TY - JOUR
T1 - Thermal expansion and magnetization studies of novel ferromagnetic shape memory alloys Ni52Mn12.5Fe12.5Ga23 and Ni2Mn0.75Cu0.25Ga
AU - Sakon, Takuo
AU - Nagashio, Hitoshi
AU - Sasaki, Kenta
AU - Susuga, Seiji
AU - Endo, Keita
AU - Nojiri, Hiroyuki
AU - Kanomata, Takeshi
PY - 2011/6
Y1 - 2011/6
N2 - Thermal expansion, permeability, and magnetization measurements of ferromagnetic shape memory alloys, Ni52Mn12.5Fe 12.5Ga23 and Ni2Mn0.75Cu 0.25Ga, were performed across the martensitic transformation temperature TM and the reverse martensitic transformation temperature 7r. When cooling from austenite phase, a steep decrease in the thermal expansion due to the martensitic transformation was found for both alloys. Considering the permeability and magnetization results of Ni2Mn 0.75Cu0.25Ga, the region above TM or T R is the paramagneticaustenite (Para-A) phase and the region below TM or TR is the ferromagnetic-martensite (Ferro-M) phase. Magnetic phase diagrams were constructed based on the results of the temperature dependence of thermal expansion. TM and TR increased gradually with increasing magnetic field. For Ni52Mn 12.5Fe12.5 Ga23 and Ni2Mn 0.75Cu0.25Ga, the shifts of TM in magnetic fields (B) were estimated as dTM/dB ≈ 0.5 K/T and 1.2 T/K, respectively. The shifts of TM indicate that the that magnetization influences martensitic transition and the increase of TM in accordance with the magnetic fields is proportional to the difference between the magnetization of austenite phase with that of martensitic phase.
AB - Thermal expansion, permeability, and magnetization measurements of ferromagnetic shape memory alloys, Ni52Mn12.5Fe 12.5Ga23 and Ni2Mn0.75Cu 0.25Ga, were performed across the martensitic transformation temperature TM and the reverse martensitic transformation temperature 7r. When cooling from austenite phase, a steep decrease in the thermal expansion due to the martensitic transformation was found for both alloys. Considering the permeability and magnetization results of Ni2Mn 0.75Cu0.25Ga, the region above TM or T R is the paramagneticaustenite (Para-A) phase and the region below TM or TR is the ferromagnetic-martensite (Ferro-M) phase. Magnetic phase diagrams were constructed based on the results of the temperature dependence of thermal expansion. TM and TR increased gradually with increasing magnetic field. For Ni52Mn 12.5Fe12.5 Ga23 and Ni2Mn 0.75Cu0.25Ga, the shifts of TM in magnetic fields (B) were estimated as dTM/dB ≈ 0.5 K/T and 1.2 T/K, respectively. The shifts of TM indicate that the that magnetization influences martensitic transition and the increase of TM in accordance with the magnetic fields is proportional to the difference between the magnetization of austenite phase with that of martensitic phase.
KW - Heusler alloys
KW - Magnetic phase diagram
KW - Magnetization
KW - Phase transition
KW - Shape memory alloys
KW - Thermal expansion
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U2 - 10.2320/matertrans.M2011038
DO - 10.2320/matertrans.M2011038
M3 - Article
AN - SCOPUS:80051927612
VL - 52
SP - 1142
EP - 1147
JO - Materials Transactions
JF - Materials Transactions
SN - 1345-9678
IS - 6
ER -