Modeling of the magnetic field-induced martensitic variant reorientation and the associated magnetic shape memory effect in MSMAs

2005 ◽  
Author(s):  
Bjorn Kiefer ◽  
Dimitris C. Lagoudas
Keyword(s):  
Magnetic Field ◽  
Shape Memory ◽  
Shape Memory Effect ◽  
Memory Effect ◽  
Magnetic Shape Memory ◽  
Martensitic Variant ◽  
The Magnetic Field

Shape Memory Effect in Fe-Pd Magnetic Shape Memory Alloy Thin Films

2010 ◽  
Vol 654-656 ◽  
pp. 2107-2110
Author(s):  
Jun Hyun Han ◽  
Tae Ahn ◽  
Hyun Kim ◽  
Kwang Koo Jee
Keyword(s):  
Magnetic Field ◽  
Thin Film ◽  
Shape Memory ◽  
Shape Memory Effect ◽  
Memory Effect ◽  
Stress Change ◽  
Composition Gradient ◽  
Cantilever Beams ◽  
Magnetic Shape Memory ◽  
Magnetic Shape Memory Alloy

The shape memory effect (SME) and magnetic shape memory effect (MSME) Fe-Pd thin film are using the film curvature method. The corresponding residual stress change due to theSME and MSME in Fe-Pd film is measuredduring thermal cycling and magnetic field changing. AFe-Pd thin film with a lateral composition gradient is deposited onto micromachined x7 cantilever beam arraysubstrate,such that each of the cantilever beams is coated with a film of different composition.There is abrupt stress change in only .1 at % Pd as the temperature of the film is cycled, and the corresponding stress change was measured as 0.16 GPa. The film with .4 at % Pd showsthe abrupt stress change at 0.7 Tesla, which means that the composition has the MSME.

Magnetic Shape Memory Effect in Ni-Mn-Ga Single Crystal

2016 ◽  
Vol 879 ◽  
pp. 738-743
Author(s):  
Oleg Heczko ◽  
Vít Kopecký ◽  
Jan Drahokoupil ◽  
Marek Vronka ◽  
Oleksiy Perevertov ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Shape Memory ◽  
Shape Memory Effect ◽  
Memory Effect ◽  
High Mobility ◽  
Type I ◽  
X Ray Diffraction ◽  
Magnetic Shape Memory ◽  
Twin Boundaries ◽  
Induced Structure

Magnetic shape memory effect is general name for several effects in which the most visible feature is huge strain induced by magnetic field. Magnetic field-induced structure reorientation (MIR) occurs due to motion of twin boundaries in single phase. As the magnetic field is a relatively weak force compared with mechanical stress, very high mobility of twin boundaries is crucial. Here we study the properties of martensite relevant for this effect using X-ray diffraction, optical and electron microscopy, magnetic observation and mechanical testing. In 10M modulated martensite, two types of mobile twin boundary (type I and type II) are observed with complex layered microstructures consisting of a hierarchy of twinning systems. We search for analogue with non-magnetic Cu-Ni-Al shape memory alloy.

A Mechanism for Magnetically Driven Shape Memory Alloys

1999 ◽  
Vol 604 ◽  
Author(s):  
P. J. Ferreira ◽  
J. B. Vander Sande
Keyword(s):  
Magnetic Field ◽  
Shape Memory Alloys ◽  
Shape Memory ◽  
Shape Memory Effect ◽  
Memory Effect ◽  
Maximum Pressure ◽  
Second Phase ◽  
Magnetic Field Direction ◽  
Second Phase Particles ◽  
The Magnetic Field

AbstractA mechanism for shape memory alloys driven by a magnetic field is proposed. The mechanism involves the motion of twin dislocations in response to the application of a magnetic field. As a consequence, twin variants oriented favorably with respect to the magnetic field direction will grow. The maximum pressure that can be exerted at the twin dislocations is when the magnetic field is at angle . The shape memory effect is significantly affected by the presence of impurities, second-phase particles and grain boundaries

Shape memory effect due to magnetic field-induced thermoelastic martensitic transformation in polycrystalline Ni–Mn–Fe–Ga alloy

2001 ◽  
Vol 291 (2-3) ◽  
pp. 175-183 ◽  
Author(s):  
A.A. Cherechukin ◽  
I.E. Dikshtein ◽  
D.I. Ermakov ◽  
A.V. Glebov ◽  
V.V. Koledov ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Martensitic Transformation ◽  
Shape Memory ◽  
Shape Memory Effect ◽  
Memory Effect ◽  
Thermoelastic Martensitic Transformation

Effects of Surface Pinning, Locking and Adaption of Twins on the Performance of Magnetic Shape-Memory Alloys

2011 ◽  
Vol 684 ◽  
pp. 177-201 ◽  
Author(s):  
Markus Chmielus ◽  
Peter Müllner
Keyword(s):  
Magnetic Field ◽  
Shape Memory Alloys ◽  
Shape Memory ◽  
Surface Damage ◽  
Magnetic Shape Memory ◽  
Magnetic Shape Memory Alloys ◽  
Fatigue Lifetime ◽  
Twin Density ◽  
External Constraints ◽  
The Magnetic Field

We study the effect of surface modifications and constraints on the mechanical properties of Ni-Mn- Ga single crystals, which are imposed by (i) structural modifications near the surface, (ii) mounting to a solid surface, and (iii) guiding the stroke. Spark eroded samples were electropolished and characterized before and after each polishing treatment. Surface damage was then produced with spark erosion and abrasive wearing. Surface damage stabilizes and pins a dense twin-microstructure and prevents twins from coarsening. The density of twins increases with increasing degree of surface deformation. Twinning stress and hardening rate during mechanical loading increase with increasing surface damage and twin density. In contrast, when a damaged surface layer is removed, twinning stresses, hardening rate, and twin density decrease. Constraining the sample by mounting and guiding reduces the magnetic-field-induced strain by locking twins at the constrained surfaces. . For single-domain crystals and for hard magnetic shape-memory alloys, external constraints strongly reduce the magnetic-field-induced strain and the fatigue lifetime is short. In contrast, for selfaccommodated martensite and for soft magnetic shape-memory alloys, the twin-microstructure adapts well to external constraints and the fatigue lifetime is long. The performance of devices with MSMA transducers requires managing stress distributions through design and control of surface properties, microstructure, and constraints.

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