scholarly journals Numerical Simulation of the Phase Transition Control in a Cylindrical Sample Made of Ferromagnetic Shape Memory Alloy

Computation ◽  
2019 ◽  
Vol 7 (3) ◽  
pp. 38
Author(s):  
Anatoli A. Rogovoy ◽  
Olga S. Stolbova
Keyword(s):  
Magnetic Field ◽  
Phase Transition ◽  
Shape Memory ◽  
Outer Surface ◽  
Original Position ◽  
Cubic Phase ◽  
Temperature Phase ◽  
Martensitic State ◽  
Ferromagnetic Shape Memory ◽  
The Magnetic Field

The paper considers ferromagnetic alloys, which exhibit the shape memory effect during phase transition from the high-temperature cubic phase (austenite) to the low-temperature tetragonal phase (martensite) in the ferromagnetic state. In these alloys, significant macroscopic strains are generated during the direct temperature phase transition from the austenitic to the martensitic state, provided that the process proceeds under the action of the applied mechanical stresses. The critical phase transition temperatures in such alloys depend not only on the stress fields, but also on the magnetic field. By changing the magnetic field, it is possible to control the process of phase transition. In this work, within the framework of the finite deformation theory, we develop a model that allows us to describe the process of the control of the direct (austenite-martensite) and reverse (martensite-austenite) phase transitions in ferromagnetic shape memory polycrystalline materials under the action of external force, thermal, and magnetic fields with the aid of the magnetic field. In view of the fact that the magnetic field affects the material deformation, which, in turn, changes the magnetic field, we formulated and solved a coupled boundary value problem. As an example, we considered the problem of a shift of the outer surface of a long hollow cylinder made of ferromagnetic alloy. The numerical implementation of the problem was based on the finite element method using the step-by-step loading procedure. Complete recovery of the strains accumulated during the direct phase transition and reverting of the axially-displaced outer surface of the cylinder to its original position occurred both on heating of the sample to the temperatures of the reverse phase transition and at a constant temperature, when the magnetic field previously applied in the martensitic state was removed.

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 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.

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.

In situ high-energy X-ray studies of magnetic-field-induced phase transition in a ferromagnetic shape memory Ni–Co–Mn–In alloy

2008 ◽  
Vol 56 (4) ◽  
pp. 913-923 ◽  
Author(s):  
Y.D. Wang ◽  
E.W. Huang ◽  
Y. Ren ◽  
Z.H. Nie ◽  
G. Wang ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Phase Transition ◽  
Shape Memory ◽  
High Energy ◽  
X Ray ◽  
Ferromagnetic Shape Memory

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.

Sign in / Sign up

Export Citation Format

Share Document