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 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.

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.

Shape Memory Effect and Superelasticity in Single Crystals of High-Strength Ferromagnetic Alloys

2014 ◽  
Vol 1013 ◽  
pp. 15-22 ◽  
Author(s):  
Yuri Chumlyakov ◽  
Irina Kireeva ◽  
Elena Panchenko ◽  
Ekaterina Timofeeva ◽  
Irina Kretinina ◽  
...  
Keyword(s):  
Chemical Composition ◽  
Martensitic Transformation ◽  
Shape Memory ◽  
Single Crystals ◽  
Shape Memory Effect ◽  
Memory Effect ◽  
Functional Properties ◽  
Volume Fraction ◽  
High Strength ◽  
Ferromagnetic Alloys

In the present study the effect of second γ'-phase particles which do not undergo martensitic transformation on the functional properties – shape memory effect and superelasticity, in ferromagnetic FeNiCoAlX (X = Ta, Nb, Ti) and NiFeGaCo single crystals are investigated. Dispersed γ'-phase particles allow to control both mechanical and functional properties due to variation of chemical composition, volume fraction and size of nanoparticles, and to obtain the nanocomposites with complex of necessary properties.

Martensitic transformation, ductility, and shape-memory effect of polycrystalline Ni56Mn25 –xFexGa19alloys

2005 ◽  
Vol 96 (8) ◽  
pp. 843-846 ◽  
Author(s):  
Yunqing Ma ◽  
Lihong Xu ◽  
Yan Li ◽  
Chengbao Jiang ◽  
Huibin Xu ◽  
...  
Keyword(s):  
Martensitic Transformation ◽  
Shape Memory ◽  
Shape Memory Effect ◽  
Memory Effect
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