TY - JOUR
T1 - Variation of atomic spacing and thermomechanical properties in Ni-Mn-Ga/alumina film composites
AU - Besseghini, Stefano
AU - Cavallin, Tommaso
AU - Chernenko, Volodymyr
AU - Villa, Elena
AU - Lvov, Victor
AU - Ohtsuka, Makoto
N1 - Funding Information:
The financial support of Fondazione Cariplo (Project 2004.1819-A10.9251) is greatly acknowledged. The authors thank G. Carcano and S. Pittaccio for technical support and M. Beiser for laser cutting the specimens.
PY - 2008/5
Y1 - 2008/5
N2 - Ni51.4Mn28.3Ga20.3 thin films deposited on alumina ceramics have been studied by X-ray powder diffraction and dynamic mechanical analysis. Substantial temperature vs. film thickness dependencies of interatomic spacing measured in the direction of the film normal are observed in the range of 25-200 °C and 0.1-5 μm, respectively. The coefficient of thermal expansion (CTE) of the film in the paramagnetic cubic phase has been determined to be equal to (15 ± 1) × 10-6 K-1 for all the films, in agreement with the CTE of bulk material. The thickness dependent shrinkage of the pseudo-cubic lattice along the film normal direction is attributed to the thermally induced tensile stress in the film plane. The thickness dependence of the elastic modulus of submicron films is obtained. It is shown that the internal stresses result in both the thickness dependence of martensitic transformation temperature and the reversible, thermally induced change in shape of the Ni-Mn-Ga/alumina cantilever actuator.
AB - Ni51.4Mn28.3Ga20.3 thin films deposited on alumina ceramics have been studied by X-ray powder diffraction and dynamic mechanical analysis. Substantial temperature vs. film thickness dependencies of interatomic spacing measured in the direction of the film normal are observed in the range of 25-200 °C and 0.1-5 μm, respectively. The coefficient of thermal expansion (CTE) of the film in the paramagnetic cubic phase has been determined to be equal to (15 ± 1) × 10-6 K-1 for all the films, in agreement with the CTE of bulk material. The thickness dependent shrinkage of the pseudo-cubic lattice along the film normal direction is attributed to the thermally induced tensile stress in the film plane. The thickness dependence of the elastic modulus of submicron films is obtained. It is shown that the internal stresses result in both the thickness dependence of martensitic transformation temperature and the reversible, thermally induced change in shape of the Ni-Mn-Ga/alumina cantilever actuator.
KW - Lattice spacing
KW - Martensitic transformation
KW - Ni-Mn-Ga/alumina film composite
KW - Thermomechanical actuation
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U2 - 10.1016/j.actamat.2007.12.025
DO - 10.1016/j.actamat.2007.12.025
M3 - Article
AN - SCOPUS:41849129263
SN - 1359-6454
VL - 56
SP - 1797
EP - 1801
JO - Acta Materialia
JF - Acta Materialia
IS - 8
ER -