| 학회 |
한국재료학회 |
| 학술대회 |
2010년 가을 (11/11 ~ 11/12, 무주리조트) |
| 권호 |
16권 2호 |
| 발표분야 |
E. Advanced Materials and processing Technology(첨단재료공정기술) |
| 제목 |
Magnetic shape memory effect in Ni-Mn-Ga alloys |
| 초록 |
Ni-Mn-Ga based magnetic shape memory (MSM) materials have been intensively studied in Finland since their discovery. This work has given basic understanding on the performance of these materials as well as several noteworthy discoveries, such as MSM-alloys with high service temperature and 10% field-induced-strain. In the recent years research has been targeted to specific fields. In particular, emphasis has been given to deepening the understanding of the twin structure and behavior of twin boundaries. Twin boundary studies have been carried out by XRD and high-resolution transmission electron microscopy (HRTEM). In-situ straining of Ni-Mn-Ga single crystals in TEM has been carried out in co-operation with the Institute of Physics in Prague, Czech. These studies together with the results obtained by neutron diffraction have given insight to the twinning mechanisms in martensites with the non-modulated crystal structure. Research has been carried out also for identifying alloys that can widen the stabile thermal property range of the MSM materials. Furthermore, modeling based on Ginsburg-Landau theory has been applied to evaluate aging and thermal fluctuations in the modulated Ni-Mn-Ga structures. Recently, increasing emphasis has been put on the service properties of these materials. Damping of Ni-Mn-Ga polymer composites has been proved to be excellent at high stiffness levels with the loss factor of = 0.6 at E ≈ 1 GPa. The long-term actuation behavior of the MSM elements has also been studied extensively and first concise information on fatigue life up to2.109 cycles has been recorded for a five-layered modulated Ni-Mn-Ga structure. The evolution of the MSM parameters during the long-term actuation have been determined and used as input data for the actuator models developed in the European MAFESMA co-operation. |
| 저자 |
Simo-Pekka Hannula |
| 소속 |
Aalto Univ. |
| 키워드 |
shape memory; ferromagnetic; twinning; fatigue; actuation; sensor
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| E-Mail |
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