Large superplastic strain in non-modulated epitaxial Ni-Mn-Ga films

The phase transformation and superplastic characteristics of free-standing epitaxial Ni-Mn-Ga stripes are reported. The stripes are prepared by micromachining a 1 μm thick Ni-Mn-Ga film sputter-deposited on a single crystalline MgO (100) substrate using optical lithography and a Chromium-based sacrificial layer technology. The stripes are oriented at angles of 0 and 45 degrees with respect to the Ni-Mn-Ga unit cell. Electrical resistance versus temperature characteristics reveal a reversible thermally induced phase transformation between 169°C and 191°C. Stress-strain measurements are performed with the stress applied along the [100]Ni-Mn-Ga as well as [110]Ni-Mn-Ga direction. Depending on the orientation, the twinning stress ranges between 25 and 30 MPa, respectively. For the [100] Ni-Mn-Ga and [110]Ni-Mn-Ga directions, superplastic behaviour with a strain plateau of 12 % and 4% are observed, respectively, indicating stress-induced reorientation of non-modulated martensite variants.

Keywords

Epitaxial Ni-Mn-Ga films, Magnetic shape memory films, Sacrificial layer technology, Superplasticity, Gallium, Gallium alloys, Nickel, Phase transitions, Photolithography, Shape memory effect, Stress-strain curves, Superplasticity, Electrical resistances, Magnetic shape memory, Ni-Mn-Ga, Sacrificial layer, Stress-induced reorientation, Stress-strain measurement, Superplastic strains, Temperature characteristic, Manganese

URI

https://doi.org/10.34657/4183
https://oa.tib.eu/renate/handle/123456789/5554

Citation

Yeduru, S. R., Backen, A., Fahler, S., Schultz, L., & Kohl, M. (2010). Large superplastic strain in non-modulated epitaxial Ni-Mn-Ga films. 10. https://doi.org//10.1016/j.phpro.2010.11.093

Collections

Physik

License

CC BY-NC-ND 3.0 Unported

https://creativecommons.org/licenses/by-nc-nd/3.0/

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