| Project/Area Number |
15560576
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| Research Category |
Grant-in-Aid for Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
Physical properties of metals
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| Research Institution | Tohoku Gakuin University |
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Principal Investigator |
KANOMATA Takeshi Tohoku Gakuin University, Faculty of Engineering, Professor, 工学部, 教授 (60048816)
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| Co-Investigator(Kenkyū-buntansha) |
KOYAMA Keiichi Tohoku University, Institute for Materials Research, Associate Professor, 金属材料研究所, 助教授 (70302205)
NASHIMA Osamu Tohoku Gakuin University, Faculty of Engineering, Lecturer, 工学部, 講師 (00265183)
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| Project Period (FY) |
2003 – 2005
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| Project Status |
Completed (Fiscal Year 2005)
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| Budget Amount *help |
¥3,800,000 (Direct Cost: ¥3,800,000)
Fiscal Year 2005: ¥600,000 (Direct Cost: ¥600,000)
Fiscal Year 2004: ¥500,000 (Direct Cost: ¥500,000)
Fiscal Year 2003: ¥2,700,000 (Direct Cost: ¥2,700,000)
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| Keywords | ferromagnetic share memory alloys / martensitic transformation / transition metal ordered alloys / magnetic field-induced-phase transition / X-ray diffraction under high field / pressure effect / ferromagnetism / Curie temperature / 遷移金属化合物 / 構造相転移 / 強磁性体 |
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| Research Abstract |
Large magnetic-field-induced strains have been observed in Heusler alloys with a body-centered cubic ordered structure and have been explained by the rearrangement of martensite structural variants due to an external magnetic field. These materials have attracted considerable attention as potential magnetic actuator materials. We have investigated systematically the intelligent materials exhibiting magnetic shape memory effect. Research results are as follows :
1.Intermetallic compounds MnCo_<1-x>Ge(0.06【less than or equal】x【less than or equal】0.08) exhibit the diffusionless thermoelastic martensitic transformation at about 300 K. The martensitic phase crystallizes in the orthorhombic TiNiSi-type and transforms to the parent one with the hexagonal Ni_2In type crystal structure at T_M with increasing temperature. These phase transformations are analyzed thermodynamically using a Landau-type thermodynamical potential.
2.The phase diagram of ferromagnetic shape memory alloys Ni_<50+x>Mn_<12.5>Fe_<12.5>Ga_<25-x> was obtained. The Curie temperature decreases gradually with x. On the other hand, the martensitic transformation temperature T_M increases steeply until x=3.0, after then they reach to the value 380 K at x=5.5. The good ductility was confirmed for the samples with x【greater than or equal】3.0.
3.Magnetic and structural properties of new ferromagnetic shape memory alloys Ni_2Mn_<1+x>Z_<1-x>(Z=In and Sn) have been investigated. In the parent phase these alloys exhibit ferromagnetic behavior. On the other hand, the spontaneous magnetization of the martensitic phase drops significantly compared with that of the parent phase, indicating that these alloys are ferrimagnetic or antiferromagnetic in the martensitic phase. We have observed a field-induced reverse martensitic transition for Ni_2Mn_<1.44>Sn_<0.56>.
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