Hostname: page-component-cd9895bd7-lnqnp Total loading time: 0 Render date: 2025-01-02T16:23:09.084Z Has data issue: false hasContentIssue false
  • English
  • Français

Evolution of the microstructure of cobalt during diffusionless transformation cycles

Published online by Cambridge University Press:  31 January 2011

A. Munier ,
J. E. Bidaux ,
R. Schaller  and
C. Esnouf
A. Munier
Affiliation:
Institut de Génie Atomique, Ecole Polytechnique Fédérale de Lausanne, CH–1015 Lausanne, Switzerland
J. E. Bidaux
Affiliation:
Institut de Génie Atomique, Ecole Polytechnique Fédérale de Lausanne, CH–1015 Lausanne, Switzerland
R. Schaller
Affiliation:
Institut de Génie Atomique, Ecole Polytechnique Fédérale de Lausanne, CH–1015 Lausanne, Switzerland
C. Esnouf
Affiliation:
Groupe d'Etudes de Métallurgie Physique et de Physique des Matériaux, Bât. 502, I.N.S.A. de Lyon, F–69621 Villeurbanne, France
Get access

Abstract

Differential scanning calorimetry and transmission electron microscopy have been used to study thermal fatigue due to diffusionless phase transformation cycling in pure cobalt. Thermal cycling through the allotropic (hcp ↔ fcc) transformation results in a temperature shift of the calorimetric peaks, which means a delay of the transformation. In addition, the transformation enthalpy, which is greater on heating than on cooling, diminishes when the number of transformation cycles increases. This is interpreted as being due to an evolution of the microstructure. Transmission electron microscopy shows the appearance of transformation-induced defects, which are mainly sessile dislocations. We can interpret the calorimetry results (enthalpy evolution and transformation delay) as due to the interactions between interface dislocations and these sessile dislocations.

Type
Articles
Information
Journal of Materials Research , Volume 5 , Issue 4 , April 1990 , pp. 769 - 775
Copyright
Copyright © Materials Research Society 1990

Access options

Get access to the full version of this content by using one of the access options below. (Log in options will check for institutional or personal access. Content may require purchase if you do not have access.)

References

REFERENCES

1Shimizu, K., Proc. of the Int. Symp.on Shape Memory Alloys (China Academic Publishers, 1986), pp. 15–22.Google Scholar
2Adams, R. and Altstetter, C., Thermodynamics of the Cobalt Transformation, TMS-AIME 242 (1968).Google Scholar
3Jeanjean, R., “Influence des Eléments d'Addition sur la Transformation Allotropique du cobalt” (thése), Service Edition-INSA, N° d'ordre 41, 1972.Google Scholar
4Seeger, A., Metallkunde, Z., Bd 47 (1956), Heft 9.CrossRefGoogle Scholar
5Kennedy, E. M., Speiser, R., and Hirth, J. P., Physical Chemistry in Metallurgy (1976).Google Scholar
6Blaschko, O., Krexner, G., Pleschiutsching, J., Ernst, G., Hitzenberger, C., Karnthaler, H.P., and Korner, A., Phys. Rev. Lett. 60, 2800(1988).CrossRefGoogle Scholar
7Hitzenberger, C., Karnthaler, H. P., and Korner, A., Acta Metall. 33 (7) (1985).CrossRefGoogle Scholar
8Hitzenberger, C., Karnthaler, H.P., and Korner, A., phys. stat. sol. (a) 89, 133 (1985).CrossRefGoogle Scholar
9Korner, A. and Karnthaler, H. P., Philos. Mag. A 48 (3) (1983).CrossRefGoogle Scholar
10Bibring, H., Lenoir, G., and Sebilleau, F., Rev. de métallurgie LVI (3) (1959).Google Scholar
11McNaughton, J. L. and Mortimer, C.T., “La Calorimétrie Différentielle à Balayage”, Perkin-Elmer.Google Scholar