Titanium alloy with wide temperature range and low invariant elastic modulus as well as thermal mechanical treatment method and application thereof

Abstract

The invention provides a thermomechanical treatment method for obtaining a titanium alloy with a wide temperature range and a low invariant elastic modulus, and relates to the technical field of titanium alloy performance design and preparation, the method comprises the following steps: firstly, carrying out solution treatment on the titanium alloy in a single-phase region, the solution temperature is 800-1000 DEG C, and the heat preservation time is 1-5 hours; the titanium alloy obtained through solid solution is subjected to aging treatment; and finally, the titanium alloy obtained after aging treatment is subjected to cold rolling deformation. The alloy prepared by the method has the characteristics of wide temperature range and low invariant modulus, the elasticity modulus is 43-56GPa, and the elasticity modulus can be kept unchanged within the temperature range of-268-350 DEG C. The method is simple in process step and low in production cost, and has a good application prospect in the fields of biomedicine, precise instruments, aerospace and the like.

Description

Technical Field

[0001] The present invention belongs to the technical field of titanium alloy performance design and preparation, and specifically relates to a titanium alloy with a low constant elastic modulus over a wide temperature range, and a thermomechanical treatment method and application thereof. Background Art

[0002] Titanium alloys have excellent biocompatibility, good superelasticity, high strength and plasticity, and have broad application prospects in the fields of aerospace and medical implants. The patent application document with publication number CN 116695041 A discloses a heat treatment method for Ti-6Al-4V alloy. Through the process of solid solution treatment → water cooling quenching → aging treatment, the shear strength of the alloy can be improved, thereby meeting the use requirements of titanium alloy fasteners in the aviation and aerospace fields. However, the elastic modulus of Ti-6Al-4V (100-110GPa) is much higher than that of human bones (10-30GPa), so it will cause stress shielding, and the doped elements Al and V are toxic to the human body, thus limiting the application of the alloy in biomedicine. The patent application document with publication number CN 107805740 B discloses a method for preparing a medical implant titanium alloy with low elastic modulus and high fatigue strength. The alloy used is a Ti-Nb-Zr-Mo-O multi-component alloy, and its room temperature elastic modulus is 50% of that of the Ti-6Al-4V alloy. The alloys in the above-mentioned technologies involve a large number of doping elements, the preparation method is complex and has a long cycle, and the production efficiency is low.

[0003] It is worth noting that the current research on low elastic modulus titanium alloys mainly focuses on the room temperature elastic modulus characteristics, and there are very few literatures reporting the elastic modulus at different temperatures. Summary of the invention

[0004] The purpose of the present invention is to provide a thermomechanical treatment method for a titanium alloy with a low constant elastic modulus over a wide temperature range, so as to solve the problem of continuous hardening or continuous softening of the elastic modulus of the material obtained by the existing preparation method.

[0005] The present invention also aims to provide a method for preparing the titanium alloy, which further simplifies the process steps, makes the process controllable and increases production efficiency.

[0006] The technical solution of the present invention is as follows:

[0007] The present invention provides a thermomechanical treatment method for a titanium alloy with a wide temperature range and low constant elastic modulus, comprising the following steps:

[0008] Step 1: Single-phase solution treatment

[0009] Performing a solid solution treatment on the titanium alloy in the single-phase region, the solid solution temperature is 800-1000°C, the holding time is 1-5 hours, and then water-cooling quenching the titanium alloy after the solid solution treatment;

[0010] Step 2: Aging treatment of phase modulation amplitude decomposition area

[0011] Performing aging treatment on the titanium alloy obtained in step 1, the aging treatment temperature is 250-450° C., the heat preservation time is 1-30 days, and then performing water cooling quenching treatment on the titanium alloy after aging treatment;

[0012] Step 3: Cold deformation treatment

[0013] The titanium alloy obtained in step 2 is subjected to cold rolling deformation with a deformation amount of 20 to 90% to obtain the titanium alloy with a wide temperature range and low constant elastic modulus.

[0014] Furthermore, the composition of the titanium alloy is Ti-(45-56) wt.% Nb binary alloy.

[0015] Furthermore, the solution temperature in step 1 is 850-950°C, and the holding time is 1 hour.

[0016] Furthermore, the aging treatment temperature in step 2 is 375-400° C., and the insulation time is 6-21 days.

[0017] Furthermore, the cold rolling deformation in step 3 is 30-50%.

[0018] The present invention also provides a titanium alloy with a wide temperature range and a low constant elastic modulus. The titanium alloy with a wide temperature range and a low constant elastic modulus is obtained by the thermomechanical treatment method of the titanium alloy with a wide temperature range and a low constant elastic modulus as mentioned above. The temperature range of the titanium alloy with a wide temperature range and a low constant elastic modulus is -268 to 350°C, and optionally -150 to 55°C; the elastic modulus is 43 to 56 GPa.

[0019] The present invention also provides applications of the above-mentioned titanium alloy with a wide temperature range and low constant elastic modulus in the fields of biomedicine, precision instruments and aerospace.

[0020] Compared with the prior art, the present invention has at least the following advantages:

[0021] 1) The present invention ensures that the alloy is a single β phase through solid solution treatment, improves the uniformity of the alloy structure, and further ensures that the alloy has excellent plastic processing performance.

[0022] 2) Through further aging treatment, the β-phase spinodal decomposition microstructure was obtained, and the formation of other metastable phases was avoided. The nanoscale β-phase spinodal decomposition organization increased the tensile strength of the alloy by 15%, ensuring that the alloy had good plasticity, with a plastic deformation of 18-20%, and significantly reduced the elastic modulus of the alloy from 85GPa to 43-56GPa.

[0023] 3) Further cold rolling deformation makes the alloy have the characteristics of low constant modulus in a wide temperature range, and the elastic modulus remains unchanged in the temperature range of -268 to 350°C, especially in the temperature range of -150 to 55°C. The alloy has great advantages in low-temperature applications.

[0024] 4) The selected alloy types are simple, which is more conducive to analyzing the effects of Nb and Ti elements on phase composition and microstructure, and this method can be applied to other binary and multi-component titanium alloy systems with spinodal decomposition. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 is a process flow chart of the present invention;

[0026] Figure 2 is the rapid scanning X-ray diffraction pattern of Example 1;

[0027] Figure 3 The slow scanning high 2θ angle X-ray diffraction patterns of the embodiments and comparative examples of the present invention, wherein (a) is the X-ray diffraction pattern of embodiment 1, (b) is the X-ray diffraction pattern of embodiment 2, (c) is the X-ray diffraction pattern of embodiment 3, and (d) is the X-ray diffraction pattern of comparative example 1;

[0028] Figure 4 1 are the high-resolution images and the corresponding Fourier transform results of Example 1, wherein (a) is the high-resolution image of Example 1, and (b) is the inverse Fourier transform result corresponding to (a);

[0029] Figure 5 1 and 2. The Young's modulus-temperature graphs of the embodiments and comparative examples of the present invention are shown in FIG. 1 , wherein (a) is the Young's modulus-temperature graph of Embodiment 1, (b) is the Young's modulus-temperature graph of Embodiment 2, (c) is the Young's modulus-temperature graph of Embodiment 3, and (d) is the Young's modulus-temperature graph of the sample of Comparative Example 1. DETAILED DESCRIPTION

[0030] The present invention is based on the controllability of heat treatment process and cold deformation process, including multiple adjustable process parameters such as aging temperature, aging time, cooling rate and cold deformation degree. By controlling the process parameters of thermomechanical treatment, the phase composition, phase distribution and morphological characteristics of the alloy can be regulated. For titanium alloys with high β-phase stabilizing elements, the characteristics of low constant elastic modulus in a wide temperature range can be obtained by regulating the β-phase amplitude modulation decomposition microstructure.

[0031] The present invention is described in detail below in conjunction with specific implementation modes.

[0032] like Figure 1 As shown, a thermomechanical treatment method for a titanium alloy with a wide temperature range and low constant elastic modulus comprises the following steps:

[0033] Step 1: β single phase solution treatment

[0034] The titanium alloy is subjected to a solid solution treatment in the β single phase region, the solid solution temperature is 800-1000°C, the heat preservation time is 1-5 hours, and the titanium alloy is subjected to a solid solution treatment above the β transformation temperature to obtain a β single phase with a uniform microstructure;

[0035] Step 2: Aging treatment of β phase amplitude modulation decomposition zone

[0036] The titanium alloy obtained after heat preservation in step 1 is subjected to aging treatment, the aging treatment temperature is 250-450°C, and the heat preservation time is 1-30 days; by adjusting the aging temperature and aging time, a β-phase spinodal decomposition microstructure is obtained, and a large amount of precipitation of other metastable phases is avoided. The formation of the nanoscale spinodal decomposition microstructure changes the elastic deformation behavior of the titanium alloy, thereby reducing the elastic modulus of the titanium alloy.

[0037] Step 3: Cold deformation treatment

[0038] The titanium alloy obtained in step 2 is subjected to cold rolling deformation, with the deformation amount being 20 to 90%.

[0039] Compared with the existing thermomechanical treatment process, the above-mentioned thermomechanical treatment process can form the excellent performance of low constant modulus in a wide temperature range, and at the same time improve the strength of the alloy and improve the plasticity of the alloy. Existing thermomechanical treatment methods usually obtain an α″ metastable phase, and the alloy regulates the elastic modulus of the alloy by undergoing a β→α″ martensitic phase transformation. This method is suitable for alloy systems with low β-phase stabilizing elements. In high β-phase stabilizing element systems, the β→α″ martensitic phase transformation is suppressed, and this mechanism is no longer applicable. The present invention only obtains the β-phase amplitude modulation decomposition structure through aging treatment, which can effectively reduce the elastic modulus of the alloy, and on this basis, performs room temperature plastic deformation to obtain a low constant elastic modulus in a wide temperature range, providing a new idea for designing the elastic properties of titanium alloys.

[0040] As a preferred embodiment of the present invention, the titanium alloy takes Ti-53wt.%Nb alloy as an example.

[0041] Embodiment 1: A thermomechanical treatment method for a titanium alloy with a wide temperature range and low constant elastic modulus, comprising the following steps:

[0042] Step 1: β single phase solution treatment

[0043] The titanium alloy is subjected to a solid solution treatment in the β single phase region, the solid solution temperature is 900°C, the holding time is 1h, and the titanium alloy is subjected to a solid solution treatment above the β transformation temperature to obtain a β single phase with a uniform microstructure;

[0044] Step 2: β phase aging treatment to obtain spinodal decomposition structure

[0045] The titanium alloy obtained after heat preservation in step 1 is subjected to aging treatment, the aging treatment temperature is 400° C., and the heat preservation time is 21 days;

[0046] Step 3: Cold rolling

[0047] The titanium alloy obtained in step 2 is subjected to cold rolling deformation with a deformation amount of 40%.

[0048] The average phase composition of the sample at room temperature was obtained by a rapid scanning method using a scanning X-ray diffractometer. The rapid scanning X-ray diffraction results are shown in Figure 2 The alloy only exhibits an average crystal structure of the β phase, and no other metastable phase is generated. Further, the slow scanning method is used to preliminarily determine whether the alloy has produced spinodal decomposition. The slow scanning high 2θ angle X-ray diffraction results are shown in Figure 3 As shown in (a), the alloy shows the phenomenon of β phase peak splitting, which preliminarily indicates that β phase spinodal decomposition structure has been produced in the alloy. Figure 4 The high-resolution transmission electron microscope image and the corresponding Fourier transform result of the alloy sample show that the alloy forms β-phase spot splitting, and its inverse Fourier transform image shows the interconnected microstructure of nanoscale β1 phase and β2 phase, and its periodic wavelength is 2-3nm. A coherent interface is formed between the β1 phase and the β2 phase, which is a typical microstructure of spinodal decomposition. Combined with the slow scanning high 2θ angle X-ray diffraction results, it is proved that the alloy has formed β-phase spinodal decomposition. The alloy was prepared into a dog-bone shaped sample, and a low-temperature extensometer was used to perform loading-unloading tensile tests at different temperatures to obtain the curve of the sample's Young's modulus changing with temperature, and liquid nitrogen was used to cool the equipment. The temperature was set to -268~350℃, and its Young's modulus-temperature curve is shown in Figure 5 As shown in (a), the Young's modulus of the alloy is around 43 GPa, and the alloy has the characteristics of low constant elastic modulus over a wide temperature range.

[0049] Embodiment 2: A thermomechanical treatment method for a titanium alloy with a wide temperature range and low constant elastic modulus, comprising the following steps:

[0050] Step 1: β single phase solution treatment

[0051] The titanium alloy is solution treated in the β single phase region, the solution temperature is 850°C, the holding time is 1h, and the titanium alloy is solution treated above the β transformation temperature to obtain a β single phase with uniform microstructure;

[0052] Step 2: β phase aging treatment to obtain spinodal decomposition structure

[0053] The titanium alloy obtained after heat preservation in step 1 is subjected to aging treatment, the aging treatment temperature is 400° C., and the heat preservation time is 6 days;

[0054] Step 3: Cold rolling

[0055] The titanium alloy obtained in step 2 is subjected to cold rolling deformation with a deformation amount of 50%.

[0056] The slow scanning high 2θ angle X-ray diffraction method is used to preliminarily determine whether the alloy has produced spinodal decomposition. The slow scanning high 2θ angle X-ray diffraction results are as follows: Figure 3 As shown in (b), the alloy shows the phenomenon of β phase peak splitting, indicating that β phase spinodal decomposition structure is also produced in the alloy. The alloy is prepared into a dog-bone shaped sample, and a loading-unloading tensile test is performed at different temperatures with a low-temperature extensometer to obtain the curve of the sample's Young's modulus changing with temperature. Liquid nitrogen is used to cool the equipment. The temperature is set to -150℃~55℃, and its Young's modulus-temperature curve is as follows Figure 5 As shown in (b), the Young's modulus of the alloy is 56 GPa, which proves that the alloy also has the characteristics of low constant elastic modulus in a wide temperature range.

[0057] Embodiment 3: A thermomechanical treatment method for a titanium alloy with a wide temperature range and low constant elastic modulus, comprising the following steps:

[0058] Step 1: β single phase solution treatment

[0059] The titanium alloy is solution treated in the β single phase region, the solution temperature is 950°C, the holding time is 1h, and the titanium alloy is solution treated above the β transformation temperature to obtain a β single phase with uniform microstructure;

[0060] Step 2: β phase aging treatment to obtain spinodal decomposition structure

[0061] The titanium alloy obtained after heat preservation in step 1 is subjected to aging treatment, the aging treatment temperature is 375° C., and the heat preservation time is 14 days;

[0062] Step 3: Cold rolling

[0063] The titanium alloy obtained in step 2 is subjected to cold rolling deformation with a deformation amount of 30%.

[0064] The slow scanning high 2θ angle X-ray diffraction method is used to preliminarily determine whether the alloy has produced spinodal decomposition. The slow scanning high 2θ angle X-ray diffraction results are as follows: Figure 3 As shown in (c), the alloy shows the phenomenon of β phase peak splitting, indicating that β phase spinodal decomposition structure is also produced in the alloy. The alloy is prepared into a dog-bone shaped sample, and a loading-unloading tensile test is performed at different temperatures with a low-temperature extensometer to obtain the curve of the sample's Young's modulus changing with temperature. Liquid nitrogen is used to cool the equipment. The temperature is set to -150℃~55℃, and its Young's modulus-temperature curve is as follows Figure 5As shown in (c), the Young's modulus of the alloy is 56 GPa, and the alloy also has the characteristics of low constant elastic modulus in the high temperature stage.

[0065] Comparative Example 1

[0066] The type of alloy used is the same as that in Example 1, except that only the alloy is subjected to β single-phase region solid solution treatment, the solid solution temperature is 900° C., and the holding time is 1 h.

[0067] After the sample is prepared, the slow scanning high 2θ angle X-ray diffraction method is used to preliminarily determine whether the alloy has produced spinodal decomposition. The slow scanning X-ray diffraction results are as follows: Figure 3 As shown in (d), the alloy shows a single peak of β phase, indicating that the alloy does not produce β phase spinodal decomposition structure, and the alloy is still a single β phase. The alloy is prepared into a dog-bone shaped sample, and a low-temperature extensometer is used to perform loading-unloading tensile tests at different temperatures to obtain the curve of the sample's Young's modulus changing with temperature. Liquid nitrogen is used to cool the equipment. The temperature is set to -150℃~55℃ to obtain the Young's modulus of the alloy at different temperatures. The Young's modulus-temperature curve is shown in Figure 5 In this comparative example, the elastic modulus of the prepared alloy varies greatly within this temperature range, and the overall Young's modulus is relatively high, indicating that the alloy does not have the low constant modulus property.

[0068] Those skilled in the art can understand that the above-mentioned embodiments are specific examples for implementing the present application, and in practical applications, various changes can be made to them in form and detail without departing from the spirit and scope of the present application. Any person skilled in the art can make their own changes and modifications without departing from the spirit and scope of the present application, so the scope of protection of the present application shall be based on the scope defined in the claims.

Claims

1. A thermomechanical treatment method for a titanium alloy with a wide temperature range and low constant elastic modulus, characterized in that: The following steps are included: Step 1: Single-phase solution treatment Performing a solution treatment on the titanium alloy in the single-phase region, the solution temperature is 800-1000° C., the holding time is 1-5 hours, and then water-cooling quenching the titanium alloy after the solution treatment; Step 2: Aging treatment of phase modulation amplitude decomposition area Performing aging treatment on the titanium alloy obtained in step 1, the aging treatment temperature is 250-450° C., the heat preservation time is 1-30 days, and then performing water cooling quenching treatment on the titanium alloy after aging treatment; Step 3: Cold deformation treatment The titanium alloy obtained in step 2 is subjected to cold rolling deformation with a deformation amount of 20 to 90% to obtain the titanium alloy with a wide temperature range and low constant elastic modulus.

2. The thermomechanical treatment method for a titanium alloy with a wide temperature range and low constant elastic modulus according to claim 1, characterized in that: The titanium alloy comprises a Ti-(45-56) wt.% Nb binary alloy.

3. The thermomechanical treatment method for a titanium alloy with a wide temperature range and low constant elastic modulus according to claim 1, characterized in that: The solution temperature in step 1 is 850-950° C., and the holding time is 1 hour.

4. The thermomechanical treatment method for a titanium alloy with a wide temperature range and low constant elastic modulus according to claim 1, characterized in that: The aging treatment temperature in step 2 is 375-400° C., and the insulation time is 6-21 days.

5. The thermomechanical treatment method for a titanium alloy with a wide temperature range and low constant elastic modulus according to claim 1, characterized in that: The cold rolling deformation in step 3 is 30-50%.

6. Titanium alloy with low constant elastic modulus over a wide temperature range, characterized in that: The wide temperature range low constant elastic modulus titanium alloy is obtained by the thermomechanical treatment method of the wide temperature range low constant elastic modulus titanium alloy as described in any one of claims 1 to 5, and the temperature range of the wide temperature range low constant elastic modulus titanium alloy is -268 to 350°C, optionally -150 to 55°C; the elastic modulus is 43 to 56 GPa.

7. Application of the titanium alloy with a wide temperature range and low constant elastic modulus as claimed in claim 6 in the fields of biomedicine, precision instruments and aerospace.

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