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arXiv · 1011.2303

Tuning macro-twinned domain sizes and the b-variants content of the adaptive 14-modulated martensite in epitaxial Ni-Mn-Ga films by co-sputtering

Jérémy Tillier·Daniel Bourgault·Philippe Odier·Luc Ortega·Sébastien Pairis·Olivier Fruchart·Nathalie Caillault·Laurent Carbone
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Abstract

In order to obtain modulated-martensite in our epitaxial Ni-Mn-Ga films, we have tuned the composition by using a co-sputtering process. Here we present how the composition affects the variant distribution of the 14-modulated martensite at room temperature. The nature of such modulated-martensites is still strongly debated for magnetic shape memory alloys. It has been very recently demonstrated that the modulated-martensites in Ni-Mn-Ga are adaptive phases. The results presented here corroborate this theory for the first time, for three different compositions. Moreover, we demonstrate with the help of the adaptive modulations theory that b-variants of the 14-modulated martensite form close to the free-surface of the film to release the stress induced by branching of macro-twinned domains during the martensitic transformation on a rigid substrate. At room temperature, the content of such b-variants is found to strongly decrease when the macro-twinned domain sizes increase.

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Jérémy Tillier, Daniel Bourgault, Philippe Odier, Luc Ortega, Sébastien Pairis, Olivier Fruchart, Nathalie Caillault, Laurent Carbone. 2010-11-10. Tuning macro-twinned domain sizes and the b-variants content of the adaptive 14-modulated martensite in epitaxial Ni-Mn-Ga films by co-sputtering. https://doi.org/10.1016/j.actamat.2010.09.006

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