High-strength and high-plasticity negative enthalpy biphase titanium alloy material and preparation method thereof

Abstract

The invention discloses a high-strength and high-plasticity negative enthalpy double-phase titanium alloy material and a preparation method thereof. The negative enthalpy double-phase titanium alloy material is Ti Al Mn < c > Si < d > Fe < e > Co < f > Ni < g >, wherein a, b, c, d, e, f and g respectively correspond to the mass percent of each element, a is equal to 80-95 wt%, b is equal to 3.5-8 wt%, c is equal to 0-3 wt%, d is equal to 0-2 wt%, e is equal to 0-2 wt%, f is equal to 0-2 wt%, g is equal to 0-2 wt%, and the mass percent of Mn is not equal to 0 wt%; the series of negative enthalpy double-phase titanium alloy materials structurally comprise a body-centered cubic structure and a close-packed hexagonal structure, and the microscopic structure and the mechanical property of the alloy can be regulated and controlled by adjusting the element proportion; the series of negative enthalpy biphase titanium alloy materials have high strength and high plasticity in mechanical properties, and are widely applied to the fields of aerospace, ocean engineering, biomedical treatment and the like.

Description

Technical Field

[0001] This invention belongs to the field of metallic materials technology, and relates to a high-strength, high-plasticity negative enthalpy dual-phase titanium alloy material and its preparation method. Background Technology

[0002] Titanium alloys, as important metallic structural materials, have wide applications in aerospace, marine engineering, and biomedicine due to their high specific strength, good corrosion resistance, and biocompatibility. However, while pursuing higher strength, traditional titanium alloy systems often suffer from reduced toughness, increased processing difficulty, and higher costs, which seriously restricts their large-scale application in a wider range of civilian and industrial fields.

[0003] Existing high-strength titanium alloys mostly rely on adding expensive β-stabilizing elements (such as V, Nb, Mo, etc.) or using complex multi-stage heat treatment processes to control the α / β phase structure in order to achieve a match between strength and toughness. These methods are not only expensive in terms of raw material costs and complex in terms of preparation processes, but also often fail to fundamentally overcome the inherent limitations of the inverse relationship between strength and toughness.

[0004] In recent years, the alloy design concept based on the thermodynamic negative enthalpy of mixing (negative enthalpy) effect has gradually attracted attention. This concept promotes enhanced interatomic bonding and the formation of short-range ordered structures by selecting elements with negative enthalpy of mixing (difference in chemical affinity) for alloy design, providing a new approach to simultaneously improve the strength and plasticity of alloys. However, research on systematically introducing the negative enthalpy design principle into titanium alloy systems is still in its early stages. Existing technologies lack complete schemes for the composition design and corresponding preparation processes of low-cost, high-strength, and tough titanium alloys with significant negative enthalpy characteristics. In addition, traditional titanium alloy smelting and processing are prone to problems such as compositional segregation and uneven microstructure, which further affect the performance consistency and service reliability of the final components.

[0005] Therefore, there is an urgent need to develop a high-strength and high-ductility titanium alloy material based on the negative enthalpy effect. Through innovative composition design and optimized preparation process, the strength and toughness can be synergistically improved while significantly reducing raw material costs, so as to meet the growing demand of modern industry for high-performance titanium alloys. Summary of the Invention

[0006] This invention overcomes the shortcomings of existing chemical composition design and preparation technologies, and provides a high-strength, high-plasticity negative enthalpy dual-phase titanium alloy material and its preparation method, which has great application potential in major fields such as aerospace, marine vessels, and national defense.

[0007] The present invention adopts the following technical solution: A high-strength, high-ductility negative enthalpy dual-phase titanium alloy material, wherein the negative enthalpy dual-phase titanium alloy material is Ti a Alb Mn c Si d Fe e Co f Ni g .

[0008] Where: a, b, c, d, e, f and g correspond to the mass percentage of each element, a=80-95 wt%, b=3.5-8 wt%, c=0-3 wt%, d=0-2 wt%, e=0-2 wt%, f=0-2 wt%, g=0-2 wt%, and the mass percentage of Mn c is not 0 wt%.

[0009] Research has shown that by selecting and adding elements with negative mixing enthalpy to Ti (including Al, Mn, Fe, Co, Ni, and Si) in the design of alloy chemical composition, and controlling their addition amounts, the bond strength can be improved, thereby increasing the strength of the titanium alloy. On the other hand, it can induce the formation of local clusters and other structures, thereby regulating dislocation movement behavior, obtaining high work hardening ability, and thus achieving high plasticity.

[0010] Specifically, the negative enthalpy dual-phase titanium alloy material contains a body-centered cubic (BCC) structure and a hexagonal close-packed (HCP) structure.

[0011] In the above technical solution, the purity of the titanium, aluminum, manganese, iron, cobalt, nickel and silicon elements in the negative enthalpy dual-phase titanium alloy material is ≥99.95%.

[0012] In the above technical solution, the negative enthalpy dual-phase titanium alloy material has a negative mixed enthalpy with aluminum, manganese, iron, cobalt, nickel and silicon.

[0013] Specifically, in the above technical solution, ΔH mix (Ti-Al) = -30 kJ / mol, ΔH mix (Ti-Mn) = -8kJ / mol, ΔH mix (Ti-Fe) = -17 kJ / mol, ΔH mix (Ti-Co) = -28 kJ / mol, ΔH mix (Ti-Ni) = -35 kJ / mol, ΔH mix (Ti-Si) = -66 kJ / mol.

[0014] Specifically, in the above technical solution, the negative enthalpy dual-phase titanium alloy material is Ti. 94.5 Al4Mn 1.5 Ti 91 Al7Mn2, Ti 89Al7Mn2Si1Fe1 and Ti 89 Al7Mn2Si1Fe 1 / 3 Co 1 / 3 Ni 1 / 3 One of them.

[0015] In another aspect, the present invention provides a method for preparing the above-mentioned high-strength, high-ductility negative enthalpy dual-phase titanium alloy material, comprising the following steps: Weigh each metal raw material according to the composition and mass percentage of the negative enthalpy dual-phase titanium alloy material, and place each metal raw material in a water-cooled metal crucible in order of melting point from low to high. Place the metal raw material with the lowest melting point at the bottom and the metal raw material with the highest melting point on the surface. Place sponge titanium in the middle copper mold and melt it under an oxygen-free environment until it is fully mixed (that is, each metal raw material melts rapidly after being heated at high temperature by the electric arc and is uniformly mixed in the liquid state to achieve composition homogenization) to obtain the negative enthalpy dual-phase titanium alloy material.

[0016] In the above technical solution, the oxygen-free environment is achieved through a process of vacuuming, filling with argon gas, and melting sponge titanium to absorb oxygen.

[0017] Furthermore, in the above technical solution, the process of vacuuming, argon filling, and oxygen absorption during the melting of sponge titanium specifically includes: Use a mechanical pump to evacuate to a vacuum level of less than 5. Pa, then a molecular pump was used to evacuate to a vacuum level of less than 0.0005. Pa, then 99.99% pure argon gas is introduced until 0.05 ppm is reached. MPa, and finally the sponge titanium is melted twice by arc ignition (each time the sponge titanium is melted by arc ignition, that is, the sponge titanium is heated at high temperature by electric arc and melts into liquid state visible to the naked eye. This melting process absorbs oxygen) to absorb residual oxygen.

[0018] In the above technical solution, the number of times the metal raw material is ignited and melted is greater than 4. After each ignition and melting, the alloy in the crucible is turned over before the next ignition and melting. Before the next ignition and melting of the alloy, the sponge titanium is melted and oxygen absorbed twice.

[0019] Furthermore, in the above technical solution, the melting time for each arc-ignition melting is 1.0-2.0 min, and in addition to the first and last arc-ignition melting, the arc-ignition melting of the metal raw material also includes magnetic stirring of the melt.

[0020] Specifically, in the above technical solution, the melting voltage and melting current of the arc-ignition melting are 10-15 V and 300-350 A, respectively.

[0021] In a preferred embodiment of the present invention, the method for preparing the high-strength, high-ductility negative enthalpy dual-phase titanium alloy material specifically includes the following steps: S1. Seven kinds of high-purity metal raw material particles (Ti, Al, Mn, Fe, Co, Ni and Si) are placed in an ultrasonic cleaner and cleaned twice. Then, they are weighed and proportioned according to the component ratio by mass percentage. They are placed in a water-cooled metal crucible in order of melting point from low to high. The element with the lowest melting point is placed at the bottom and the element with the highest melting point is placed at the top. At the same time, sponge titanium is placed at the middle copper mold position. S2. Close the electric arc melting furnace door, turn on the circulating water, turn on the mechanical pump, and begin vacuuming. When the vacuum level is below 5 Pa, turn on the molecular pump for further vacuuming. When the vacuum level is below 5.0*10 Pa... -4 When the pressure is Pa, high-purity argon gas (approximately 0.05 MPa) is introduced as a protective gas; S3. Arc ignition is performed in a high-purity argon atmosphere to melt the sponge titanium twice and absorb residual oxygen in the furnace. S4. First, high-current melting (melting voltage 10-15 V, melting current 300-350 A) is used to melt and mix all metal particles evenly. After the alloy button is cast and cooled, it is flipped by a robotic arm and melted in the same way. Magnetic stirring is turned on during each subsequent melting process. After each melting, the alloy button is flipped 180 degrees. A total of 4 melting processes are carried out to make the alloy composition more uniform. During the last melting, magnetic stirring is turned off to make it a smooth ingot, which is then suction-cast.

[0022] S5. After the alloy button ingot has completely cooled, open the furnace door and take out the sample.

[0023] Compared with the prior art, the beneficial effects of the present invention are: (1) This invention provides a Ti a Al b Mn c Si d Fe e Co f Ni g This series of negative enthalpy dual-phase titanium alloy materials are composed of titanium, aluminum, manganese, iron, cobalt, nickel and silicon elements, and are produced by vacuum arc melting furnace. The negative enthalpy dual-phase titanium alloy materials all contain BCC and HCP structures in their structure, and the microstructure and mechanical properties of the alloy can be controlled by adjusting the element ratio. On the one hand, it can improve the bond strength, thereby improving the strength of the titanium alloy. On the other hand, it can induce the formation of local clusters and other structures, thereby controlling the dislocation motion behavior, obtaining high work hardening ability, and thus achieving high plasticity. (2) The Ti provided by the present invention a Al bMn c Si d Fe e Co f Ni g The series of negative enthalpy dual-phase titanium alloy materials possess both high strength and high ductility in terms of mechanical properties, among which: Ti 94.5 Al4Mn 1.5 The room temperature tensile yield strength is 635 MPa, the breaking strength is 718 MPa, and the uniform elongation is 7.2%; Ti 91 Al7Mn2 has a room temperature tensile yield strength of 864 MPa, a fracture strength of 956 MPa, and a uniform elongation of 7.6%; Ti 89 The room temperature tensile yield strength of Al7Mn2Si1Fe1 is 1260 MPa, the fracture strength is 1330 MPa, and the uniform elongation is 5.7%; Ti 89 Al7Mn2Si1Fe 1 / 3 Co 1 / 3 Ni 1 / 3 The room temperature tensile yield strength is 1275 MPa, the breaking strength is 1370 MPa, and the uniform elongation is 11.5%. Attached Figure Description

[0024] To more clearly illustrate the technical solutions in the embodiments of the present 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 some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0025] Figure 1 Ti prepared in the embodiments of the present invention a Al b Mn c Si d Fe e Co f Ni g X-ray diffraction patterns of a series of negative enthalpy dual-phase titanium alloy materials; Figure 2 This is a room temperature tensile stress-strain curve prepared in an embodiment of the present invention. Detailed Implementation

[0026] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to embodiments.

[0027] It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.

[0028] In the embodiments, unless otherwise specified, all methods used are conventional methods in the art.

[0029] The terms “comprising,” “including,” or any other variations thereof, as used herein, are intended to cover non-exclusive inclusion. For example, a composition, step, method, article, or apparatus that includes the listed elements is not necessarily limited to those elements, but may include other elements not expressly listed or elements inherent to such composition, step, method, article, or apparatus.

[0030] Furthermore, the technical features involved in the various embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0031] This invention provides a high-strength, high-plasticity Ti a Al b Mn c Si d Fe e Co f Ni g A series of negative enthalpy dual-phase titanium alloy materials and their preparation methods are disclosed, wherein a, b, c, d, e, f and g correspond to the mass percentages of each element, a=80-95 wt%, b=3.5-8 wt%, c=0-3 wt%, d=0-2 wt%, e=0-2 wt%, f=0-2 wt%, g=0-2 wt%, and the mass percentage of Mn c is not taken as 0 wt%.

[0032] The Ti provided in the embodiments of the present invention a Al b Mn c Si d Fe e Co f Ni g The series of negative enthalpy dual-phase titanium alloys contain both body-centered cubic (BCC) and hexagonal close-packed (HCP) structures. Furthermore, the microstructure and mechanical properties of the alloys can be controlled by adjusting the proportions of different metallic elements, thereby regulating the Ti content. a Al b Mn c Si d Fe e Co f Ni g The series of titanium alloys have mixed enthalpy values ​​(-8.039 kJ / mol ~ -17.019 kJ / mol), thus achieving both high strength and high plasticity in mechanical properties, and have great application potential in major fields such as aerospace, marine vessels and national defense.

[0033] Compared to traditional titanium alloys, the embodiments of the present invention add aluminum (Al), manganese (Mn), iron (Fe), cobalt (Co), nickel (Ni), and silicon (Si), all of which have negative enthalpy of mixing with titanium, while controlling the amount added. On the one hand, this can improve the bond strength, thereby increasing the strength of the titanium alloy. On the other hand, it can induce the formation of local clusters and other structures, thereby regulating the dislocation movement behavior, obtaining high work hardening ability, and thus achieving high plasticity.

[0034] Specifically, the enthalpy of mixing titanium (Ti) with aluminum (Al), manganese (Mn), iron (Fe), cobalt (Co), nickel (Ni), and silicon (Si) are as follows: ΔH mix (Ti-Al) = -30 kJ / mol, ΔH mix (Ti-Mn) = -8 kJ / mol, ΔH mix (Ti-Fe) = -17 kJ / mol, ΔH mix (Ti-Co) = -28 kJ / mol, ΔH mix (Ti-Ni) = -35 kJ / mol, ΔH mix (Ti-Si) = -66 kJ / mol.

[0035] As an example, the Ti provided in the embodiments of the present invention a Al b Mn c Si d Fe e Co f Ni g The series of negative enthalpy dual-phase titanium alloy materials are Ti 94.5 Al4Mn 1.5 Ti 91 Al7Mn2, Ti 89 Al7Mn2Si1Fe1 and Ti 89 Al7Mn2Si1Fe 1 / 3 Co 1 / 3 Ni 1 / 3 One of them, wherein: Ti 94.5 Al4Mn 1.5 The room temperature tensile yield strength is 635 MPa, the breaking strength is 718 MPa, and the uniform elongation is 7.2%; Ti 91 Al7Mn2 has a room temperature tensile yield strength of 864 MPa, a fracture strength of 956 MPa, and a uniform elongation of 7.6%; Ti 89 The room temperature tensile yield strength of Al7Mn2Si1Fe1 is 1260 MPa, the fracture strength is 1330 MPa, and the uniform elongation is 5.7%; Ti 89 Al7Mn2Si1Fe1 / 3 Co 1 / 3 Ni 1 / 3 The room temperature tensile yield strength is 1275 MPa, the breaking strength is 1370 MPa, and the uniform elongation is 11.5%.

[0036] The embodiments of the present invention also provide Ti a Al b Mn c Si d Fe e Co f Ni g The preparation methods for a series of negative enthalpy dual-phase titanium alloy materials specifically include: Weigh each metal raw material according to the composition and mass percentage of the negative enthalpy dual-phase titanium alloy material, and place each metal raw material in a water-cooled metal crucible in order of melting point from low to high. Place the metal raw material with the lowest melting point at the bottom and the metal raw material with the highest melting point at the top. Place sponge titanium in the middle copper mold and melt it in an oxygen-free environment until it is fully mixed to obtain the negative enthalpy dual-phase titanium alloy material.

[0037] In detail, the aforementioned oxygen-free environment is achieved through a process of vacuuming, purging with argon gas, and melting sponge titanium to absorb oxygen. Specifically, the process involves using a mechanical pump to evacuate the vacuum to a level less than 5. Pa, then a molecular pump was used to evacuate to a vacuum level of less than 0.0005. Pa, then 99.99% pure argon gas is introduced until 0.05 ppm is reached. MPa, and finally, the sponge titanium was melted twice by arc ignition to absorb residual oxygen.

[0038] In detail, the above-mentioned metal raw materials are ignited and melted more than 4 times. After each ignition and melting, the alloy in the crucible is turned over before the next ignition and melting. Before the next ignition and melting of the alloy, the sponge titanium is melted and oxygen absorbed twice.

[0039] In detail, the melting voltage and melting current for the above-mentioned arc-ignition melting are 10-15 V and 300-350 A, respectively.

[0040] Example 1

[0041] This invention provides a negative enthalpy dual-phase titanium alloy material and its preparation method, comprising 94.5 wt% Ti, 4 wt% Al and 1.5 wt% Mn, denoted as Ti. 94.5 Al4Mn 1.5 The alloy has a mixing enthalpy of -8.039 kJ / mol.

[0042] The negative enthalpy biphase Ti 94.5Al4Mn 1.5 The preparation method of the alloy specifically includes the following steps: S1. Place the high-purity raw material particles of Ti, Al and Mn (commercially available products, all with a purity ≥99.95%) in an ultrasonic cleaner and clean them twice. Then, weigh and mix them according to the component ratio by mass percentage, and put them into a water-cooled metal crucible in order of melting point from low to high. Place the element with the lowest melting point at the bottom and the element with the highest melting point at the top. At the same time, put sponge titanium at the middle copper mold position. S2. Close the electric arc melting furnace door, turn on the circulating water, turn on the mechanical pump, and begin vacuuming. When the vacuum level is below 5 Pa, turn on the molecular pump for further vacuuming. When the vacuum level is below 5.0*10 Pa... -4 At pressure of Pa, 99.99% pure argon gas (approximately 0.05 MPa) is introduced as a protective gas. S3. Arc ignition is performed in a high-purity argon atmosphere (purity 99.99%) to melt the sponge titanium twice and absorb residual oxygen in the furnace. S4. First, high-current melting (melting voltage 12.5 V, melting current 340 A) is used to melt and mix all metal particles evenly. After the alloy button is cast and cooled, it is flipped by a robotic arm and melted in the same way. Magnetic stirring is turned on during each subsequent melting process. After each melting, the alloy button is flipped 180 degrees. A total of 4 melting processes are carried out to make the alloy composition more uniform. During the last melting, magnetic stirring is turned off to make it a smooth ingot, which is then suction-cast.

[0043] S5. After the alloy button ingot has completely cooled, open the furnace door and take out the sample.

[0044] Example 2

[0045] This invention provides a negative enthalpy dual-phase titanium alloy material and its preparation method, comprising 91 wt% Ti, 7 wt% Al and 2 wt% Mn, denoted as Ti. 91 The Al7Mn2 alloy has a mixing enthalpy of -12.87 kJ / mol.

[0046] The negative enthalpy biphase Ti 91 The preparation method of Al7Mn2 alloy specifically includes the following steps: S1. Place the high-purity raw material particles of Ti, Al and Mn (commercially available products, all with a purity ≥99.95%) in an ultrasonic cleaner and clean them twice. Then, weigh and mix them according to the component ratio by mass percentage, and put them into a water-cooled metal crucible in order of melting point from low to high. Place the element with the lowest melting point at the bottom and the element with the highest melting point at the top. At the same time, put sponge titanium at the middle copper mold position. S2. Close the electric arc melting furnace door, turn on the circulating water, turn on the mechanical pump, and begin vacuuming. When the vacuum level is below 5 Pa, turn on the molecular pump for further vacuuming. When the vacuum level is below 5.0*10 Pa... -4 At pressure of Pa, 99.99% pure argon gas (approximately 0.05 MPa) is introduced as a protective gas. S3. Arc ignition is performed in a high-purity argon atmosphere (purity 99.99%) to melt the sponge titanium twice and absorb residual oxygen in the furnace. S4. First, high-current melting (melting voltage 12.5 V, melting current 340 A) is used to melt and mix all metal particles evenly. After the alloy button is cast and cooled, it is flipped by a robotic arm and melted in the same way. Magnetic stirring is turned on during each subsequent melting process. After each melting, the alloy button is flipped 180 degrees. A total of 4 melting processes are carried out to make the alloy composition more uniform. During the last melting, magnetic stirring is turned off to make it a smooth ingot, which is then suction-cast.

[0047] S5. After the alloy button ingot has completely cooled, open the furnace door and take out the sample.

[0048] Example 3

[0049] This invention provides a negative enthalpy dual-phase titanium alloy material and its preparation method, comprising 89 wt% Ti, 7 wt% Al, 2 wt% Mn, 1 wt% Si and 1 wt% Fe, denoted as Ti. 89 The Al7Mn2Si1Fe1 alloy has a mixing enthalpy of -16.756 kJ / mol.

[0050] The negative enthalpy biphase Ti 89 The preparation method of Al7Mn2Si1Fe1 alloy specifically includes the following steps: S1. Place the high-purity raw material particles of Ti, Al, Mn, Si and Fe (commercially available products, all with a purity ≥99.95%) in an ultrasonic cleaner and clean them twice. Then, weigh and mix them according to the component ratio by mass percentage, and put them into a water-cooled metal crucible in order of melting point from low to high. Place the element with the lowest melting point at the bottom and the element with the highest melting point at the top. At the same time, place sponge titanium at the middle copper mold position. S2. Close the electric arc melting furnace door, turn on the circulating water, turn on the mechanical pump, and begin vacuuming. When the vacuum level is below 5 Pa, turn on the molecular pump for further vacuuming. When the vacuum level is below 5.0*10 Pa... -4 At pressure of Pa, 99.99% pure argon gas (approximately 0.05 MPa) is introduced as a protective gas. S3. Arc ignition is performed in a high-purity argon atmosphere (purity 99.99%) to melt the sponge titanium twice and absorb residual oxygen in the furnace. S4. First, high-current melting (melting voltage 12.5 V, melting current 340 A) is used to melt and mix all metal particles evenly. After the alloy button is cast and cooled, it is flipped by a robotic arm and melted in the same way. Magnetic stirring is turned on during each subsequent melting process. After each melting, the alloy button is flipped 180 degrees. A total of 4 melting processes are carried out to make the alloy composition more uniform. During the last melting, magnetic stirring is turned off to make it a smooth ingot, which is then suction-cast.

[0051] S5. After the alloy button ingot has completely cooled, open the furnace door and take out the sample.

[0052] Example 4

[0053] This invention provides a negative enthalpy dual-phase titanium alloy material and its preparation method, comprising 89 wt% Ti, 7 wt% Al, 2 wt% Mn, 1 wt% Si, 1 / 3 wt% Fe, 1 / 3 wt% Co, and 1 / 3 wt% Ni, denoted as Ti. 89 Al7Mn2Si1Fe 1 / 3 Co 1 / 3 Ni 1 / 3 The alloy has a mixing enthalpy of -17.019 kJ / mol.

[0054] The negative enthalpy biphase Ti 89 Al7Mn2Si1Fe 1 / 3 Co 1 / 3 Ni 1 / 3 The preparation method of the alloy specifically includes the following steps: S1. Place the high-purity raw material particles of Ti, Al, Mn, Si, Fe, Co and Ni (commercially available products, all with a purity ≥99.95%) in an ultrasonic cleaner and clean them twice. Then, weigh and mix them according to the component ratio by mass percentage, and put them into a water-cooled metal crucible in order of melting point from low to high. Place the element with the lowest melting point at the bottom and the element with the highest melting point at the top. At the same time, put sponge titanium at the middle copper mold position. S2. Close the electric arc melting furnace door, turn on the circulating water, turn on the mechanical pump, and begin vacuuming. When the vacuum level is below 5 Pa, turn on the molecular pump for further vacuuming. When the vacuum level is below 5.0*10 Pa... -4 At pressure of Pa, 99.99% pure argon gas (approximately 0.05 MPa) is introduced as a protective gas. S3. Arc ignition is performed in a high-purity argon atmosphere (purity 99.99%) to melt the sponge titanium twice and absorb residual oxygen in the furnace. S4. First, high-current melting (melting voltage 12.5 V, melting current 340 A) is used to melt and mix all metal particles evenly. After the alloy button is cast and cooled, it is flipped by a robotic arm and melted in the same way. Magnetic stirring is turned on during each subsequent melting process. After each melting, the alloy button is flipped 180 degrees. A total of 4 melting processes are carried out to make the alloy composition more uniform. During the last melting, magnetic stirring is turned off to make it a smooth ingot, which is then suction-cast.

[0055] S5. After the alloy button ingot has completely cooled, open the furnace door and take out the sample.

[0056] Test and Result Analysis: The Ti prepared in Examples 1-4 a Al b Mn c Si d Fe e Co f Ni g A series of negative enthalpy dual-phase titanium alloy materials were subjected to X-ray diffraction (XRD) tests, and the results are as follows: Figure 1 As shown; from Figure 1 As can be seen from the examples, the negative enthalpy dual-phase titanium alloy materials prepared in Examples 1-4 all contain body-centered cubic (BCC) and hexagonal close-packed (HCP) structures.

[0057] Figure 2 The Ti prepared in Examples 1-4 of this invention a Al b Mn c Si d Fe e Co f Ni g Room temperature tensile stress-strain curves of a series of negative enthalpy dual-phase titanium alloy materials; from Figure 2 As can be seen, with the addition of negative enthalpy elements Al, Mn, Fe, Co, Ni and Si, the strength and plasticity of the alloy are effectively improved.

[0058] The Ti provided in the embodiments of the present invention a Al b Mn c Si d Fe e Co f Ni g The series of negative enthalpy dual-phase titanium alloy materials possess both high strength and high ductility in terms of mechanical properties. Among them: Ti 94.5Al4Mn 1.5 The room temperature tensile yield strength is 635 MPa, the breaking strength is 718 MPa, and the uniform elongation is 7.2%; Ti 91 Al7Mn2 has a room temperature tensile yield strength of 864 MPa, a fracture strength of 956 MPa, and a uniform elongation of 7.6%; Ti 89 The room temperature tensile yield strength of Al7Mn2Si1Fe1 is 1260 MPa, the fracture strength is 1330 MPa, and the uniform elongation is 5.7%; Ti 89 Al7Mn2Si1Fe 1 / 3 Co 1 / 3 Ni 1 / 3 The room temperature tensile yield strength is 1275 MPa, the breaking strength is 1370 MPa, and the uniform elongation is 11.5%.

[0059] In summary, this invention provides a high-strength and high-plasticity Ti a Al b Mn c Si d Fe e Co f Ni g A series of negative enthalpy dual-phase titanium alloy materials and their preparation methods are disclosed. These materials are prepared by selectively adding elements with negative enthalpy of mixing with Ti (including Al, Mn, Fe, Co, Ni, and Si) using a vacuum arc melting furnace. a Al b Mn c Si d Fe e Co f Ni g The series of negative enthalpy dual-phase titanium alloys all contain BCC and HCP structures in their structure. The microstructure and mechanical properties of the alloy can be controlled by adjusting the element ratio. On the one hand, it can improve the bond strength, thereby improving the strength of the titanium alloy. On the other hand, it can induce the formation of local clusters and other structures, thereby controlling the dislocation motion behavior, obtaining high work hardening ability, and thus achieving high plasticity.

[0060] The above embodiments are merely examples of several implementation methods of the present invention, and their descriptions are relatively specific and detailed, but they should not be construed as limiting the scope of the invention patent.

[0061] It should be noted that those skilled in the art can make various modifications and improvements without departing from the inventive concept, and these all fall within the scope of protection of this invention. Therefore, the scope of protection of this patent should be determined by the appended claims.

Claims

1. A high-strength, high-ductility negative enthalpy dual-phase titanium alloy material, characterized in that, The negative enthalpy dual-phase titanium alloy material is Ti. a Al b Mn c Si d Fe e Co f Ni g ; Where: a, b, c, d, e, f, and g correspond to the mass percentages of each element, a = 80-95 wt%, b = 3.5-8 wt%, c = 0-3 wt%, d = 0-2 wt%, e = 0-2 wt%, f = 0-2 wt%, g = 0-2 wt%, and the mass percentage of Mn, c, is not taken as 0 wt%. The negative enthalpy dual-phase titanium alloy material has a body-centered cubic and close-packed hexagonal structure.

2. The high-strength, high-ductility negative enthalpy dual-phase titanium alloy material according to claim 1, characterized in that, In the negative enthalpy dual-phase titanium alloy material, the purity of the titanium, aluminum, manganese, iron, cobalt, nickel and silicon elements in the corresponding raw materials is ≥99.95%.

3. The high-strength, high-ductility negative enthalpy dual-phase titanium alloy material according to claim 1, characterized in that, In the negative enthalpy dual-phase titanium alloy material, titanium has a negative mixed enthalpy with aluminum, manganese, iron, cobalt, nickel and silicon. in: ΔH mix ΔH(Ti - Al) = -30 kJ / mol mix ΔH(Ti - Mn) = -8 kJ / mol mix ΔH(Ti - Fe) = -17 kJ / mol mix ΔH(Ti - Co) = -28 kJ / mol mix ΔH(Ti - Ni) = -35 kJ / mol mix ΔH(Ti - Si) = -66 kJ / mol 4. The high-strength, high-ductility, negative enthalpy dual-phase titanium alloy material according to any one of claims 1-3, characterized in that, The negative enthalpy dual-phase titanium alloy material is Ti. 94.5 Al4Mn 1.5 Ti 91 Al7Mn2, Ti 89 Al7Mn2Si1Fe1 and Ti 89 Al7Mn2Si1Fe 1 / 3 Co 1 / 3 Ni 1 / 3 One of them.

5. A method for preparing a high-strength, high-ductility, negative enthalpy dual-phase titanium alloy material according to any one of claims 1-4, characterized in that, Includes the following steps: Weigh each metal raw material according to the composition and mass percentage of the negative enthalpy dual-phase titanium alloy material, and place each metal raw material in a water-cooled metal crucible in order of melting point from low to high. Place the metal raw material with the lowest melting point at the bottom and the metal raw material with the highest melting point at the top. Place sponge titanium in the middle copper mold and melt it in an oxygen-free environment until it is fully mixed to obtain the negative enthalpy dual-phase titanium alloy material.

6. The method for preparing the high-strength, high-ductility negative enthalpy dual-phase titanium alloy material according to claim 5, characterized in that, The oxygen-free environment is achieved through a process of vacuuming, argon filling, and smelting sponge titanium to absorb oxygen.

7. The method for preparing the high-strength, high-ductility negative enthalpy dual-phase titanium alloy material according to claim 6, characterized in that, The specific process of vacuuming, argon filling, and oxygen absorption during the melting and smelting of sponge titanium is as follows: A mechanical pump was used to evacuate the vacuum to less than 5 Pa, followed by a molecular pump to evacuate the vacuum to less than 0.0005 Pa. Then, 99.99% pure argon gas was introduced to 0.05 MPa. Finally, the sponge titanium was melted twice by arc ignition to absorb residual oxygen.

8. The method for preparing the high-strength, high-ductility negative enthalpy dual-phase titanium alloy material according to claim 5, characterized in that, The number of times the metal raw material is ignited and melted is greater than 4. After each ignition and melting, the alloy in the crucible is turned over before the next ignition and melting. Before the next ignition and melting of the alloy, the sponge titanium is melted and oxygen absorbed twice.

9. The method for preparing the high-strength, high-ductility negative enthalpy dual-phase titanium alloy material according to claim 8, characterized in that, The melting time for each arc-ignition melting is 1.0-2.0 min, and in addition to the first and last arc-ignition melting, the arc-ignition melting of the metal raw materials also includes magnetic stirring of the melt.

10. The method for preparing the high-strength, high-ductility negative enthalpy dual-phase titanium alloy material according to claim 8 or 9, characterized in that, The melting voltage and melting current for the arc-ignition melting are 10-15 V and 300-350 A, respectively.

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