A low-density super-elastic functional titanium alloy and a preparation method thereof

Abstract

The application provides a low-density super-elastic functional titanium alloy and a preparation method thereof, and the titanium alloy is composed of the following elements in percentage by mass: Al: 4.2-5.0%, Cr: 1.6-2.2%, Fe: 0.8-1.2%, Mo: 3.0-4.2%, and the balance is Ti and inevitable impurity elements. The preparation method comprises alloy ingot smelting, forging and rolling deformation processing and annealing treatment. The alloy prepared by the application has excellent comprehensive properties such as high damping, high work hardening rate and high strength plasticity, and solves the key problems of processing difficulty, high cost and large density of the existing super-elastic metal materials, and has a significant application prospect in new-generation advanced equipment such as aerospace, ships and intelligent robots.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of advanced structure-function integrated metal materials, and particularly relates to a low-density super-elastic functional titanium alloy and a preparation method thereof. BACKGROUND

[0002] Structure-function integrated metal materials with special physical, chemical or mechanical properties such as superconductivity, hydrogen storage, super-elasticity and shape memory play a key role in high-tech industries such as aerospace, energy, medicine and electronics. The research and development of new structure-function integrated metal materials and their preparation technology can significantly promote the development of frontier technologies such as deep space exploration, nuclear fusion, intelligent robots and hydrogen energy, and is one of the important research directions in the field of new materials for international and domestic universities and research institutions.

[0003] As a structure-function integrated metal material with super-elasticity and shape memory, nickel-titanium alloy has high strength, fatigue resistance and corrosion resistance, and is widely used in key components such as medical stents, satellite antennas and aerospace seals. However, nickel-titanium alloy has problems such as high density (about 6.5 g / cm 3 ), high cost, difficult processing and biological toxicity, which limit its application in key fields such as medicine, electronics and automobiles. Among them, the presence of about 55.8 wt.% of nickel element in the alloy is the root cause of the problems of high density, high cost and biological toxicity, and there is currently no technical method to fundamentally solve this problem. Therefore, the development of super-elastic functional alloy materials without nickel element and their preparation technology has significant application prospects in new equipment in key fields.

[0004] Metastable titanium alloys with martensitic transformation behavior have the characteristics of low density, high specific strength, corrosion resistance and excellent biocompatibility. Researchers have developed a series of super-elastic functional alloy materials with excellent performance through the selection of alloying elements and microstructure control. Among them, Ti-Nb-Zr metastable titanium alloys are the focus of domestic researchers due to their low modulus, super-elasticity, shape memory and other comprehensive mechanical properties and functional characteristics, and related research has high maturity. They have achieved key applications in aerospace, medical, electronic and other fields. However, this series of alloys usually contain a large amount of Nb element (≥15 wt.%, and even ≥30 wt.%), and Nb has a high melting point (2468 °C), a large density (8.6 g / cm 3 ), and is expensive, which leads to problems such as difficult preparation and processing, high density and high cost, hindering its engineering application in more fields.

[0005] Therefore, based on the characteristics of the alpha / beta two isomeric transformation in titanium alloy, the appropriate low-density and low-cost alloying elements are selected or the addition of high-density and valuable elements is reduced, and the existing high-density and high-cost alloying system is broken through. On this basis, combined with the traditional preparation and processing technology of titanium alloy, the short process deformation processing technology route is innovatively developed, and the new generation of super-elastic functional titanium alloy materials and preparation and processing technology are developed from the aspects of composition design and processing preparation, which has important engineering application value. SUMMARY

[0006] In view of the technical problems in the above background art, the present application provides a low-density super-elastic functional titanium alloy and a preparation method thereof, which has reasonable concept, is based on the beta phase stability coefficient and d electronic titanium alloy design theory, and through optimization of alloying elements and short process preparation and processing technology, a low-density and low-cost super-elastic functional titanium alloy with recoverable strain of more than 5% and a preparation method thereof are successfully developed; at the same time, the alloy has excellent comprehensive properties such as high damping, high work hardening rate, high strength and plasticity, solves the key problems of processing difficulty, high cost and large density of existing super-elastic metal materials, and has significant application prospect in new generation of advanced equipment such as aerospace, ships and intelligent robots.

[0007] To solve the above technical problems, the present application provides a low-density super-elastic functional titanium alloy, which is composed of the following mass percentages of elements: Al: 4.2-5.0%, Cr: 1.6-2.2%, Fe: 0.8-1.2%, Mo: 3.0-4.2%, and the balance of Ti and inevitable impurity elements.

[0008] The low-density super-elastic functional titanium alloy, wherein the alloy has d electronic titanium alloy design theory and The parameter ranges are respectively; the beta phase stability coefficient of the alloy is K β The numerical range is 0.491≤ K β ≤0.695.

[0009] The low-density super-elastic functional titanium alloy, wherein the density r of the alloy is 4.6≤r≤4.8.

[0010] The low-density super-elastic functional titanium alloy, wherein the recoverable strain of the alloy is greater than 5%; and the damping coefficient of the alloy is greater than 0.01 at 250ºC-400ºC.

[0011] The low-density super-elastic functional titanium alloy, wherein: the storage modulus E' of the alloy ranges from 55 GPa to 85 GPa, and the storage modulus E' does not show a rapid decrease with the increase of temperature within the range from 25°C to 400°C.

[0012] The low-density super-elastic functional titanium alloy, wherein: the tensile strength of the alloy is greater than 1 GPa, the elongation is greater than 10%, and the characteristic peak of work hardening rate is greater than 5 GPa.

[0013] A preparation method of a low-density super-elastic functional titanium alloy, mainly comprising the following steps:

[0014] (1) Alloy ingot smelting

[0015] Sponge titanium, pure aluminum particles, pure chromium sheets, pure iron particles and aluminum-molybdenum intermediate alloy are used as raw materials and are proportioned according to the designed mass percentage of the alloy, and then the proportioned raw materials are uniformly mixed and repeatedly smelted by using a vacuum smelting furnace to obtain an alloy ingot;

[0016] (2) Forging and rolling deformation processing

[0017] The alloy ingot prepared in the above step (1) is sequentially heated to a target temperature and then held, and then subjected to forging, medium-temperature and room-temperature rolling deformation processing, and an alloy rolling plate is obtained;

[0018] (3) Annealing treatment

[0019] The alloy rolling plate obtained in the above step (2) is placed in a heat treatment furnace at a temperature T4 for a holding time t4, then taken out and rapidly cooled, and then the surface is polished to finally obtain a super-elastic titanium alloy material.

[0020] The preparation method of the low-density super-elastic functional titanium alloy, wherein: when the alloy ingot with a weight greater than or equal to 20 kg is prepared in the step (1), a vacuum electron beam smelting furnace or a vacuum consumable smelting furnace is selected for the vacuum smelting furnace, and the smelting frequency of the vacuum electron beam smelting furnace is 1-2 times;

[0021] When the alloy ingot with a weight less than 20 kg is prepared in the step (1), a vacuum suspension smelting furnace or a vacuum non-consumable smelting furnace is selected for the vacuum smelting furnace, wherein the repeated smelting frequency of the vacuum suspension smelting furnace or the vacuum consumable smelting furnace is 2-4 times, and the repeated smelting frequency of the vacuum non-consumable smelting furnace is 5-8 times, and the vacuum degree is 10 -4 Pa~10 -2 Pa.

[0022] The preparation method of the low-density super-elastic functional titanium alloy, wherein: in the step (1), when repeatedly melting the alloy ingot, the ingot melted in the previous time is inverted before starting the new melting to reduce segregation and obtain the ingot with uniform composition.

[0023] The preparation method of the low-density super-elastic functional titanium alloy, wherein: in the step (2), the specific process of the forging shaping, the medium-temperature and room-temperature rolling deformation treatment is as follows:

[0024] (2.1) Forging shaping

[0025] The alloy ingot obtained in the step (1) is placed in a heat treatment furnace at a temperature T1 for a holding time t1, and then subjected to forging processing, surface grinding treatment to obtain an alloy plate blank;

[0026] (2.2) Medium-temperature rolling

[0027] The alloy plate blank obtained in the step (2.1) is placed in a heat treatment furnace at a temperature T2 for a holding time t2, and then subjected to temperature T2 rolling, surface treatment and segmentation to obtain an alloy primary plate;

[0028] (2.3) Room-temperature rolling

[0029] The alloy primary plate obtained in the step (2.2) is placed in a heat treatment furnace at a temperature T3 for a holding time t3, and then subjected to room-temperature rolling treatment to obtain an alloy rolled plate.

[0030] The preparation method of the low-density super-elastic functional titanium alloy, wherein: in the step (2.1), the temperature T1 in the forging shaping is 1050ºC~1200ºC, the time t1 is 4h~8h, and the total deformation amount is greater than or equal to 120%.

[0031] The preparation method of the low-density super-elastic functional titanium alloy, wherein: in the step (2.2), the temperature T2 in the medium-temperature rolling is 720ºC~850ºC, the time t2 is 2h~4h, and the total deformation amount is greater than or equal to 50%.

[0032] The preparation method of the low-density super-elastic functional titanium alloy, wherein: in the step (2.3), the temperature T3 in the room-temperature rolling is 580ºC~660ºC, the time t3 is 0.2h~1h, and when the room-temperature rolling deformation amount is greater than 20%, the temperature T3 heat treatment is repeated, and the total deformation amount is greater than or equal to 60%.

[0033] The preparation method of the low-density super-elastic functional titanium alloy, wherein: in the step (3), the temperature T4 in the annealing treatment is 680ºC~900ºC, and the time t4 is 0.5h~4h.

[0034] The preparation method of the low-density super-elastic functional titanium alloy, wherein the mass percentage of the alloy ingot obtained in the step (1) is: Al: 4.2-5.0%, Cr: 1.6-2.2%, Fe: 0.8-1.2%, Mo: 3.0-4.2%, and the balance is Ti and inevitable impurity elements.

[0035] By adopting the technical scheme, the application has the following beneficial effects:

[0036] The application has reasonable concept, and when developing the low-density super-elastic functional titanium alloy, the close correlation between the martensite (alpha' and alpha'') phase change and super-elasticity in the titanium alloy is considered, the critical shear stress of the stress-induced martensite phase change, the start temperature and end temperature of the martensite phase change, the start temperature and end temperature of the austenite phase change and other factors in different stability titanium alloy systems are analyzed, the quantitative relationship between the beta phase stability coefficient of the titanium alloy and the same is focused on, and the ideal numerical range of the beta phase stability coefficient of the titanium alloy for the stress-induced martensite (especially the reversible thermal-elastic martensite) is summarized. At the same time, the plastic deformation mode of the metastable titanium alloy is also closely related to the stability of the alloy, and can be predicted by the parameters of the electronic titanium alloy design theory, the applicant summarizes the parameter value range of the titanium alloy with the stress-induced martensite phase change effect. d The electronic titanium alloy design theory Md and Bo The parameter value range of the titanium alloy with the stress-induced martensite phase change effect. and The parameter value range of the titanium alloy with the stress-induced martensite phase change effect. d The electronic titanium alloy design theory

[0037] For the selection of alloying elements of the low-density super-elastic functional titanium alloy, the applicant jumps out of the relatively mature super-elastic Ti-Nb-Zr titanium alloy system, avoids the high-cost high-density low-beta stability Nb and Zr elements, and selects the low-density alpha phase stable Al element and the high-beta stability Cr, Fe and Mo elements, so as to reduce the alloying degree of the titanium alloy and further reduce the density of the titanium alloy. For the determination of the addition amount of the alloying elements, one is according to the ideal numerical range of the beta phase stability coefficient in the super-elastic titanium alloy composition design theory and the and The third is that the content of Al alloying element is preferentially increased under the same condition, so that the alloying composition of the low-density super-elastic functional titanium alloy in the application is finally determined, i.e., Al: 4.2-5.0%, Cr: 1.6-2.2%, Fe: 0.8-1.2%, Mo: 3.0-4.2%, and the balance is Ti and inevitable impurity elements.

[0038] Compared with the nickel-titanium alloy, the density of the low-density super-elastic functional titanium alloy in the application is reduced by more than 30%, and the cost of alloying elements is also reduced by more than 30%; compared with the commonly used titanium alloy TC4 in aviation, the density of the alloy in the application is increased by about 5%, but the cost of alloying elements is reduced by 40%; compared with the Ti-Nb-Zr titanium alloy, the density and the cost of alloying elements of the alloy in the application are significantly reduced. It can be seen that the super-elastic titanium alloy with a recoverable strain of more than 5% in the application has great advantages in density and cost from the perspective of alloying.

[0039] In the preparation method, a three-step deformation processing route is adopted, and the general idea is to improve the deformation processing capacity of the alloy by a large margin, obtain an ideal titanium alloy microstructure, ensure uniform deformation of the titanium alloy material, and shorten the preparation and processing flow, thereby reducing the preparation cost of the super-elastic titanium alloy material in preparation and processing, solving the key problems of processing difficulty, high cost and large density of existing super-elastic metal materials, and having a significant application prospect in new-generation advanced equipment such as aerospace, ships, intelligent robots, etc.

[0040] In the preparation method, the selection of the forging and shaping heating temperature and the holding time is based on the process of traditional titanium alloy homogenization treatment and cogging forging, and the selection of the temperature and the time ensures that the core and the surface layer of the alloy ingot are uniformly heated, and the long holding time is to diffuse the alloying elements sufficiently to eliminate the interdendritic segregation formed during the alloy solidification process, so that a more uniform microstructure is obtained. In addition, the large total deformation in this step is to reduce the deformation difference between the core and the surface layer of the alloy ingot, so that a rectangular plate blank with uniform internal and external microstructure is obtained.

[0041] The medium-temperature rolling and room-temperature rolling in the preparation method of the application are combined by using two kinds of rolling deformation processing modes, which are aimed at the stress-induced phase change characteristics of the alloy, that is, the dynamic fine-grain strengthening mechanism in the deformation process, so that the preparation and processing flow can be shortened well. The medium-temperature rolling is to reduce the plastic deformation resistance of the alloy and obtain a structure with a specific directional texture; the room-temperature rolling is to use more severe cold deformation of the alloy to refine the structure of the alloy more efficiently and shorten the deformation processing time. The selection of the heating temperature of the medium-temperature rolling is to take into account the regulation of the microstructure and the effect of stress relief annealing.

[0042] By using the low-density super-elastic functional titanium alloy and the preparation method thereof, a super-elastic material with low density and a recoverable deformation of more than 5% is obtained, and the alloy has high tensile strength (more than 1 GPa), good plasticity (elongation rate of more than 10%), excellent work hardening rate (characteristic peak value of more than 5 GPa), and good damping characteristics. As can be seen, the low-density super-elastic functional titanium alloy provided by the application has good comprehensive mechanical properties and excellent functional characteristics, and has a significant application prospect in new-generation advanced equipment such as aerospace, ships, intelligent robots, etc. BRIEF DESCRIPTION OF DRAWINGS

[0043] In order to more clearly illustrate the specific embodiments of the application or the technical solutions in the prior art, the drawings needed in the following description of the specific embodiments or the prior art will be briefly introduced. Obviously, the drawings in the following description are some embodiments of the application, and other drawings can also be obtained by those skilled in the art without creative labor.

[0044] Figure 1 It is a flowchart of the preparation method of the low-density super-elastic functional titanium alloy of the application;

[0045] Figure 2 It is a stress-strain relationship diagram of the low-density super-elastic functional titanium alloy in the embodiment of the application under tensile-unloading;

[0046] Figure 3 It is a stress-strain relationship diagram of the low-density super-elastic functional titanium alloy in the embodiment of the application under room-temperature tensile conditions;

[0047] Figure 4 It is a work hardening curve diagram of the low-density super-elastic functional titanium alloy in the embodiment of the application;

[0048] Figure 5 It is a temperature-loss factor diagram of the low-density super-elastic functional titanium alloy in the embodiment of the application;

[0049] Figure 6Temperature-loss modulus diagram of the low-density super-elastic functional titanium alloy in the embodiments of the present application. DETAILED DESCRIPTION

[0050] The technical solutions of the present application will be described clearly and completely below in conjunction with the drawings. Obviously, the described embodiments are part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor fall within the scope of protection of the present application.

[0051] The present application will be further explained and described below in conjunction with specific embodiments.

[0052] The low-density super-elastic functional titanium alloy provided in the embodiments is composed of the following elements in mass percentage: Al: 4.2-5.0%, Cr: 1.6-2.2%, Fe: 0.8-1.2%, Mo: 3.0-4.2%, and the balance of Ti and inevitable impurity elements.

[0053] The low-density super-elastic functional titanium alloy provided in the present application has the following characteristics: d In the design theory of electronic titanium alloy and The parameter range is ; the beta phase stability coefficient of the alloy is K β The numerical range is 0.491≤ K β ≤0.695.

[0054] The density r of the low-density super-elastic functional titanium alloy provided in the present application is calculated as 4.6≤r≤4.8; the recoverable strain of the alloy is greater than or equal to 5%; the damping coefficient of the alloy within 250ºC-400ºC is greater than 0.01; the storage modulus E' of the alloy has a numerical range of 55GPa≤E'≤85GPa, and within 25ºC-400ºC, E' does not show a rapid decline with the increase of temperature. In addition, the tensile strength of the alloy is greater than or equal to 1GPa, the elongation is greater than 10%, and the characteristic peak value of work hardening rate is greater than or equal to 5GPa. It can be seen that the low-density super-elastic functional titanium alloy provided in the present application has excellent functional characteristics and good comprehensive mechanical properties, and has a significant application prospect in new-generation advanced equipment such as aerospace, ships, and intelligent robots.

[0055] As shown in Figure 1 , the preparation method of the low-density super-elastic functional titanium alloy provided in the present application mainly includes the following steps:

[0056] (1) Melting and ingot casting

[0057] The alloy ingot is obtained by using sponge titanium, pure aluminum particles, pure chromium sheet, pure iron particles and aluminum molybdenum intermediate alloy as raw materials, proportioning the components according to the designed mass percentage of the alloy, uniformly mixing the proportioned raw materials, and then melting the raw materials by using a vacuum melting furnace, wherein the vacuum degree is 10 -4 Pa 10 -2 Pa. As for the selection of the melting furnace, when the weight of the alloy ingot is greater than or equal to 20 kg, the melting furnace can be selected as a vacuum electron beam melting furnace or a vacuum consumable melting furnace, and the melting frequency of the vacuum electron beam melting furnace is 1-2 times; when the weight of the alloy ingot is less than 20 kg, the melting furnace can be selected as a vacuum suspension melting furnace or a vacuum non-consumable melting furnace; wherein the repeated melting frequency n of the vacuum suspension melting furnace or the vacuum consumable melting furnace is 2-4 times, and the repeated melting frequency n of the vacuum non-consumable melting furnace is 5-8 times. When the alloy ingot is repeatedly melted, the ingot melted in the previous time is inverted to start new melting, so as to reduce segregation and obtain an ingot with uniform composition;

[0058] (2) Deformation processing

[0059] This step can be divided into three parts, and the alloy material is heated to the target temperature and kept for a certain time, then the deformation processing of forging, medium temperature and room temperature rolling is carried out, and the rolled plate is obtained. The specific technical route is introduced as follows:

[0060] (2.1) Forging

[0061] The alloy ingot in step (1) is placed in a heat treatment furnace with a temperature T1 of 1050ºC~1200ºC and a holding time t1 of 4h~8h, and then the forging processing (which is a common forging processing for titanium alloy, that is, upsetting and elongation) is carried out, and the total deformation amount in the length, height and width directions is greater than or equal to 120%, and the square or other shaped alloy plate blank is obtained after surface grinding treatment;

[0062] (2.2) Medium temperature rolling

[0063] The alloy plate blank in step (2.1) is placed in a heat treatment furnace with a temperature T2 of 720ºC~850ºC and a holding time t2 of 2h~4h, and then the temperature T2 rolling is carried out, the total deformation amount in the thickness direction is greater than or equal to 50%, and the alloy primary plate is obtained after surface treatment (which refers to the machining treatment of mechanical polishing of the surface of the rolled plate, cutting of the edge, and removal of the oxide layer) and segmentation;

[0064] (2.3) Room temperature rolling

[0065] Put the alloy primary plate in step (2.2) into a heat treatment furnace with a temperature T3 of 580°C~660°C for a holding time t3 of 0.2h~1h, and after cooling, carry out room temperature (usually refers to 0-30°C) rolling treatment, and when the room temperature rolling deformation is greater than 20%, repeat the heat treatment at the temperature T3, and the total deformation in the thickness direction is greater than or equal to 60%, to obtain an alloy rolling plate;

[0066] (3) Annealing treatment

[0067] Put the alloy rolling plate in step (2.3) into a heat treatment furnace with a temperature T4 of 680°C~900°C for a holding time t4 of 0.5h~4h, take out and carry out rapid cooling (put the sample into water for cooling), and then polish the surface, to finally obtain a super-elastic titanium alloy material.

[0068] The density r of the low-density super-elastic functional titanium alloy provided by the application is calculated as 4.6≤r≤4.8; the recoverable strain of the alloy is greater than or equal to 5%; the damping coefficient of the alloy is greater than or equal to 0.01 within 250°C~400°C; the storage modulus E' of the alloy is in the range of 55GPa≤E'≤85GPa, and within 25°C~400°C, E' does not show a rapid decrease with the increase of temperature. In addition, the tensile strength of the alloy is greater than or equal to 1GPa, the elongation is greater than 10%, and the characteristic peak of the work hardening rate is greater than or equal to 5GPa. It can be seen that the low-density super-elastic functional titanium alloy provided by the application has excellent functional characteristics and good comprehensive mechanical properties, and has a significant application prospect in new-generation advanced equipment such as aerospace, ships, intelligent robots, etc.

[0069] Example 1:

[0070] The low-density super-elastic functional titanium alloy in Example 1 of the application is composed of the following elements by mass percentage: Al is 4.8%, Cr is 2.0%, Fe is 1.0%, Mo is 3.2%, and the balance is Ti and inevitable impurity elements.

[0071] The low-density super-elastic functional titanium alloy provided in Example 1 of the application has the following characteristics: d In the electronic titanium alloy design theory, the and parameters are 2.389 and 2.762 respectively, and the beta phase stability coefficient K β The value is 0.584, and the density r is calculated as 4.69.

[0072] In combination with the preparation method flowchart of the low-density super-elastic functional titanium alloy shown in Figure 1 , the predetermined melting ingot mass is 2kg, and the specific steps can include the following steps:

[0073] (1) Smelting and casting ingots

[0074] Using sponge titanium, pure aluminum granules, pure chromium flakes, pure iron granules, and aluminum-molybdenum master alloy as raw materials, the components are proportioned according to the designed alloy mass percentage. After the raw materials are mixed evenly, they are repeatedly melted three times in a vacuum levitation melting furnace to obtain an alloy ingot. The vacuum degree is 10. -3 Pa, and when repeatedly melting alloy ingots, the ingot head and tail are reversed before a new melting begins.

[0075] (2) Deformation processing

[0076] This step can be divided into three parts: first, heating the alloy material to the target temperature and holding it at that temperature; then, forging and shaping; and finally, medium-temperature and room-temperature rolling deformation treatments to obtain the rolled sheet. The specific technical routes are described below:

[0077] (2.1) Forging and shaping

[0078] The alloy ingot in step (1) is placed in a heat treatment furnace with a temperature T1 of 1150ºC and held for t1 for 4 hours. Then it is forged and the total deformation in the length, height and width directions is greater than 150%. After surface grinding, a square alloy plate billet is obtained.

[0079] (2.2) Medium temperature rolling

[0080] The alloy plate billet in step (2.1) is placed in a heat treatment furnace at a temperature of 750ºC for a holding time of 2h, and then subjected to medium-temperature rolling with a total deformation of 58% in the thickness direction. After surface treatment and segmentation, the primary alloy plate is obtained.

[0081] (2.3) Room temperature rolling

[0082] The primary alloy sheet from step (2.2) is placed in a heat treatment furnace at a temperature of 600ºC and held for 0.5 hours. After cooling, it is rolled at room temperature. When the room temperature rolling deformation is greater than 20%, the heat treatment at temperature T3 is repeated. The total deformation in the thickness direction is 82%, and the alloy rolled sheet is obtained.

[0083] (3) Annealing treatment

[0084] The alloy rolled plate from step (2.3) is placed in a heat treatment furnace at a temperature of 830ºC for 1 hour and then rapidly cooled. Its surface is then polished to obtain a superelastic titanium alloy material.

[0085] like Figures 2-6 As shown ( Figures 2-6The curve 1 in the figure represents the test analysis curve of the example 1, the mechanical property and functional characteristic test analysis is conducted on the low-density super-elastic functional titanium alloy in the example 1 of the application, the test result shows that the recoverable strain of the alloy is greater than 5%, the tensile strength is 1070 MPa, the elongation is greater than 10%, the characteristic peak value of the work hardening rate is 15.2 GPa; within 25ºC~400ºC, the damping coefficient of the alloy is greater than 0.01 and the storage modulus E' slowly increases with the temperature rise, and slightly decreases at 380ºC. It can be seen that the low-density super-elastic functional titanium alloy provided in the example 1 of the application has good comprehensive mechanical property and excellent functional characteristics.

[0086] Example 2

[0087] The low-density super-elastic functional titanium alloy in the example 2 of the application is composed of the following mass percentages of elements: Al is 4.2%, Cr is 1.8%, Fe is 1.0%, Mo is 4.0%, and the balance is Ti and inevitable impurity elements.

[0088] The low-density super-elastic functional titanium alloy provided in the example 2 of the application has the following characteristics: d In the electronic titanium alloy design theory, the and The parameters are 2.391 and 2.767 respectively, the beta phase stability coefficient K β The numerical value is 0.602, and the density r is calculated as 4.74.

[0089] Combined with the preparation method of the low-density super-elastic functional titanium alloy shown in the figure, the predetermined melting and ingot quality is 5 kg, and the specific steps can include the following steps: Figure 1

[0090] (1) Melting and ingot casting

[0091] Sponge titanium, pure aluminum particles, pure chromium sheet, pure iron particles and aluminum molybdenum intermediate alloy are used as raw materials, the components are proportioned according to the designed mass percentage of the alloy, the raw materials are mixed uniformly, and the alloy ingot is obtained after repeated melting 3 times by using a vacuum suspension melting furnace, the vacuum degree is 10 -3 Pa, and the ingot head and tail are inverted before starting new melting during repeated melting of the alloy ingot.

[0092] (2) Deformation processing

[0093] This step can be divided into 3 parts, the alloy material is heated to the target temperature and kept warm, then the forging shaping, medium temperature and room temperature rolling deformation treatment are conducted, and the rolling plate is obtained, and the specific technical route is introduced as follows:

[0094] (2.1) Forging shaping ​

[0095] The alloy ingot in step (1) is placed in a heat treatment furnace at a temperature of 1160ºC and held for 4.5 hours. Then it is forged and the total deformation in the length, height and width directions is greater than 120%. After surface grinding, a square alloy plate billet is obtained.

[0096] (2.2) Medium temperature rolling

[0097] The alloy plate billet in step (2.1) is placed in a heat treatment furnace at a temperature of 720ºC for a holding time of t2 for 2 hours, and then subjected to medium-temperature rolling with a total deformation of 65% in the thickness direction. After surface treatment and segmentation, the primary alloy plate is obtained.

[0098] (2.3) Room temperature rolling

[0099] The primary alloy sheet from step (2.2) is placed in a heat treatment furnace at a temperature of 620ºC and held for 0.75 hours. After cooling, it is rolled at room temperature. When the room temperature rolling deformation is greater than 20%, the heat treatment at temperature T3 is repeated. The total deformation in the thickness direction is 86%, and the alloy rolled sheet is obtained.

[0100] (3) Annealing treatment

[0101] The alloy rolled plate from step (2.3) is placed in a heat treatment furnace at a temperature of 820ºC for 0.5 hours and then rapidly cooled. Its surface is then polished to obtain a superelastic titanium alloy material.

[0102] like Figures 2-6 As shown ( Figures 2-6 Curve 2 in the figure represents the test curve of Example 2. Mechanical properties and functional characteristics of the low-density superelastic functional titanium alloy in Example 2 of this invention were tested and analyzed. The test results show that the recoverable strain of the alloy is greater than 5%, the tensile strength is 1078 MPa, the elongation is greater than 10%, and the characteristic peak value of the work hardening rate is 7.3 GPa. Within the temperature range of 180ºC to 400ºC, the alloy damping coefficient is greater than 0.01, and the storage modulus E' increases slowly with increasing temperature, showing a slight decrease at 375ºC. Therefore, the low-density superelastic functional titanium alloy provided in Example 2 of this invention possesses both good comprehensive mechanical properties and excellent functional characteristics.

[0103] Example 3:

[0104] The low-density superelastic functional titanium alloy in Embodiment 3 of the present invention is composed of the following elements by mass percentage: Al 4.5%, Cr 2%, Fe 1.0%, Mo 3.5%, with the balance being Ti and unavoidable impurity elements.

[0105] The low-density, superelastic functional titanium alloy provided in Embodiment 3 of this invention, in d In the design theory of electronic titanium alloys and The parameters are 2.389 and 2.765, respectively, and the β-phase stability coefficient... K β The value is 0.602, and its density r is calculated to be 4.71.

[0106] Combination Figure 1 The diagram shows a process flow chart of a low-density superelastic functional titanium alloy according to the present invention. The predetermined ingot mass for melting and casting is 200 kg, and the process may include the following steps:

[0107] (1) Smelting and casting ingots

[0108] Using sponge titanium, pure aluminum particles, pure chromium sheets, pure iron particles, and aluminum-molybdenum master alloy as raw materials, the components are proportioned according to the designed alloy mass percentage. After the raw materials are mixed evenly, electrodes are prepared. The electrodes are then repeatedly melted three times in a vacuum consumable furnace to obtain alloy ingots. The vacuum degree is 10. -3 Pa, and when repeatedly melting alloy ingots, the ingot head and tail are reversed before a new melting begins.

[0109] (2) Deformation processing

[0110] This step can be divided into three parts: first, heating the alloy material to the target temperature and holding it at that temperature; then, forging and shaping; and finally, medium-temperature and room-temperature rolling deformation treatments to obtain the rolled sheet. The specific technical routes are described below:

[0111] (2.1) Forging and shaping

[0112] The alloy ingot in step (1) is placed in a heat treatment furnace with a temperature T1 of 1150ºC and held for t1 for 6 hours. Then it is forged and the total deformation in the length, height and width directions is greater than 180%. After surface grinding, a square alloy plate billet is obtained.

[0113] (2.2) Medium temperature rolling

[0114] The alloy plate billet in step (2.1) is placed in a heat treatment furnace at a temperature of 760ºC for a holding time of t2 for 4 hours, and then subjected to medium-temperature rolling with a total deformation of 90% in the thickness direction. After surface treatment and segmentation, the primary alloy plate is obtained.

[0115] (2.3) Room temperature rolling

[0116] The primary alloy sheet from step (2.2) is placed in a heat treatment furnace at a temperature of 600ºC for 1 hour. After cooling, it is rolled at room temperature. When the room temperature rolling deformation is greater than 20%, the heat treatment at temperature T3 is repeated. The total deformation in the thickness direction is 81%, and the alloy rolled sheet is obtained.

[0117] (3) Annealing treatment

[0118] The alloy rolled plate from step (2.3) is placed in a heat treatment furnace at a temperature T4 of 850ºC and held for 0.5h. After being removed and rapidly cooled, its surface is polished to obtain a superelastic titanium alloy material.

[0119] like Figures 2-6 As shown ( Figures 2-6 Curve 3 in the figure represents the experimental analysis curve of Example 3. Mechanical properties and functional characteristics of the low-density superelastic functional titanium alloy in Example 3 of this invention were tested and analyzed. The test results show that the alloy has a recoverable strain greater than 5%, a tensile strength of 1115 MPa, an elongation greater than 10%, and a characteristic peak value of 11.8 GPa for work hardening rate. Within the temperature range of 225ºC to 400ºC, the alloy damping coefficient is greater than 0.01. Therefore, the low-density superelastic functional titanium alloy provided in Example 3 of this invention possesses both good comprehensive mechanical properties and excellent functional characteristics.

[0120] This invention has a reasonable concept, based on the stability coefficient of the β phase of titanium alloys and d Based on the design theory of electronic titanium alloys, and through the optimization of alloying elements and short-process preparation technology, a low-density, low-cost hyperelastic functional titanium alloy with recoverable strain exceeding 5% and its preparation method have been successfully developed. Simultaneously, this alloy possesses excellent comprehensive properties such as high damping, high work hardening rate, and high strength and plasticity, solving the key problems of difficult processing, high cost, and high density faced by existing hyperelastic metallic materials. It shows significant application prospects in next-generation advanced equipment such as aerospace, shipbuilding, and intelligent robots.

[0121] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A low density superelastic functional titanium alloy, characterized in that, Consist of the following mass percentages of elements: Al: 4.2~5.0%, Cr: 1.6~2.2%, Fe: 0.8~1.2%, Mo: 3.0~4.2%, the balance is Ti and inevitable impurity elements; The preparation method of the low-density super-elastic functional titanium alloy comprises the following steps: (1) alloy ingot smelting Sponge titanium, pure aluminum particles, pure chromium sheet, pure iron particles and aluminum-molybdenum intermediate alloy are used as raw materials and are proportioned according to the designed mass percentage of the alloy, then the proportioned raw materials are uniformly mixed, and the alloy ingot is obtained by repeated smelting using a vacuum melting furnace; (2) forging and rolling deformation processing The alloy ingot obtained in the above step (1) is heated to a target temperature and then is kept for a certain time, and then is subjected to forging, medium-temperature and room-temperature rolling deformation processing, and finally the alloy rolling plate is obtained; (3) annealing treatment The alloy rolling plate obtained in the above step (2) is placed in a heat treatment furnace with a temperature of T4 for a time t4, then is taken out and rapidly cooled, and then the surface is polished, and finally the super-elastic titanium alloy material is obtained; The specific process of the forging, medium-temperature and room-temperature rolling deformation processing in step (2) is as follows: (2.1) forging The alloy ingot obtained in step (1) is placed in a heat treatment furnace with a temperature T1 for a time t1, and then is subjected to forging processing, and finally the alloy plate blank is obtained after surface grinding treatment; (2.2) medium-temperature rolling The alloy plate blank obtained in the above step (2.1) is placed in a heat treatment furnace with a temperature T2 for a time t2, and then is subjected to temperature T2 rolling, surface treatment and segmentation, and finally the alloy primary plate is obtained; (2.3) room-temperature rolling The alloy primary plate obtained in the above step (2.2) is placed in a heat treatment furnace with a temperature T3 for a time t3, and then is subjected to room-temperature rolling processing after cooling, and finally the alloy rolling plate is obtained; The temperature T1 in the forging of step (2.1) is 1050ºC~1200ºC, the time t1 is 4h~8h, and the total deformation amount is greater than or equal to 120%; The temperature T2 in the medium-temperature rolling of step (2.2) is 720ºC~850ºC, the time t2 is 2h~4h, and the total deformation amount is greater than or equal to 50%; The temperature T3 in the room-temperature rolling of step (2.3) is 580ºC~660ºC, the time t3 is 0.2h~1h, and the room-temperature rolling deformation amount is greater than 20%, and the heat treatment at temperature T3 is repeated, and the total deformation amount is greater than or equal to 60%; The temperature T4 in the annealing treatment of step (3) is 680ºC~900ºC, and the time t4 is 0.5h~4h.

2. The low density, super-elastic functional titanium alloy of claim 1 wherein: The alloy is in the d-electron titanium alloy design theory and The parameter ranges are respectively 2.365≤ ≤2.395, 2.762≤ ≤2.778; the β phase stability coefficient Kβ of the alloy is in the numerical range of 0.491≤Kβ≤0.

695.

3. The low density, super-elastic functional titanium alloy of claim 1 wherein: Density of the alloy 4.6 ≤ 4.

8.

4. The low density, super-elastic functional titanium alloy of claim 1 wherein: The recoverable strain of the alloy is greater than 5%, and the damping coefficient of the alloy within 250ºC~400ºC is greater than 0.

01.

5. The low density, super-elastic functional titanium alloy of claim 1 wherein: The storage modulus E' of the alloy is in the range of 55GPa≤E'≤85GPa, and the storage modulus E' does not show a rapid decrease with the increase of temperature within 25ºC~400ºC.

6. The low density, super-elastic functional titanium alloy of claim 1 wherein: The tensile strength of the alloy is greater than 1GPa, the elongation is greater than 10%, and the characteristic peak of work hardening rate is greater than 5GPa.

7. A method of producing the low-density super-elastic functional titanium alloy according to any one of claims 1 to 6, characterized by, Mainly comprising the following steps: (1) alloy ingot smelting The alloy ingot is obtained by repeatedly melting the raw materials of sponge titanium, pure aluminum particles, pure chromium sheet, pure iron particles and aluminum-molybdenum intermediate alloy in a vacuum melting furnace according to the designed mass percentage of the alloy; (2) forging and rolling deformation processing The alloy ingot obtained in step (1) is heated to a target temperature and then held for a certain time, and then subjected to forging, medium-temperature rolling and room-temperature rolling deformation processing, and finally an alloy rolled plate is obtained. (3) annealing treatment The alloy rolled plate obtained in step (2) is placed in a heat treatment furnace at a temperature of T4 for a holding time of T4, then taken out and rapidly cooled, and then the surface is polished to obtain a super-elastic titanium alloy material.

8. The method of making a low density super-elastic functional titanium alloy of claim 7 wherein: In step (1), when the weight of the alloy ingot is greater than or equal to 20 kg, the vacuum melting furnace is selected to be a vacuum electron beam melting furnace or a vacuum consumable melting furnace, and the melting frequency of the vacuum electron beam melting furnace is 1-2 times, and the repeated melting frequency of the vacuum consumable melting furnace is 2-4 times. In the step (1), when the alloy ingot with a weight less than 20 kg is prepared, the vacuum melting furnace is selected from a vacuum floating melting furnace and a vacuum non-consumable melting furnace, wherein the vacuum floating melting furnace has a repeated melting number of 2-4 times, and the vacuum non-consumable melting furnace has a repeated melting number of 5-8 times, and the vacuum degree is .

9. The method of making a low density super-elastic functional titanium alloy of claim 7 wherein: In step (1), when the alloy ingot is repeatedly melted, the ingot from the previous melting is inverted before starting the new melting to reduce segregation and obtain an ingot with uniform composition.

10. The method of making a low density superelastic functional titanium alloy of claim 7 wherein In step (2), the specific process of the forging, medium-temperature rolling and room-temperature rolling deformation processing is as follows: (2.1) forging The alloy ingot obtained in step (1) is placed in a heat treatment furnace at a temperature T1 for a holding time t1, and then subjected to forging and surface grinding to obtain an alloy plate blank. (2.2) medium-temperature rolling The alloy plate blank obtained in step (2.1) is placed in a heat treatment furnace at a temperature T2 for a holding time t2, and then subjected to temperature T2 rolling, surface treatment and division to obtain an alloy primary plate. (2.3) room-temperature rolling The alloy primary plate obtained in step (2.2) is placed in a heat treatment furnace at a temperature T3 for a holding time t3, and then subjected to room-temperature rolling to obtain an alloy rolled plate.

11. The method of making a low density super-elastic functional titanium alloy of claim 10 wherein: In step (2.1), the temperature T1 is 1050ºC~1200ºC, the time t1 is 4h~8h, and the total deformation is greater than or equal to 120%.

12. The method of making a low density, super-elastic functional titanium alloy of claim 10 wherein: In step (2.2), the temperature T2 is 720ºC~850ºC, the time t2 is 2h~4h, and the total deformation is greater than or equal to 50%.

13. The method of making a low density super-elastic functional titanium alloy of claim 7 wherein: In step (2.3), the temperature T3 is 580ºC~660ºC, the time t3 is 0.2h~1h, and when the room-temperature rolling deformation is greater than 20%, the temperature T3 is repeated, and the total deformation is greater than or equal to 60%.

14. The method of making a low density, super-elastic functional titanium alloy of claim 7 wherein: In step (3), the temperature T4 is 680ºC~900ºC, and the time t4 is 0.5h~4h.

15. The method of making a low density, super-elastic functional titanium alloy of claim 7 wherein, In step (1), the mass percentage of the alloy ingot is: Al: 4.2~5.0%, Cr: 1.6~2.2%, Fe: 0.8~1.2%, Mo: 3.0~4.2%, and the balance is Ti and unavoidable impurities.

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