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Magnetic-field-induced shape recovery by reverse phase transformation.
1Department of Materials Science, Graduate School of Engineering, Tohoku University, 6-6-02 Aoba-yama, Sendai 980-8579, Japan. kainuma@material.tohoku.ac.jp
Nature
|February 24, 2006
Summary
This study reports a NiCoMnIn alloy exhibiting significant magnetic-field-induced shape recovery, generating over 100 MPa stress. This Heusler alloy shows potential for advanced magnetic actuator applications.
Area of Science:
- Materials Science
- Condensed Matter Physics
- Magnetism
Background:
- Heusler alloys with body-centered cubic structures exhibit large magnetic-field-induced strains.
- These strains are attributed to the rearrangement of martensite structural variants under an external magnetic field.
- Such materials are promising candidates for magnetic actuator applications.
Purpose of the Study:
- To investigate the magnetic-field-induced shape recovery in a compressively deformed NiCoMnIn alloy.
- To quantify the stress generation and deformation recovery capabilities of this alloy.
- To elucidate the underlying transformation mechanisms responsible for the observed behavior.
Main Methods:
- Experimental investigation of a Ni45Co5Mn36.7In13.3 single crystal.
- Application of a 70 kOe magnetic field to induce shape recovery in a pre-deformed sample.
- Measurement of generated stresses and observed deformation recovery percentage.
Main Results:
- The NiCoMnIn alloy generated stresses exceeding 100 MPa upon application of a 70 kOe magnetic field.
- A deformation of 3% was observed, with nearly complete recovery of the original shape.
- The generated stress levels are approximately 50 times greater than those reported for previous ferromagnetic shape-memory alloys.
Conclusions:
- The observed magnetic-field-induced shape recovery and high stress generation are attributed to a reverse transformation.
- This transformation occurs from the antiferromagnetic (or paramagnetic) martensitic phase to the ferromagnetic parent phase at 298 K.
- The NiCoMnIn alloy demonstrates exceptional potential as a high-performance magnetic actuator material.
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