EP2141251B1 - Shape memory alloys based on iron, manganese and silicon - Google Patents

Shape memory alloys based on iron, manganese and silicon Download PDF

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EP2141251B1
EP2141251B1 EP09162774.5A EP09162774A EP2141251B1 EP 2141251 B1 EP2141251 B1 EP 2141251B1 EP 09162774 A EP09162774 A EP 09162774A EP 2141251 B1 EP2141251 B1 EP 2141251B1
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Prior art keywords
shape
memory alloy
shape memory
weight
vanadium
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French (fr)
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EP2141251A1 (en
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Dong Zhizhong
Ulrich Klotz
Andrea Bergamini
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Empa Duebendorf
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    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
    • C22C38/40—Ferrous alloys, e.g. steel alloys containing chromium with nickel
    • C22C38/58—Ferrous alloys, e.g. steel alloys containing chromium with nickel with more than 1.5% by weight of manganese
    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
    • C21D6/00—Heat treatment of ferrous alloys
    • C21D6/004—Heat treatment of ferrous alloys containing Cr and Ni
    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
    • C21D6/00—Heat treatment of ferrous alloys
    • C21D6/005—Heat treatment of ferrous alloys containing Mn
    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
    • C21D6/00—Heat treatment of ferrous alloys
    • C21D6/008—Heat treatment of ferrous alloys containing Si
    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
    • C21D6/00—Heat treatment of ferrous alloys
    • C21D6/02—Hardening by precipitation
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/001—Ferrous alloys, e.g. steel alloys containing N
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/02—Ferrous alloys, e.g. steel alloys containing silicon
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
    • C22C38/40—Ferrous alloys, e.g. steel alloys containing chromium with nickel
    • C22C38/46—Ferrous alloys, e.g. steel alloys containing chromium with nickel with vanadium
    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
    • C21D2201/00—Treatment for obtaining particular effects
    • C21D2201/01—Shape memory effect

Definitions

  • the present invention describes a shape memory alloy comprising a base alloy of manganese, silicon, chromium and nickel and a residual mass fraction of at least 50 weight percent iron, the shape memory alloy being 17 to 20 weight percent manganese, 4 to 6 weight percent silicon, 8 to 10 weight percent chromium, 4 to 7 weight percent nickel, 0.2 to 1.0 weight percent vanadium, 0.2 to 1.0 weight percent carbon and / or 0.2 to 1.0 weight percent nitrogen.
  • titanium-based and nickel-based shape memory alloys have mostly been used technologically and commercially.
  • the titanium and nickel-based shape memory alloys have interesting properties in terms of transition temperatures and shape memory effect, but costs of the order of a hundred dollars per kilogram limit retransmission of the fields of application.
  • shape memory alloys The memory capability of shape memory alloys is the result of typical diffusionless phase transformations in a known temperature or voltage range.
  • Iron-based shape memory alloys exhibit a phase transition to the martensite phase when the shape memory alloy is deformed and mechanically stressed by the austenite phase. This phase transition is reversible.
  • the phase transition from the martensite phase to the austenite phase can be achieved by heating the shape memory alloy.
  • thermo-mechanical training has a favorable effect on the thickness and the width of the martensite plates, which form the martensite phase and determine the shape memory effect.
  • the shape memory alloys of the time did not succeed in industrial application.
  • Known iron-based shape memory alloys have austenite start temperatures A S of at best 80 ° C to 90 ° C and austenite finish temperatures A F of at least 160 ° C to 170 ° C. This results in an approximately 80 ° C wide austenite transition temperature range A S -A F.
  • Shape memory alloys are known, which in addition to iron and manganese, inter alia, silicon, chromium, nickel, vanadium and essentially a proportion of nitrogen.
  • JP2004115864 Another shape memory alloy with enhanced shape memory effect is described, which is based on iron-manganese and silicon and includes inter alia vanadium nitrides and / or vanadium carbides.
  • a further object of the shape memory alloys according to the invention is to provide shape memory alloys whose austenite start temperature and austenite finish temperature are significantly below the corresponding temperatures of known iron and manganese based shape memory alloys according to the prior art.
  • a further object is to provide shape memory alloys which each have austenite transition temperature ranges A S -A F , which are significantly below the previous iron-based shape memory alloys, whereby application areas can be expanded or newly developed, for example in civil engineering.
  • Shape memory alloys have austenite phases and martensite phases of identical chemical composition but different crystal structures, the occurrence of which depends on the instantaneous temperature of the shape memory alloy. While deformation of the shape memory alloy takes place at low temperatures, in particular room temperature and below, shape recovery can take place by heating the shape memory alloy to high temperatures.
  • An approximately ideal hysteresis curve of the proportion of the martensite phase and the austenite phase as a function of the temperature is in FIG. 1 shown.
  • the austenite phase or austenite has a cubic-face-centered lattice structure which occurs at high temperatures and is therefore also called the high-temperature phase. From an austenite start temperature A S up to an austenite finish temperature A F , the proportion of austenite increases.
  • the austenite phase has a low hardness and some elements such as nickel (Ni), cobalt (Co) and manganese (Mn) are known which promote the formation of austenite, so-called austenite formers.
  • the range between A S -A F is called austenite transition temperature range in this application and this is below the hitherto known on iron-based shape memory alloys for the shape memory alloys according to the invention. Also, the width of the austenite transition temperature range A S -A F is significantly narrower than known from shape memory alloys of the prior art.
  • the martensite phase or martensite designated here by the symbol ⁇ , generally forms a hexagonal close-packed spherical packing, occurs at low temperatures and forms a metastable low-temperature phase.
  • the martensite is from one Martensite start temperature M S up to a martensite final temperature M F.
  • the austenite start temperature and the martensite start temperature are generally and here also referred to as transition temperatures and represent a decisive and characteristic of many applications physical property.
  • the shape memory alloy consists of 50% by weight and more of iron.
  • Vanadium nitride and / or vanadium carbide nanoparticles cause the shape memory alloys according to the invention have desired satisfactory shape memory properties without the need for thermo-mechanical training.
  • the size of the nanoparticles occurring is in the range of nanometers (10 -9 m) and these precipitates, a precipitate or a precipitate-forming nanoparticles are finely distributed in the shape memory alloy.
  • the shape memory alloys according to the invention each comprising a base alloy consisting of manganese, silicon, chromium and nickel and a mass fraction of iron.
  • the example sma1 in addition to the base alloy on a mass fraction of vanadium carbide while the example sma2 a mass fraction of vanadium carbide and vanadium nitride particles and the shape memory alloy according to Example sma3 in addition to the base alloy has a mass fraction of vanadium nitride.
  • FIG. 2 shows measured different shape returns in percent depending on the applied heat aging temperature during each two hours of heat aging of the above-mentioned exemplary alloys sma1, sma2 and sma3.
  • Heat aging temperatures in the range of 650 ° C to 900 ° C were used, with the amount of vanadium carbide and / or vanadium nitride particles occurring during heat aging between 750 ° C and 850 ° C are excreted lead to particularly advantageous results.
  • shape memory alloys with shape-feedback quotients result more than 50%.
  • the admixture of carbon precipitates vanadium carbide particles, resulting in a mold recycle ratio of over 70%.
  • the shape recovery stresses achievable with the shape memory alloys according to the invention are in FIG. 4 plotted on the ordinate against the temperature on the abscissa.
  • FIG. 4 plotted on the ordinate against the temperature on the abscissa.
  • Square shaped measured values Shape feedback voltages of a sample of a prior art Fe-15Mn-9Si-9Cr-5Cr-5Ni-1.5Nb-0.6C prior art niobium carbide shape memory alloy for comparison. From the typical hysteresis-like curve, it can be seen that the austenite finish temperature A F of the sample of the invention is below the sample According to the prior art.
  • the measured values show that the width of the austenite transition temperature range A S -A F of the new shape memory alloy according to the invention is significantly narrower than in the prior art.
  • the electrical resistance of the shape memory alloys was determined as a function of the temperature in measurement series.
  • the resulting hysteresis curves are in FIG. 5 shown.
  • a martensite final temperature M F of about -120 ° C (about 150 K) and a martensite start temperature M S of about -50 ° C (about 220 K) can be read.
  • the austenite start temperature A S is about + 70 ° C (about 340 K) and the austenite finish temperature A F is about + 110 ° C (about 380 K).
  • a combined process of solution treatment and aging which is also called aging, is performed on a solid shape memory alloy comprising the above-mentioned elements in the above-mentioned concentration.
  • the heat treatment solution heat treatment and heat aging are carried out in a preferred embodiment of the inventive method in one and the same heat treatment furnace.
  • the heat aging is carried out directly after the solution annealing.
  • the individual solid constituents of the shape memory alloy according to the invention are fused prior to solution heat treatment and heat aging to form a solid shape memory alloy according to the prior art.
  • Solution heat treatment dissolves precipitated vanadium carbide and / or vanadium nitride particles homogeneously in a matrix of the solid shape memory alloy.
  • aging of the shape memory alloy after solution annealing at at least approximately 850 ° C. leads to advantageous results.
  • vanadium carbide and / or vanadium nitride particles are precipitated and form finely divided precipitates in the structure of the shape memory alloy.
  • the vanadium carbide precipitates and / or vanadium nitride precipitates resulting from the treatment described above result in a change in the physical properties of the shape memory alloy, thereby optimizing shape memory properties while maintaining chemical composition.
  • the described shape memory alloy according to the invention and mixing ratios varied within the abovementioned limits are used in civil engineering, in machine and vehicle construction, in the aerospace industry, and in implants and instruments in medical technology.
  • the cost-effective production of the iron-based novel shape memory alloys expands the fields of application, for example, to concrete structures in construction.
  • the Material costs for the novel shape memory alloys are in the range of known stainless steels.
  • the shape memory alloys according to the invention have narrow austenite transition temperature ranges A S -A F of about 40 ° C width. Due to the achievable shape memory properties, the shape memory alloys according to the invention can be used in concrete structures in civil engineering.

Description

Technisches GebietTechnical area

Die vorliegende Erfindung beschreibt eine Formgedächtnislegierung, umfassend eine Basislegierung aus Mangan, Silizium, Chrom und Nickel und einem Restmassenanteil von mindestens 50 Gewichtsprozent Eisen, wobei die Formgedächtnislegierung 17 bis 20 Gewichtsprozent Mangan, 4 bis 6 Gewichtsprozent, Silizium, 8 bis 10 Gewichtsprozent Chrom, 4 bis 7 Gewichtsprozent Nickel, 0.2 bis 1.0 Gewichtsprozent Vanadium, 0.2 bis 1.0 Gewichtsprozent Kohlenstoff und/oder 0.2 bis 1.0 Gewichtsprozent Stickstoff enthält.The present invention describes a shape memory alloy comprising a base alloy of manganese, silicon, chromium and nickel and a residual mass fraction of at least 50 weight percent iron, the shape memory alloy being 17 to 20 weight percent manganese, 4 to 6 weight percent silicon, 8 to 10 weight percent chromium, 4 to 7 weight percent nickel, 0.2 to 1.0 weight percent vanadium, 0.2 to 1.0 weight percent carbon and / or 0.2 to 1.0 weight percent nitrogen.

Stand der TechnikState of the art

In der Vergangenheit wurden meist auf Titan und Nickel basierende Formgedächtnislegierungen technologisch und kommerziell eingesetzt. Die auf Titan und Nickel basierenden Formgedächtnislegierungen haben betreffend Übergangstemperaturen und Formgedächtniseffekt interessante Eigenschaften, wobei aber Kosten in der Grössenordnung von hundert US-Dollar pro Kilogramm eine Weiterverbreitung der Anwendungsgebiete begrenzen.In the past, titanium-based and nickel-based shape memory alloys have mostly been used technologically and commercially. The titanium and nickel-based shape memory alloys have interesting properties in terms of transition temperatures and shape memory effect, but costs of the order of a hundred dollars per kilogram limit retransmission of the fields of application.

Heute sind ausserdem auf Eisen, Mangan und Silizium basierende Formgedächtnislegierungen mit zufriedenstellenden Formgedächtniseffekten interessant und werden in der Industrie zunehmend eingesetzt.Today, iron, manganese and silicon based shape memory alloys with satisfactory shape memory effects are also of interest and are increasingly used in industry.

Die Erinnerungsfähigkeit von Formgedächtnislegierungen ist die Folge der typischen diffusionslosen Phasenumwandlungen in einem bekannten Temperatur- oder Spannungsbereich.The memory capability of shape memory alloys is the result of typical diffusionless phase transformations in a known temperature or voltage range.

Auf Eisen basierende Formgedächtnislegierung zeigen einen Phasenübergang zur Martensitphase, wenn die Formgedächtnislegierung von der Austenitphase deformiert wird und mechanisch belastet wird. Dieser Phasenübergang ist reversibel. Der Phasenübergang von der Martensitphase in die Austenitphase kann durch Erwärmung der Formgedächtnislegierung erreicht werden.Iron-based shape memory alloys exhibit a phase transition to the martensite phase when the shape memory alloy is deformed and mechanically stressed by the austenite phase. This phase transition is reversible. The phase transition from the martensite phase to the austenite phase can be achieved by heating the shape memory alloy.

Mit den bekannten Zusammensetzungen von Formgedächtnislegierung konnten nur beinahe zufriedenstellende Formgedächtniseffekte erreicht werden, wenn ein sogenanntes "thermomechanisches Training" nach der Herstellung der Formgedächtnislegierung durchgeführt wurde. Das thermomechanische Training wirkt günstig auf die Dicke und die Breite der Martensitplatten, welche die Martensitphase bilden und den Formgedächtniseffekt bestimmen. Da aber eine Mehrzahl von Zyklen von Deformationen des Gefüges der Martensitphase bei Raumtemperatur und die Wiederumwandlung in die Austenitphase nötig sind, welche Zeit und Energie kosten, haben sich die damaligen Formgedächtnislegierungen nicht in der industriellen Anwendung durchsetzen können.With the known shape memory alloy compositions, only almost satisfactory shape memory effects could be achieved when so-called "thermo-mechanical training" was performed after the shape memory alloy was fabricated. The thermo-mechanical training has a favorable effect on the thickness and the width of the martensite plates, which form the martensite phase and determine the shape memory effect. However, since a plurality of cycles of deformation of the microstructure of the martensite phase at room temperature and the reversion to the austenite phase are required, which cost time and energy, the shape memory alloys of the time did not succeed in industrial application.

In der EP1123983 werden auf Fe-Mn-Si basierende Formgedächtnislegierungen offenbart, welche ohne thermomechanisches Training akzeptable Formgedächtniseffekte aufweisen. Durch geeignete Beimischung von Massenanteilen von Chrom und Nickel zur Steigerung der Korrosionsbeständigkeit, konnten verbesserte Formgedächtniseffekte durch die Anreicherung mit Niob und Kohlenstoff und letztlich die Bildung von ausgefällten Niobcarbidpartikeln während des Herstellungsprozesses erreicht werden. Die resultierenden Grössen der möglichen Formgedächtniseffekte reichen aber für viele gewünschte Anwendungen noch nicht aus.In the EP1123983 discloses Fe-Mn-Si based shape memory alloys that exhibit acceptable shape memory effects without thermomechanical training. By suitable incorporation of chromium and nickel mass fractions to increase corrosion resistance, improved shape memory effects could be achieved through niobium and carbon enrichment and ultimately the formation of precipitated niobium carbide particles during the manufacturing process. However, the resulting sizes of possible shape memory effects are not sufficient for many desired applications.

Gemäss " Characterization of Fe-Mn-Si-Cr shape memory alloys containing VN precipitates" von Kubo et al aus "Material Science and Engineering A378 (2004) 343-348 " konnten die mechanischen Eigenschaften, vor allem die Rückführungsdehnung (recovery strain) der auf Eisen, Mangan, Silizium und Chrom basierenden Formgedächtnislegierungen markant gesteigert werden. Der Basislegierung wurden Massenanteile von Vanadium und Stickstoff zugegeben. Durch Wärmealterung fallen Vanadiumnitridpartikel aus, welche günstige Auswirkungen auf die mechanischen Eigenschaften haben. Es werden keine Aussagen über die genauen Mischungsverhältnisse der Elemente, den Bereich der erreichbaren Austenitstarttemperaturen und Martensitstarttemperaturen, welche im weiteren Übergangstemperaturen genannt werden und den Austenitübergangstemperaturbereich AS-AF gemacht, wodurch die kommerzielle Anwendbarkeit und die Erschliessung neuer Anwendungsgebiete nicht eingeschätzt werden kann.
Bekannte auf Eisen basierende Formgedächtnislegierungen weisen Austenitstarttemperaturen AS von bestenfalls 80°C bis 90°C und Austenitfinaltemperaturen AF von mindestens 160°C bis 170°C auf. Daraus resultiert ein etwa 80°C breiter Austenitübergangstemperaturbereich AS-AF.According to " Characterization of Fe-Mn-Si-Cr shape memory alloys containing VN precipitates "by Kubo et al" Material Science and Engineering A378 (2004) 343-348 "The mechanical properties, in particular the recovery strain of the iron, manganese, silicon and chromium based shape memory alloys could be significantly increased.""The base alloy was added to vanadium and nitrogen by mass No statements are made as to the exact mixing ratios of the elements, the range of achievable austenite start temperatures and martensite start temperatures, which are referred to as transition temperatures, and the austenite transition temperature range A S -A F , thus failing to appreciate the commercial applicability and development of new applications can be.
Known iron-based shape memory alloys have austenite start temperatures A S of at best 80 ° C to 90 ° C and austenite finish temperatures A F of at least 160 ° C to 170 ° C. This results in an approximately 80 ° C wide austenite transition temperature range A S -A F.

Aus der WO9703215 sind Formgedächtnislegierungen bekannt, welche neben Eisen und Mangan unter anderem auch Silizium, Chrom, Nickel, Vanadium und im Wesentlichen einen Anteil Stickstoff aufweisen. In der JP2004115864 wird eine weitere Formgedächtnislegierung mit gesteigertem Formgedächtniseffekt beschrieben, welche auf Eisen-Mangan und Silizium basiert und unter anderem Vanadiumnitride und/oder Vanadiumcarbide umfasst.From the WO9703215 Shape memory alloys are known, which in addition to iron and manganese, inter alia, silicon, chromium, nickel, vanadium and essentially a proportion of nitrogen. In the JP2004115864 Another shape memory alloy with enhanced shape memory effect is described, which is based on iron-manganese and silicon and includes inter alia vanadium nitrides and / or vanadium carbides.

Darstellung der ErfindungPresentation of the invention

Die vorliegende Erfindung hat sich zur Aufgabe gestellt auf Eisen basierende Formgedächtnislegierungen mit einem ausreichend hohen Formgedächtniseffekt zu schaffen, welche aufgrund ihrer Phasenübergangseigenschaften Einsatz in bislang nicht erreichbaren Temperaturbereichen finden, wobei auf ein thermomechanisches Training im Anschluss an die Herstellung zur Erleichterung und Kostenreduzierung des Herstellungsverfahrens verzichtet werden kann.It is an object of the present invention to provide iron-based shape memory alloys with a sufficiently high shape memory effect which, due to their phase transition properties, find use in hitherto unreachable temperature ranges, omitting thermo-mechanical training following manufacture for facilitating and reducing the cost of the production process can.

Eine weitere Aufgabe der erfindungsgemässen Formgedächtnislegierungen ist es, Formgedächtnislegierungen zu schaffen dessen Austenitstarttemperatur und Austenitfinaltemperatur deutlich unter den entsprechenden Temperaturen von bekannten auf Eisen und Mangan basierenden Formgedächtnislegierungen gemäss dem Stand der Technik liegen.A further object of the shape memory alloys according to the invention is to provide shape memory alloys whose austenite start temperature and austenite finish temperature are significantly below the corresponding temperatures of known iron and manganese based shape memory alloys according to the prior art.

Ausserdem ist eine weitere Aufgabe Formgedächtnislegierungen zu schaffen, welche jeweils Austenitübergangstemperaturbereiche AS-AF aufweisen, die deutlich unterhalb der bisherigen auf Eisen basierenden Formgedächtnislegierungen liegen, wodurch Einsatzgebiete beispielsweise im Bauingenieurwesen erweitert oder neu erschlossen werden können.In addition, a further object is to provide shape memory alloys which each have austenite transition temperature ranges A S -A F , which are significantly below the previous iron-based shape memory alloys, whereby application areas can be expanded or newly developed, for example in civil engineering.

Neben der Schaffung einer Formgedächtnislegierung mit den oben erwähnten Eigenschaften werden in weiteren unabhängigen Ansprüchen Verwendungen und ein Herstellungsverfahren beansprucht, mit welchem diese neuartige Formgedächtnislegierung kostengünstig und einfach herstellbar sind.In addition to the creation of a shape memory alloy having the above-mentioned properties, claims and a manufacturing method are claimed in further independent claims, with which these novel shape memory alloy are inexpensive and easy to produce.

Kurze Beschreibung der ZeichnungenBrief description of the drawings

Einige Ausführungsbeispiel von erfindungsgemässen Formgedächtnislegierungen werden nachstehend im Zusammenhang mit den anliegenden Figuren beschrieben.

Figur 1
zeigt schematisch eine Temperaturkurve in Form einer Hysteresekurve, wobei der Anteil der Martensitphase ξ auf der Ordinate und die Temperatur auf der Abzisse dargestellt ist.
Figur 2
zeigt Formrückführungsquotienten für drei erfindungsgemässe Formgedächtnislegierungen (sma1, sma2 und sma3), welche bei unterschiedlichen Wärmealterungstemperaturen gealtert wurden.
Figur 3
zeigt Formrückführungsquotienten für Proben der Formgedächtnislegierungen gemäss Figur 2, wobei die Verformung der Proben bei unterschiedlichen Temperaturen unterhalb von Raumtemperatur stattfanden.
Figur 4
zeigt Messergebnisse von Formrückführspannungen, welche gegen die Temperatur aufgetragen sind, wobei eine Formgedächtnislegierung gemäss Stand der Technik mit der erfindungsgemässen Formgedächtnislegierung sma3 vergleichbar dargestellt sind.
Figur 5
zeigt Messkurven des elektrischen Widerstands gegen die absolute Temperatur für die Beispiellegierungen sma1, sma2 und sma3.
Some embodiments of shape memory alloys according to the invention are described below in conjunction with the appended figures.
FIG. 1
schematically shows a temperature curve in the form of a hysteresis curve, wherein the proportion of the martensite phase ξ is shown on the ordinate and the temperature on the abscissa.
FIG. 2
Figure 3 shows shape recycle quotients for three shape memory alloys of the invention (sma1, sma2, and sma3) aged at different heat aging temperatures.
FIG. 3
shows shape recovery quotients for samples of shape memory alloys according to FIG. 2 wherein the deformation of the samples took place at different temperatures below room temperature.
FIG. 4
shows measurement results of Formrückführspannungen which are plotted against the temperature, wherein a shape memory alloy according to the prior art with the novel shape memory alloy sma3 are shown comparable.
FIG. 5
shows measured curves of the electrical resistance against the absolute temperature for the sample alloys sma1, sma2 and sma3.

Beschreibungdescription

Formgedächtnislegierungen weisen Austenitphasen und Martensitphasen mit identischer chemischer Zusammensetzung, aber unterschiedlichen Kristallstrukturen auf, deren Auftreten von der augenblicklichen Temperatur der Formgedächtnislegierung abhängen. Während eine Deformation der Formgedächtnislegierung bei tiefen Temperaturen, insbesondere Raumtemperatur und darunter stattfindet, kann eine Formrückkehr durch das Aufheizen der Formgedächtnislegierung auf Hochtemperaturen stattfinden. Eine etwa ideale Hystereskurve des Anteils der Martensitphase und der Austenitphase in Abhängigkeit von der Temperatur ist in Figur 1 dargestellt.Shape memory alloys have austenite phases and martensite phases of identical chemical composition but different crystal structures, the occurrence of which depends on the instantaneous temperature of the shape memory alloy. While deformation of the shape memory alloy takes place at low temperatures, in particular room temperature and below, shape recovery can take place by heating the shape memory alloy to high temperatures. An approximately ideal hysteresis curve of the proportion of the martensite phase and the austenite phase as a function of the temperature is in FIG. 1 shown.

Die Austenitphase oder der Austenit, meist mit dem Formelzeichen γ bezeichnet, besitzt eine kubisch-flächenzentrierte Gitterstruktur, welche bei hohen Temperaturen auftritt und deswegen auch Hochtemperaturphase genannt wird. Ab einer Austenitstarttemperatur AS bis zu einer Austenitfinaltemperatur AF erhöht sich der Anteil des Austenit. Die Austenitphase weist eine geringe Härte auf und es sind einige Elemente wie Nickel (Ni), Kobalt (Co) und Mangan (Mn) bekannt, welche die Bildung von Austenit unterstützen, sogenannte Austenitbildner. Der Bereich zwischen AS-AF wird in dieser Anmeldung Austenitübergangstemperaturbereich genannt und dieser liegt für die erfindungsgemässen Formgedächtnislegierungen unterhalb der bisher bekannten auf Eisen basierenden Formgedächtnislegierungen. Auch die Breite des Austenitübergangstemperaturbereiches AS-AF ist deutlich schmaler, als von Formgedächtnislegierungen des Stands der Technik bekannt.The austenite phase or austenite, usually denoted by the symbol γ, has a cubic-face-centered lattice structure which occurs at high temperatures and is therefore also called the high-temperature phase. From an austenite start temperature A S up to an austenite finish temperature A F , the proportion of austenite increases. The austenite phase has a low hardness and some elements such as nickel (Ni), cobalt (Co) and manganese (Mn) are known which promote the formation of austenite, so-called austenite formers. The range between A S -A F is called austenite transition temperature range in this application and this is below the hitherto known on iron-based shape memory alloys for the shape memory alloys according to the invention. Also, the width of the austenite transition temperature range A S -A F is significantly narrower than known from shape memory alloys of the prior art.

Die Martensitphase oder der Martensit, hier mit dem Formelzeichen ε bezeichnet, bildet im allgemeinen eine hexagonal dichteste Kugelpackung, tritt bei tiefen Temperaturen auf und bildet eine metastabile Tieftemperaturphase. Der Martensit liegt ab einer Martensitstarttemperatur MS bis zu einer Martensitfinaltemperatur MF vor.The martensite phase or martensite, designated here by the symbol ε, generally forms a hexagonal close-packed spherical packing, occurs at low temperatures and forms a metastable low-temperature phase. The martensite is from one Martensite start temperature M S up to a martensite final temperature M F.

Die Austenitstarttemperatur und die Martensitstarttemperatur werden im Allgemeinen und hier auch als Übergangstemperaturen bezeichnet und stellen eine für viele Anwendungsgebiete entscheidende und kennzeichnende physikalische Eigenschaft dar.The austenite start temperature and the martensite start temperature are generally and here also referred to as transition temperatures and represent a decisive and characteristic of many applications physical property.

Die vorliegenden erfindungsgemässen auf Eisen basierenden Formgedächtnislegierungen weisen neben den Elementen einer Basislegierung bestehend aus (Massenanteile in Gewichtsprozent):

17% bis 20%
Mangan
4% bis 6%
Silizium
8% bis 10%
Chrom
4% bis 7%
Nickel
und einen hohen Massenanteil Eisen,
einen zusätzliche Partikelanteil in Gewichtsprozent bestehend aus:
0.2% bis 1.0%
Kohlenstoff und/oder Stickstoff
0.2% bis 1.0%
Vanadium
auf.The present iron-based shape memory alloys according to the invention have, in addition to the elements of a base alloy consisting of (mass fractions in percent by weight):
17% to 20%
manganese
4% to 6%
silicon
8% to 10%
chrome
4% to 7%
nickel
and a high mass fraction of iron,
an additional percentage by weight of particles consisting of:
0.2% to 1.0%
Carbon and / or nitrogen
0.2% to 1.0%
vanadium
on.

Üblicherweise besteht die Formgedächtnislegierung zu 50 Gewichtsprozent und mehr aus Eisen.Usually, the shape memory alloy consists of 50% by weight and more of iron.

Der Zusatz von Vanadium, Stickstoff und/oder Kohlenstoff bildet ein Präzipitat oder einen Niederschlag aus Vanadiumnitrid und/oder Vanadiumcarbid, wobei stabile Ausscheidungen aus Vanadiumnitrid und/oder Vanadiumcarbid, welche in Partikeln und Nanopartikeln nach der Herstellung in der Formgedächtnislegierung verteilt verbleiben. Vanadiumnitrid und/oder Vanadiumcarbid Nanopartikel führen dazu, dass die erfindungsgemässen Formgedächtnislegierungen gewünschte zufriedenstellende Formgedächtniseigenschaften aufweisen, ohne dass ein thermomechanisches Training durchgeführt werden muss. Die Grösse der auftretenden Nanopartikel liegt im Bereich von Nanometern (10-9 m) und diese die Ausscheidungen, ein Präzipiat oder einen Niederschlag bildenden Nanopartikel liegen fein verteilt in der Formgedächtnislegierung vor.The addition of vanadium, nitrogen and / or carbon forms a precipitate or precipitate of vanadium nitride and / or vanadium carbide, leaving stable precipitates of vanadium nitride and / or vanadium carbide, which remain dispersed in particles and nanoparticles after manufacture in the shape memory alloy. Vanadium nitride and / or vanadium carbide nanoparticles cause the shape memory alloys according to the invention have desired satisfactory shape memory properties without the need for thermo-mechanical training. The size of the nanoparticles occurring is in the range of nanometers (10 -9 m) and these precipitates, a precipitate or a precipitate-forming nanoparticles are finely distributed in the shape memory alloy.

Messungen an den erfindungsgemässen Formgedächtnislegierungen haben gezeigt, dass die, wie in Figur 1 gezeigt direkt benachbarten Werte von AS und MS bis etwa 50°C unterhalb der entsprechenden Werte von bekannten auf Eisen basierenden Formgedächtnislegierungen gemäss des Stands der Technik liegen.Measurements on the shape memory alloys according to the invention have shown that, as in FIG. 1 shown directly adjacent values of A S and M S to about 50 ° C below the corresponding values of known prior art iron-based shape memory alloys.

BeispieleExamples

Im Folgenden werden beispielhaft drei bevorzugte Ausführungsformen der erfindungsgemässe Formgedächtnislegierungen, umfassend jeweils eine Basislegierung bestehend aus Mangan, Silizium, Chrom und Nickel und einem Massenanteil Eisen, beschrieben. Dabei weist das Beispiel sma1 neben der Basislegierung einen Massenanteil Vanadiumcarbid auf, während das Beispiel sma2 einen Massenanteil Vanadiumcarbid und Vanadiumnitrid Partikel und die Formgedächtnislegierung gemäss Beispiel sma3 neben der Basislegierung einen Massenanteil Vanadiumnitrid aufweist.Below, by way of example, three preferred embodiments of the shape memory alloys according to the invention, each comprising a base alloy consisting of manganese, silicon, chromium and nickel and a mass fraction of iron, are described. In this case, the example sma1 in addition to the base alloy on a mass fraction of vanadium carbide, while the example sma2 a mass fraction of vanadium carbide and vanadium nitride particles and the shape memory alloy according to Example sma3 in addition to the base alloy has a mass fraction of vanadium nitride.

Figur 2 zeigt gemessene unterschiedliche Formrückführungen in Prozent in Abhängigkeit der angewandten Wärmealterungstemperatur während einer jeweils zwei Stunden dauernden Wärmealterung der oben erwähnten Beispiellegierungen sma1, sma2 und sma3. Es wurden Wärmealterungstemperaturen im Bereich von 650°C bis 900°C verwendet, wobei die Menge von Vanadiumcarbid- und/oder Vanadiumnitridpartikeln, welche bei einer Wärmealterung zwischen 750°C und 850°C ausgeschieden werden zu besonders vorteilhaften Ergebnissen führen. Bei einer Wärmealterungstemperatur von 850°C resultieren Formgedächtnislegierungen mit Quotienten der Formrückführung von mehr als 50%. Durch die Beimischung von Kohlenstoff fallen Vanadiumcarbidpartikel aus, woraus ein Formrückführungsquotient von über 70% resultiert. Durch Beimischung von Kohlenstoff und Stickstoff von 0.2% bis 1.0% Gewichtsprozent der Formgedächtnislegierung fallen Partikel Vanadiumcarbid und -nitrid aus, welche zu einem Formrückführungsquotienten von etwa 65% führen. Alle Proben der verschiedenen Formgedächtnislegierungen wurden bei Raumtemperatur um 4% verformt, woran anschliessend die Formrückführungsquotienten in einzelnen Messreihen ermittelt wurden. FIG. 2 shows measured different shape returns in percent depending on the applied heat aging temperature during each two hours of heat aging of the above-mentioned exemplary alloys sma1, sma2 and sma3. Heat aging temperatures in the range of 650 ° C to 900 ° C were used, with the amount of vanadium carbide and / or vanadium nitride particles occurring during heat aging between 750 ° C and 850 ° C are excreted lead to particularly advantageous results. At a heat aging temperature of 850 ° C, shape memory alloys with shape-feedback quotients result more than 50%. The admixture of carbon precipitates vanadium carbide particles, resulting in a mold recycle ratio of over 70%. By admixing carbon and nitrogen from 0.2% to 1.0% by weight of the shape memory alloy, particles of vanadium carbide and nitride precipitate, resulting in a mold recycle quotient of about 65%. All samples of the various shape memory alloys were deformed by 4% at room temperature, after which the shape recirculation quotients in individual measurement series were determined.

Versuchsreihen haben gezeigt, dass der Formrückführungsquotient der verschiedenen Formgedächtnislegierungen sma1, sma2 und sma3 gesteigert und ein beinahe perfekter Formgedächtniseffekt erreichbar wird, wenn die Deformation der Proben um 4% bei Temperaturen deutlich unterhalb der Raumtemperatur stattfinden. Es konnte ein vorteilhafter Temperaturbereich von kleiner gleich -25°C (≤ 248K) in Versuchsreihen ausgewertet werden, in welchem ein gesteigerter Formgedächtniseffekt erreicht wird. Wie in Figur 3 dargestellt, zeigten alle Proben Formrückführungsquotienten grösser als 90%, wenn die Deformation vor der Formrückführung bei Temperaturen von kleiner als -45°C stattfand. Auch hier zeigte die Probe sma1, umfassend eine Ausscheidung, oder Präzipitat aus ausschliesslich Vanadiumcarbidpartikeln, die höchsten Formrückführungsquotienten von grösser als 97%.Trials have shown that the shape recovery quotient of the various shape memory alloys sma1, sma2 and sma3 is increased and an almost perfect shape memory effect can be achieved if the deformation of the samples is 4% at temperatures well below room temperature. It was possible to evaluate an advantageous temperature range of less than or equal to -25 ° C. (≦ 248 K) in test series, in which an increased shape memory effect is achieved. As in FIG. 3 As shown, all the samples showed mold recycle quotients greater than 90% if the deformation occurred before the mold recycle at temperatures less than -45 ° C. Again, the sample sma1, comprising precipitate, or precipitate of vanadium carbide particles alone, exhibited the highest shape recycle quotients of greater than 97%.

Die mit den erfindungsgemässen Formgedächtnislegierungen erreichbaren Formrückführungsspannungen (Shape recovery stress) sind in Figur 4 auf der Ordinate gegen die Temperatur auf der Abszisse aufgetragen. Dabei stellen die quadratisch geformten Messwerte Formrückführspannungen einer Probe einer bekannten Niobcarbid umfassenden Fe-15Mn-9Si-9Cr-5Ni-1.5Nb-0.6C Formgedächtnislegierung gemäss Stand der Technik zum Vergleich dar. Aus der typischen hystereseartigen Kurve ist erkennbar, dass die Austenitfinaltemperatur AF der erfindungsgemässen Probe unterhalb der Probe gemäss Stand der Technik liegt. Die Messwerte zeigen, dass die Breite des Austenitübergangstemperaturbereiches AS-AF der neuen erfindungsgemässen Formgedächtnislegierung deutlich schmaler ist, als beim Stand der Technik.The shape recovery stresses achievable with the shape memory alloys according to the invention are in FIG. 4 plotted on the ordinate against the temperature on the abscissa. Here are the square shaped measured values Shape feedback voltages of a sample of a prior art Fe-15Mn-9Si-9Cr-5Cr-5Ni-1.5Nb-0.6C prior art niobium carbide shape memory alloy for comparison. From the typical hysteresis-like curve, it can be seen that the austenite finish temperature A F of the sample of the invention is below the sample According to the prior art. The measured values show that the width of the austenite transition temperature range A S -A F of the new shape memory alloy according to the invention is significantly narrower than in the prior art.

Experimentell wurden für die Beispiellegierung sma1 eine Martensitfinaltemperatur von -120°C, eine Martensitstarttemperatur von -50°C, eine Austenitstarttemperatur von 70°C und eine Austenitfinaltemperatur von 110°C gemessen. Daraus ergibt sich ein Austenitübergangstemperaturbereich AS-AF von etwa 40°C, was in etwa halb so breit ist, wie der von auf Eisen basierenden Formgedächtnislegierungen des Stands der Technik.Experimentally, a martensite final temperature of -120 ° C, a martensite start temperature of -50 ° C, an austenite start temperature of 70 ° C, and an austenite finish temperature of 110 ° C were measured for the example alloy sma1. This results in an austenite transition temperature range A S -A F of about 40 ° C, which is about half the width of that of prior art iron-based shape memory alloys.

Die erreichbaren Formrückführungsspannungen der erfindungsgemässen Formgedächtnislegierungen sind deutlich höher, als die entsprechenden Vergleichwerte von bekannten Formgedächtnislegierungen gemäss Stand der Technik.The achievable shape return stresses of the shape memory alloys according to the invention are significantly higher than the corresponding comparative values of known shape memory alloys according to the prior art.

Um die Übergangstemperaturen der Beispiellegierungen sma1, sma2 und sma3 experimentell zu bestimmen, wurde der elektrische Widerstand der Formgedächtnislegierungen in Abhängigkeit von der Temperatur in Messreihen bestimmt. Die resultierenden Hysteresekurven sind in Figur 5 dargestellt. Für das Beispiel sma1 sind eine Martensitfinaltemperatur MF von etwa -120°C (etwa 150 K) und eine Martensitstarttemperatur MS von etwa -50°C (etwa 220 K) ablesbar. Die Austenitstarttemperatur AS liegt bei etwa +70°C (etwa 340 K) und die Austenitfinaltemperatur AF bei etwa +110°C (etwa 380 K).In order to experimentally determine the transition temperatures of the sample alloys sma1, sma2 and sma3, the electrical resistance of the shape memory alloys was determined as a function of the temperature in measurement series. The resulting hysteresis curves are in FIG. 5 shown. For the example sma1, a martensite final temperature M F of about -120 ° C (about 150 K) and a martensite start temperature M S of about -50 ° C (about 220 K) can be read. The austenite start temperature A S is about + 70 ° C (about 340 K) and the austenite finish temperature A F is about + 110 ° C (about 380 K).

Herstellungsverfahrenproduction method

Auf die Herstellung der auf Eisen und Mangan basierenden Formgedächtnislegierung durch die Schmelze der Basismetalle in einem Wärmebehandlungsofen wird hier nicht näher eingegangen, da dies dem Fachmann bekannt ist, bzw. aus dem Stand der Technik entnehmbar ist.The preparation of the iron and manganese-based shape memory alloy by the melt of the base metals in a heat treatment furnace will not be discussed here, since this is known to the person skilled in the art or can be taken from the prior art.

Zur Herstellung der erfindungsgemässen Formgedächtnislegierungen wird ein kombiniertes Verfahren aus einem Lösungsglühen (solution treatment) und einer Wärmealterung (aging), welche auch Altern genannt wird, auf eine feste Formgedächtnislegierung, umfassend oben erwähnte Elemente in oben erwähnter Konzentration durchgeführt. Die Wärmebehandlungen Lösungsglühen und Wärmealterung werden in einer bevorzugten Ausführungsform des erfindungsgemässen Verfahrens in ein und demselben Wärmebehandlungsofen durchgeführt. Dabei wird die Wärmealterung direkt im Anschluss an das Lösungsglühen durchgeführt. Die einzelnen festen Bestandteile der erfindungsgemässen Formgedächtnislegierung werden vor dem Lösungsglühen und der Wärmealterung zu einer festen Formgedächtnislegierung gemäss Stand der Technik verschmolzen.For the production of the shape memory alloys of the present invention, a combined process of solution treatment and aging, which is also called aging, is performed on a solid shape memory alloy comprising the above-mentioned elements in the above-mentioned concentration. The heat treatment solution heat treatment and heat aging are carried out in a preferred embodiment of the inventive method in one and the same heat treatment furnace. The heat aging is carried out directly after the solution annealing. The individual solid constituents of the shape memory alloy according to the invention are fused prior to solution heat treatment and heat aging to form a solid shape memory alloy according to the prior art.

Durch das Lösungsglühen werden präzipitierte Vanadiumcarbid und/oder Vanadiumnitrid Partikel homogen in einer Matrix der festen Formgedächtnislegierung verteilt gelöst.Solution heat treatment dissolves precipitated vanadium carbide and / or vanadium nitride particles homogeneously in a matrix of the solid shape memory alloy.

Versuche haben gezeigt, dass ein optimaler Herstellungsvorgang ein Lösungsglühen bei 1050°C bis 1150°C über einen Zeitraum von fünf bis zehn Stunden und ein direkt anschliessendes Altern bei 750°C bis 900°C für einen Zeitraum von ein bis zwei Stunden, zu Formgedächtnislegierungen mit ausreichend guter Formrückführung und damit gutem Formgedächtniseffekt führen.Experiments have shown that an optimal manufacturing process involves solution annealing at 1050 ° C to 1150 ° C over a period of five to ten hours and directly subsequent aging at 750 ° C to 900 ° C for a period of one to two hours, too Shape memory alloys with sufficiently good shape feedback and thus good shape memory effect lead.

Insbesondere führt ein Altern der Formgedächtnislegierung nach dem Lösungsglühen bei mindestens annähernd 850°C zu vorteilhaften Ergebnissen.In particular, aging of the shape memory alloy after solution annealing at at least approximately 850 ° C. leads to advantageous results.

Durch das Altern werden, je nach Wahl der zugeführten Legierungselemente des Partikelanteils, Vanadiumcarbid und/oder Vanadiumnitrid Partikel ausgeschieden und bilden fein verteilte Ausscheidungen im Gefüge der Formgedächtnislegierung.By aging, depending on the choice of the supplied alloying elements of the particle fraction, vanadium carbide and / or vanadium nitride particles are precipitated and form finely divided precipitates in the structure of the shape memory alloy.

Die durch die oben beschriebene Behandlung ausfallenden Vanadiumcarbidausscheidungen und/oder Vanadiumnitridausscheidungen führen zu einer Änderung der physikalischen Eigenschaften der Formgedächtnislegierung, wodurch bei gleichbleibender chemischer Zusammensetzung die Formgedächtniseigenschaften optimiert werden.The vanadium carbide precipitates and / or vanadium nitride precipitates resulting from the treatment described above result in a change in the physical properties of the shape memory alloy, thereby optimizing shape memory properties while maintaining chemical composition.

Es ist zu erwähnen, dass keine Vordeformation zwischen dem Lösungsglühen und der Wärmealterung notwendig ist und kein anschliessendes aufwendiges Training, umfassend eine Vielzahl von thermomechanischen Behandlungszyklen durchzuführen ist.It should be noted that no pre-deformation between the solution annealing and the heat aging is necessary and no subsequent elaborate training comprising a plurality of thermomechanical treatment cycles is to be carried out.

Die beschriebene erfindungsgemässe Formgedächtnislegierung und in den oben genannten Grenzen variierte Mischungsverhältnisse finden Einsatz im Bauingenieurwesen, im Maschinen- und Fahrzeugbau, in der Luft- und Raumfahrtindustrie, sowie in Implantaten und Instrumenten der Medizintechnik.The described shape memory alloy according to the invention and mixing ratios varied within the abovementioned limits are used in civil engineering, in machine and vehicle construction, in the aerospace industry, and in implants and instruments in medical technology.

Die kostengünstige Herstellung der auf Eisen basierenden erfindungsgemässen Formgedächtnislegierungen erweitert die Einsatzgebiete beispielsweise auf Betonstrukturen im Bauwesen. Die Materialkosten für die erfindungsgemässen Formgedächtnislegierungen liegen im Bereich von bekannten rostfreien Edelstählen.The cost-effective production of the iron-based novel shape memory alloys expands the fields of application, for example, to concrete structures in construction. The Material costs for the novel shape memory alloys are in the range of known stainless steels.

Neben erreichbaren tiefen Austenitstarttemperaturen AS von etwa 70°C weisen die erfindungsgemässen Formgedächtnislegierungen schmale Austenitübergangstemperaturbereiche AS-AF von etwa 40°C Breite auf. Aufgrund der erreichbaren Formgedächtniseigenschaften sind die erfindungsgemässen Formgedächtnislegierungen in Betonstrukturen im Bauingenieurwesen einsetzbar.In addition to achievable low austenite start temperatures A S of about 70 ° C, the shape memory alloys according to the invention have narrow austenite transition temperature ranges A S -A F of about 40 ° C width. Due to the achievable shape memory properties, the shape memory alloys according to the invention can be used in concrete structures in civil engineering.

Aufgrund der im Vergleich zum Stand der Technik niedrigeren Austenitstarttemperatur und der Austenitfinaltemperatur, werden vor allem im Bauingenieurwesen neue Anwendungen wie z.B. vorgespannte Umschnürung von Stützen, innerlich vorgespannte zementgebundene Werkstücke oder die Schaffung verbesserter Verankerungselemente beispielsweise Dübel aus den neuartigen Formgedächtnislegierungen möglich. Aufgrund der gemäss dem Stand der Technik nötigen stärkeren Erwärmungen der bekannten Formgedächtnislegierungen, ist der Einsatz bisher schwierig bis teilweise unmöglich gewesen.Because of the lower austenite start temperature and the austenite finish temperature compared to the prior art, new applications such as prestressed necking of supports, internally prestressed cement-bonded workpieces or the provision of improved anchoring elements, for example dowels made of the novel shape memory alloys, become possible. Due to the required according to the prior art stronger heating of the known shape memory alloys, the use has been difficult to partially impossible.

BezugszeichenlisteLIST OF REFERENCE NUMBERS

εε
Martensitphasemartensite
AF A F
AustenitfinaltemperaturAustenitfinaltemperatur
AS A S
Austenitstarttemperaturaustenite
AS-AF A S -A F
AustenitübergangstemperaturbereichesAustenitübergangstemperaturbereiches
MF M F
MartensitfinaltemperaturMartensitfinaltemperatur
MS M s
Martensitstarttemperaturmartensite
sma1SMA1
Basislegierung + VanadiumcarbidBase alloy + vanadium carbide
sma2SMA2
Basislegierung + Vanadiumcarbid und VanadiumnitridBase alloy + vanadium carbide and vanadium nitride
sma3SMA3
Basislegierung + VanadiumnitridBase alloy + vanadium nitride

Claims (10)

  1. A shape-memory alloy, comprising
    a base alloy formed from manganese, silicon, chromium and nickel and a remaining mass fraction of at least 50 % by weight iron, wherein
    the shape-memory alloy contains
    17 to 20 % by weight manganese
    4 to 6 % by weight silicon
    8 to 10 % by weight chromium
    4 to 7 % by weight nickel
    0.2 to 1.0 % by weight vanadium
    0.2 to 1.0 % by weight carbon and/or 0.2 to 1.0 % by weight nitrogen,
    characterised in that
    the shape-memory alloy contains precipitated vanadium carbide sediments and/or vanadium nitride sediments, which are present in the form of a precipitate formed from nanoparticles dimensioned within the nanometre range, finely distributed in the shape-memory alloy.
  2. Use of a shape-memory alloy according to claim 1 in structural engineering, in particular for encasing supports, for use in internally prestressed cement-bound workpieces or for creating improved anchoring elements, characterised in that the shape-memory alloy has an austenite transformation temperature range As-AF spanning less than 80°C, in particular at least approximately equal to 40°C.
  3. The use of a shape-memory alloy in structural engineering according to claim 2, characterised in that the shape-memory alloy has an austenite start temperature (As) of less than 80°C, in particular at least approximately equal to 70°C.
  4. The use of a shape-memory alloy in structural engineering according to claim 2, characterised in that the shape-memory alloy has an austenite final temperature (AF) of less than 150°C, in particular at least approximately equal to 110°C.
  5. The use of a shape-memory alloy in structural engineering according to claim 2, characterised in that a deformation of the shape-memory alloy takes place prior to the shape return at temperatures lower than or equal to -25°C.
  6. The use of a shape-memory alloy in structural engineering according to claim 2, characterised in that a deformation of the shape-memory alloy takes place prior to the shape return at temperature lower than -45°C, whereby shape return quotients greater than 90% can be achieved.
  7. A method for producing a shape-memory alloy according to claim 1, characterised in that
    a base alloy formed from manganese, silicon, chromium, nickel and a mass fraction of iron is melted in a heat treatment furnace, after which a mass fraction of vanadium is subsequently added, whereupon a purposeful addition of a mass fraction of carbon is provided and this solid shape-memory alloy is treated by solution annealing in a temperature range of from approximately 1050°C to 1150°C in a period of from five to ten hours, the solution annealing being directly followed by a heat aging for approximately one to two hours in a temperature range of from 650°C to 900°C, whereby sediments of vanadium carbide form in the shape-memory alloy.
  8. The method according to claim 7, characterised in that a mass fraction of nitrogen is additionally incorporated purposefully into the melting furnace prior to the heat aging, whereby sediments comprising vanadium nitride particles precipitate out.
  9. The method according to claim 7, characterised in that a heat aging is applied at a heat aging temperature of 850°C in a period of a total of two hours.
  10. The method according to claim 7, characterised in that the solution annealing and the subsequent heat aging are combined in one and the same heat treatment furnace and can be carried in direct succession one after the other.
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Cited By (3)

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WO2020104290A1 (en) 2018-11-23 2020-05-28 Thyssenkrupp Steel Europe Ag Method for prestressing a structure with a tensioning device, and use of such a tensioning device for fastening to a structure
WO2020108754A1 (en) 2018-11-29 2020-06-04 Thyssenkrupp Steel Europe Ag Flat product consisting of an iron-based shape memory material

Families Citing this family (9)

* Cited by examiner, † Cited by third party
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Family Cites Families (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
RU2009256C1 (en) * 1992-06-01 1994-03-15 Евгений Захарович Винтайкин Iron based shape-metal alloy
JP2000501778A (en) * 1995-07-11 2000-02-15 ウラコ，カリ，マーティ Nitrogen-containing iron-based shape memory and vibration damping alloy
JP3542754B2 (en) 2000-02-09 2004-07-14 独立行政法人物質・材料研究機構 Shape memory alloy
JP2004115864A (en) * 2002-09-26 2004-04-15 Hiroshi Kubo Iron-based shape memory alloy
CN1280444C (en) * 2004-04-13 2006-10-18 刘文西 Iron based shape memory alloy containing vanadium carbide and application of shape memory packer

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