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In Situ Hvem of Crystallization of Amorphous TiNi Thin Films

Published online by Cambridge University Press:  26 July 2012

Warren J. Moberly ,
J. D. Busch ,
A. D. Johnson  and
M. H. Berkson
Warren J. Moberly
Affiliation:
Dept. of Materials Science & Engineering, Stevens Institute of Technology, Hoboken, NJ
J. D. Busch
Affiliation:
TiNi Alloy Company, Oakland, CA
A. D. Johnson
Affiliation:
TiNi Alloy Company, Oakland, CA
M. H. Berkson
Affiliation:
Dept. of Materials Science & Engineering, University of California at Berkeley, CA.
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Abstract

TiNi alloys have been extensively studied for their shape memory properties, arising from a martensitic transformation between the cubic B2 crystal structure and the monoclinic B19′ structure. However, only recently has the application of TiNi alloys as thin film actuators been considered. Well-controlled thicknesses of TiNi films have been deposited via d.c. magnetron ion sputtering, with as-deposited films exhibiting an amorphous structure. These ductile metallic glass films may be bent into various macroscopic shapes and then heated to crystallize the B2 structure, thereby determining its parent (memory) shape. In situ high voltage electron microscopy (HVEM) heating and cooling experiments are utilized to observe the crystallization of the B2 structure and the martensitic transformation from B2 to B19∼500°C to ∼600°C. Isothermal annealing determines the kinetics of the crystallization process to be nucleation limited. The nucleation of B2 crystallites in thicker regions of TEM specimens, which occurs prior to nucleation in thinner regions, indicates that nucleation does not occur preferentially at surfaces, but rather homogeneously. After crystallization is completed, the existence of random orientations of B2 grains provides films that will exhibit shape memory in any desired orientation. Video-recording of the crystallization processes has been acquired.

Type
Research Article
Information
MRS Online Proceedings Library (OPL) , Volume 230: Symposium R – Phase Transformation Kinetics in Thin Films , 1991 , 85
Copyright
Copyright © Materials Research Society 1992

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References

1. Busch, J. D., Berkson, M. H. and Johnson, A. D., presented at the 1991 MRS Spring Meeting, Anaheim, CA (unpublished).Google Scholar
2. Johnson, A.D., “Vacuum-deposited TiNi shape memory film: characterization and applications in microdevices.” J. Micromech. Microeng., V1, p34–41, (1991).Google Scholar
3. Hu-Simpson, C., Chang, L., and Grummon, D. S., presented at the 1990 MRS Fall Meeting, Boston, MA (unpublished).Google Scholar
4. Jardine, A. P. and Wasielesky, L. D., presented at the 1990 MRS Fall Meeting, Boston, MA (unpublished).Google Scholar
5. Moberly, W. J., to be published in Ultramicroscopy.Google Scholar
6. Thomas, G., Mori, H., Fujita, H. and Sinclair, R., Scripta Met. V16, p589–592, (1982).Google Scholar
7. Pelton, A. R., in Proc. 7th Int. Conf. on HVEM, edited by Fisher, R. M., Gronsky, R. and Westmaccott, K. H., p. 245 (1983).Google Scholar
8. Hetherington, C. and W. Moberly (unpublished results).Google Scholar
9. Moberly, W. J., Busch, J. D. and Johnson, A. D., to be published in J. of Matls Sci.Google Scholar
10. Moine, P., Pelton, A. R. and Sinclair, R., J. Non-Cryst. Sol. V101, p213–222 (1988).Google Scholar
11. Murty, B. S., Rao, M. M. and Ranganathan, S., Scripta Met. V24, p1819–1824 (1990).Google Scholar
12. Busch, J. D., Johnson, A. D., Lee, C. H. and Stevenson, D. A., J. Appl. Phys. V68, p6224–6228 (1990).Google Scholar
13. Clemens, B. M., Phys. Rev. B V33, p.7615–7624 (1986).Google Scholar
14. Johnson, W. L., Prog. in Matls. Sci. V30, p81–134 (1986).Google Scholar
15. Marshall, A. F., Lee, Y. S. and Stevenson, D. A., Acta Met. V31, p1225–1231, (1983).Google Scholar
16. Michal, G., Ph.D. Thesis, Dept. Matls. Sci. and Eng., Stanford University (1979).Google Scholar
17. Marshall, A.F., Walmsley, R. G. and Stevenson, D. A., Matls. Sci. and Engin. V63, p215–227 (1984).Google Scholar
18. Marshall, A.F., Lee, Y.S. and Stevenson, D.A., J. Non-Cryst. Sol. V64, p399–419(1984).Google Scholar
19. Batstone, J. L. and Smith, D. A. in Proc. EMSA, p524–525 (1990).Google Scholar
20. Bolotov, I. E., Kolosov, V. Y. and Kozhyn, A. V., Phys. Stat. Sol. A V72, p645–654 (1982).Google Scholar