KR102430417B1 - Twinning induced plasticity copper alloys and method for manufacturing the same - Google Patents

Abstract

Provided are a twin-organic enhanced plasticity (TWIP) copper-based alloy and a method for manufacturing the same.
Twin organic plasticity enhanced (TWIP) copper-based alloy of the present invention, by weight, Al: more than 3% 20% or less, Zn: more than 3% 30% or less Ni: more than 3% 30% or less, Mn: more than 3% 20% or less, Sn: more than 1% and less than 10%, Si: more than 1% and less than 10%, Ga: more than 3% and less than 20%, Ge: more than 2 kinds selected from the group consisting of more than 3% and less than 20%, balance Cu and unavoidable impurities.

Description

TWINNING INDUCED PLASTICITY COPPER ALLOYS AND METHOD FOR MANUFACTURING THE SAME

The present invention relates to a copper-based alloy exhibiting twin organic plasticity characteristics, and more particularly, by controlling the stacking fault energy through atomic size factor and alloy element control, not only dislocation-based deformation but also twin organic plasticity enhancement (TWIP) characteristics. It relates to a twin crystalline organic plasticity-enhanced (TWIP) copper-based alloy with improved mechanical properties by simultaneously increasing strength and ductility by increasing the work hardening rate using the deformation mechanism shown, and a method for manufacturing the same.

Research to increase strength and ductility at the same time has been attempted in various ways for a long time, and it is being studied steadily even now. In designing structural metals and alloys, strength and ductility are important issues in the selection and design of materials, and have limited the industrial applications and applications of many structural alloys.

Twin induced plasticity (TWIP) strengthening due to the interaction between dislocations as a method of increasing strength and ductility has enabled the development of high-performance steels that go beyond the conventional strength-ductility relationship. In addition, the synergistic effect of strain-twin and dislocation enables novel design strategies for the composition, processing and microstructural properties of structural metals and alloys. The simultaneous enhancement of strength and ductility in TWIP steel is attributed to the high work hardening rate associated with the interaction between strain-twin and dislocation.

As the prior art of TWIP copper-based alloy, there are Non-Patent Documents 1 and 2. According to Non-Patent Document 1, according to the concept of TWIP steel, it is known that the strength and plasticity are simultaneously increased in a Cu-Al binary alloy called “TWIP copper alloy”. According to Non-Patent Document 1, it was found that the interaction between strain-twins and dislocations in TWIP copper alloy leads to improvement of strength and plasticity as in TWIP steel.

Recently, through Non-Patent Document 2, based on the concept that the bonding between the lamination defect and the partial dislocation in the TWIP copper binary alloy is affected by the solute atom, the lamination defect energy (SFE) for the dislocation motion, the friction imposed by the solute atom, etc. A model for predicting the TWIP behavior based on the interaction between friction stress and alloying elements is presented.

As in Non-Patent Document 1 and Non-Patent Document 2, a binary TWIP copper-based alloy having a solid solution has attracted attention as a new technology because it has excellent mechanical properties, and various studies are being conducted in recent years. Since it remains at the level of evaluating primordial alloys, research on the development of alloys to obtain more improved mechanical properties based on multi-component twin-organic plasticity enhancement (twip) copper-based alloys is insufficient.

In addition, when changes in structural and mechanical properties due to stacking fault energy, atomic size factor, and alloying element addition amount are applied to existing non-ferrous materials and steel materials, new properties are likely to be induced or existing properties to be further improved. Research and invention to improve properties by applying the concept of atomic size factor and alloying element addition amount to the alloy system are not being made.

Microscopic mechanisms contributing to the synchronous improvement of strength and plasticity (SISP) for TWIP copper alloys, Sci. Rep. 5 (2015) 9550 (7pp). ) Criteria for predicting twin-induced plasticity in solid solution copper alloys, Materials Science & Engineering A 711 (2018) 492-497.

One aspect of the present invention is a type of various alloying elements by introducing the concept of interaction between twinning organic plasticity enhanced (TWIP) copper alloy stacking fault energy, frictional stress due to hardened atoms, atomic size factor, and alloying elements to non-ferrous materials. An object of the present invention is to provide a twin-organic plasticity-enhanced (TWIP) copper-based alloy with excellent workability and work hardening performance by designing the and content in a direction in which the stacking fault energy is reduced.

That is, by controlling the stacking fault energy through atomic size factor and alloying element control, strength and ductility are simultaneously increased by increasing the work hardening rate by using a deformation mechanism that exhibits not only dislocation-based deformation but also twin crystalline plasticity enhancement (TWIP) characteristics. It is an object of the present invention to provide a twin crystal organic plasticity enhanced (TWIP) copper-based alloy with improved mechanical properties and a method for manufacturing the same.

The problems to be solved by the present invention are not limited to the problems mentioned above, and other problems not mentioned will be clearly understood by those skilled in the art from the following description.

In one embodiment of the present invention, in wt%, Al: more than 3% and less than 20%, Zn: more than 3% and less than 30% Ni: more than 3% and less than 30%, Mn: more than 3% and less than 20%, Sn: 1 % more than 10%, Si: more than 1% and less than 10%, Ga: more than 3% and less than 20%, Ge: more than 3% and less than 20%, processability including the remainder Cu and unavoidable impurities and a twin-organic plasticity-enhanced (TWIP) copper-based alloy having excellent work hardening performance.

Twin crystal organic plasticity enhanced (TWIP) copper-based alloy of the present invention, the elastic modulus corrected stacking fault energy (γ/G) (×10 ¹¹ , cm) is 8.9 or less, and the composition supplementation atomic size misfit index (= atomic size difference × alloy %) is 0.04 or more, so it can exhibit plastic properties of twin and slip simultaneous operation.

Also in another embodiment of the present invention,

In wt%, Al: more than 3% and less than 20%, Zn: more than 3% and less than 30% Ni: more than 3% and less than 30%, Mn: more than 3% and less than 20%, Sn: more than 1% and less than 10%, Si: Preparing a metal material including more than 1% and less than 10%, Ga: more than 3% and less than 20%, Ge: more than 3% and less than 20%, the balance of Cu and unavoidable impurities;

preparing an alloy by melting the prepared metal material;

Homogenizing heat treatment of the prepared alloy in a temperature range of 850 ~ 1050 ℃;

cooling after the homogenization heat treatment; and

Secondary heat treatment of the cooled alloy in a temperature range of 350 to 850 ° C. provides a method for producing a twin-organic plasticity enhanced (TWIP) copper-based alloy having excellent workability and work hardening performance, including;

The alloy cooled after the homogenization treatment may further include processing using one method selected from forging, extrusion, rolling, and drawing.

According to the present invention, the twin crystal organic plasticity enhancement (TWIP) copper-based alloy uses copper (Cu) and alloying elements such as Al, Zn, Ni, Mn, Sn, Si, Ga, Ge, which are alloying elements with high solubility. Twin organic plasticity enhancement (TWIP) copper alloy of this alloy composition has a large solid solubility with Cu, and when an element with a large atomic size difference is added to increase the atomic size difference×alloy composition % value, the alloying elements react with the dislocation and become dislocation The principle of inducing deformation-twining by inhibiting movement or inducing expansion of partial twin dislocations can be applied to non-ferrous materials to increase the strength and workability of copper-based alloys.

When the principle of the present invention is applied, it induces twin organic plastic deformation and work hardening behavior even when the stacking fault energy is high as well as in a material with low stacking fault energy, unlike existing technologies, and has higher mechanical properties and economic efficiency compared to conventional copper-based alloys. This improved twin-organic plasticity-enhanced (TWIP) copper-based alloy can be implemented.

In addition, the twin crystal organic plasticity enhanced (TWIP) copper-based alloy of the present invention has significantly improved mechanical properties, so that it can be widely applied as a structural material in various fields, and when the atomic size difference × alloy composition% value is increased, the alloy Elements react with dislocations to suppress dislocation movement or induce expansion of partial twin dislocations to induce strain twins, so it exhibits twin-induced plastic deformation and work hardening behavior even in materials with low stacking fault energy as well as high stacking fault energy. There is an advantage that more diverse applications of copper-based alloys are possible.

1 shows a conceptual diagram schematically illustrating the balance of forces between partial dislocations.
2 is a schematic diagram of the twin-organic plasticity-enhanced (TWIP) copper-based alloy design by the influence of the alloy composition and the stacking fault energy of the twin-organic plasticity-enhanced (TWIP) copper-based alloy of the present invention.
Figure 3 is a process flow chart showing an example of a method for manufacturing a twin crystalline organic plasticity enhanced (TWIP) copper-based alloy of the present invention.
4 is a photograph observing the microstructure of Inventive Example 1 among the Examples of the present invention.
5 is a photograph observing the microstructure of Inventive Example 2 among the Examples of the present invention.

Hereinafter, the present invention will be described.

The inventors of the present invention conducted research on the development of a new material exhibiting mechanical properties of high strength and high ductility in order to solve problems such as a recent increase in the price of raw materials due to resource limitations and strict environmental problems such as greenhouse gas related issues. As a result, by introducing the concept of twin-organic plasticity enhancement (TWIP) alloy to non-ferrous materials, the types and contents of various alloying elements are designed in a direction in which stacking fault energy is reduced to provide a copper-based alloy with excellent workability and work hardening performance. confirmed that it can be done. Specifically, the present invention is presented after confirming that the twin boundary by strain-twin prevents the movement of dislocations and increases the work hardening rate to realize excellent strength and ductility.

In other words, in the twin-organic plasticity-enhancing (TWIP) copper-based alloy of the present invention, the added alloying elements are segregated at dislocations to improve strength or workability, and thus prevent/inhibit the movement of full dislocations or twin partial dislocations to induce deformation-twins, As a result, strain-twins are activated and work hardening and twin-induced plastic deformation behavior may occur even when the stacking fault energy (SFE) is low as well as when the atomic size misfit of the additive element is large.

In addition, the twin-organic plasticity enhancement (TWIP) copper-based alloy of the present invention is different from the existing copper-based alloy, when the atomic size difference × alloy composition% value is increased, the alloying elements react with the dislocation to suppress dislocation movement or to expand the partial twin dislocation. Because it induces deformation-twins, it can exhibit twin-induced plastic deformation and work hardening behavior even in materials with low stacking fault energy as well as high stacking fault energy.

Hereinafter, the twin crystal organic plasticity enhanced (TWIP) copper-based alloy of the present invention will be described in detail.

Twin organic plasticity enhanced (TWIP) copper-based alloy of the present invention, by weight, Al: more than 3% 20% or less, Zn: more than 3% 30% or less Ni: more than 3% 30% or less, Mn: more than 3% 20% or less, Sn: more than 1% and less than 10%, Si: more than 1% and less than 10%, Ga: more than 3% and less than 20%, Ge: more than 3% and less than 20%, the balance Cu and unavoidable impurities.

The Cu, Zn. Ni, Mn, Ga, and Ge are basic elements constituting a twin-organic plasticity-enhanced (TWIP) copper-based alloy, and are a group of four-period transition elements.

Al, Mn and Ni are elements that promote a face-centered cubic (FCC) solid solution, and Al and Ni form a solid solution with Cu to improve mechanical properties.

On the other hand, the Al, Zn, Ni, Mn, Sn, Si, Ga and Ge are segregated into dislocations as substitutional elements and interfere with dislocation movement and partial dislocation and bonding, thereby inducing strain-twins, preventing the movement of dislocations by twin boundaries. to increase the work hardening rate.

In the present invention, it is preferable to limit the content of the Al, Zn, Ni, Mn, Ga, and Ge elements to each weight %, more than 3% and not more than 30%. If the content is less than 3%, the effect of segregation and reaction with dislocations is too small, whereas if it exceeds 30%, lattice distortion is severe, leaving the solid solution limit to embrittle the matrix, and the reaction efficiency with dislocations decreases. .

The twin organic plastic deformation and work hardening mechanism of the twin-organic plasticity-enhanced (TWIP) copper-based alloy of the present invention having the above-described compositional components can be predicted as follows.

First, the balance of forces between the partial dislocations is schematically shown in FIG. 1 based on the concept that the bonding of the stacking defect and the partial dislocation is affected by the solute atom, and two partial dislocations separated by the stacking fault (SF) are shown. The total force (F _T ) required to combine can be described by Relation 1 below.

[Relational Expression 1]

F _T /G = γ/G - F _R /G - 2F _f /G

where, F _f : frictional stress, F _R : repulsion force, γ: stacked fault energy, G: shear modulus

When solute atoms exist at partial dislocations in a solid solution alloy, as shown in FIG. 1, the stacking fault energy is high, and since the stacking fault energy attracts the partial dislocations, the distance between the partial dislocations is reduced, and conversely, the partial dislocations approach each other. Accordingly, the repulsive force between the partial dislocations substantially increases, thereby increasing the frictional force imposed by the solute atoms F _f . Therefore, an additional force is required for the partial dislocations to couple, which can be explained by Relation 2 below.

[Relational Expression 2]

W _R = F _T /G + F _R /G = γ/G- 2F _f /G

Here, W _R has the dimension of length and is defined as “reciprocal width” because it is inversely proportional to the partial width, and W _R (=γ/G-2F _f /G) is the effect of the stacking fault energy between partial dislocations and the partial dislocation. The frictional stress exerted by the separated solute atoms on the transformation mode conversion is shown.

The present inventors developed a model that can predict the occurrence of TWIP considering the influence of the atomic size mismatch factor, alloy composition, and shear modulus as well as the slip mode change according to the reduction in stacking fault energy from Relation 2, which is described in Relation 3 below. can be

[Relational Expression 3]

Here, γ: stacking fault energy, G: shear modulus, Ω: atomic size mismatch factor, a: lattice constant, v : Poisson's ratio, C: alloy element (solute atom).

From Equation 3, the wavy slip or planar slip deformation mode can be predicted from the relationship between the stacking fault energy (γ/G), the frictional stress (2F _f /G), the atomic size mismatch factor, and the amount of alloying elements, and the friction force between partial dislocations can be predicted. By increasing it, planar slip can be predicted even in materials with high stacking fault energy. In addition, when applied to a solid solution copper alloy, the TWIP behavior can be predicted by considering the atomic size mismatch factor and the amount of alloying elements added.

FIG. 2 is a schematic diagram of the twin-organic plasticity-enhanced (TWIP) copper alloy of the present invention, which is deformed by the influence of stacking fault energy and alloy composition - twin-organic alloy design.

As shown in Figure 2, wavy slip is exhibited in the high stacking fault energy region, and as the atomic size difference x alloy composition % value increases, alloying elements react with dislocations to inhibit dislocation movement or induce expansion of partial twin dislocations and deform -Because it induces twins, it changes from wavy slip region to planar slip region and TWIP region even for materials with low stacking fault energy as well as high stacking fault energy. As such, the copper-based alloy with the lower stacking fault energy induces strain-twins to prevent the movement of dislocations, thereby increasing the work hardening rate, thereby exhibiting superior strength and ductility compared to the existing copper-based alloys.

Next, a method of manufacturing a twin-organic plasticity-enhanced (TWIP) copper-based alloy of the present invention will be described in detail.

Preparing a metal material having the alloy composition of the present invention; preparing an alloy by melting the prepared metal material; Homogenizing heat treatment of the prepared alloy in a temperature range of 850 ~ 1050 ℃; cooling after the homogenization heat treatment; and secondary heat treatment of the cooled alloy in a temperature range of 350 to 850°C.

3 is a process flow chart showing an example of a method of manufacturing a twin-organic plasticity-enhanced (TWIP) copper-based alloy of the present invention.

3, in the present invention, first, in wt%, Al: more than 3% and less than 20%, Zn: more than 3% and less than 30% Ni: more than 3% and less than 30%, Mn: more than 3% and less than 20% , Sn: more than 1% and less than 10%, Si: more than 1% and less than 10%, Ga: more than 3% and less than 20%, Ge: more than 3% and less than 20%, the remainder Cu and unavoidable impurities Prepare the metal material so that it is made of

Then, the metal material is melted. The melting process is for alloying the manufactured metal material, and the method is not particularly limited in the present invention, and the method is generally performed in the technical field to which the present invention belongs. For example, the metal material is manufactured into an alloy through casting, arc melting, powder metallurgy, thermal spray casting, thermal spray coating, spray coating, 3D-printing, and the like.

And in the present invention, the manufactured alloy is homogenized and heat treated. Since various elements are mixed in the twin crystal organic plasticity enhancement (TWIP) copper alloy, a homogenization heat treatment is performed to induce sufficient diffusion. The homogenization heat treatment is preferably maintained for 1 to 48 hours in a temperature range of 850 to 1050 ℃. If the homogenization heat treatment temperature is less than 850 ℃, it takes a lot of time for the alloying elements to be uniformly dissolved in the alloy matrix, and if it exceeds 1050 ℃, it may cause a problem that some alloying elements cause partial melting.

After the homogenization heat treatment, cooling is performed. Since the cooling method is not particularly limited, it can be carried out by methods such as water cooling, oil cooling, and air cooling. Through the cooling process, some metal components that are not dissolved in the matrix in the microstructure are uniformly distributed.

Then, in the present invention, the step of processing the cooled alloy; may further include. In other words. In the present invention, the alloy cooled after the homogenization treatment may be processed using one of forging, extrusion, rolling, drawing, and the like.

Subsequently, in the present invention, after the processing, a secondary heat treatment is performed to create a microstructure in which twin crystals and various shapes of phase transformation precipitates by phase transformation exist simultaneously in a single-phase solid solution matrix structure. The secondary heat treatment is a process for evenly precipitating phase transformation precipitates of various shapes by twins and phase transformation on a matrix, and is maintained at a temperature range of 350 to 850° C. for 0.5 to 72 hours and cooled. At this time, the cooling may be performed in the same manner as above, such as water cooling, oil cooling, air cooling, furnace cooling, or the like.

Hereinafter, the present invention will be described in detail through the present embodiment.

(Example)

First, as shown in Table 1, Comparative Examples 1 to 2 and Inventive Examples 1 to 12 twin crystalline organic plasticity enhancement (TWIwip) copper-based alloys were prepared.

Specifically, metal materials having the composition (wt%) of Table 1 below were prepared, and the alloys were prepared by arc melting in a vacuum atmosphere, respectively. Thereafter, homogenization heat treatment was performed at 1050° C. for 24 hours, followed by cooling.

Thereafter, after each of the cooled alloys was rolled, the final alloy product was manufactured by heat treatment at 850° C. for 1 hour in order to evenly precipitate the phase transformation precipitates of various shapes by twins and phase transformation on the matrix.

On the other hand, for the twin crystal organic plasticity-enhanced (TWIP) copper-based alloy prepared as described above, a 1 mm thick plate was made, a tensile test was performed to evaluate the mechanical properties, and the atomic size difference × alloy composition % value, elastic modulus correction value They are written together in Table 1.

division Alloy (weight ratio) Elastic modulus correction Lamination fault energy (γ/G)(×10 ¹¹ ,cm) Atomic size difference × alloy% The tensile strength
(MPa) yield strength
(MPa) elongation
(%) Comparative Example 1 Cu ₈₄ Al ₁₆ 2.01 0.0626. 360 90 82 Comparative Example 2 Cu ₈₀ Mn ₂₀ 8.94 0.103. 365 125 57 Invention Example 1 Cu ₈₀ Al ₁₅ Zn ₅ 2.51 0.078 425 127 61 Invention Example 2 Cu ₈₀ Zn ₁₅ Ni ₅ 4.39 0.046 410 130 59 Invention example 3 Cu ₈₀ Mn ₁₅ Zn ₅ 4.95 0.057 405 130 62 Invention Example 4 Cu ₈₀ Al ₁₅ Mn ₅ 2.70 0.084 390 105 75 Invention Example 5 Cu ₇₅ Al ₁₅ Ni ₅ Zn ₅ 3.29 0.102 430 132 63 Invention example 6 Cu ₇₅ Mn ₁₅ Zn ₅ Ge ₅ 4.95 0.057 395 120 59 Invention Example 7 Cu ₇₀ Al ₁₀ Mn ₁₀ Ni ₅ Ga ₅ 4.42 0.138 455 134 64 Invention Example 8 Cu ₇₀ Zn ₁₅ Ni ₅ Mn ₅ Ge ₅ 6.72 0.070 404 124 60 Invention Example 9 Cu ₇₀ Al ₁₀ Zn ₁₀ Ni ₅ Ge ₅ 5.79 0.181 460 137 62 Invention example 10 Cu ₇₀ Mn ₁₅ Ni ₅ Al ₅ Zn ₅ 8.90 0.104 465 139 64 Invention Example 11 Cu ₈₀ Sn ₁₀ Zn ₅ Ge ₅ 6.85 0.194 448 135 63 Invention Example 12 Cu ₈₀ Si ₁₀ Mn ₅ Al ₅ 7.24 0.064 413 128 58

As shown in Table 1, in the case of Inventive Examples 1 to 12, which satisfy the composition of the present invention and in which twin crystals and dislocations of various shapes exist simultaneously when deformed in a solid solution matrix, superior strength and ductility compared to Comparative Examples 1-2 You can see what can be achieved in a balanced way.

In particular, compared with Comparative Example 1-2, in Inventive Example 1-12 of the present invention, the twin-organic plasticity-enhancing (TWIP) copper-based alloy induces deformation in the matrix when deformed in the solid solution matrix structure - twins, thereby preventing the movement of dislocations. It can be confirmed that excellent strength and ductility can be secured by increasing the work hardening rate. That is, as shown in Table 1 above, the twin crystalline organic plasticity enhancement (TWIP) copper-based alloy of the present invention has an elastic modulus correction stacking fault energy (γ/G) (×10 ¹¹ , cm) of 8.9 or less, composition supplementation atomic size misfit index (= atomic size difference×alloy %) 0.04 or more, it can be seen that it has twin crystal and slip simultaneous operation plasticity characteristics.

As described above, the TWIP copper-based alloy of the present invention is a material with low stacking fault energy because alloying elements react with dislocations to inhibit dislocation movement or induce expansion of partial twin dislocations to induce strain twins. Of course, it can be confirmed that twin crystal organic plastic deformation and work hardening behavior can be obtained even when the stacking fault energy is high, and thus high mechanical properties can be obtained through plastic organic work hardening.

Meanwhile, FIG. 4 is a photograph observing the microstructure of Inventive Example 1 among Examples of the present invention, and FIG. 5 is a photograph observing the microstructure of Inventive Example 2 among Examples of the present invention. 4-5, it can be confirmed that twins are formed in the alloy matrix of Inventive Example 1-2.

The present invention is not limited to the above embodiments and examples, but can be manufactured in various different forms, and those of ordinary skill in the art to which the present invention pertains can use other methods without changing the technical spirit or essential features of the present invention. It will be understood that it may be implemented in specific forms. Therefore, it should be understood that the embodiments and embodiments described above are illustrative in all respects and not restrictive.

Claims (4)

In wt%, Al: more than 3% and less than 20%, Zn: more than 3% and less than 10%, Ni: more than 5% and less than 30%, Mn: more than 3% and less than 20%, Sn: more than 1% and less than 10%, Si : more than 1% and less than 10%, Ga: more than 3% and less than 20%, and Ge: more than 3% and less than 20%, including two or more selected from the group consisting of, the remainder Cu and unavoidable impurities,
Twin crystal with excellent workability and work hardening performance with elastic modulus correction stacking fault energy (γ/G) (×10 ¹¹ ,cm) of 8.9 or less, and composition supplementation atomic size misfit index (= atomic size difference × alloy%) of 0.04 or more Organic Enhanced Plasticity (TWIP) copper-based alloy.
delete In wt%, Al: more than 3% and less than 20%, Zn: more than 3% and less than 10%, Ni: more than 5% and less than 30%, Mn: more than 3% and less than 20%, Sn: more than 1% and less than 10%, Si : preparing a metal material containing more than 1% and less than 10%, Ga: more than 3% and less than 20%, and Ge: more than 3% and less than 20%, the remainder being Cu and unavoidable impurities;
preparing an alloy by melting the prepared metal material;
Homogenizing heat treatment of the prepared alloy in a temperature range of 850 ~ 1050 ℃;
cooling after the homogenization heat treatment; and
Secondary heat treatment of the cooled alloy in a temperature range of 350 to 850 °C; including,
The secondary heat-treated alloy has an elastic modulus correction stacking fault energy (γ/G) (×10 ¹¹ , cm) of 8.9 or less, and a composition-complementary atomic size misfit index (= atomic size difference × alloy%) of 0.04 or more A method of manufacturing a twin-organic plasticity enhancement (TWIP) copper-based alloy with excellent workability and work hardening performance.
According to claim 3, wherein after the homogenization treatment, the cooled alloy is further processed using one method selected from forging, extrusion, rolling, and drawing. ) Manufacturing method of copper-based alloy

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