DE10142998B4 - Shape memory composite with inherent motion sequence - Google Patents

Abstract

Shape memory composite (V) comprising a first shape memory alloy (F1) which is present in a martensite phase (M) and / or in an austenite phase (A) as a function of the temperature (T),
wherein the phase transition of the shape memory alloy (F1) takes place during a warming into the austenite phase (A) or during a cooling into the martensite phase (M) in a hysteresis loop which has a hysteresis width (B1) with respect to the temperature (T),
characterized,
the shape memory composite (V) comprises at least one second shape memory alloy (F2), which is connected directly or indirectly to the first shape memory alloy (F1),
and which is present in a martensite phase (M) and / or in an austenite phase (A) as a function of the temperature (T),
wherein the phase transition of the shape memory alloy (F2) takes place during a heating into the austenite phase (A) or during a cooling into the martensite phase (M) in a hysteresis loop which has a hysteresis width (B2) with respect to the temperature (T),
and wherein the hysteresis width (B1) of the first shape memory alloy (F1) within the ...

Description

The Invention relates to a shape memory composite, comprising a first shape memory alloy, the dependent of the temperature in a martensite phase and / or in an austenite phase, where the phase transition the shape memory alloy in a warming into the austenite phase or during a cooling into the martensite phase takes place in a hysteresis loop, which with respect to the temperature a certain Has hysteresis width. The invention further relates to a method for Change the shape of such a shape memory composite and preferred Uses as an actuator or as a drive for the movement of mechanical / electronic Systems, in particular of micro-robots.

such Shape memory composites are well known. Shape memory materials are characterized in particular by the fact that they are in a low-temperature phase (Martensite) can be deformed into a first shape and that they are after a warming and deformation in a high-temperature phase (austenite) and subsequent cooling in the low-temperature phase reminiscent of this shape and to accept the first form again.

Shape Memory Alloys go through a martensitic transformation and change it their crystal structure. With the change to change the structure at the transition from the low temperature phase martensite to the high temperature phase Austenite also the elastic properties of the material. Becomes applied a mechanical bias voltage, so can at this transition depending on the boundary condition big Voltages Δσ exercised or undergo large changes in shape Δε become.

Shape memory composites in which a shape memory layer is deposited on a substrate can in this way perform actuator movements, especially in small microsystems. The necessary bias voltage is provided by the stress between the shape memory layer and the substrate that results when the shape memory layer crystallizes at high temperatures and then cools. For this purpose, moreover, the German patent application DE 100 19 183 A1 Reference is made to the content of which reference is made.

Shape Memory Alloys have a high work capacity, can size Movements or step sizes and are due to low Control voltages directly over Resistor heating controllable. Actuators with shape memory alloys can therefore used in various fields of technology. However, they are for applications of the Moving objects, especially micro-robots with the Disadvantage connected to that Movements during the deflection from a starting position to an end position and then back again into the starting position in the same way. One due to one Deflection of an actor made Fortbewegungsschritt is undone, so that in total a movement of the object can not be done.

at The movement of objects or robots are different drives known with wave-like motion. So a robot in the country run or swim in or under water, he must like man perform a movement, during which, within a complete phase pass, and way back differ from each other. Would do not apply this principle, the robot would only go back and forth wobbling.

Essential for this Wave-like locomotion is the phase-locked driving independently acting Partial actuators in an overall system. This working principle can be through standing or running waves in magnetostrictive or piezoelectric Actuators are generated.

at Drives with magnetostrictive layers due to standing waves are for example linear and rotary ultrasonic motors with known magnetostrictive layers. The magnetostrictive Layers in an alternating magnetic field to a sinusoidal structure and movement of the substrate. Decisive for locomotion is, that tooth-like Structures perpendicular to the substrate between wave crest and wave node exist. Cause it these teeth one ellipsoidal Movement through. There and back The tooth movement are therefore different. However, such magnetostrictive "wave" drives are only for certain applications suitable. They were able to join so far a structurally high effort in particular therefore not prevail, because the magnetostrictive effect is relatively small and the necessary immediate proximity a strong alternating magnetic field the use of the drive for running movements and prevents swimming movements of robots.

Furthermore, drives with piezoelectric layers by means of running waves are known. The principle of locomotion by means of traveling waves in piezoelectric materials is already used commercially, for example, in autofocus systems in cameras. Due to the small travel ranges of a few micrometers must, however, piezoelectric actuators with frequencies of a few kHz and high voltages are used to achieve significant locomotion, which also requires a high design effort and a large amount of energy and excludes a variety of applications.

Around wave-like movements in previously known shape memory actuators The actor must bring about this divided into sections, all individually controlled Need to become. Shape memory actuators be through heat transfer excited to movements. Because the wavy spread of heat through An actuator is very problematic and easily by the environmental influences disturbed must be one wave-like motion through the independent control of individual Actuator components are generated. The disadvantages of this drive are in the high design effort, especially in the complex Wiring and the phase-locked control of the individual Sections that also make the principle very expensive.

Especially in aerospace and underwater technology, the demand for running or buoyant micro robots, whose movement can be coordinated by simple control signals. In order to reduce the expense of control electronics to a minimum, should be the actuators used, by design and choice of materials already be designed so that, for example a single control signal is sufficient to complete a sequence of movements perform.

task The present invention is therefore a structurally simple, inexpensive to produce, easy to handle and easy to control To provide a product based on shape memory alloys, with as possible low energy consumption when acting on a control pulse learns from a starting position a deflection over a certain way and then take a different route back to the starting position. In particular, to create a simple mechanism in this way be used as a lightweight and small-sized propulsion means for locomotion technical objects or systems, preferably micro-robots can serve.

These The object is achieved by a Shape memory composite solved according to claim 1. Advantageous embodiments and further developments of the invention result from the dependent claims.

Essential in the inventive solution it that the Shape memory composite at least one second shape memory alloy comprises directly or indirectly with the first shape memory alloy is connected, and also depending on the temperature in a martensite phase and / or in an austenite phase, where also the phase transition the shape memory alloy in a warming into the austenite phase or during a cooling into the martensite phase takes place in a hysteresis loop, which with respect to the temperature a hysteresis width has, and where the hysteresis wide of the first shape memory alloy within the hysteresis width of the second shape memory alloy lies. The hysteresis width of the first shape memory alloy is narrower as the hysteresis width of the second shape memory alloy.

Of the The main advantage is that the actuator due to a a single control signal undergoes a cyclic process, with back and forth movement so different that after completed cycle process results in a net motion of the actuator. This allows in a particularly simple manner different movements of Objects, systems or robots can be achieved.

The movement of the actuator according to the invention with two shape memory alloys F1 and F2 with different hysteresis widths proceeds as follows:
If both alloys are in the martensite state and the temperature is increased, first the first alloy F1 and then the second alloy F2 is changed into the austenitic state. Upon cooling, first the first alloy F1 and then the second alloy F2 goes into the martensite state. While the first alloy is already in the austenitic state during the heating phase, the second alloy is still in the martensite state. During the cooling phase the situation is exactly the opposite: the first alloy is already in the martensite state and the second alloy is still in the austenitic state. If the shape memory alloys now exert forces in different directions, this produces the desired circular process with a different sequence of movements in the forward and backward movement with alternating transformation sequences F1 → F2 → F1 → F2.

Essential is that the Hystereses of the two alloys are not arranged one behind the other, because an actor doing the way there and back exactly the same way with the transformation sequence F1 → F2 → F2 → F1 would. However, this process can not result in a net movement, so that the Actuator only for a back and forth movement ensures and no movement occurs.

The solution according to the invention thus makes it possible to wave-shaped movements of actuators to create the base of shape memory alloys and thereby enable microrobots to drive, enabling them to travel with large travel ranges or perform swimming motions. The shape memory composite according to the invention is simple to manufacture inexpensive, easy to handle and easy to control. It can be used with very little weight and with very little space, even in microsystems varied for locomotion.

The inventive training can also be used multiple times in nested applications, each hysteresis of a shape memory alloy within the Hysteresis one next Shape memory alloy located. It is also possible several shape memory alloys different or equal hysteresis widths together to combine that all Hystereses of these alloys within the hysteresis width of one another shape memory alloy lie.

For certain Purposes can also be a limiting case of the solution according to the invention are used either only the phase transformation from martensite to austenite or conversely, only the phase transformation from austenite to martensite in both shape memory alloys falls to the same temperature range. The temperature range However, the other phase transformation is also here so to choose that the Hysteresis of alloy with narrower hysteresis width overall within the wider hysteresis of the other alloy.

Around especially big To achieve movements or step sizes is proposed that means for applying a force or a tension on one or on both shape memory alloy (s) are provided. These funds can be formed for example by a spring.

According to one particularly preferred embodiment of the invention are the first shape memory alloy and the second Shape memory alloy each on a substrate with a thermal expansion coefficient applied, which is different from the thermal expansion coefficient the shape memory alloys. at a temperature change brings the substrate here for a large deformation or movement required forces or tensions. Dependent on changes from the temperature the stress in the shape memory layer deposited on a substrate, causing a bimetal effect. Here is with the different voltage values a change the curvature of the Shape memory composite connected. Is the shape memory layer in the austenitic state, the shape memory composite is in a curved state. Is the shape memory layer against it in Martensitzustand before, so is the shape memory composite in a nearly planar state, as oriented by education Martensitvarianten the layer composite tension on a relative low value is reduced.

It However, it is not mandatory that a Actuator bent in Austenitzustand and in Martensitzustand is flat. By overlaying a bimetallic effect By means of a third layer in a shape memory composite, an output curvature or an offset curvature be achieved, whereby the flexibility of the composite regarding its applications elevated becomes.

Especially It is advantageous if the first shape memory alloy and the second Shape memory alloy are applied to the same substrate. By using only a single substrate can be a particularly simple construction be achieved.

Advantageously, the substrate may be a metal, a semi-metal, a polymer or a ceramic. It is preferably proposed that the substrate is formed of or with steel, molybdenum (Mo), silicon (Si), silicon carbide (SiC), silicon dioxide (SIO ₂ ) or silicon nitride (Si ₃ Ni ₄ ).

Especially small-sized and lightweight constructions can be obtained by that this Substrate formed in the form of a strip or a layer is. It is also in this regard of Advantage, although the first shape memory alloy and / or the second shape memory alloy is formed in the form of a strip or a layer.

The both shape memory alloys can preferably combined in a layer composite. In a structurally particularly simple embodiment of the shape memory composite thereby form a layer composite consisting of a single substrate layer and exactly two shape memory layers consists. It is preferably proposed that the thicknesses of the two shape memory layers at least approximately are the same size.

Especially It is also advantageous if the substrate has one or more Has areas in which or not all, but only a part number of all shape memory alloys, preferably only a shape memory alloy is applied. As a result, with a simple construction, a wave-like movement be achieved.

Preferably, at each point of the Substrate applied only a part number of all shape memory alloys, in particular only a single shape memory alloy. There may also be areas of the substrate in which no shape memory alloy is applied.

According to one Another particularly advantageous embodiment of the invention the substrate is formed by a strip that divides into two or more sections is split, wherein in a first section on a surface (top) of the strip the first shape memory alloy is applied and in the second section on the other surface (underside) of the strip the second shape memory alloy is applied. Such an actuator can be particularly good for running movements or for swimming movements be used.

For certain Areas of use may be advantageous if the shape memory composite according to the invention additional Having layers, which are preferably made of materials, the a higher one elasticity have as the shape memory alloys and / or the substrate. In particular, this can be a desired output form be specified by the actuator.

Preferably can the shape memory composite externally be surrounded by a polymer layer, for example, a protection against environmental influences to reach.

In particularly preferred embodiments consist of shape memory alloys made of alloys with titanium (Ti) and nickel (Ni), in particular TiNi, Ti (Ni, Cu), Ti (Ni, Fe), Ti (Ni, Pd), Ti (Ni, Au), (Ti, Hf) Ni or (Ti, Zr) Ni. Also can the shape memory alloys Alloys based on copper, in particular CuZnAl or CuNiAl be.

The Properties of these alloys can be added by adding certain alloying elements are specifically influenced. That's how it works the successive substitution of Ni by Pd or the substitution of Ti by Hf the transition temperatures the shape memory layers to temperatures of up to 500 ° C increase. The substitution of Ni by Fe allows the transition temperatures to be determined reduce it. This makes it possible to change the transition temperatures in one set wide range.

The Hysteresis width with respect the temperature depends also from the attached Substituents from, so that too the hysteresis width by suitable choice of the shape memory alloy can be adjusted. This increases the Ni / Nb and the Ti / Hf substitution the hysteresis width, while the Ni / Cu substitution this decreases.

The The invention also relates to a method for changing the shape of a shape memory composite of the type described above. According to this method, the Form of the composite layer changed by the fact that the shape memory composite heated or cooled becomes.

Especially can be a shape memory composite according to the invention be changed in shape with this method so that it is in a cycle of an initial shape to a final shape and deformed back to the initial shape is by the shape memory composite first heated and then cooled becomes.

On The heating of the shape memory composite can be particularly simple be induced by the supply of electric current.

On this way can be an inventive shape memory composite especially in no microsystems as an actuator for the conversion of thermal and / or electrical energy into mechanical work or as an actuator for the movement of mechanical / electronic systems deploy.

Further Advantages and features of the invention will become apparent from the following Description and the embodiments illustrated in the drawings.

It demonstrate:

1 : Schematic stress-strain diagram of a shape memory alloy in the martensite and austenite state

2 : Stress-temperature diagram of a shape memory composite with a large hysteresis width

3 : Stress-temperature diagram of a shape memory composite with a narrow hysteresis width

4 : Displacement-temperature diagram of two shape memory composites

5 : Cross section through an actuator according to the invention

6 : Schematic representation of the deflection-temperature curve of the actuator 5

7 : Measured deflection-temperature curve of the actuator 5

8th : Cross section through an actuator for running movements

9 : Movement sequence of the actuator 8th during a running movement

10 : Cross section through an actuator for swimming movements

11 : Movement sequence of the actuator 10 during a swimming movement

In 1 shows schematically how change the elastic properties of a shape memory alloy during the transition from the low temperature phase martensite M to the high temperature phase austenite A. Here, the stress σ is plotted against the strain ε. In particular, a titanium-nickel-based alloy can be used as the shape memory alloy for a layer composite V according to the invention, for example TiNi, Ti (Ni, Cu), Ti (Ni, Fe), Ti (Ni, Pd), Ti (Ni, Au ), (Ti, Hf) Ni or (Ti, Zr) Ni.

The voltage-temperature diagram in 2 shows the change of the layer stress σ (in MPa) as a function of the temperature T (in ° C) at a TiNi shape memory layer F2, which was deposited on a substrate S of molybdenum. The recorded values are obtained for a 2 μm thick Ti ₄₈ Hf ₈ Ni ₄₄ shape memory layer on a 100 μm thick molybdenum substrate S after a one hour annealing at 600 ° C. The transition temperatures indicated designate the martensite start temperature M _S , the martensite end temperature M _f , the austenite start temperature A _S and the austenite end temperature A _f .

by virtue of The low expansion coefficient of molybdenum is formed after annealing Tensile stress of about 600 MPa, which is below 30 ° C by the Orientation of martensite variants by about 500 MPa is reduced. When heating is through the inverse transformation at about 60 ° C the layer tension rebuilt. With the different ones Voltage values σ is at the same time a change the curvature of the shape memory layer F2 and the substrate S existing shape memory network V connected.

The hysteresis width with respect to temperature may be affected by variations in the alloying elements added to the shape memory alloy. So shows the voltage-temperature diagram in 3 the change in the layer stress σ (in MPa) as a function of the temperature T (in ° C) for a 2 μm thick Ti ₅₅ Ni ₃₀ CU ₁₅ memory layer F1 on a 100 μm thick molybdenum substrate S after a one hour annealing at 600 ° C. The width of the hysteresis with respect to the temperature is significantly lower than in 2 ,

In 4 are the deflection temperature curves of two different shape memory alloys F1 and F2 with the properties according to FIGS 2 and 3 faced each other. The transformations of austenite to martensite are characterized by A → M and the phase transformations of martensite to austenite by M → A. According to the invention, two shape memory alloys F1 and F2 of different hysteresis widths B1, B2 are combined with one another such that the hysteresis of the alloy F1 with a narrower hysteresis width B1 lies within the further width B2 of the hysteresis of the alloy F2.

The effect of the transformation sequence F1 → F2 → F1 → F2 on the deflection L of actuators can be checked by measuring technology, if an actuator is considered which consists of a layer composite V according to FIG 5 consists. The layer composite V consists of three layers S, F1, F2. Two of the layers F1 and F2 are shape memory alloys. The substrate S is located between these two shape memory layers F1 and F2. In the simplest and clearest case, the layer thicknesses of the two shape memory layers are just the same. The shape memory alloy F1 has a narrow hysteresis and the shape memory alloy F2 has a broad hysteresis.

Corresponding In the preceding description, the layers F1, F2 are made Shape Memory Alloys on substrates S with lower coefficient of thermal expansion in the Austenitzustand A under a large tension and Martensitzustand M under a much lower tension. The sequence of layers made of shape memory alloy F1, a passive substrate S and shape memory alloy F2 has to Consequence, that the opposite Shape memory layers F1, F2 in Austenitzustand A pull the substrate S on each side want. If both layers F1 and F2 are in the martensite state M or In Austenitzustand A, the tensile stresses lift straight up and the actor remains flat. Is only one of the two shape memory layers F1 or F2 in austenitic state A, so their tensile stress and the outweighs Actuator is deflected in their direction.

Since according to the invention, the hysteresis of the shape memory layer F1 is within the hysteresis of the other shape memory layer F2, this comes in 6 Outlined deflection behavior of the actuator. Way out (above) and way back (below) have a significantly different course.

In 7 is the measured course of the Deflection of such a layer composite V shown. The composite layer V here consists of a molybdenum substrate of thickness 100 microns and two shape memory layers of Ti ₅₅ Ni ₃₀ Cu ₁₅ and Ti ₄₉ Hf ₉ Ni ₄₂ with a thickness of 2.7 microns.

8th shows a particularly preferred embodiment of an actuator according to the invention, which can be used for running movements. The actuator essentially corresponds to the strip-shaped actuator 5 However, wherein the two shape memory alloys F1 and F2 with different hysteresis widths B1 and B2 are divided into two different sections A1 and A2. In the first section A1, the first shape memory alloy F1 is applied on the underside of the substrate strip S, and in the second section A2, the second shape memory alloy F2 is applied on the top side of the substrate strip S.

The possible with this actor movement forms are in the 9 in five steps 1) to 5).

At the in 9 shown running motion is the actuator off 8th arranged vertically down to an object O, which may be a mechanical / electronic system, in particular a micro robot. If both shape memory alloys F1 and F2 are in the martensite state M, the object O stands on the floor B in accordance with partial step 1.

The subsequently resulting curvature the lower half or section A1 with the alloy F1 to the right leads to Repel and thus to a movement of the object O to the left (sub-step 2). The arrow P shows the moment of repulsion. In this liner of the actuator, the alloy F1 is in Austenitzustand A and the alloy F2 still in Martensitzustand M.

The second alloy F2 ensured subsequently a return movement the actuator without contact with the ground, if other actuators, in particular more Legs of the robot at this moment the ground contact and thus the Take over weight of object O After the upper half or the section A2 is curved with the second alloy F2 and both shape memory alloys F1 and F2 in austenitic state A are (substep 3), deforms the lower section with the alloy F1 back to the starting position back (Sub-step 4). In this second intermediate position of the actuator is located the alloy F1 again in Martensitzustand M, while the Alloy F2 is still in the austenitic state A.

Finally deformed also the upper section with the alloy F2 again in the Starting position back (Sub-step 5), so that the actuator is again in the starting position and both alloys F1 and F2 are again in the martensite state M. Of the Circular process of Movement is thus once passed and can be used for more Running steps are repeated.

10 shows a particularly preferred embodiment of an actuator according to the invention, which can be used for swimming movements. The actuator essentially corresponds to the strip-shaped actuator 8th However, both shape memory alloys F1 and F2 are applied with different hysteresis widths B1 and B2 in the two sections A1 and A2 on the same side of the substrate strip S.

At the in 11 shown floating movement are two actuators according to 10 arranged laterally opposite each other on an object O, which in turn may be a mechanical / electronic system, in particular a micro robot. In this illustration, the two actuators are arranged such that both shape memory alloys F1 and F2 are located on the underside of the substrate strip S. The possible with the actors movement forms are in the 11 in five steps 1) to 5).

For an actuator for swimming movements, the same criteria apply as for the previously described actor for running movements. Again, the span of the actuator in the forward movement (sub-steps 1 → 2 → 3) should be as large as possible, while for the return movement (sub-steps 3 → 4 → 5), the span must be as small as possible. However, it makes sense in a swimming movement that in the starting position 1) in 11 both alloys F1 and F2 are in the martensite state M and that both shape memory alloys F1 and F2 work in the same direction (downwards) upon their first deformation. The curved martensite state M of the actuator section A1 of alloy F1 can be achieved by superimposing a bimetallic effect by means of a third layer which makes it possible to produce the desired offset curvature. This third layer can be found in the in 11 represented example advantageously be provided on the upper side of the substrate strip S.

First, in the starting position 1), both shape memory alloys F1 and F2 are in the martensite state M, with both actuators facing upwards. The deformation or stretching of the inner half or section A1 with the alloy F1 downwards leads to a floating movement of the object O upwards. The arrows P1 and P2 show the propulsive forces exerted by the sections A1 and A2. In this intermediate layer 2) of the actuators, the alloy F1 is in Austenitzustand A and the alloy F2 still in Marten seating state M. Both alloys F1 and F2 are straight in this case.

Then deformed or curves also the outer half resp. the section with the second alloy F2 down, where a further swimming movement of the object O is up. The arrows P2 show the propulsive forces exerted by sections A2. Both shape memory alloys F1 and F2 are now in Austenitzustand A. in this end position 3.

Then deformed the inner section with the alloy F1 returns to its original position back. In this second intermediate layer 4) of the actuators is the Alloy F1 again in martensite M, while the Alloy F2 is still in the austenitic state A. Both alloys F1 and F2 are here in a curved position.

Finally deformed also the outer section with the alloy F2 back to the starting position 5), so that both Actuators overall is back in the starting position and both Alloys F1 and F2 are again in Martensitzustand M. The cycle of movement has gone through it once and can be repeated for further swimming steps become.

M

martensite

A

austenite

σ

tension

ε

strain

V

Layer composite, Shape memory composite

T

temperature

S

substratum

M _s

martensite

M _f

martensite

A _S

austenite

A _f

austenite

F1

first Shape memory alloy, Shape memory layer

F2

second Shape memory alloy, Shape memory layer

L

deflection

B1

hysteresis the first shape memory alloy

B2

hysteresis the second shape memory alloy

A1

first section

A2

second section

 O

object

B

ground

P

moment the repulsion

P1

propulsive force

P2

propulsive force

Claims (22)

A shape memory composite (V) comprising a first shape memory alloy (F1) present in a martensite phase (M) and / or an austenite phase (A) as a function of temperature (T), the phase transition of the shape memory alloy (F1) upon heating into the austenite phase (A) or during a cooling into the martensite phase (M) in a hysteresis loop which has a hysteresis width (B1) with respect to the temperature (T), characterized in that the shape memory composite (V) comprises at least one second shape memory alloy ( F2) which is directly or indirectly connected to the first shape memory alloy (F1) and which is present in a martensite phase (M) and / or an austenite phase (A) as a function of the temperature (T), the phase transition of the shape memory alloy (F2) takes place when heated to the austenite phase (A) or when cooled to the martensite phase (M) in a hysteresis loop, which bez of the temperature (T) has a hysteresis width (B2), and the hysteresis width (B1) of the first shape memory alloy (F1) is within the hysteresis width (B2) of the second shape memory alloy (F2). Shape memory composite according to claim 1, characterized in that either the phase transformation from martensite (M) to austenite (A) or vice versa from austenite (A) to martensite (M) in both shape memory alloys (F1, F2) falls to the same temperature range. Shape memory composite according to claim 1 or 2, characterized in that means for applying a force or stress (σ) to at least one shape memory alloy (F1, F2) are provided. Shape memory composite according to one of the preceding claims, characterized in that the first shape memory alloy (F1) and the second shape memory alloy (F2) are each applied to a substrate (S) having a has thermal expansion coefficient that is different to the thermal expansion coefficient of the shape memory alloys (F1, F2). Shape memory composite according to claim 4, characterized in that the first shape memory alloy (F1) and the second shape memory alloy (F2) on the same substrate (S) are applied. Shape memory composite according to claim 4 or 5, characterized in that the substrate (S) is a metal, a semi-metal, a polymer or a ceramic. Shape memory composite according to claim 6, characterized in that the substrate is formed of or with steel, molybdenum (Mo), silicon (Si), silicon carbide (SiC), silicon dioxide (SIO ₂ ) or silicon nitride (Si ₃ Ni ₄ ). Shape memory composite according to one of the claims 4 to 7, characterized in that the substrate (S) in the form a strip or a plane is formed. Shape memory composite according to one of the preceding claims, characterized in that the first shape memory alloy (F1) and / or the second shape memory alloy (F2) is formed in the form of a strip or a layer. Shape memory composite according to the claims 5, 8 and 9, characterized in that exactly two shape memory alloys (F1, F2) combined with a substrate layer (S) in a composite layer (V) are. Shape memory composite according to one of the claims 5 to 10, characterized in that the substrate (S) at least a region (A1, A2) in which only a part number of all Shape Memory Alloys (F1, F2), preferably only a shape memory alloy (F1, F2) applied is. Shape memory composite according to claim 11, characterized in that at each point of the substrate (S) each a maximum of a part number of all shape memory alloys (F1, F2), preferably only a shape memory alloy (F1, F2) applied is. Shape memory composite according to claim 12, characterized in that the substrate (S) by a Strip is formed, which has two sections (A1, A2), wherein in the first section (A1) on the top or bottom of the Strip's first shape memory alloy (F1) is applied and in the second section (A2) on the top or underside of the strip, the second shape memory alloy (F2) applied is. Shape memory composite according to one of the preceding claims, characterized in that additional Layers are provided, which are preferably made of materials, which have a higher elasticity as the shape memory alloys (F1, F2) and / or the substrate (S). Shape memory composite according to one of the preceding claims, characterized characterized in that it is outside surrounded by a polymer layer. Shape memory composite according to one of the preceding claims, characterized in that the Shape Memory Alloys (F1, F2) alloys with titanium (Ti) and nickel (Ni), in particular TiNi, Ti (Ni, Cu), Ti (Ni, Fe), Ti (Ni, Pd), Ti (Ni, Au), (Ti, Hf) Ni or (Ti, Zr) are Ni. Shape memory composite according to one of the preceding claims, characterized in that the Shape Memory Alloys (F1, F2) alloys based on copper, in particular CuZnAl or CuNiAl are. Method for changing the shape of a shape memory composite (V) according to one of the preceding claims, characterized that the Shape memory composite (V) heated or cooled becomes. Method for changing the shape of a shape memory composite (V) according to one of the preceding claims of an initial form to a final form and back to the initial shape in a cyclic process, characterized that the shape memory composite (V) heated and then cooled becomes. Method according to claim 18 or 19, characterized that the warming is caused by electric current. Use of a shape memory composite (V) after one the claims 1 to 17, in particular using the method according to one the claims 18 to 20, as an actuator for the conversion of thermal and / or electrical Energy in mechanical work. Use of a shape memory composite (V) after one the claims 1 to 17, in particular using the method according to one the claims 18 to 20, as an actuator for the movement of mechanical / electronic Systems.