Stabilisation and Irreversibility of Martensite in Copper Base Shape Memory Alloys

  • J. Dutkiewicz
Part of the NATO ASI Series book series (NSSB, volume 355)

Abstract

Application of martensitic shape memory alloys requires reproducible transformation temperatures independently of the time of low temperature ageing, in order to ensure the shape recovery in the same temperature interval. Martensite in copper base alloys is a metastable phase, since it decomposes into equilibrium phases below the temperature of the start of reversible martensitic transformation - As. The tempered martensite cannot be retransformed to the parent β as shown in CuZnSi alloys1. The thermal stability of martensite is rather poor in CuZnSi alloys and in CuZnSn alloys decomposing rapidly at 200°C1,2, while other alloys still retransform after prolonged ageing at 300°C as demonstrated by Dutkiewicz3 for CuAIMn and by Kobus4 in CuAlNiMnTi alloys. Martensite in copper base alloys possess in most cases an orthorhombic disordered 2H, 3R or 9R or ordered 4H, 6R or 18R structures5. These structures result from a periodic arrangement of stacking faults and usually possess a high density of random stacking faults. It is caused by a low stacking fault energy (SFE) in these alloys below 30 erg/cm2. In fact alloying additions used in shape memory alloys were reported to lower the SFE in α phase copper base alloys as summarised by Gallagher6. When alloys are kept in the martensitic state, they tend to raise the retransformation temperature to parent β as pointed out by Hansen7 and Scarsbrook8. This phenomenon is known as stabilisation of martensite. Several mechanisms have been proposed for the stabilisation of martensite: (i) vacancy pinning of interfaces7,9,10 preventing martensite/matrix interfaces to move; higher temperature is needed to overcome its resistance.

Keywords

Furnace Argon Martensite Kato Kobus 

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References

  1. 1.
    J. Dutkiewicz and T. Czeppe, Stabilization of Martensite in CuZnSi alloys, in The Martensitic Transformation in Science and Technology ed. E.Hornbogen, N.Jost,DGM Verlag, 1989Google Scholar
  2. 2.
    J. Dutkiewicz and J. Morgiel, Effect of ageing on martensitic transformation in CuZn and CuZnSn alloys, ref. 1 p. 141.Google Scholar
  3. 3.
    J. Dutkiewicz, E.Cesari, C. Segui and J. Pons, Response of CuAIMn alloys to ageing in β phase, J.de Physique IV, Colloque C4, 229, 1991.Google Scholar
  4. 4.
    E. Kobus, S. Eucken, E. Hornbogen, Characterisation of the Microstructure and Shape memory effect of a CuAlNiMnTi alloy for high temperature applications, Pract. Met., 26, 318, (1989).Google Scholar
  5. 5.
    B.I. Nikolin, Mnogosloinye struktury i politipizm v metallicheskikh splavakh, Naukova Dumka, Kiev, 1984.Google Scholar
  6. 6.
    P.C. J. Gallagher, The Influence of Alloying, temperature and related effects on the stacking fault energy, Met Transactions, 1, 2429, 1970.Google Scholar
  7. 7.
    J. Jansen, J. Van Humbeeck, M. Chandrasekaran, N. Nwamba and L. Delaey, Stabilisation of martensite in Copper-Zinc-aluminium alloys, J. de Physique, Colloque C4–43, 639, 1982.Google Scholar
  8. 8.
    G. Scarsbrook, J. Cook, and W.M. Stobbs, Ageing effects in CuAlZn alloys, J. de Physique, Colloque C4–43, 703, 1982, p. 703.Google Scholar
  9. 9.
    T. Suzuki, R. Kojima, Y. Fuji and A. Nagasawa, Reverse transformation behaviour of the stabilized martensite in CuZnAl alloy, Acta metall., 37, 163, 1989.CrossRefGoogle Scholar
  10. 10.
    M. Morin and G.Guenin, Study of the Pinning of the martensite interfaces in a Cu-Zn-Al alloy by internal friction measurements, Materials Science Forum, 56–58, 499, 1990.Google Scholar
  11. 11.
    A.Abu Arab and M. Ahlers, The stabilization of martensite in CuAlZn alloys. Acta metall 36, 2629, 1988.Google Scholar
  12. 12.
    Y. Nakata, O. Yamamoto and K. Shimizu, Effect of ageing in CuZnAl shape memory alloys, Materials Transactions JIM, 34, 429, 1993.Google Scholar
  13. M. Chandrasekaran, E. Cesari, J. Wolska, I. Hurtado, R. Stalmans and J. Dutkiewicz, Stabilisation of martensite in copper base shape memory alloys, J. de Physique, Colloque C2, 5, 143, 1995.Google Scholar
  14. 14.
    M. Ahlers, The stabilization of martensite in CuAlZn alloys, in ICOMAT 86, ed. Japan Institute of Metals, p. 786, 1986.Google Scholar
  15. 15.
    F.Saule, A.Tolley and M. Ahlers, The stabilization of 6R martensite in Cu-Zn-Al single crystals, Scripta met. materialia, 24, 363, 1990.CrossRefGoogle Scholar
  16. 16.
    F. Saule, M. Ahlers, Stability, Stabilization and lattice parameters in Cu-Zn-Al martensites, Informe Technico CNEA-CAB, 4042, 1994.Google Scholar
  17. 17.
    J. Dutkiewicz, V.V. Martynov and U. Messerschmidt, Structure of martensite formed in CuAlFe single crystals during in-situ HVEM pseudoelastic tensile experiment, J. Materials Sci., 24, 3904, 1989.ADSCrossRefGoogle Scholar
  18. 18.
    M. Andrade, L. Delaey and M. Chandrasekaran, On some lesser known planar defects in β’, Cu-Zn-Al martensite, J.de Physique C4–43, 673 1982.Google Scholar
  19. 19.
    L.Delaey, T. Suzuki and J. Van Humbeeck, The stabilisation of step quenched copper-zinc aluminium martensite, part II Crystal structure and reordering, Scripta Met., 18, 899, 1984.CrossRefGoogle Scholar
  20. 20.
    I.Cornelis and C.M. Wayman, Direct observation of the 3R stacking sequence in CuZnSi martensite, Mat. Res. Bull. 9, 1057, 1974.Google Scholar
  21. 21.
    H. Kato, J. Dutkiewicz and S. Miura, Pseudoelasticity and shape memory effect in Cu-23at.%Al-7at.%Mn alloy single crystals, Acta metall. mater., 42, 1359, 1994.CrossRefGoogle Scholar

Copyright information

© Plenum Press 1996

Authors and Affiliations

  • J. Dutkiewicz
    • 1
  1. 1.Institute of Metallurgy and Materials Science of the Polish Academy of SciencesKrakówPoland

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