CN116516270A - Two-step training method for efficiently improving nickel-titanium alloy double-pass shape memory effect - Google Patents
Two-step training method for efficiently improving nickel-titanium alloy double-pass shape memory effect Download PDFInfo
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- 229910001000 nickel titanium Inorganic materials 0.000 title claims abstract description 91
- 238000012549 training Methods 0.000 title claims abstract description 46
- 230000003446 memory effect Effects 0.000 title claims abstract description 37
- 238000000034 method Methods 0.000 title claims abstract description 36
- 230000032683 aging Effects 0.000 claims abstract description 42
- 125000004122 cyclic group Chemical group 0.000 claims abstract description 21
- 239000000463 material Substances 0.000 claims abstract description 14
- 238000010791 quenching Methods 0.000 claims abstract description 10
- 230000000171 quenching effect Effects 0.000 claims abstract description 10
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims abstract description 10
- 238000005452 bending Methods 0.000 claims abstract description 6
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- XKRFYHLGVUSROY-UHFFFAOYSA-N Argon Chemical compound [Ar] XKRFYHLGVUSROY-UHFFFAOYSA-N 0.000 claims description 24
- PXHVJJICTQNCMI-UHFFFAOYSA-N Nickel Chemical group [Ni] PXHVJJICTQNCMI-UHFFFAOYSA-N 0.000 claims description 24
- 239000010936 titanium Substances 0.000 claims description 17
- 229910045601 alloy Inorganic materials 0.000 claims description 16
- 239000000956 alloy Substances 0.000 claims description 16
- 238000002844 melting Methods 0.000 claims description 13
- 230000008018 melting Effects 0.000 claims description 13
- 229910052786 argon Inorganic materials 0.000 claims description 12
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- 239000006104 solid solution Substances 0.000 claims description 10
- 239000000243 solution Substances 0.000 claims description 8
- 229910052719 titanium Inorganic materials 0.000 claims description 8
- 230000008569 process Effects 0.000 claims description 7
- RYGMFSIKBFXOCR-UHFFFAOYSA-N Copper Chemical compound [Cu] RYGMFSIKBFXOCR-UHFFFAOYSA-N 0.000 claims description 6
- RTAQQCXQSZGOHL-UHFFFAOYSA-N Titanium Chemical compound [Ti] RTAQQCXQSZGOHL-UHFFFAOYSA-N 0.000 claims description 6
- 239000010949 copper Substances 0.000 claims description 6
- 229910052802 copper Inorganic materials 0.000 claims description 6
- 238000005266 casting Methods 0.000 claims description 2
- 239000012535 impurity Substances 0.000 claims description 2
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- HZEWFHLRYVTOIW-UHFFFAOYSA-N [Ti].[Ni] Chemical compound [Ti].[Ni] HZEWFHLRYVTOIW-UHFFFAOYSA-N 0.000 abstract description 17
- 229910001285 shape-memory alloy Inorganic materials 0.000 abstract description 14
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- 230000001427 coherent effect Effects 0.000 description 7
- 238000001816 cooling Methods 0.000 description 6
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Abstract
The invention relates to a two-step training method for efficiently improving a nickel-titanium alloy double-pass shape memory effect, which comprises the following steps: step 1, carrying out solution treatment on nickel-titanium alloy strips in a closed inert atmosphere pipe, and carrying out water quenching after the solution treatment is finished; step 2, carrying out stretching cyclic loading on the nickel-titanium alloy strip in the step 1, introducing dislocation, and carrying out thickness reduction treatment on the material subjected to the stretching cyclic loading to obtain a sample strip; and 3, bending the sample strip treated in the step 2 in a semi-cylindrical constraint die, and performing aging treatment on the die for loading the sample strip at the temperature of 450 ℃ for 5 hours, wherein water quenching is performed immediately after the treatment is finished, so that training is completed. The response temperature range of the nickel-titanium double-pass shape memory alloy obtained by the invention is 29-42 ℃, the recovery rate is improved from 101.0% to 115.5%, the remarkable improvement of the nickel-titanium double-pass shape memory effect is realized efficiently, and the trained nickel-titanium alloy can be widely applied to intelligent driving occasions with large deformation above room temperature.
Description
Technical Field
The invention relates to the technical field of nickel-titanium double-pass shape memory alloy, in particular to a two-step training method for efficiently improving the nickel-titanium double-pass shape memory effect.
Background
The nickel-titanium double-way shape memory alloy can realize automatic switching of different shapes when the temperature changes, so that the nickel-titanium double-way shape memory alloy can replace a traditional electromechanical actuating mechanism in more and more engineering fields to realize a driving function, thereby achieving the purposes of light weight and simplification, such as the fields of aerospace, biomedical treatment, consumer electronics and the like. The two-way shape memory effect of nickel-titanium alloys can be achieved through training. The aim of the training is to introduce a directional stress field to induce a preferred orientation martensitic variant during cooling, which in turn macroscopically produces a spontaneous shape change. The preferential orientation stress field may be formed by introducing directionally aligned dislocations or preferentially oriented Ni 4 Ti 3 Coherent precipitation phase is generated. Constraint aging is a method for introducing preferred orientation Ni 4 Ti 3 The training method for coherent precipitation phase can obtain a more stable function than the method by introducing dislocation structure. But the recovery rate of constraint aging is low, which limits the application of the method in the advanced industrial field to a great extent.
The oriented stress field influences the thermoelastic martensitic transformation, is the reason for obtaining the double-pass shape memory effect and is a way for improving the double-pass shape memory effect. Research has found that Ni is improved 4 Ti 3 The magnitude of the oriented coherent stress field is the key to improving the recovery rate. At present, ni is regulated and controlled mainly by optimizing constraint ageing process, such as regulating ageing time, ageing temperature, two-step constraint ageing and other methods 4 Ti 3 Nucleation and growth of the phase, and further strengthening the precipitated phase orientation coherent stress field, so as to optimize the double-pass shape memory effect. As reported in the literature (Li et al, materials&Design,2017, 118:99-106): by changing the constraint ageing temperature and time, the influence of the constraint ageing temperature and time on the double-pass shape memory effect is researched, and the double-pass shape memory with the maximum constraint ageing of 92.9% at 400 ℃/100h is foundRecovery rate.
The prior art discloses a near-equiatomic-ratio nickel-rich nickel-titanium alloy double-pass shape memory effect training method, which adopts two-step constraint aging to accurately regulate and control the growth behavior of a precipitated phase, so that the coherent stress field in a matrix is maximized, and the maximum double-pass shape memory recovery rate of 96.4% is achieved after constraint aging is carried out at 500 ℃/1h+300 ℃/39 h.
The aging temperature and aging time are important factors influencing the growth of the precipitated phase. The higher the ageing temperature, the larger the size of the precipitated phase. The effect of aging time on the precipitated phase is similar, but the effect of aging temperature is more pronounced. However, when the temperature is too high and the aging time is too long, the precipitated phase grows up, the coherent stress field is removed from the matrix, and the double-pass shape memory effect is also removed.
The Ni content and the stress level affect the Ni of the precipitated phase 4 Ti 3 Is a nucleation rate of (a). Higher nickel content can improve overssolvus supersaturation degree and improve precipitated phase Ni 4 Ti 3 Nucleation rate, forming densely dispersed precipitated phases, thereby improving the double-pass shape memory effect of the alloy. However, too high Ni content can increase the strength of the material and reduce the shaping, and the material has hard and brittle properties, which is unfavorable for the material to work in a complex service environment. The stress level is improved, which is beneficial to improving the precipitated phase Ni 4 Ti 3 Is a nucleation rate of (a). However, too high a stress level is detrimental to the growth of the precipitated phase, resulting in a reduction in the volume of the precipitated phase, while lower stress levels have a limited effect on the nucleation rate of the precipitated phase.
In summary, the method of simply changing the aging time, aging temperature, alloy composition and constraint stress to regulate the two-way shape memory effect of the nickel-titanium alloy has limitations, and cannot meet the increasing demands of the nickel-titanium alloy in the engineering field. In view of the low recovery rate of the nickel-titanium alloy double-pass shape memory effect, it is necessary to invent a process for greatly improving the recovery rate of the nickel-titanium double-pass shape memory effect, so that the nickel-titanium alloy can realize intelligent driving occasions with large deformation at room temperature.
Disclosure of Invention
Aiming at the problems existing in the prior art, the invention aims at: the two-step training method for efficiently improving the double-pass shape memory effect of the nickel-titanium alloy can strengthen the oriented stress field, improve the double-pass shape memory effect of the nickel-titanium alloy and enable the nickel-titanium alloy to have the service capacity above room temperature.
In order to achieve the above purpose, the invention adopts the following technical scheme:
a two-step training method for efficiently improving the double-pass shape memory effect of nickel-titanium alloy comprises the following steps:
(1) Carrying out solution treatment on the nickel-titanium alloy strip in a closed inert atmosphere, and carrying out water quenching after the solution treatment is finished;
(2) Introducing dislocation defects into the nickel-titanium alloy strip subjected to stretching cyclic loading in the step (1), and performing thickness reduction treatment on the material subjected to stretching cyclic loading to obtain a sample strip;
(3) Bending the sample strip treated in the step (2) in a semi-cylindrical constraint die, aging the die for loading the sample strip at 450 ℃ for 5 hours, and immediately performing water quenching after the treatment is finished, thus finishing training.
Preferably, the inert atmosphere in the step (1) is argon, and the pressure in the sealing tube is-100 mbar.
Preferably, the temperature of the solid solution treatment in the step (1) is 850-1000 ℃, the time of the solid solution treatment is 1-10 h, the solid solution treatment is carried out in a tube furnace, argon gas is introduced into the tube for protection, and the gas flow is 1-5L/min.
Preferably, the thickness of the thinned sample strip in the step (1) is recorded as t, and the strain is expressed according to the formulaCalculated, wherein ε max For the maximum strain value of the sample strip, 0 < epsilon max Less than or equal to 2 percent; r is the curvature radius of the arc-shaped groove of the semi-cylindrical constraint die.
Preferably, the thickness of the sample strip in the step (2) is 0.5-0.7 mm; the radius of curvature of the arc-shaped groove of the semi-cylindrical constraint die in the step (3) is 15-35 mm;
preferably, the stretching cyclic loading in step (2) means: at a strain rate of 1.6X10 -4 And/s, carrying out tensile loading on the sample strip and then unloading.
Preferably, the stretching cyclic loading in step (2) means: the sample strip is firstly stretched, loaded and unloaded, and circulated for 1 to 50 times; preferably 5 cycles.
Preferably, the stretching cyclic loading refers to stretching loading the sample strip to 250-450 MPa, then unloading, and repeating the process; preferably 250MPa.
The nickel-titanium alloy sample strip is prepared by vacuum melting and suction casting. Before smelting nickel-titanium alloy ingots, 8-10 g of pure titanium ingots are firstly smelted to reduce the impurity atmosphere in a smelting furnace. Each nickel-titanium alloy ingot is smelted for five times, and after each smelting, the alloy ingot is turned over to ensure that the components and the tissues of the smelted nickel-titanium alloy ingot are uniform. And then, rapidly sucking the nickel-titanium alloy in the liquid state into a water-cooling copper mold die to obtain the nickel-titanium alloy with uniform components and tissues.
Nickel atoms in the nickel-titanium alloy strip: atomic ratio of titanium atoms=50.5 to 52:49.5 to 48.
In general, the invention has the following advantages:
(1) According to the invention, the two-step training treatment (the stretching cyclic loading is carried out for 5 times under the stress of 250MPa and then the constraint aging is carried out at the speed of 450 ℃/5 h), firstly, dislocation is simply and rapidly introduced into the nickel-titanium alloy in a stretching cyclic loading mode, the dislocation is used as heterogeneous nuclear points of a precipitated phase to regulate and control the distribution of the precipitated phase, and then, the precipitated phase with preferred orientation and dense distribution is formed in the nickel-titanium alloy through the subsequent constraint aging treatment, so that the stress field of orientation is enhanced, and the double-pass shape memory effect of the nickel-titanium alloy is improved.
(2) The method only needs to carry out stretching and cyclic loading on the alloy before aging treatment, and is simple and convenient to operate.
(3) Through experiments, the recovery rate of the nickel-titanium alloy strip subjected to the two-step training treatment (constraint aging at 450 ℃/5h after stretching and cyclic loading for 5 times under the stress of 250 MPa) is 115.5%, which is far higher than that of a nickel-titanium alloy strip subjected to single-step training (constraint aging at 450 ℃/5 h) by 101.0%. The training method of the invention greatly improves the double-pass shape memory effect of the nickel-titanium alloy strip. In addition, the phase transition temperature of the material R exceeds the room temperature in the two-step training process, namely, the material R can automatically deform when cooled to the room temperature, and the material R is suitable for intelligent driving occasions with large deformation above the room temperature.
Drawings
FIG. 1 is a bending deformation at-196℃of a nickel-titanium shape memory alloy strip prepared in example 1 of the present invention in a single step training (constraint aging at 450 ℃ C./5 h) and in a two step training (constraint aging at 450 ℃ C./5 h after 5 times of tensile cyclic loading at 250MPa stress).
FIG. 2 is a stress-strain curve for a 5-time tensile cycle load of 250MPa in example 1 of the present invention.
FIG. 3 is a microstructure of a nickel titanium shape memory alloy bar after 5 times of tensile cyclic loading at 250MPa after solutionizing in example 1.
FIG. 4 is a DSC curve of a nickel titanium alloy strip after two training steps in example 1.
FIG. 5 is a bright field image of a transmission electron microscope of a single-step training and two-step training NiTi shape memory alloy strip prepared in example 1 of the present invention.
Detailed Description
The invention is further illustrated by the following examples, which are not intended to be limiting in any way, in connection with the specific embodiments and the accompanying drawings.
Example 1
Two-step training for efficiently improving the shape memory effect of nickel-titanium alloy in double-pass comprises the following specific steps:
(1) Nickel-titanium alloy with the atomic ratio of nickel to titanium of 51:49 is prepared by vacuum arc melting, the molten nickel-titanium alloy is sucked and cast into a water-cooling copper mold by utilizing pressure difference after five times of melting, and nickel-titanium alloy strips with the corresponding dimensions of 70mm (length) x 8mm (width) x 1mm (thickness) are prepared.
(2) Placing the nickel-titanium alloy strip in the step (1) into a quartz tube, and vacuumizing the tube to 5 multiplied by 10 through a molecular pump matched with a vacuum tube sealing machine -3 Pa, filling the tube with a protective gasAfter pure argon to-150 mbar, the alloy strips were enclosed in quartz tubes.
(3) And placing the sealed sample in a tubular sintering furnace, introducing protective atmosphere argon into the tubular furnace at the gas flow of 1L/min, and then carrying out solution treatment at the temperature of 850 ℃ for 3 hours. Immediately after the completion of the solid solution, the sample was water-quenched and taken out.
(4) And (3) stretching and loading the sample strip subjected to the step (3) to 250MPa, unloading, and repeating the process for 5 times.
(5) And (3) thinning the thickness of the material treated in the step (4) through a stainless steel thinning die to enable the thickness of the sample to reach 0.7mm.
(6) Inserting the sample strip in the step (5) into a semi-cylindrical constraint die, wherein the radius of an arc groove is 33mm, placing the die loaded with the alloy strip into a box-type resistance furnace, performing constraint aging treatment at the temperature of 450 ℃ for 5 hours, and immediately performing water quenching after the completion of the constraint aging treatment.
FIG. 1 is a bending deformation at-196℃of a nickel-titanium shape memory alloy strip prepared in example 1 of the present invention in a single step training (constraint aging at 450 ℃ C./5 h) and in a two step training (constraint aging at 450 ℃ C./5 h after 5 times of tensile cyclic loading at 250MPa stress).
FIG. 2 is a stress-strain curve for a 5-time tensile cycle load of 250MPa in example 1 of the present invention.
FIG. 3 is a microstructure of a nickel titanium shape memory alloy bar after 5 times of tensile cyclic loading at 250MPa after solutionizing in example 1. After the stretching cyclic loading, the dislocation with orientation arrangement appears in the nickel-titanium shape memory alloy matrix, which is the precipitated phase Ni in the subsequent restraint aging treatment 4 Ti 3 Heterogeneous nucleation sites are provided.
FIG. 4 is a DSC curve of a nickel-titanium alloy strip after two training steps in example 1, R phase transition onset temperature R was measured by the tangent method s And end temperature R f All exceeding room temperature at 29 and 42 c, respectively. This demonstrates that the samples obtained by the two-step training method are suitable for intelligent driving applications above room temperature.
FIG. 5 shows a single step training and a two step training prepared in example 1 of the present inventionA transmission electron microscope bright field image of the nickel-titanium shape memory alloy strip. As can be seen from fig. 5: ni with preferred orientation and dense Ni distributed in nickel-titanium shape memory alloy strip for two-step training 4 Ti 3 And (3) phase precipitation. The number of precipitated phases per unit area is 208 μm -2 Far greater than 120 μm in a single step training alloy -2 . The high-density precipitated phase introduces a larger comprehensive coherent stress field in the matrix, so that the sample shows excellent double-pass shape memory effect on a macroscopic scale.
Example 2
Two-step training for efficiently improving the shape memory effect of nickel-titanium alloy in double-pass comprises the following specific steps:
(1) Nickel-titanium alloy with the atomic ratio of nickel to titanium of 51:49 is prepared by vacuum arc melting, the molten nickel-titanium alloy is sucked and cast into a water-cooling copper mold by utilizing pressure difference after five times of melting, and nickel-titanium alloy strips with the corresponding dimensions of 70mm (length) x 8mm (width) x 1mm (thickness) are prepared.
(2) Placing the nickel-titanium alloy strip in the step (1) into a quartz tube, and vacuumizing the tube to 5 multiplied by 10 through a molecular pump matched with a vacuum tube sealing machine -3 Pa, after filling the tube with a protective gas, high purity argon, to-150 mbar, the alloy strip is enclosed in a quartz tube.
(3) And placing the sealed sample in a tubular sintering furnace, introducing protective atmosphere argon into the tubular furnace at the gas flow of 1L/min, and then carrying out solution treatment at the temperature of 850 ℃ for 3 hours. Immediately after the completion of the solid solution, the sample was water-quenched and taken out.
(4) And (3) loading the sample strip subjected to the step (3) to 300MPa, unloading, and repeating the process for 5 times.
(5) And (3) thinning the thickness of the material treated in the step (4) through a stainless steel thinning die to enable the thickness of the sample to reach 0.7mm.
(6) Inserting the sample strip in the step (5) into a semi-cylindrical constraint die, wherein the radius of an arc groove is 33mm, placing the die loaded with the alloy strip into a box-type resistance furnace, performing constraint aging treatment at the temperature of 450 ℃ for 5 hours, and immediately performing water quenching after the completion of the constraint aging treatment.
Example 3
Two-step training for efficiently improving the shape memory effect of nickel-titanium alloy in double-pass comprises the following specific steps:
(1) Nickel-titanium alloy with the atomic ratio of nickel to titanium of 51:49 is prepared by vacuum arc melting, the molten nickel-titanium alloy is sucked and cast into a water-cooling copper mold by utilizing pressure difference after five times of melting, and nickel-titanium alloy strips with the corresponding dimensions of 70mm (length) x 8mm (width) x 1mm (thickness) are prepared.
(2) Placing the nickel-titanium alloy strip in the step (1) into a quartz tube, and vacuumizing the tube to 5 multiplied by 10 through a molecular pump matched with a vacuum tube sealing machine -3 Pa, after filling the tube with a protective gas, high purity argon, to-150 mbar, the alloy strip is enclosed in a quartz tube.
(3) And placing the sealed sample in a tubular sintering furnace, introducing protective atmosphere argon into the tubular furnace at the gas flow of 1L/min, and then carrying out solution treatment at the temperature of 850 ℃ for 3 hours. Immediately after the completion of the solid solution, the sample was water-quenched and taken out.
(4) Loading the sample strip subjected to step (3) to 350MPa and then unloading.
(5) And (3) thinning the thickness of the material treated in the step (4) through a stainless steel thinning die to enable the thickness of the sample to reach 0.7mm.
(6) Inserting the sample strip in the step (5) into a semi-cylindrical constraint die, wherein the radius of an arc groove is 33mm, placing the die loaded with the alloy strip into a box-type resistance furnace, performing constraint aging treatment at the temperature of 450 ℃ for 5 hours, and immediately performing water quenching after the completion of the constraint aging treatment.
Example 4
Two-step training for efficiently improving the shape memory effect of nickel-titanium alloy in double-pass comprises the following specific steps:
(1) Nickel-titanium alloy with the atomic ratio of nickel to titanium of 51:49 is prepared by vacuum arc melting, the molten nickel-titanium alloy is sucked and cast into a water-cooling copper mold by utilizing pressure difference after five times of melting, and nickel-titanium alloy strips with the corresponding dimensions of 70mm (length) x 8mm (width) x 1mm (thickness) are prepared.
(2) Placing the nickel-titanium alloy strip in the step (1) into a quartz tube, and using a molecular pump matched with a vacuum tube sealing machineThe tube was evacuated to 5X 10 -3 Pa, after filling the tube with a protective gas, high purity argon, to-150 mbar, the alloy strip is enclosed in a quartz tube.
(3) And placing the sealed sample in a tubular sintering furnace, introducing protective atmosphere argon into the tubular furnace at the gas flow of 1L/min, and then carrying out solution treatment at the temperature of 850 ℃ for 3 hours. Immediately after the completion of the solid solution, the sample was water-quenched and taken out.
(4) Loading the sample strip subjected to step (3) to 450MPa and then unloading.
(5) And (3) thinning the thickness of the material treated in the step (4) through a stainless steel thinning die to enable the thickness of the sample to reach 0.7mm.
(6) Inserting the sample strip in the step (5) into a semi-cylindrical constraint die, wherein the radius of an arc groove is 33mm, placing the die loaded with the alloy strip into a box-type resistance furnace, performing constraint aging treatment at the temperature of 450 ℃ for 5 hours, and immediately performing water quenching after the completion of the constraint aging treatment.
Performance test:
the shape memory effect of the nickel-titanium alloy sample strip is characterized by using a photographic method, and the specific method comprises the following steps of: the sample is placed in the medium with different temperatures, the pictures of the bending state of the sample with different temperatures are recorded by a camera, the curvatures of the sample strip with different temperatures (100 ℃ and-196 ℃) are extracted by means of AutoCAD software, and the double-pass shape memory recovery rate of the sample in the martensitic state is calculated. The recovery rate of the nickel-titanium shape memory alloy strip of the two-step training (constraint aging at 450 ℃/5h after 5 tensile cycles at 250MPa stress) prepared in example 1 was as high as 115.5%, while the recovery rate of the nickel-titanium shape memory alloy strip of the single-step training (constraint aging at 450 ℃/5 h) was 101.3%. The nickel-titanium alloy double-pass shape memory effect is greatly improved.
The above examples are preferred embodiments of the present invention, but the embodiments of the present invention are not limited to the above examples, and any other changes, modifications, substitutions, combinations, and simplifications that do not depart from the spirit and principle of the present invention should be made in the equivalent manner, and the embodiments are included in the protection scope of the present invention.
Claims (9)
1. A two-step training method for efficiently improving the double-pass shape memory effect of nickel-titanium alloy is characterized in that: the method comprises the following steps:
step 1, carrying out solution treatment on nickel-titanium alloy strips in a closed inert atmosphere pipe, and carrying out water quenching after the solution treatment is finished;
step 2, carrying out stretching cyclic loading on the nickel-titanium alloy strip in the step 1, introducing dislocation, and carrying out thickness reduction treatment on the material subjected to the stretching cyclic loading to obtain a sample strip;
and 3, bending the sample strip treated in the step 2 in a semi-cylindrical constraint die, and performing aging treatment on the die for loading the sample strip at the temperature of 450 ℃ for 5 hours, wherein water quenching is performed immediately after the treatment is finished, so that training is completed.
2. The two-step training method for efficiently improving the shape memory effect of the nickel-titanium alloy in double pass according to claim 1, which is characterized in that: the inert atmosphere in the step 1 is argon, the pressure in an inert atmosphere pipe is-150-0 mbar, the solid solution treatment temperature is 850-1000 ℃, and the solid solution time is 1-10 h.
3. The two-step training method for efficiently improving the shape memory effect of the nickel-titanium alloy in double pass according to claim 1, which is characterized in that: the solid solution treatment in the step 1 is carried out in a tube furnace, argon gas is introduced into the tube for protection, and the gas flow is 1-5L/min.
4. The two-step training method for efficiently improving the shape memory effect of the nickel-titanium alloy in double pass according to claim 1, which is characterized in that: and 2, the thickness of the thinned sample strip is 0.5-0.7 mm.
5. The two-step training method for efficiently improving the shape memory effect of the nickel-titanium alloy in double pass according to claim 1, which is characterized in that: step 2, stretching cyclic loading refers to: at a strain rate of 1 to 5X 10 -4 At/s, the sample strip is subjected to stretching loading and then unloadingThe cycle is recorded as one time.
6. The two-step training method for efficiently improving the shape memory effect of the nickel-titanium alloy in double pass according to claim 1, which is characterized in that: step 2, stretching cyclic loading refers to: and (3) carrying out tensile loading and unloading on the nickel-titanium alloy, and circulating for 1-50 times.
7. The two-step training method for efficiently improving the shape memory effect of the nickel-titanium alloy in double pass according to claim 1, which is characterized in that: the stretching cyclic loading means that the alloy strip is stretched and loaded to 250-450 MPa, then unloaded, and the process is repeated.
8. The two-step training method for efficiently improving the shape memory effect of the nickel-titanium alloy in two passes according to any one of claims 1 to 7, which is characterized in that: the nickel-titanium alloy strip is prepared by vacuum melting and suction casting, 8-10 g of pure titanium ingots are firstly melted before each time of melting of the nickel-titanium alloy ingots so as to reduce impurity atmosphere in a melting furnace, each nickel-titanium alloy ingot is melted for five times, after each time of melting, the alloy ingots are turned over so as to ensure that the components and the tissues of the melted nickel-titanium alloy ingots are uniform, and then the nickel-titanium alloy in a liquid state is quickly sucked into a water-cooled copper mold by utilizing pressure difference, so that the nickel-titanium alloy with uniform components and tissues is obtained.
9. The two-step training method for efficiently improving the shape memory effect of the nickel-titanium alloy in two passes according to any one of claims 1 to 7, which is characterized in that: nickel atoms in the nickel-titanium alloy sample strip: atomic ratio of titanium atoms=50.5 to 52:49.5 to 48.
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| CN114836654A (en) * | 2022-04-08 | 2022-08-02 | 华南理工大学 | Efficient training method for one-way shape memory effect of nickel-titanium alloy with equal atomic ratio |
| CN114855008A (en) * | 2022-04-07 | 2022-08-05 | 华南理工大学 | Nickel-titanium alloy double-pass shape memory effect training method with high nickel-rich content |
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