KR20140102846A - Shape-memory alloy having excellent cold workability - Google Patents

Abstract

The present invention relates to a shape-memory alloy having excellent cold workability. In particular, the shape-memory alloy has more excellent cold workability and requires lower production cost compared to the existing shape-memory alloy. The shape-memory alloy of the present invention includes: 81-82.5 wt% of copper, 7.5-8.5 wt% of aluminum, and 9-11 wt% of manganese. According to the present invention, the shape-memory alloy has significantly increased cold workability compared to the prior shape-memory alloy such as nitinol commonly used in the past. Therefore, the shape-memory alloy: can be used for manufacturing a product having a micro cross section shape such as a microtube, a thin plate, or a microwire; has significantly increased applicability; and thus has marketability.

Description

[0001] Shape-memory alloy having excellent cold workability [0002]

The present invention relates to a shape memory alloy excellent in cold workability. More particularly, the present invention relates to a shape memory alloy excellent in cold workability as compared with a conventional shape memory alloy and excellent in cold workability with low manufacturing cost.

In general, shape memory alloys have two unique characteristics of shape memory effect and super elasticity and are widely used as functional materials in various fields.

Here, the shape memory effect refers to a property of storing a shape of a high temperature phase which is returned to a shape of a high temperature before the transformation if the molding is heated to a transformation temperature after applying a deformation in a low temperature martensitic state, To the temperature range of Af + 30 ° C from the knit transformation completion temperature) to the temperature range of the existing metal, and the above-mentioned shape memory effect and superelasticity are common features resulting from the martensitic transformation, Have.

Examples of shape memory alloys that have been extensively studied or commercialized in the past include nickel-titanium (Ni-Ti) alloys, copper-aluminum-nickel alloys, and copper- Al-Zn) shape memory alloys. Among them, nickel-titanium type shape memory alloys are widely used as engineering fields and biomaterials because of their excellent shape memory ability and super elastic properties. However, And it is also difficult to process the copper-aluminum-nickel type shape memory alloy and the copper-aluminum-zinc type shape memory alloy.

Disclosure of Invention Technical Problem [8] The present invention has been made to solve the above-mentioned problems and it is an object of the present invention to provide a copper-aluminum-manganese alloy having a low manufacturing cost, excellent cold workability, shape recovery ratio of 80% Cu-Al-Mn) based material having excellent cold workability.

In order to achieve the above object, according to a preferred embodiment of the present invention, there is provided a shape memory alloy having excellent cold workability in a shape memory alloy including copper, aluminum, and manganese, wherein the shape memory alloy contains copper at a weight ratio of 81 to 82.5, And manganese in a weight ratio of 9 to 11.

The copper may be oxygen free copper, the aluminum may be pure aluminum, and the manganese may be electrolytic manganese.

According to the present invention, compared with the shape memory alloy material such as Nitinol, which has been conventionally used, the cold workability is greatly improved, and it is possible to manufacture a product having a micro sectional shape such as microtube, thin plate, And thus has an effect of securing the marketability.

In addition, since it can be manufactured at low cost in comparison with a conventional shape memory alloy material such as Nitinol, it has an effect of securing economical efficiency.

1 to 4 are views for a method of manufacturing a shape memory alloy excellent in cold workability according to a preferred embodiment of the present invention,
5 to 9 are reference views for a cold workability test of a shape memory alloy excellent in cold workability according to a preferred embodiment of the present invention,
10 and 11 are reference views for a shape memory ability test of a shape memory alloy excellent in cold workability according to a preferred embodiment of the present invention,
12 to 14 are reference views of microstructure analysis results of a shape memory alloy excellent in cold workability according to a preferred embodiment of the present invention,
FIGS. 15 to 17 are reference views of phase analysis results of a shape memory alloy excellent in cold workability according to a preferred embodiment of the present invention by an X-ray fluorescence analyzer (XRD)
18 to 26 are reference views for a shape memory capability test according to a heat treatment for a shape memory alloy excellent in cold workability according to a preferred embodiment of the present invention,
FIG. 27 is a reference view for a shape memory ability test according to a processing direction of a shape memory alloy excellent in cold workability according to a preferred embodiment of the present invention; FIG.
28 is a reference graph for a critical strain test of a shape memory alloy excellent in cold workability according to a preferred embodiment of the present invention,
29 to 32 are graphs showing the result of a superelasticity property test of a shape memory alloy excellent in cold workability according to a preferred embodiment of the present invention,
33 is a reference graph for measurement results of differential scanning calorimetry (DSC) of a shape memory alloy excellent in cold workability according to a preferred embodiment of the present invention, and
34 is a graph showing a tensile test result of a shape memory alloy excellent in cold workability according to a preferred embodiment of the present invention.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. In the drawings, the same reference numerals are used to designate the same or similar components throughout the drawings. In the following description of the present invention, a detailed description of known functions and configurations incorporated herein will be omitted when it may make the subject matter of the present invention rather unclear. Further, the preferred embodiments of the present invention will be described below, but it is needless to say that the technical idea of the present invention is not limited thereto and can be practiced by those skilled in the art.

1 to 4 are reference views for a method of manufacturing a shape memory alloy excellent in cold workability according to a preferred embodiment of the present invention.

In this case, the shape memory alloy having excellent cold workability according to a preferred embodiment of the present invention includes copper of 81 to 82.5 weight ratio, aluminum of 7.5 to 8.5 weight ratio, and manganese of 9 to 11 weight ratio, the copper being oxygen free copper, Pure aluminum, and the manganese may be electrolytic manganese.

In the case of the shape memory alloy manufacturing method excellent in cold workability according to the preferred embodiment of the present invention, manganese (Mn), copper (Cu), and And then heated to 1300 ° C to dissolve them in the order of aluminum (Al), and the molten metal is injected into the graphite mold shown in FIG. 1 (B).

In addition, for the homogenization treatment, it is possible to manufacture an ingot-shaped shape memory alloy shown in FIG. 2 in which unevenness of the surface is removed by grinding after being maintained at 900 ° C for 6 hours.

3 and 4, the ingot-shaped shape memory alloy was hot-rolled into specimens having a length of 20 mm, a width of 15 mm, and a thickness of 3 mm, maintained at 900 ° C for 4 hours in an electric furnace, Annealing treatment and polishing can remove the thin oxide layer on the surface.

The characteristics of the shape memory alloy excellent in cold workability according to the preferred embodiment of the present invention will be described in more detail through various characteristic tests. As described above, the shape memory alloy has a copper weight ratio of 81 to 82.5, Aluminum, and manganese in the weight ratio of copper, aluminum, and manganese to the characteristics of the shape memory alloy excellent in cold workability according to the preferred embodiment of the present invention, And manganese weight ratios were prepared as shown in Table 1 below.

Sample Number Sample 1 Sample 2 Sample 3 Sample 4 Sample 5 Cu (wt%) 82.5 82.0 81.5 83.0 81.0 Al (wt%) 7.5 8.0 8.5 8.0 8.0 Mn (wt%) 10.0 10.0 10.0 9.0 11.0

5 to 9 are reference views for a cold workability test of a shape memory alloy having excellent cold workability according to a preferred embodiment of the present invention.

In the cold workability test, as described above, cold rolling was performed in a step of 0.5 mm increments using a specimen rolled up to 3 mm by hot rolling, and cracks were observed at the edge. In the case of the cold workability evaluation, the thickness of the specimen at the moment of occurrence of the crack is measured, and it can be expressed in more detail as follows.

Where t ₀ is the initial thickness and t ₁ is the final thickness of the specimen.

6 is a reference chart of a cold workability test for Sample 2, FIG. 7 is a reference chart of a cold workability test for Sample 3, and FIG. 8 is a chart for a cold workability test for Sample 4 9 is a reference diagram for the cold workability test for Sample 5, and the results of the cold workability test for Sample 1 to Sample 5 are shown in Table 2 below.

Sample 1 Sample 2 Sample 3 Sample 4 Sample 5 Cold workability (%) 90 66 33 66 66

The results of the cold workability test for Samples 1 to 5 will be described in more detail with reference to FIGS. 5 to 9. FIG.

Sample 1 shown in FIG. 5 exhibited a higher degree of cold working than other specimens (ie, no cracks occurred in the specimen when rolling to a final thickness of 0.3 mm), which was 7.5 in Sample 1 % (wt.%) of aluminum was added to the sample, and it was confirmed that the addition ratio of aluminum in Sample 1 to Sample 5 was the lowest.

The sample 2 shown in FIG. 6 had a poor degree of cold working than the sample 1 (that is, cracking occurred at a thickness of 1.0 mm), indicating that Sample 2 had an aluminum content of 8% (wt% It can be confirmed that it has more aluminum content.

The sample 3 shown in Fig. 7 had a poor degree of cold working (i.e., cracking at a thickness of 2.0 mm) compared to Sample 1 and Sample 2, which resulted in an aluminum content of 8.5% (wt%) in Sample 3, , Which is higher than that of Sample 1 and Sample 2.

In Sample 4 shown in FIG. 8, the degree of cold working tends to be similar to Sample 2 having the same aluminum composition (that is, a crack occurs at a thickness of 1.0 mm), and also in Sample 5 shown in FIG. 9 The degree of cold working is similar to that of Sample 2 and Sample 4 having an aluminum composition (in other words, a crack occurs at a thickness of 1.0 mm).

According to the above results, in the case of the shape memory alloy according to the preferred embodiment of the present invention including copper, aluminum and manganese, the manganese content has little effect on the cold workability, while the aluminum content has a very sensitive influence Can be confirmed.

10 and 11 are reference views for a shape memory ability test of a shape memory alloy excellent in cold workability according to a preferred embodiment of the present invention.

Here, in the shape memory capacity test of the shape memory alloy excellent in cold workability according to the preferred embodiment of the present invention, the shape memory performance of the shape memory alloy excellent in cold workability according to the preferred embodiment of the present invention having the composition ratios of Sample 1 to Sample 5 The alloy was processed into a size of 50 mm x 10 mm x 0.5 mm and then heat-treated in the manner as shown in Fig. 10, then water-cooled, immediately immersed in liquid nitrogen, molded, and then immersed in boiling water to check whether the shape was restored .

The shape memory effect (ie, shape memory effect) was measured by applying a constant surface strain to each specimen and then quantifying the extent of surface deformation when the specimen was immersed in boiling water. (2) " (2) "

Where ε is the surface strain, t is the thickness of the specimen, and R is the radius of curvature at the time of deformation of the specimen.

At this time, since the thickness t of the specimen is fixed at 0.5 mm, each specimen has a curvature radius of R = 12.5 mm in order to have a surface strain of 2%. For this purpose, liquid nitrogen After the immersion, the deformations were made. After that, the curvature was measured after immersing in boiling water to recover the shape, and the surface deformation was calculated and then the shape recovery rate was calculated.

FIG. 11 is a reference view of the shape memory test results of Sample 1 to Sample 5. As shown in FIG. 11, Sample 1, Sample 2, and Sample 5 exhibited excellent shape memory effect. Sample 3 and Sample 4, it can be confirmed that the deformed shape is maintained without any shape memory effect.

In addition, the shape memory recovery rates of Sample 1 to Sample 5 can be expressed as shown in Table 3 below.

Sample 1 Sample 2 Sample 3 Sample 4 Sample 5 Recovery rate 100% 100% 0% 0% 0%

12 to 14 are reference views of microstructure analysis results of a shape memory alloy excellent in cold workability according to a preferred embodiment of the present invention.

In the case of a shape memory alloy of a copper-aluminum-manganese (Cu-Al-Mn) material such as a shape memory alloy excellent in cold workability according to a preferred embodiment of the present invention, In order to compare the microstructure before and after etching, sample 1 to sample 5 were etched with a corrosion solution (50DI-water + 50HNO) for 5 seconds and then observed under optical microscope for 200 And observed at a magnification of twice.

As shown in FIG. 12, in the case of Sample 1 to Sample 5, the coarse α-phase is a main species in the case of the sample 1, whereas the α-phase + β-phase is present in the sample 2 to the sample 5.

Fig. 13 is a microstructure photograph of Sample 1 to Sample 5 in the state of being maintained at 900 ° C for 30 minutes and quenched with water. As shown in Fig. 14, the tissue photographs of Sample 1, Sample 2, Sample 4, Of the martensite (? ') Is produced.

However, in the case of Sample 3, only a small amount of martensite appearing as acicular texture is observed, and thus Sample 3 shows almost no shape memory effect.

14 is a microstructure photograph of Sample 1 to Sample 5 maintained at 900 ° C for 30 minutes and then cooled in ice water and then cooled again in liquid nitrogen. The martensite of sample 1, sample 2, and sample 5 exhibited a very thin shape of martensite and the shape memory recovery ability of the sample was also excellent .

However, in Sample 3, it can be seen that no martensite was formed. This means that martensite was not formed in the sample, and therefore it can be judged that the shape memory effect does not appear.

In addition, Sample 4, Sample 2, and Sample 5 show that a martensite structure having a large needle bed is formed, which is similar to Sample 1, Sample 2, and Sample 5 5 shows that the shape memory effect is superior to that of Sample 1, Sample 2, and Sample 5, indicating that the shape memory effect is excellent when martensite is formed in the shape observed in Sample 1, Sample 2, and Sample 5.

FIGS. 15 to 17 are reference views of phase analysis results of a shape memory alloy excellent in cold workability according to a preferred embodiment of the present invention by an X-ray fluorescence analyzer (XRD).

Here, the XRD test conditions were set at 20 to 80 ° in the 2θ section, and the phase analysis was performed using the Cu target X-ray.

FIG. 15 is a graph showing XRD measurement results in the raw material state before the heat treatment of Sample 1 to Sample 5, and it is confirmed that there is no specimen having a different peak value among Sample 1 to Sample 5 as shown in FIG. .

16 is a graph showing the results of XRD measurement in a state where Sample 1 to Sample 5 are maintained at 900 ° C for 15 minutes in a state where the above-described XRD experimental conditions are maintained and quenched and quenched in water at room temperature, The peaks of Sample 1, Sample 2 and Sample 5 were equally observed (at this time, {110} β was the strongest and the other peaks were not measured for the measured peaks). Sample 3 and Sample 4 , No martensite phase of? 'Phase was found, without any change in the peak of? (That is, with peaks similar to those of FIG. 16) and no change even after the heat treatment.

17 is a graph showing the results of XRD measurement in a state of being immersed in liquid nitrogen in order to further lower the Ms and Mf temperatures of Sample 1 to Sample 5 while maintaining the above-described XRD experimental conditions. As shown in FIG. 17, Sample 1, Sample 2, and Sample 5, which exhibit excellent shape memory effect, are first compared with those of water. In the case of the water sample, only the peak of the β region was found, but when martensite was formed by immersion in liquid nitrogen, Peak was found in Sample 1, Sample 2, and Sample 5, and the β-phase found in water was found as the parent phase in the texture of the specimen and was deposited in liquid nitrogen to form martensite of α ' It is observed that the larger the intensity of α 'phase peak is, the more martensite is generated.

However, in Sample 3 and Sample 4 in which the shape memory effect was not observed, peaks similar to those in FIGS. 16 and 17 were measured.

As described above, it can be confirmed that the shape memory effect is excellent when the peak of? 'Phase and the peak of? Phase are simultaneously measured by XRD measurement.

18 to 26 are reference views for a shape memory test according to a heat treatment for a shape memory alloy excellent in cold workability according to a preferred embodiment of the present invention.

Here, Sample 1, Sample 2 and Sample 5, which are recognized as having excellent shape memory effect according to the above-mentioned test results among Sample 1 to Sample 5, were subjected to a shape memory ability test by heat treatment, As shown in FIG. 18, in order to confirm the change with the heat treatment temperature and the holding time, the holding temperature was 800 ° C and 900 ° C, and the holding time was 1 hour and 3 hours, (Fig. 18 (a)), a solution treatment at 900 ° C and a holding time of 3 hours (Fig. 18 (b)), a solution treatment at 800 ° C and a holding time of 1 hour 18, (c)), and the solution heat treatment at 800 ° C and the holding time for 3 hours (FIG. 18 (d)), the shape memory test of Sample 1, Sample 2, .

FIG. 19 is a reference diagram of the shape memory test result of Sample 1 under each heat treatment condition, FIG. 20 is a reference diagram of the shape memory ability test result of Sample 2 under each heat treatment condition, and FIG. And the shape memory retention rates of Sample 1, Sample 2, and Sample 5 are shown in Table 4 below.

(a) (b) (c) (d) Sample 1 100% 88.1% 86.85% 91.4% Sample 2 100% 86.85% 88.1% 82.15% Sample 5 90% 87.5% 82.15% 87.2%

19 to 21, Sample 1 exhibited excellent shape recovery performance of 80% or more for each of the heat treatment conditions. In Sample 2, all of the heat treatment conditions were 80 %. In Sample 5, it was confirmed that all of the heat treatment conditions showed excellent shape recovery ability by 80% or more.

22 shows the microstructure according to the respective heat treatment conditions of Sample 1. As shown in FIG. 22, it can be confirmed that martensite (α 'phase) texture was well formed under each heat treatment condition in Sample 1, When the holding time was increased at the same temperature, there was no significant difference, but when the holding temperature was increased, the grain size increased at the same holding time.

Fig. 23 is a photograph of microstructure according to each heat treatment condition of Sample 2, and Fig. 24 is an enlarged structure photograph of Sample 2 under the conditions (c) and (d) described above among the respective heat treatment conditions.

As shown in FIG. 23 and FIG. 24, in the sample heat-treated at 900 ° C., α 'martensite phase was mainly observed as in sample 1. However, in the photographs (c) and (d) The α 'martensite phase is observed between α and β phases. This is because the composition of sample 2 exists in two regions of α + β near 800 ℃, It is because it exists.

Fig. 25 is a photograph of a microstructure according to each heat treatment condition of sample 5, and Fig. 26 is an enlarged structure photograph of sample 5 under the condition (d) described above among the respective heat treatment conditions.

As shown in FIG. 25 and FIG. 26, sample 5 shows α 'martensite at 900 ° C., which indicates that the composition of sample 5 is in the β single phase region at 900 ° C., It can be seen that the α phase fraction is larger when the holding time is increased to 3 hours while the α phase is mostly observed in the heated state, though it is mostly α 'martensite.

Further, when the structure of the sample 5 is enlarged and examined, it can be confirmed that α 'martensite can be reliably confirmed, and an α phase is observed in a spherical shape therebetween.

FIG. 27 is a reference view for a shape memory capability test according to a processing direction of a shape memory alloy excellent in cold workability according to a preferred embodiment of the present invention. FIG.

In order to investigate the influence of the machining direction on the shape memory performance, a plate test material hot-rolled to a thickness of 1 mm with respect to the composition of Sample 1, Sample 2, and Sample 5 was cut in a longitudinal direction perpendicular to the rolling direction Each specimen was cut into a width of 1 cm x 4 cm and maintained in an electric furnace at 900 ° C for 30 minutes. The specimen was curved in a liquid form in liquid nitrogen, And the shape memory ability according to the direction was analyzed.

27 (a) is a reference view of the shape memory ability test result according to the machining direction of the sample 1, FIG. 27 (b) is a reference view of the shape memory ability test result according to the machining direction of the sample 2, FIG. 27 (c) is a reference view of the shape memory capability test result according to the processing direction of sample 5, and in the reference diagram for each shape memory ability test result, the four specimens have shape memory effect Before confirming, the specimens were subjected to surface strain on the specimen, and the deformed specimens. Specimens confirmed the shape memory effect of the specimen in the same direction as the rolling direction of the specimen, and the shape of the specimen perpendicular to the rolling direction Means the specimen after confirmation of memory effect.

As shown in Fig. 27, the shape memory recovery ratio according to the machining direction shows satisfactory results of 80% or more in both the lateral and longitudinal profiles, but it is confirmed that the machining to the cross section showing the closest recovery tendency to the original state shows the best result .

28 is a reference graph for a critical strain test of a shape memory alloy according to a preferred embodiment of the present invention.

Here, in order to obtain the maximum strain rate for evaluation of the shape memory ability, sample 1, sample 2, and sample 5, which have proven shape memory effect in sample 1 to sample 5, Tests were conducted to determine the percentage of surface deformation recovered by measuring the curvature of the recovered specimen when it was subjected to nitrogen heat treatment, taken out, molded into a circular shape, and put into boiling water. The surface deformation was varied up to 3.2% The specimens with three thicknesses of 0.3 mm, 0.5 mm, and 0.8 mm were prepared for each sample, and then subjected to the critical strain test under the condition that a rod of 25 mm diameter was encapsulated.

In addition, in the case of a test for a larger surface strain rate, it was difficult to mold each sample into a circular shape, and it was performed using a tensile tester. In other words, the strain was applied to each sample to have a strain of 6% and 8% Was taken out, put in boiling water, and the gauge distance was measured to determine the degree to which each sample was finally restored.

At this time, when strain was applied to the specimen, a strain gage with a gauge length of 50 mm was mounted, the cross head speed was 12 mm / min, and the results of the shape memory recovery rate according to the thickness of each sample can be shown in Table 5 below .

Strain rate
Sample Number 1.2% 2.0% 3.2% Sample 1 98.1% 96.1% 88.8% Sample 2 96.9% 98.0% 91.1% Sample 5 97.2% 96.0% 92.6%

As shown in Table 5, the surface strain according to the thickness of each specimen is 1.2% at 0.3 mm, 2.0% at 0.5 mm, and 3.25% at 0.8 mm, It can be seen that the shape recovery rate is slightly lowered as the volume ratio increases, and that the excellent shape memory effect is 90% or more at all under the present conditions.

28 is a graph showing the result of measurement of the shape memory limit strain rate by the tensile test for Sample 1. As shown in FIG. 28, when a tensile specimen has a gauge length of 50 mm, a deformation amount of 3 mm and an elongation of 6% As shown in FIG. 28, when the load applied to the specimen was removed at a load of 441 N / mm 2, the amount of deformation applied to the specimen was gradually reduced, , And 6% and 8% for sample 2 and sample 5, respectively, in the same manner. The residual strain after the tensile strain is removed and the residual strain after heating are shown in Table 6 below.

Sample
Number Strain Before tensile test
(mm) Maximum Seal
(mm) After tensile test
(mm) After heating
(mm) Shape recovery rate
(%) Sample 1 6% 50 53 51.0 50.0 100 8% 50 54 50.4 50.4 90 Sample 2 6% 50 53 51.2 50.5 83.3 8% 50 54 52.0 51.0 75 Sample 5 6% 50 53 50.3 50.0 100 8% 50 54 50.5 50.3 92.5

29 to 32 are reference graphs for the result of superelasticity property test of a shape memory alloy excellent in cold workability according to a preferred embodiment of the present invention.

In order to test the superelastic characteristics of the shape memory alloy according to the preferred embodiment of the present invention, a repeated tensile test was performed. In the case of the above test method, after setting the gauge distance to 50 mm in the tensile specimen, And the strain remaining in the specimen was measured repeatedly when the load was removed from the tensile tester.

29 is a graph showing the result of repeated tensile test on Sample 1. As shown in FIG. 29, it can be seen that deformation is not removed as much as the slope in the initial elastic region at the time of stress relief, and much deformation is removed. In addition, the part where the deformation is removed is due to the incipient effect, and the amount of deformation to be recovered increases as the total deformation increases.

FIG. 30 is a graph of a repeated tensile test result for Sample 2, and FIG. 31 is a graph of a repeated tensile test result for Sample 5. As shown in FIGS. 30 and 31, On the other hand, sample 5 is smaller than sample 1 but larger than sample 2.

Figure 32 is a comparison graph of the superelastic effect of each Sample, the elongation at the time given away by applying a load to the specimen ε ^A d refers, the elongation at the time when removing the load on the specimen Speaking ε ^P, in the graph of FIG. 33 The y-axis PE strain can be expressed as the following equation.

It can be seen from the graph shown in FIG. 32 that Sample 1 and Sample 5 have almost the same ε ^PE value. Among them, ε ^PE of Sample 1 is slightly higher, so that the superelastic effect is most excellent in Sample 1 Can be seen.

In addition, unlike Sample 1 and Sample 5, Sample 2 showed that the value of ε ^PE was small from the initial 3% elongation, and that when the strain was continuously applied, the value of ε ^PE decreased, indicating that the superelastic effect did not appear to be excellent .

It can be seen that the superelastic limit converges to about 2.8% for sample 1 and sample 5, and 2.5% for sample 2 is measured as the maximum value.

FIG. 33 is a reference graph for a measurement result of differential scanning calorimetry (DSC) of a shape memory alloy excellent in cold workability according to a preferred embodiment of the present invention.

The graph shown in the graph of each sample in FIG. 33 shows Ms and Mf temperatures obtained by cooling the specimen. The graphs below show the As and Af temperatures obtained while the temperature is raised. As a result, it can be confirmed that the As, Af, Ms, and Mf temperatures of the respective samples are similar to each other with no significant difference. This shows that these samples show similar results, When the shape memory effect is tested at an Af temperature of 25 ° C or lower, it is expected that the shape memory effect will appear even at a room temperature.

In addition, As, Af, Ms, and Mf temperatures for each sample can be summarized as shown in Table 7 below.

Sample
Number As (° C) Af (° C) Ms (° C) Mf (° C) Sample 1 14.11 18.77 24.54 8.21 Sample 2 12.56 19.00 23.06 8.71 Sample 5 13.70 18.93 23.55 7.71

34 is a graph showing a tensile test result of a shape memory alloy excellent in cold workability according to a preferred embodiment of the present invention.

Here, Sample 1, Sample 2, and Sample 5 exhibiting excellent shape memory effect in the case of tensile test were subjected to a tensile test on Sample 1 shown in FIG. 35, and the total elongation of Sample 1 was found to be 6.37% , The breaking strength is 710 N / mm 2, and the tensile test results for Sample 1, Sample 2, and Sample 5 are shown in Table 8 below.

Sample Number Maximum elongation (%) Breaking strength (N / mm ² ) Sample 1 6.37 710 Sample 2 6.32 317 Sample 5 7.88 548

The shaped alloy of the present invention has excellent cold workability and is formed of a copper-aluminum-manganese-based material and contains copper in an amount of 81 to 82.5 parts by weight, aluminum in an amount of 7.5 to 8.5 parts by weight, and manganese in a proportion of 9 to 11 parts by weight, It is possible to manufacture a product having a microstructure such as a microtube, a thin plate, or a fine wire, so that the utilization can be greatly improved and the marketability can be secured accordingly.

In addition, compared to a shape memory alloy material such as Nitinol which has been conventionally used, it can be manufactured at low cost, thereby ensuring economic efficiency.

It will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the spirit and scope of the invention as defined by the appended claims. It will be possible. Therefore, the embodiments disclosed in the present invention and the accompanying drawings are intended to illustrate and not to limit the technical spirit of the present invention, and the scope of the technical idea of the present invention is not limited by these embodiments and the accompanying drawings . The scope of protection of the present invention should be construed according to the following claims, and all technical ideas within the scope of equivalents thereof should be construed as being included in the scope of the present invention.

Claims (2)

In a shape memory alloy comprising copper, aluminum, and manganese,
Characterized in that the alloy comprises 81 to 82.5 weight percent of copper, 7.5 to 8.5 weight percent of aluminum, and 9 to 11 weight percent of manganese. The method according to claim 1,
Wherein said copper is oxygen free copper, said aluminum is pure aluminum, and said manganese is electrolytic manganese.

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