Magneto-Mechanical Behaviour of Textured Polycrystals of NiMnGa Ferromagnetic Shape Memory Alloys

2008 ◽  
Vol 52 ◽  
pp. 29-34 ◽  
Author(s):  
Stefan Roth ◽  
Uwe Gaitzsch ◽  
Martin Pötschke ◽  
Ludwig Schultz
Keyword(s):  
Magnetic Field ◽  
Heat Treatment ◽  
Shape Memory ◽  
Directional Solidification ◽  
Mechanical Behaviour ◽  
Martensitic Structure ◽  
Ferromagnetic Shape Memory Alloys ◽  
Induced Stress ◽  
Ferromagnetic Shape Memory ◽  
Induced Changes

Textured polycrystalline NiMnGa alloys were prepared by directional solidification. Alloys were chosen to have either the 7M or the 5M modulated martensitic structure after proper heat treatment. Mechanical training allowed to reduce the twin boundary pinning stress to below the magnetically induced stress. Thus, magnetic field induced changes in the mechanical behaviour could be demonstrated. The conditions of preparation and mechanical training will be discussed together with their influence on structure, microstructure, and the magneto-mechanical behaviour.

Polycrystalline Ni-Mn-Ga as a Potential Material for Magnetically Driven Actuators

2011 ◽  
Vol 684 ◽  
pp. 129-137 ◽  
Author(s):  
Martin Pötschke ◽  
Stefan Roth ◽  
Uwe Gaitzsch ◽  
Claudia Hürrich ◽  
Andrea Böhm ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Heat Treatment ◽  
Directional Solidification ◽  
Twin Boundary ◽  
Mechanical Behaviour ◽  
Martensitic Structure ◽  
Training Process ◽  
Stress Strain ◽  
Induced Stress ◽  
Strain Behaviour

Textured polycrystalline Ni-Mn-Ga alloys were prepared by directional solidification. Alloys were chosen to have the 5M modulated martensitic structure after proper heat treatment. A two-side mechanical training decreased the twin boundary pinning stress. The stress-strain behaviour for the training process and the magnetically induced stress depends on the training direction. Magnetic field induced strain was demonstrated in samples with a plate-like geometry. The influence of the microstructure on the magneto-mechanical behaviour is discussed.

On the stress-assisted magnetic-field-induced phase transformation in Ni2MnGa ferromagnetic shape memory alloys

2007 ◽  
Vol 55 (13) ◽  
pp. 4253-4269 ◽  
Author(s):  
H.E. Karaca ◽  
I. Karaman ◽  
B. Basaran ◽  
D.C. Lagoudas ◽  
Y.I. Chumlyakov ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Phase Transformation ◽  
Shape Memory Alloys ◽  
Shape Memory ◽  
Ferromagnetic Shape Memory Alloys ◽  
Ferromagnetic Shape Memory

scholarly journals Training of the Ni–Mn–Fe–Ga ferromagnetic shape-memory alloys due cycling in high magnetic field

2003 ◽  
Vol 258-259 ◽  
pp. 523-525 ◽  
Author(s):  
A.A. Cherechukin ◽  
V.V. Khovailo ◽  
R.V. Koposov ◽  
E.P. Krasnoperov ◽  
T. Takagi ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Shape Memory Alloys ◽  
Shape Memory ◽  
High Magnetic Field ◽  
Ferromagnetic Shape Memory Alloys ◽  
Ferromagnetic Shape Memory

DETERMINATION OF CRYSTAL STRUCTURE AND CRYSTALLOGRAPHIC CHARACTERISTICS IN Ni-Mn-Ga FERROMAGNETIC SHAPE MEMORY ALLOYS

2009 ◽  
Vol 23 (06n07) ◽  
pp. 1771-1776
Author(s):  
D. Y. CONG ◽  
Y. D. ZHANG ◽  
C. ESLING ◽  
Y. D. WANG ◽  
X. ZHAO ◽  
...  
Keyword(s):  
Crystal Structure ◽  
Shape Memory Alloys ◽  
Shape Memory ◽  
High Performance ◽  
Room Temperature ◽  
Martensitic Structure ◽  
Magnetic Shape Memory ◽  
Ferromagnetic Shape Memory Alloys ◽  
Electron Backscattered Diffraction ◽  
Ferromagnetic Shape Memory

Ni - Mn - Ga ferromagnetic shape memory alloys (FSMAs) have received great attention during the past decade due to their giant magnetic shape memory effect and fast dynamic response. The crystal structure and crystallographic features of two Ni - Mn - Ga alloys were precisely determined in this study. Neutron diffraction measurements show that Ni 48 Mn 30 Ga 22 has a Heusler austenitic structure at room temperature; its crystal structure changes into a seven-layered martensitic structure when cooled to 243K. Ni 53 Mn 25 Ga 22 has an I4/mmm martensitic structure at room temperature. Electron backscattered diffraction (EBSD) analyses reveal that there are only two martensitic variants with a misorientation of ~82° around <110> axis in each initial austenite grain in Ni 53 Mn 25 Ga 22. The investigation on crystal structure and crystallographic features will shed light on the development of high-performance FSMAs with optimal properties.

Effects on Temperature-Induced Phase Transition of Ni2MnGa Polycrystalline Ferromagnetic Shape Memory Alloys

2014 ◽  
Vol 697 ◽  
pp. 12-16
Author(s):  
Yu Ping Zhu ◽  
Yun Ling Gu ◽  
Hong Guang Liu
Keyword(s):  
Mechanical Properties ◽  
Phase Transition ◽  
Shape Memory Alloy ◽  
Shape Memory Alloys ◽  
Shape Memory ◽  
Directional Solidification ◽  
Smart Material ◽  
Ferromagnetic Shape Memory Alloy ◽  
Ferromagnetic Shape Memory Alloys ◽  
Ferromagnetic Shape Memory

Ferromagnetic shape memory alloy is a kind of new smart material. Directional solidification method in producing polycrystalline Ni2MnGa is mature and effective. In order to increase the strain of Ni2MnGa polycrystalline prepared by directional solidification, mechanical training is an effective method. In this paper, the tests of temperature-induced strain are carried out in different directions of Ni2MnGa prepared by directional solidification using three kinds of specimens with various mechanical training. Through analyzing the mechanical properties in different directions, the influence of mechanical training on the temperature-induced strain are investigated. Some conclusions which may provide references for the engineering applications of this material are gained.

Giant Magnetostriction in Ferromagnetic Shape-Memory Alloys

MRS Bulletin ◽  
2002 ◽  
Vol 27 (2) ◽  
pp. 105-109 ◽  
Author(s):  
Tomoyuki Kakeshita ◽  
Kari Ullakko
Keyword(s):  
Magnetic Field ◽  
Shape Memory Alloys ◽  
Shape Memory ◽  
Martensite Phase ◽  
Ferromagnetic Shape Memory Alloys ◽  
Recoverable Strain ◽  
Martensitic State ◽  
Magnetostrictive Behavior ◽  
Ferromagnetic Shape Memory ◽  
The Magnetic Field

AbstractShape-memory alloys are now widely used because they exhibit a large recoverable strain, which is caused by the conversion of variants in the martensite phase. The conversion of variants is usually promoted by the application of external stress. Recently, however, it was found that the conversion of variants can also be promoted by the application of a magnetic field to induce the martensitic state in ferromagnetic Ni2MnGa shape-memory alloys. Since then, the research in this field has focused considerable attention on applications for using the materials as actuators and sensors because their response to a magnetic field is much faster than their response to heating or cooling. Furthermore, the mechanism of the conversion of variants by the magnetic field has attracted academic interest from many researchers. In this article, we show giant magnetostrictive behavior in three ferromagnetic shape-memory alloys—Ni2MnGa, Fe-Pd, and Fe3Pt—and review the investigations performed so far by many researchers, including the present authors.

Sign in / Sign up

Export Citation Format

Share Document