TY - JOUR
T1 - Martensitic transformation and shape memory effect of Ni-rich Ni2MnGa sputtered films under magnetic field
AU - Ohtsuka, M.
AU - Matsumoto, M.
AU - Koike, K.
AU - Takagi, T.
AU - Itagaki, K.
N1 - Funding Information:
This research was partly supported by the Grants-in-Aid for Scientific Research from the Japan Society for the Promotion of Science (JSPS).
PY - 2007/3
Y1 - 2007/3
N2 - The inference of a magnetic field on the martensitic transformation (MT) temperatures and shape memory effect (SME) was investigated for the Ni-rich Ni2MnGa sputtered films. The compositions of the films were Ni51.4Mn28.3Ga20.3, Ni54.1Mn23.0Ga22.9 and Ni54.4Mn21.3Ga24.3. The films were heat treated at 1073 K for 3.6 ks and aged at 673 K for 3.6 ks in a constrained condition. Hereafter, the constraint-aged films were described as N51.4(AG), N54.1(AG) and N54.4(AG) using nickel content, respectively. The reversible two-way SME by the thermal change was confirmed for the all constraint-aged films through the MT and its reversion. The gradient of the strain-temperature curve, the amount of strain accompanied by the two-way SME and the width of thermal hysteresis were dependent on the composition of the films. The strain-temperature curves shifted to a high temperature region and the martensitic phase was stabilized by the magnetic field. The strain at the outer surface was given by ε{lunate}=d/2r, where d was the thickness of the films and r was the radius of a curvature for the films. The increase of MT temperatures caused by a magnetic field was about 1 K/T. Furthermore, the two-way SME by the magnetic field was observed around the MT temperature on cooling for the N54.4(AG) film with the large gradient and small thermal hysteresis in the strain-temperature curve.
AB - The inference of a magnetic field on the martensitic transformation (MT) temperatures and shape memory effect (SME) was investigated for the Ni-rich Ni2MnGa sputtered films. The compositions of the films were Ni51.4Mn28.3Ga20.3, Ni54.1Mn23.0Ga22.9 and Ni54.4Mn21.3Ga24.3. The films were heat treated at 1073 K for 3.6 ks and aged at 673 K for 3.6 ks in a constrained condition. Hereafter, the constraint-aged films were described as N51.4(AG), N54.1(AG) and N54.4(AG) using nickel content, respectively. The reversible two-way SME by the thermal change was confirmed for the all constraint-aged films through the MT and its reversion. The gradient of the strain-temperature curve, the amount of strain accompanied by the two-way SME and the width of thermal hysteresis were dependent on the composition of the films. The strain-temperature curves shifted to a high temperature region and the martensitic phase was stabilized by the magnetic field. The strain at the outer surface was given by ε{lunate}=d/2r, where d was the thickness of the films and r was the radius of a curvature for the films. The increase of MT temperatures caused by a magnetic field was about 1 K/T. Furthermore, the two-way SME by the magnetic field was observed around the MT temperature on cooling for the N54.4(AG) film with the large gradient and small thermal hysteresis in the strain-temperature curve.
KW - Ferromagnetic shape memory alloy
KW - Magnetic-field induced shape memory effect
KW - Martensitic transformation
KW - NiMnGa
KW - Sputtered film
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U2 - 10.1016/j.jmmm.2006.10.1048
DO - 10.1016/j.jmmm.2006.10.1048
M3 - Article
AN - SCOPUS:33847684796
SN - 0304-8853
VL - 310
SP - 2782
EP - 2784
JO - Journal of Magnetism and Magnetic Materials
JF - Journal of Magnetism and Magnetic Materials
IS - 2 SUPPL. PART 3
ER -