The Stability of Magnetic-Field-Induced Strain in a NiMnGa Ferromagnetic Shape Memory Alloy

2005 ◽  
Vol 475-479 ◽  
pp. 2025-2028
Author(s):  
Feng Chen ◽  
Zhiyong Gao ◽  
Wei Cai ◽  
Lian Cheng Zhao
Keyword(s):  
Magnetic Field ◽  
Martensitic Transformation ◽  
Twin Boundary ◽  
Boundary Mobility ◽  
Martensitic Transformation Temperature ◽  
Ferromagnetic Shape Memory Alloy ◽  
Field Cycling ◽  
The Stability ◽  
Increasing Temperature ◽  
Ferromagnetic Shape Memory

The stability of magnetic field induced strain (MFIS) in Ni52Mn24Ga24 single crystal under temperature and magnetic field cycling is investigated and the corresponding micro-mechanism is also discussed. It shows that the saturated MFIS is very sensitive to temperature. Below martensitic transformation temperature(Tm), with increasing temperature, the saturated MFIS increases almost linearly. Besides, the saturated MFIS initially decreases with increasing the field cycling number less than four times, then does not change with further increasing the number of field cycles. The decrease of saturated MFIS can be attributed to the decrease of twin boundary mobility, which is related to the crystal defect introduced by immigration of twin boundary under field cycling.

Effect of Constant-Strain Aging on Microstructure, Martensitic Transformation and Magnetic Property of Ni53Mn23.5Ga23.5 Ferromagnetic Shape Memory Alloy

2014 ◽  
Vol 1015 ◽  
pp. 114-118
Author(s):  
G.F. Dong
Keyword(s):  
Magnetic Field ◽  
Martensitic Transformation ◽  
Shape Memory Alloy ◽  
Curie Temperature ◽  
Shape Memory ◽  
Aged Sample ◽  
Ferromagnetic Shape Memory Alloy ◽  
Solution Treated ◽  
Treated Sample ◽  
Ferromagnetic Shape Memory

The effect of constant-strain aged and unaged on microstructure, martensite transformation, Curie temperature and magnetic field induction strain of Ni53Mn23.5Ga23.5ferromagnetic shape memory alloy was investigated in detail. The results show that reverse martensitic transformation temperatures of constant-strain aged sample slowly decrease, which martensitic transformation temperatures almost unchanged. In addition, Curie temperature of constant-strain aged sample is almost maintains consistent with solution-treated sample, but slowly increases saturation magnetization of constant-strain aged sample than solution-treated sample. Finally, the sample of constant-strain aged sample showed a larger magnetic field induction strain of 402 ppm.

Intrinsic Position Sensing of a Ni-Mn-Ga Microactuator

2008 ◽  
Author(s):  
Daniel Auernhammer ◽  
Manfred Kohl ◽  
Berthold Krevet ◽  
Makoto Ohtsuka
Keyword(s):  
Magnetic Field ◽  
Thin Film ◽  
Martensitic Transformation ◽  
Inhomogeneous Magnetic Field ◽  
Ferromagnetic Transition ◽  
Ferromagnetic Shape Memory Alloy ◽  
Position Sensing ◽  
Double Beam ◽  
Ferromagnetic Shape Memory ◽  
Magneto Resistance

This paper presents an investigation of the intrinsic magnetoresistance of a ferromagnetic shape memory alloy (FSMA) microactuator for position sensing. The microactuator is designed as a double-beam cantilever of a polycrystalline Ni-Mn-Ga thin film, which exhibits both, a martensitic transformation in the temperature range 333–359 K and a ferromagnetic transition at about 370 K. The microactuator is placed in the inhomogeneous magnetic field of a miniature Nd-Fe-B magnet causing a mixed thermo-magneto-resistance effect upon actuation. The maximum in-plane magnetic field is about 0.38 Tesla. In this case, the maximum magnetoresistance (MR) is 0.19%.

scholarly journals Microstructure and Magnetic Field-Induced Strain of a Ni-Mn-Ga-Co-Gd High-Entropy Alloy

Materials ◽  
2021 ◽  
Vol 14 (10) ◽  
pp. 2514
Author(s):  
Jia Ju ◽  
Liang Hu ◽  
Chenwei Bao ◽  
Liguo Shuai ◽  
Chen Yan ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Martensitic Transformation ◽  
High Entropy Alloy ◽  
Martensitic Transition ◽  
Martensitic Transformation Temperature ◽  
Ferromagnetic Shape Memory Alloys ◽  
High Entropy ◽  
Increasing Trend ◽  
Ferromagnetic Shape Memory ◽  
The Magnetic Field

The effect of a high-entropy design on martensitic transformation and magnetic field-induced strain has been investigated in the present study for Ni-Mn-Ga-Co-Gd ferromagnetic shape-memory alloys. The purpose was to increase the martensitic transition temperature, as well as the magnetic field-induced strain, of these materials. The results show that there is a co-existence of β, γ, and martensite phases in the microstructure of the alloy samples. Additionally, the martensitic transformation temperature shows a markedly increasing trend for these high-entropy samples, with the largest value being approximately 500 °C. The morphology of the martensite exhibits typical twin characteristics of type L10. Moreover, the magnetic field-induced strain shows an increasing trend, which is caused by the driving force of the twin martensite re-arrangement strengthening.

Martensitic Transformation and Mechanical Properties of Fe-Doped Ni54Mn21Ga25 Alloys

2011 ◽  
Vol 687 ◽  
pp. 500-504
Author(s):  
S. X. Xue ◽  
S.S. Feng ◽  
P. Y. Cai ◽  
Q T Li ◽  
H. B. Wang
Keyword(s):  
Magnetic Field ◽  
Mechanical Properties ◽  
Magnetic Properties ◽  
Martensitic Transformation ◽  
Curie Temperature ◽  
Directional Solidification ◽  
Transformation Temperature ◽  
Room Temperature ◽  
Martensitic Transformation Temperature ◽  
Polycrystalline Alloys

Ni54Mn21-xFexGa25（x=0,1,3,5,7,9）polycrystalline alloys were prepared by the technique of directional solidification and the effect of substituting Fe for Mn on the martensitic transformation and mechanical properties of the alloys was analyzed. It was found that the Curie temperature increased with increasing substitution while the martensitic transformation temperature decreased. The Fe-doped Ni54Mn21Ga25 alloys exhibit excellent magnetic properties at room temperature; the typical Ni54Mn20Fe1Ga25 alloy shows a large magnetic-induced-strain of -1040 ppm at a magnetic field of 4000 Oe.

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