J. Phys. IV France
Volume 112, October 2003
Page(s) 865 - 868

J. Phys. IV France
112 (2003) 865
DOI: 10.1051/jp4:20031018

Nickel ion irradiation of plasitically deformed martensitic titanium nickel thin films

T. LaGrange1, R. Schäublin2, D.S. Grummon3 and R. Gotthardt1

1  Swiss Federal Institute of Technology Lausanne (EPFL), Department of Basic Sciences, Institute of Physics of Complex Materials, 1015 Lausanne, Switzerland
2  EPFL-CRPP Fusion Technology-Materials, 5232 Villigen, Switzeriand
3  Michigan State University, Department of Chemical Engineering and Materials Science, East Lansing Michigan 48824, U.S.A.

At present, little is known about the response of the martensitic phase in TiNi alloys to heavy ion irradiation. However, previous studies [2, 3] of ion and electron irradiation show that these alloys are highly susceptible to disorder and amorphization at damage levels below 1 dpa. This substantially affects their transformation characteristics and their shape memory effect. The present study focuses on the effect of 5 MeV Ni ion irradiation of plastically strained ( $\varepsilon\sim 4\%$) martensitic TiNi thin films, which is used as a processing technique for a novel out of plane bending actuator. Conceptually, the frustration of the martensitic transformation due to ion beam damage in a 2  $\mu$pm surface layer of a 6  $\mu$pm thick film will create a sharp differential latent strain on reverse transformation. This latent strain causes a two-way bending motion during cycling heating and cooling. This processing technique can be used to do useful mechanical work on both heating and cooling. To better understand the behavior of these ion irradiated thin films, TEM observations and motion experiments were conducted. Results are presented and discussed as they relate to the ion induced microstructure and its influence on the martensitic transformation.

© EDP Sciences 2003