Ferromagnetic Shape-Memory Alloys

2006 ◽  
Vol 512 ◽  
pp. 145-152 ◽  
Author(s):  
Antoni Planes ◽  
Lluís Mañosa
Keyword(s):  
Martensitic Transformation ◽  
Shape Memory ◽  
Shape Memory Effect ◽  
Memory Effect ◽  
Intermetallic Alloys ◽  
Magnetic Shape Memory ◽  
Ferromagnetic Shape Memory Alloys ◽  
Magnetic Shape Memory Alloy ◽  
Ferromagnetic Shape Memory ◽  
Variant Structure

The magnetic shape-memory effect is a consequence of the coupling between magnetism and structure in ferromagnetic alloys undergoing a martensitic transformation. In these materials large reversible strains can be magnetically induced by the rearrangement of the martensitic twin-variant structure. Several Heusler and intermetallic alloys have been studied in connec- tion with this property. In this paper we will focus on the Ni-Mn-Ga Heusler alloy which is considered to be the prototypical magnetic shape-memory alloy. After a brief summary of the general properties of this class of materials, we will present recent results of relevance for the understanding of the effect of magnetism on the martensitic transformation. Finally, we will discuss the requirements for the occurrence of the magnetic shape-memory effect.

Phase Transformation and Microstructures in Ni and Cu Base Ferromagnetic Shape Memory Alloys

2007 ◽  
Vol 539-543 ◽  
pp. 3157-3162 ◽  
Author(s):  
Takuro Kushima ◽  
Koichi Tsuchiya ◽  
Yasuyoshi Sho ◽  
Takafumi Yamada ◽  
Yoshikazu Todaka ◽  
...  
Keyword(s):  
Phase Transformation ◽  
Magnetic Property ◽  
Chemical Composition ◽  
Martensitic Transformation ◽  
Curie Temperature ◽  
Shape Memory ◽  
Shape Memory Effect ◽  
Memory Effect ◽  
Ferromagnetic Shape Memory Alloys ◽  
Ferromagnetic Shape Memory

Effect of chemical composition was investigated on martensitic transformation temperatures, Curie temperature, magnetization and microstructures for Ni-(Mn, Fe, Co)-Ga and Cu-Mn-Ga systems. In the Ni-(Mn, Fe, Co)-Ga alloys, which is a modification of Ni-Mn-Ga systems, the Af and TC over 400 K were achieved. Cu-Mn-Ga alloy exhibited shape memory effect at temperatures above 373 K and had TC over 400 K. Furthermore, Cu-Mn-Ga exhibits good ductility even in polycrystalline condition unlike the case of Ni-Mn-Ga. Effect of addition of the fourth element to improve the magnetic property is under investigation.

Ferromagnetic Shape Memory Heusler Alloys

2012 ◽  
Vol 189 ◽  
pp. 189-208 ◽  
Author(s):  
Vijay Srivastava ◽  
Kanwal Preet Bhatti
Keyword(s):  
Magnetic Properties ◽  
Shape Memory ◽  
Shape Memory Effect ◽  
Memory Effect ◽  
Heusler Alloy ◽  
Heusler Alloys ◽  
Structural Similarity ◽  
Magnetic Shape Memory ◽  
Half Metallicity ◽  
Ferromagnetic Shape Memory

Although Heusler alloys have been known for more than a century, but since the last decade there has been a quantum jump in research in this area. Heusler alloys show remarkable properties, such as ferromagnetic shape memory effect, magnetocaloric effect, half metallicity, and most recently it has been shown that it can be used for direct conversion of heat into electricity. Heusler alloys Ni-Mn-Z (Z=Ga, Al, In, Sn, Sb), show a reversible martensitic transformation and unusual magnetic properties. Other classes of intermetallic Heusler alloy families that are half metallic (such as the half Heusler alloys Ni-Mn-Sb and the full Heusler alloy Co2MnGe) are attractive because of their high Curie temperature and structural similarity to binary semiconductors. Unlike Ni-Mn-Ga, Ni-Mn-In and Ni-Mn-Sn transform from ferromagnetic austenite to non-ferromagnetic martensite. As is consistent with the Clausius-Clapeyron equation, the martensitic phase transformation can be manipulated by a magnetic field, leading to possible applications of these materials enabling the magnetic shape memory effect, energy conversion and solid state refrigeration. In this paper, we summarize the salient features of Heusler alloys, like the structure, magnetic properties and potential application of this family of alloys in industry.

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.

Martensitic Transformation and Shape Memory Effect of Ni53.25Mn21.75Ga25 Ferromagnetic Shape Memory Alloy

2012 ◽  
Vol 476-478 ◽  
pp. 1504-1507
Author(s):  
Hai Bo Wang ◽  
Shang Shen Feng ◽  
Pei Yang Cai ◽  
Yan Qiu Huo
Keyword(s):  
Magnetic Field ◽  
Martensitic Transformation ◽  
Shape Memory ◽  
Shape Memory Effect ◽  
Memory Effect ◽  
Parent Phase ◽  
Transformation Strain ◽  
Scanning Calorimetry ◽  
Reversible Transformation ◽  
Ferromagnetic Shape Memory

The martensitic transformation, crystalline structure, microstructure and shape memory effect of the Ni53.25Mn21.75Ga25 (at.%) alloy are investigated by means of Differential Scanning Calorimetry (DSC), X-ray diffraction (XRD), Transmission Electron Microscope (TEM) and the standard metal strain gauge technique. The XRD results showed that the Ni53.25Mn21.75Ga25 alloy is composed of cubic parent phase at room temperature. TEM observation proved that the typical twin martensite is tetragonal structure and tweed-like contrast which is typical image for the parent phase. A large reversible transformation strain, about 0.54%, is obtained in this undeformed polycrystalline alloy due to martensitic transformation and its reverse transformation. This transformation strain is also increased to 0.65% by the external magnetic field. It is believed that the effect of the magnetic field on the preferential orientation of martensitic variants increases the transformation strain.

A chemical-structural model for coherent martensite/parent interface in Mn-based antiferromagnetic shape memory alloys

2016 ◽  
Vol 18 (43) ◽  
pp. 29923-29934 ◽  
Author(s):  
S. Shi ◽  
J. F. Wan ◽  
X. W. Zuo ◽  
N. L. Chen ◽  
J. H. Zhang ◽  
...  
Keyword(s):  
Martensitic Transformation ◽  
Shape Memory Alloys ◽  
Shape Memory ◽  
Shape Memory Effect ◽  
Memory Effect ◽  
Structural Model ◽  
Significant Part ◽  
Magnetic Shape Memory ◽  
Coherent Interface

The martensite/parent coherent interface of Mn-based shape memory alloys (SMAs) is a significant part in the research of their martensitic transformation, reversible shape memory effect and magnetic shape memory effect.

scholarly journals Crystallographic insights into diamond-shaped 7M martensite in Ni–Mn–Ga ferromagnetic shape-memory alloys

IUCrJ ◽  
2019 ◽  
Vol 6 (5) ◽  
pp. 909-920 ◽  
Author(s):  
Zong-Bin Li ◽  
Bo Yang ◽  
Yu-Dong Zhang ◽  
Claude Esling ◽  
Xiang Zhao ◽  
...  
Keyword(s):  
Martensitic Transformation ◽  
Shape Memory Alloys ◽  
Shape Memory ◽  
Electron Backscatter Diffraction ◽  
Deformation Gradient ◽  
Type I ◽  
Magnetic Shape Memory ◽  
Ferromagnetic Shape Memory Alloys ◽  
Ferromagnetic Shape Memory ◽  
Habit Planes

For Heusler-type Ni–Mn–Ga ferromagnetic shape-memory alloys, the configuration of the martensite variants is a decisive factor in achieving a large magnetic shape-memory effect through field-induced variant reorientation. Based upon the spatially resolved electron backscatter diffraction technique, the microstructural evolution associated with the martensitic transformation from austenite to seven-layered modulated (7M) martensite was investigated on a polycrystalline Ni53Mn22Ga25 alloy. It was clearly shown that grain interior nucleation led to the formation of diamond-shaped 7M martensite within the parent austenite matrix. This diamond microstructure underwent further growth through an isotropic expansion with the coordinated outward movement of four side habit planes, followed by an anisotropic elongation with the forward extension of a type-I twin pair. A two-step growth model is proposed to describe the specific morphology and crystallography of 7M martensite. In addition, the habit planes were revealed to possess a stepped structure, with the {1 0 1}A plane as the terrace and the {0 1 0}A plane as the step. The characteristic combination of martensite variants and the underlying mechanism of self-accommodation in the martensitic transformation have been analysed in terms of the minimum total transformation strain, where the deformation gradient matrix was constructed according to the experimentally determined orientation relationship between the two phases. The present results may deepen the understanding of special martensite microstructures during the martensitic transformation in ferromagnetic shape-memory alloys.

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