scholarly journals Coexisting Multiple Martensites in Ni57−XMn21+XGa22 Ferromagnetic Shape Memory Alloys: Crystal Structure and Phase Transition

Metals ◽  
2021 ◽  
Vol 11 (10) ◽  
pp. 1534
Author(s):  
Lian Huang ◽  
Daoyong Cong ◽  
Mingguang Wang ◽  
Yandong Wang
Keyword(s):  
Magnetic Field ◽  
Crystal Structure ◽  
Phase Transition ◽  
Shape Memory Alloys ◽  
Shape Memory ◽  
Alloy System ◽  
Magnetic Shape Memory ◽  
Ferromagnetic Shape Memory Alloys ◽  
Ferromagnetic Shape Memory ◽  
The Magnetic Field

A comprehensive study of the crystal structure and phase transition as a function of temperature and composition in Ni57−xMn21+xGa22 (x = 0, 2, 4, 5.5, 7, 8) (at. %) magnetic shape memory alloys was performed by a temperature-dependent synchrotron X-ray diffraction technique and transmission electron microscopy. A phase diagram of this Ni57−xMn21+xGa22 alloy system was constructed. The transition between coexisting multiple martensites with monoclinic and tetragonal structures during cooling was observed in the Ni51.5Mn26.5Ga22 (x = 5.5) alloy, and it was found that 5M + 7M multiple martensites coexist from 300 K to 160 K and that 5M + 7M + NM multiple martensites coexist between 150 K and 100 K. The magnetic-field-induced transformation from 7M martensite to NM martensite at 140 K where 5M + 7M + NM multiple martensites coexist before applying the magnetic field was observed by in situ neutron diffraction experiments. The present study is instructive for understanding the phase transition between coexisting multiple martensites under external fields and may shed light on the design of novel functional properties based on such phase transitions.

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.

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.

scholarly journals Magnetoelastic Nature of Ferromagnetic Shape Memory Effect

2008 ◽  
Vol 583 ◽  
pp. 1-20 ◽  
Author(s):  
Volodymyr A. Chernenko ◽  
Victor A. L'vov
Keyword(s):  
Magnetic Field ◽  
Shape Memory ◽  
Sufficient Conditions ◽  
Alloy System ◽  
Ferromagnetic Shape Memory Alloys ◽  
Fundamental Conception ◽  
Spontaneous Deformation ◽  
Ferromagnetic Shape Memory ◽  
Necessary And Sufficient ◽  
The Magnetic Field

The giant magnetically-induced deformation of ferromagnetic shape memory alloys results from the magnetic field-induced rearrangement of twinned martensite under the magnetic field. This deformation is conventionally referred to as the magnetic-field-induced-strain (MFIS). The MFIS is comparable in value with the spontaneous deformation of crystal lattice during the martensitic transformation of an alloy. Although the first observations of MFIS were reported more than 30 years ago, it has got a world-wide interest 20 years later after the creation of the Ni–Mn–Ga alloy system with its practically important room-temperature martensitic structure and experimental evidence of the large magnetostriction. The underlying physics as well as necessary and sufficient conditions for the observation of MFIS are the main focus of this chapter. A magnetostrictive mechanism of the unusual magnetic and magnetomechanical effects observed in Ni–Mn–Ga alloys is substantiated and a framework of consistent theory of these effects is outlined starting from the fundamental conception of magnetoelasticity and the commonly known principles of ferromagnetism and linear elasticity theories. A reasonable agreement between the theoretical deductions and available experimental data is demonstrated and, in this way, a key role of magnetoelastic coupling in the magnetomechanical behavior of Ni–Mn–Ga alloys is proved. A correspondence of magnetostrictive mechanism to the crystallographic features of MFIS and the basic relationships of the thermodynamics of solids are discussed.

Magnetron Sputtering Applied in Ni-Mn-Ga Films Preparation

2012 ◽  
Vol 569 ◽  
pp. 7-10 ◽  
Author(s):  
Jia Zi Shi ◽  
Chuan Zhong Chen ◽  
Xing Dang
Keyword(s):  
Magnetic Field ◽  
Magnetron Sputtering ◽  
Shape Memory Alloys ◽  
Shape Memory ◽  
Functional Materials ◽  
Research Direction ◽  
Ferromagnetic Shape Memory Alloys ◽  
Short Response Time ◽  
Ferromagnetic Shape Memory ◽  
The Magnetic Field

Shape memory alloys (SMAs) thin films have attracted much attention in recent years as intelligent and functional materials because of their unique properties. Ferromagnetic shape memory alloys (FSMAs) show large straining output, high impetus and short response time induced by the magnetic field, compared with traditional shape memory alloys. In this paper, Ni-Mn-Ga ferromagnetic shape memory alloys flims prepared by magnetron sputtering are introduced, and the research direction of Ni-Mn-Ga films is presented.

Neutron Diffraction Studies of Magnetic Shape Memory Alloys

2011 ◽  
Vol 684 ◽  
pp. 73-84 ◽  
Author(s):  
José M. Barandiarán ◽  
Jon Gutiérrez ◽  
Patricia Lázpita ◽  
J. Feuchtwanger
Keyword(s):  
Crystal Structure ◽  
Neutron Diffraction ◽  
Shape Memory Alloys ◽  
Shape Memory ◽  
Site Occupancy ◽  
Magnetic Shape Memory ◽  
Ferromagnetic Shape Memory Alloys ◽  
Magnetic Shape Memory Alloys ◽  
Moment Distribution ◽  
Ferromagnetic Shape Memory

The characteristics of neutron diffraction applied to the study of Ferromagnetic Shape Memory Alloys are revised. Main studies refer to crystal structure, preferential site occupancy, variant reorientation and magnetic moment distribution in the alloys

3D Energy Analysis of Magnetic-Field Induced Martensite Reorientation in Magnetic Shape Memory Alloys

2013 ◽  
Vol 738-739 ◽  
pp. 400-404 ◽  
Author(s):  
Yong Jun He ◽  
Xue Chen ◽  
Ziad Moumni
Keyword(s):  
Magnetic Field ◽  
Shape Memory Alloys ◽  
Shape Memory ◽  
Energy Analysis ◽  
Three Dimensional ◽  
Rotating Magnetic Field ◽  
Magnetic Shape Memory ◽  
Ferromagnetic Shape Memory Alloys ◽  
Ferromagnetic Shape Memory ◽  
Martensite Reorientation

This paper explains the magnetic-field induced martensite reorientation in Ferromagnetic Shape Memory Alloys (FSMA) through a simple energy analysis from which the role of the martensite’s magnetic anisotropy is emphasized. In particularly, with a three-dimensional (3D) energy analysis, we study the switching between the three tetragonal martensite variants driven by a rotating magnetic field (with a constant magnitude) and a non-rotating magnetic field (with a fixed direction but varying magnitudes). Finally, a simple planar phase diagram is proposed to describe the martensite reorientation in general 3D loadings.

Effects of Annealing on Microstructure and Martensitic Transition of Ni-Mn-Co-In Ferromagnetic Shape Memory Alloys

2011 ◽  
Vol 674 ◽  
pp. 171-175
Author(s):  
Katarzyna Bałdys ◽  
Grzegorz Dercz ◽  
Łukasz Madej
Keyword(s):  
Electron Microscopy ◽  
Shape Memory Alloys ◽  
Shape Memory ◽  
Smart Materials ◽  
Martensitic Transition ◽  
Magnetic Shape Memory ◽  
Ferromagnetic Shape Memory Alloys ◽  
Initial State ◽  
X Ray ◽  
Ferromagnetic Shape Memory

The ferromagnetic shape memory alloys (FSMA) are relatively the brand new smart materials group. The most interesting issue connected with FSMA is magnetic shape memory, which gives a possibility to achieve relatively high strain (over 8%) caused by magnetic field. In this paper the effect of annealing on the microstructure and martensitic transition on Ni-Mn-Co-In ferromagnetic shape memory alloy has been studied. The alloy was prepared by melting of 99,98% pure Ni, 99,98% pure Mn, 99,98% pure Co, 99,99% pure In. The chemical composition, its homogeneity and the alloy microstructure were characterized using scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The phase composition was also studied by X-ray analysis. The transformation course and characteristic temperatures were determined by the use of differential scanning calorimetry (DSC) and magnetic balance techniques. The results show that Tc of the annealed sample was found to decrease with increasing the annealing temperature. The Ms and Af increases with increasing annealing temperatures and showed best results in 1173K. The studied alloy exhibits a martensitic transformation from a L21 austenite to a martensite phase with a 7-layer (14M) and 5-layer (10M) modulated structure. The lattice constants of the L21 (a0) structure determined by TEM and X-ray analysis in this alloy were a0=0,4866. The TEM observation exhibit that the studied alloy in initial state has bigger accumulations of 10M and 14M structures as opposed from the annealed state.

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