EP0095798B1 - Verfahren zur Wärmebehandlung von Gegenständen aus Formgedächtnislegierungen und Gegenstände nach diesem Verfahren hergestellt - Google Patents

Verfahren zur Wärmebehandlung von Gegenständen aus Formgedächtnislegierungen und Gegenstände nach diesem Verfahren hergestellt Download PDF

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EP0095798B1
EP0095798B1 EP83200677A EP83200677A EP0095798B1 EP 0095798 B1 EP0095798 B1 EP 0095798B1 EP 83200677 A EP83200677 A EP 83200677A EP 83200677 A EP83200677 A EP 83200677A EP 0095798 B1 EP0095798 B1 EP 0095798B1
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temperature
article
beta
crystal structure
articles
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EP0095798A1 (de
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Luc Delaey
Jan Van Humbeeck
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Katholieke Universiteit Leuven
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Katholieke Universiteit Leuven
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    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22F—CHANGING THE PHYSICAL STRUCTURE OF NON-FERROUS METALS AND NON-FERROUS ALLOYS
    • C22F1/00—Changing the physical structure of non-ferrous metals or alloys by heat treatment or by hot or cold working
    • C22F1/006—Resulting in heat recoverable alloys with a memory effect

Definitions

  • the invention relates to heat recoverable metallic articles and to processes for producing them with the purpose of improving their heat recoverability as defined below, e.g. by maintaining said property stable in time.
  • Heat recoverable articles consist of an alloy containing e.g. copper, zinc and aluminium as described e.g. in the US patent No. 3.783.037.
  • Heat recoverability is to be understood hereinafter as to comprise pseudo-elasticity, shape memory, reversible shape memory, good mechanical vibration damping and change in electrical conductivity which properties all relate to the transformation of an ordered Beta-crystal structure as metallic compound to a martensitic crystal structure.
  • the temperatures which define the change of the crystal structure when following the transformation cycle are known as As, A f , M s and M f .
  • composition of copper-zinc- aluminium alloys particularly with more than 5% of aluminium-e.g. with about 6%-and with 21% zinc-the As temperature can increase so much after a certain time of holding the article at room temperature that the transformation from martensite to the beta crystal structure (on further heating) can be traversed by a recrystallization reaction
  • Cu-Zn-AI alloys and alloys similar thereto or related therewith are therefore not always usable as such with respect to their properties of heat recoverability.
  • alloy compositions useful for the invention will be given in weight percentages, wherein the sum of all metallic components are calculated as a 100% composition and wherein additions as some or other non-metallic phase such as oxides are not considered.
  • substituting elements of the metallic phase in the composition will be regarded as a substitution of copper because aluminium and zinc are the main elements which determine the characteristic transformation temperatures M s , M f , As and A f .
  • the alloys are, applicable according to the invention, have an As temperature which generally, but not necessarily, corresponds to the M s temperature of which only differs by a few °C from it and which moreover is above 0°C and preferably even above room temperature. Below these temperatures, the diffusion rate of vacancies in the lattice is sufficiently low to reduce the change of As as is intended by the invention.
  • the process according to the invention is especially applicable in those circumstances where during the thermal treatment no equilibrium phase of alpha or gamma type nor a transition phase such as bainite is formed, which would lead to an equilibrium phase. In other words the thermal treatment will be executed in such a way that these equilibrium or transition phases are not formed.
  • aluminium-containing precipitates of intermetallic compounds such as e.g. cobalt, which have a high grain boundary plane energy, seem to be able to favourably influence the stability of the heat recoverability over a longer time.
  • the present invention aims at keeping As at a substantially unchanged level, even after a long stay of the heat recoverable articles in martensitic condition at As or just below As.
  • the stay in these conditions is generally and also hereafter called ripening.
  • ripening In practice a very slow heating has often the effect of ripening.
  • the tendency however, to raise the temperature As by ripening does not exist for the M s and M f -temperatures.
  • the effect of ripening is more difficult to master, but the invention can usefully be applied for ripening temperatures between e.g. 50°C and 120°C.
  • the invention consists in reducing the number of lattice vacancies in the beta structure by a factor of at least one hundred before its transformation to martensite and even to bring them to a negligible level (in the order of 10- 7 to 10- 9 .
  • concentration of vacancies which is too high, either a change in the parameter S of long range ordering in the martensitic stage is reached or a pinning of lattice vacancies with nuclei and with grain boundary planes in the martensite is reached.
  • These martensite grain boundary plates are the boundaries of the different martensite plates or twin plates which form in the martensitic structure.
  • the boundary plates are not grain boundaries as such, but the boundaries of areas (subgrains) which are in a fixed orientation relationship with respect to each other and in relation to the crystallographic parameters.
  • Figure 1 shows in a schematic way for an article made of an alloy containing 73.5% copper, 20.5% zinc and 6% aluminium how the hysteresis loop, which is a characteristic of heat recoverability, changes when running through the transformation cycle of the beta-crystal structure towards martensite as a function of temperature.
  • the figure is relative to the extent that the different loops were drawn separate from each other to avoid confusion through overlaps.
  • the characteristic of heat recoverability was measured as the change in electrical resistivity R (in ordinate) with temperature. Analogously also another parameter can be used.
  • a type indication of the hysteresis loop 1 with the characteristic temperatures is shown in frame 2.
  • the hysteresis loop recorded hereafter is shown by the line sections 3 and 4.
  • Figure 2 shows as an example the composition range of the copper, zinc, aluminium diagram where the invention is very well applicable.
  • the compositions lie between the points 11, 12, 13 and 14 shown in Table 1 and can be completed with the already discussed subsidiary elements such as for example cobalt. A limited amount of accidental subsidiary elements is thereby not excluded.
  • the transformation temperature may then shift with the composition.
  • the connecting line between the points 11 and 14 corresponds with an As transformation temperature of about 0°C and that between the points 13 and 12 with a transformation temperature As of about 190°C.
  • the alloys to which the invention relates include the ternary Cu-Zn-AI alloys which have an As temperature above 0°C and preferably above 20°C because at lower temperatures the diffusion speed becomes so small that a change of As due to ripening will be hardly noticable.
  • Table I shows by way of example target compositions (weight %) within which the invention can be applied:
  • these alloys possess at a temperature To a disordered beta-crystal structure in the absence of a precipitate of an equilibrium phase or of a transition phase, which may lead to an equilibrium phase and at a temperature below M s , but higher than 0°C the alloy consists of martensite with a low concentration of lattice vacancies resulting from a reduction of concentration of lattice vacancies in the beta lattice structure by a factor of at least one hundred before their transformation.
  • the alloy will optionally contain between 0.01 and 2% cobalt, between 0.01 % and 0.1 % boron, between 0% and 8% manganese and between 0% and 4% of nickel.
  • the invention relates also to a process for treating heat recoverable articles defined above with the temperatures As, A f , M s , M f as features determining the recoverability.
  • the articles are cooled or quenched down from a disordered beta-crystal structure at elevated temperature To at least to a lower temperature T 1 .
  • These articles are kept for a sufficiently long time in the beta-crystal structure above the M s temperature to stabilize the temperatures M s , M f , As, A f at their equilibrium level, after which the articles are cooled down to the martensitic state below M s .
  • the term equilibrium level is meant herein to refer to the situation where the transformations always occur at the same respective temperatures upon repetitive application of the heating and cooling cycles, e.g. after deformation.
  • the concentration of lattice vacancies is reduced and an increase in As temperature after ripening is counteracted (whereas also the other transformation temperatures M s and M f are kept constant).
  • the reduction of the number of lattice vacancies is obtained by quenching the material of the articles from the disordered higher temperature beta-crystal structure (at To) to a first temperature range T 1 in the beta structure, to keep the articles at these temperatures for a time interval t 1 , to cool the material down to a second temperature range T 2 , to maintain this temperature for a second time interval t 2 , and subsequently to cool the articles down to the martensitic state below M f .
  • the limits imposed on these time and temperature parameters are relative, i.e. the imposed treatment time may be shorter according as the temperature becomes higher.
  • the treatment times t 1 or t 2 may be so short that cooling in the air or in the furnace are sufficiently slow within a given time interval, to pass through the appropriate temperature ranges to obtain the desired stability of the As temperature. This also depends on the alloy composition.
  • the temperature T 1 is for example 50°C higher than T 2 and lower than the alpha or gamma precipitation or the beta-recrystallization limits, and lies (depending on alloy and treatment time) preferably between 150°C and 500°C.
  • the treatment time t 1 is preferably as short as possible, e.g. from a few seconds to 30 minutes, preferably between 10 seconds and'10 minutes.
  • the temperature T 2 is higher than the M s temperature and smaller than or equal to 0.7 T cDO3 , whereby T cDO3 is in absolute scale the critical temperature at which the D03 superlattice is formed from the B 2 superiattice.
  • the treatment time t 2 must satisfy a minimum criterion and may extend from 1 minute to a few hours, preferably from 5 minutes to 2 hours. Since a great number of vacancies are absorbed in the grain boundaries, especially the treatment time t 1 may be strongly limited when an alloy with a fine grain structure is used, for example when the average grain size is inferior to 200 ⁇ m.
  • Figure 3a shows the temperature evolution in time for an article which is submitted to a stepwise heat treatment such as described above in the first process according to the invention.
  • the point of departure is an annealing operation at high temperature in the beta-crystal structure which, for most alloys is conducted at 750°C (To) for a minimum duration of e.g. 5 minutes and preferably 15 minutes.
  • the article After quenching from To, the article is kept in point 15 of the graph at temperature T, for the time t, to be cooled further down towards T 2 for a time t 2 , according to line 16, prior to cooling it further in a conventional way to below M f according to the line 17.
  • a first test rod of a ternary alloy of 73.5% copper, 20.5% zinc and 6.0% aluminium was annealed at 750°C for 15 minutes, quenched in water at 80°C, kept for two hours at this temperature and then cooled until full transformation into martensite.
  • a check rod showed an M s of 60°C and an As of 62°C.
  • the check rod was then divided into pieces and stored in a ripening test at different temperatures for different durations.
  • a ⁇ A s 3°C was measured.
  • the ⁇ A s 10°C, after 7 days it was 17°C.
  • a second test rod which after having been cooled down was kept at 250°C for 5 minutes and subsequently further cooled as the first test rod, (hence after further quenching to 80°C and maintaining at this temperature for 2 hours and then cooling down to under M,), shows under comparable conditions in the ripening test a ⁇ A s which is less than half that of the first test rod.
  • the evolution of the transformation temperatures was measured on the basis of the electrical resistivity to avoid parasitic effects of mechanical deformation.
  • the article is kept at a temperature T 2 for a predetermined time as in the first process.
  • a content of 0.01% to 2% and preferably less than 1% and around 0.4% of copper can be substituted by a subsidiary element such as cobalt or by cobalt in combination with another metal.
  • a subsidiary element such as cobalt or by cobalt in combination with another metal.
  • the element cobalt which forms a metallic compound together with aluminium may also be substituted by the elements palladium and platinum. These elements may even be partially, and for at most 50%, be replaced by titanium, chromium or nickel or by a combination thereof. This mixture of elements will be designated; hereinafter, as cobalt, insofar as they produce similar effects of grain refinement and uniformly distributed precipitates.
  • a heat recoverable article as used in the first process is quenched from the high-temperature disordered beta-crystal structure (at To) to a temperature T 3 below T 1 and above M s where the metallic lattice is in the beta superlattice, but quenching may take place in a medium which has a temperature in the area of T 2 .
  • the treatment time t 3 at this temperature is set at a minimum for obtaining a uniform temperature T 3 throughout the article after which the temperature is preferably returned to T 1 as quickly as possible and the treatment, as described in the first process, is applied: the article is again quenched to T 2 where it is held for a period t 2 prior to being further cooled down to the martensitic state.
  • Figure 3b shows the temperature evolution of a thermal treatment corresponding with the third process according to the invention.
  • the treated article After an annealing treatment at 750°C (To) for 15 minutes, the treated article is quenched to a temperature T 3 above the M s temperature and significantly below T i . This is shown by the line section 19 of the cooling curve 20.
  • the temperature T 3 is selected between the uppermost limit shown by the dotted line 25 and the bottom limit 26.
  • the corresponding time t 3 is preferably limited to the minimum level to obtain a uniform temperature in the article.
  • the main purpose of the preliminary cooling is to obtain a greater treatment efficiency for thicker objects.
  • the reduction in lattice vacancies is mainly obtained through a combination of the subsequent treatment at temperature T, for a time t 1 and at T 2 for a time t 2 .
  • the heat recoverable article is initially quenched from To to a lower temperature, this time at a temperature at which transformation to martensite takes place, preferably even below M f . Heating to a temperature at least equal to T 1 must then follow immediately.
  • This quenching treatment is applicable to some alloys, for example to an alloy containing 70% copper, 24% zinc and 4% aluminium. As for other alloys, for example composed of 73% copper, 21% zinc and 6% aluminium, the possibility of using shape memory characteristics is strongly reduced except in combination with certain production methods, such as hot drawing or extrusion. In some cases, an additional annealing treatment in the beta-crystal structure is necessary. In other cases, the shape memory is recoverable by rapid heating and holding at a temperature above T 1 for a very short time.
  • FIG. 4 shows the cooling curve 21 of an article corresponding with the fourth process according to the invention.
  • the quenching treatment from To is conducted at a temperature below M f , after which it is heated to a temperature T 1 in a beta-crystal structure for a time t,, followed by a second treatment time t 2 after cooling to a lower temperature T 2 also in the beta-crystal structure.
  • the further cooling to below M f may be conducted without special precautionary measures.
  • a slowed-down cooling as from T 1 according to the dotted line 22 can be applied, for example in a furnace; so that the treatment time in the T 2 temperature range is equivalent to the proposed time t 2 .
  • This fourth method has been advantageously applied after extrusion or hot rolling alloys into elongated articles such as wire and profiles.
  • the heat deformation provides a high concentration of lattice defects. It is assumed that through the intermediate treatments at T 1 and T 2 more lattice vacancies can be absorbed in dislocation clusters and in the grain boundaries with the consequence that hence the concentration of lattice vacancies in martensite is considerably reduced.
  • a quenching temperature between M s and M is also applicable. The quenching treatment is applied until above M s for those alloys whereby the heat recoverability of the article would be jeopardized or endangered.
  • the treatment temperatures T 1 and T 2 and the treatment times t 1 and t 2 are preferably optimized on the basis of a limited test on a collection of samples.
  • the third and fourth process according to the invention also have practical significance to alloys of which the time required to form a precipitate from an equilibrium phase such as alpha, gamma or bainite is very short.
  • an equilibrium phase such as alpha, gamma or bainite
  • the tip of the T.T.T. curve can be more easily avoided because the cooling speed is higher.
  • the treatment time t can be increased without danger of precipitation at T 1 .
  • the overall average vacancy density in the martensite or beta-crystal structure is reduced by preferential absorption of vacancies in some places such as the grain boundaries.
  • the structure may contain a precipitate with high grain boundary plane energy such as an aluminium-cobalt compound, so that the average grain size is smaller than 200 ⁇ m.
  • This kind of precipitate formation may also occur in the presence of boron.
  • an increased dislocation density may be achieved through hot deformation in the disordered beta-crystal structure.
  • the transformation temperature As of all samples is then immediately determined by means of resistivity measurements. All samples are returned to the martensitic state all for the same duration, e.g. two days at the same temperature, e.g. 2°C-3°C below the determined As. The As temperature is measured again. In this manner the different AS can be determined. Circumstances causing disturbing precipitation or other inconveniences are avoided.
  • the treatment parameters (such as e.g. treatment temperatures and stress) at temperatures T 1 and T 2 during the cooling process are therefore dependent upon the M s temperature, the composition of the alloy out of which the article is composed and the absolute temperature at which for this composition the vacancies are reduced to a lower level.
  • the heat treatment according to the invention results thus in a substantial decrease in ⁇ A s .
  • the invention is not limited to the Cu-Zn-AI containing alloys mentioned hereinbefore. It is also applicable e.g. to alloys which contain (apart from unavoidable impurities) 4-40% zinc, 1-12% aluminium, 0-8% manganese, 0 ⁇ 4% nickel, 0,005-1 % boron and the balance copper.
  • the zinc content is then preferably 5-32% and the aluminium content 3-10%.
  • the heat treatments on the shape memory alloys according to the invention enable them be used as actuator for temperature control.
  • a change in temperature can thus be identified and signalized by the articles of the invention between a lower temperature which is lower than or equal to A s of the alloy and a higher temperature which is (preferably) at least equal to A f of the alloy.
  • the change in shape or tendency to such change which occurs at this change in temperature then forms the signal which permits identification of the change in temperature.
  • the difference between the higher and the lower temperature can thereby be smaller than 50°C and the lower temperature can be at room temperature or above.
  • thermo-responsive actuator for a longer time at the lower temperature without creating a substantial upward shift in the As temperature.
  • Apparatuses or devices comprising said actuators are of course within the contemplation of the invention.
  • These actuators then comprise heat treated articles described above as means which enable them to reproducibly change in shape or a to tend to such change upon crossing a predetermined temperature range with the actuator.

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Claims (16)

1. Durch Wärme in den alten Zustand rückkehrfähiger Gegenstand, umfassend eine Legierung, die bei einer Temperatur To eine ungeordnete Beta-Kristallstruktur und bei einer Temperatur Ti, niedriger als To, eine geordnete Beta-Kristallstruktur in der Abwesenheit eines Niederschlags einer Gleichgewichtsphase oder einer Übergangsphase besitzt, die zu einer Gleichgewichtsphase führen kann, und daß die Legierung bei einer Temperatur unterhalb von Ms, aber höher als 0°C, aus Martensit mit einer niedrigen Konzentration von Gitterfehlstellen besteht, die aus einer Herabsetzung der Konzentration von Gitterfehlstellen in der Beta-Gitterstruktur um einen Faktor von zumindest einhundert von ihrer Umwandlung in Martensit herrührt, wobei der Gegenstand eine Zusammensetzung in Gewichtprozent im ternären Kupfer-Zink-Aluminium-Diagramm innerhalb der Grenzpunkte (11) 64% Cu, 35% Zn, 1% AI; (12) 74% Cu, 21% Zn, 5% Al; (13) 87,5% Cu, 0% Zn, 12,5% Al; (14) 86% Cu, 0% Zn, 14% AI besitzt und fakultativ zwischen 0,01 % und 2% Kobalt, zwischen 0,01% und 0,1% Bor, zwischen 0% bis 8% Mangan und zwischen 0% und 4% Nickel enthält.
2. Gegenstand nach Anspruch 1, dadurch gekennzeichnet, daß der Kobaltgehalt weniger als bis 1% ist.
3. Gegenstand nach Anspruch 1, dadurch gekennzeichnet, daß die Legierung weniger als 0,05% Bor enthält.
4. Gegenstand nach einem beliebigen der Ansprüche 1 bis 3, dadurch gekennzeichnet, daß die Legierung eine mittlere Korngröße kleiner als 200 µm besitzt.
5. Durch Wärme in den alten Zustand rückkehrfähiger Gegenstand, umfassend eine Legierung, die bei einer Temperatur To eine ungeordnete Beta-Kristallstruktur und bei einer Temperatur T1, niedriger als To, eine geordnete Beta-Kristallstruktur in den Abwesenheit eines Niederschlags einer Gleichgewichtsphase oder einer Übergangsphase besitzt, die zu einer Gleichgewichtsphase führen kann, und daß die Legierung bei einer Temperatur unterhalb von MS, aber höher als 0°C aus Martensit mit einer niedrigen Konzentration von Gitterfehlstellen besteht, die von einer Herabsetzung der Konzentration von Gitterfehlstellen in der Beta-Gitterstruktur um einen Faktor von zumindest einhundert vor ihrer Umwandlung in Martensit herrührt, wobei der Gegenstand eine Zusammensetzung von 4 bis 40% Zink, 1 bis 12% Aluminium, 0 bis 8% Mangan, 0 bis 4% Nickel, 0,005 bis 1% Bor und das Gleichgewichtskupfer besitzt.
6. Gegenstand nach Anspruch 5, dadurch gekennzeichnet, daß er 5-32% Zink und 3-10% Aluminium umfaßt.
7. Verfahren zur Herstellung eines durch Wärme in den alten Zustand rückkehrfähigen metallischen Gegenstands nach einem beliebigen der Ansprüche 1 bis 5 mit Temperaturen As, Af, Ms, Mf als Merkmalen für die Rückkehrfähigkeit in den alten Zustand, umfassend die Schritte, daß der Gegenstand aus einem Temperaturpegel To, bei dem der Gegenstand eine Beta-Kristallstruktur besitzt, auf einen ersten Temperaturbereich (T1) abgeschreckt wird, der niedriger als die Rekristallisationsgrenze ist, er dort während eines ersten Zeitintervalls (t1), das kleiner als 30 Minuten ist, gehalten wird, der Gegenstand anschließend sofort auf einen zweiten Temperaturbereich (T2) abgekühlt wird, der zwischen der Ms-Temperatur und 0,7 TcDO3 liegt, wobei TcDO3 in der absoluten Skala die kritische Übergangstemperatur eines D03-Übergitters zum B2-Übergitter ist, für ein zweites Zeitintervall (t2) von zumindest einer Minute, und der Gegenstand anschließend unter Mf zu seinem martensitischen Zustand abgekühlt wird.
8. Verfahren nach Anspruch 7, dadurch gekennzeichnet, daß der erste Temperaturbereich T1 niedriger als 500°C ist.
9. Verfahren nach Anspruch 7, dadurch gekennzeichnet, daß das erste Zeitintervall t1 zwischen zehn Sekunden und zehn Minuten ist.
10. Verfahren nach Anspruch 7, dadurch gekennzeichnet, daß das zweite Zeitintervall t2 zumindest fünf Minuten bis 2 Stunden ist.
11. Verfahren nach Anspruch 7, dadurch gekennzeichnet, daß die Gegenstände in ungeordneter Beta-Kristallstruktur bei der Temperatur To für zumindest fünf Minuten einer Vergütungsbehandlung unterzogen werden.
12. Verfahren nach Anspruch 7, dadurch gekennzeichnet, daß die Gegenstände in ungeordneter Beta-Kristallstruktur bei der Temperatur To wärmeverformt werden.
13. Verfahren nach Anspruch 12, dadurch gekennzeichnet, daß die Wärmeverformung eine Strangpreßbehandlung umfaßt.
14. Verfahren nach Anspruch 7, dadurch gekennzeichnet, daß die Metallgegenstände aus einer ungeordneten Beta-Kristallstruktur bei einer Temperatur To zu dem Pegel des Temperaturbereichs T3 unterhalb von T1 und oberhalb der Ms-Temperatur abgeschreckt werden und wo das metallische Gitter im Beta-Übergitter ist, und in diesem Temperaturbereich für ein begrenztes Zeitintervall (t3) gehalten werden, das auf den Minimalpegel begrenzt ist, um einen einheitlichen Temperaturpegel im Gegenstand zu erhalten, wonach sie wieder zum ersten Temperaturbereich T1 erwärmt werden und wieder auf den zweiten Temperaturbereich T2 abgeschreckt werden, wo sie für eine Zeitperiode (t2) gehalten werden, bevor sie weiter zum martensitischen Zustand abgekühlt werden.
15. Verfahren nach Anspruch 7, dadurch gekennzeichnet, daß die Metallgegenstände aus der ungeordneten Beta-Kristallstruktur bei einer Temperatur To auf unter die Ms-Temperatur abgeschreckt werden und bei dieser Temperatur für eine begrenzte Zeitperiode gehalten werden, nach der sie wieder auf den ersten Temperaturbereich T1 erwärmt werden, und nacheinander, nachdem sie bei dieser Temperatur für ein Zeitintervall (t1) gehalten worden sind, wieder auf diesen zweiten Temperaturbereich T2 abgeschreckt werden, wo sie während einer Zeitperiode (t2) gehalten werden und nachher zur vollen Umwandlung zum martensitischen Zustand abgekühlt werden.
16. Auf Wärme ansprechender Schalter, umfassend Einrichtungen zur Identifizierung und Signalisierung eine Temperaturänderung, wobei die Einrichtungen durch Wärme in den alten Zustand rückkehrfähige Gegenstände gemäß einem beliebigen der Ansprüche 1 bis 6 enthalten, dadurch gekennzeichnet, daß sie in der Lage sind, sich in der Form reproduzierbar zu ändern, oder zu einer solchen Änderung durch Kreuzen eines Temperaturbereichs von unterhalb der As des Gegenstandes, die bei Zimmertemperatur oder darüber liegt, und bis zu oberhalb ihrer Af zu führen.
EP83200677A 1982-05-13 1983-05-11 Verfahren zur Wärmebehandlung von Gegenständen aus Formgedächtnislegierungen und Gegenstände nach diesem Verfahren hergestellt Expired EP0095798B1 (de)

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AT83200677T ATE26468T1 (de) 1982-05-13 1983-05-11 Verfahren zur waermebehandlung von gegenstaenden aus formgedaechtnislegierungen und gegenstaende nach diesem verfahren hergestellt.

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NL8201986 1982-05-13
NL8201986A NL8201986A (nl) 1982-05-13 1982-05-13 Vormgeheugenlegering met verhoogde stabiliteit.
NL8203120 1982-08-05
NL8203120 1982-08-05

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EP0095798B1 true EP0095798B1 (de) 1987-04-08

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DE3370828D1 (en) 1987-05-14
ES522400A0 (es) 1984-03-01
ES8402880A1 (es) 1984-03-01
EP0095798A1 (de) 1983-12-07

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