting, forging or rolling, solution treatment and water quenching. The technological parameters of the solution heat treatment are as follows: the heating rate is 5-15 ℃/min, the solid solution temperature is 750-850 ℃, and the solid solution heat preservation time is 30-120 min; the technological parameters of water quenching are as follows: after the solid solution treatment, the material is immediately put into clean water or saline water for cooling until the temperature reaches room temperature, and the quenching cooling rate is 500-800 ℃/s.
Claims (10)
1. A titanium alloy having a fully equiaxed grain structure and an ultra-high yield strength, characterized in that
The value is 2.35 to 2.37,
a value of 2.77-2.79; the titanium alloy comprises the following components: 1-3wt% Mo,2.5-4.5wt% Co,2.5-4.5wt% Fe, the balance Ti and unavoidable impurities; the structure of the titanium alloy is an equiaxed crystal structure, and the yield strength is greater than 1100MPa.
2. The titanium alloy of claim 1, wherein the composition of said titanium alloy is: 2wt% of Mo,3.6wt% of Co,3.4wt% of Fe, and the balance of Ti and unavoidable impurities.
3. The titanium alloy of claim 1 or 2, wherein said titanium alloy is produced by melting, casting, forging or rolling, said titanium alloy having an equiaxed grain size in the range of 10-150 μm and a yield strength greater than 1100MPa.
4. The titanium alloy of claim 1 or 2, wherein said titanium alloy is produced by additive manufacturing, said titanium alloy having an equiaxed grain size in the range of 1-70 μ ι η and a yield strength greater than 1200MPa.
5. A method of producing a titanium alloy having a fully equiaxed grain structure and an ultra-high yield strength as defined in claim 3, comprising the steps of:
(1) Preparing a block sample by proportioning raw materials according to alloy components and carrying out smelting, casting, forging or rolling;
(2) And carrying out solid solution heat treatment and water quenching on the massive sample.
6. A method of producing the titanium alloy having a fully equiaxed grain structure and an ultra-high yield strength as set forth in claim 4, comprising the steps of:
(1) Mixing spherical pure Ti powder, pure Fe powder and pure Co powder by using a three-dimensional swinging powder mixer to obtain mixed powder;
(2) Adding high-melting-point pure Mo powder particles into the mixed powder, and performing ball milling by using a horizontal high-energy ball mill;
(3) Melting and sampling the mixed powder after ball milling by using any one of selective laser melting, selective electron beam melting and laser direct deposition to obtain a block sample;
(4) And carrying out solid solution heat treatment and water quenching on the massive sample.
7. The method for preparing the titanium alloy according to claim 6, wherein in the step (1), the particle sizes of the spherical pure Ti powder, the pure Fe powder and the pure Co powder are 15-53 microns, and the technological parameters of the mixed powder are as follows: mixing for 6 hours at the rotating speed of 28 rpm; in the step (2), the grain diameter of the high-melting-point pure Mo powder is 1-3 microns, and the ball milling process parameters are as follows: and (3) ball-milling and mixing for 20 minutes under the conditions of the ball powder ratio of 4.
8. A method of producing the titanium alloy having a fully equiaxed grain structure and an ultra-high yield strength as set forth in claim 4, comprising the steps of:
(1) Proportioning raw materials according to alloy components, smelting, casting to prepare a pre-alloyed bar, and preparing pre-alloyed powder by using any one of an inert gas atomization method, a plasma atomization method or a rotary electrode powder preparation method;
(2) Melting and sampling the mixed powder after ball milling by using any one of selective laser melting, selective electron beam melting and laser direct deposition to obtain a block sample;
(3) And carrying out solid solution heat treatment and water quenching on the massive sample.
9. A method of producing the titanium alloy having a fully equiaxed grain structure and an ultra-high yield strength as set forth in claim 4, comprising the steps of:
(1) Proportioning raw materials according to alloy components, smelting, casting to prepare a pre-alloyed bar, and preparing the alloyed bar into a metal wire;
(2) Melting and sampling the wire material by using laser direct deposition equipment to obtain a block sample;
(3) And carrying out solid solution heat treatment and water quenching on the massive sample.
10. The method for producing a titanium alloy according to any one of claims 5 to 9, wherein the process parameters of the solution heat treatment are: the heating rate is 5-15 ℃/min, the solid solution temperature is 750-850 ℃, and the solid solution heat preservation time is 30-120 min; the water quenching process parameters are as follows: immediately putting the solution into clear water or saline water for cooling until the temperature reaches room temperature, wherein the quenching cooling rate is 500-800 ℃/s.
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