Effect of External Fields on the Martensitic Transformation in Ni-Mn Based Heusler Alloys

In this paper, we discuss the possibility of inducing a martensitic transition by means of an applied magnetic field or hydrostatic pressure in Ni-Mn based Heusler shape memory alloys. We report on the shift of the martensitic transition temperatures with applied magnetic field and applied pressure and we show that it is possible to induce the structural transformation in a Ni50Mn34In16 alloy by means of both external fields due to: (i) the low value of the entropy change and (ii) the large change of magnetization and volume, which occur at the martensitic transition.

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Martensitic Transformation of Ni-Mn-Ga Alloys under Magnetic Field and Hydrostatic Pressure

Materials Science Forum ◽

10.4028/www.scientific.net/msf.512.189 ◽

2006 ◽

Vol 512 ◽

pp. 189-194 ◽

Cited By ~ 3

Author(s):

Jae Hoon Kim ◽

Takashi Fukuda ◽

Tomoyuki Kakeshita

Keyword(s):

Magnetic Field ◽

Hydrostatic Pressure ◽

Martensitic Transformation ◽

Applied Magnetic Field ◽

Transformation Temperature ◽

Intermediate Phase ◽

Parent Phase ◽

Clapeyron Equation ◽

Transformation Temperatures ◽

The Magnetic Field

The effects of magnetic field and hydrostatic pressure on martensitic transformation have been systematically investigated by using Ni2MnGa, Ni2.14Mn0.84Ga1.02, and Ni2.14Mn0.92Ga0.94, which exhibit P(parent phase)-I(intermediate phase)-10M, P-14M-2M, and P-2M transformation, respectively. The following results were obtained. (i) The P-I transformation temperature does not change by magnetic field. (ii) The I-10M and the P-14M transformation temperatures decrease under applied magnetic field up to 0.8 MA/m and 0.4 MA/m, respectively, and then increase with increasing applied magnetic field higher than those fields. (iii) The 14M-2M transformation temperature increases under a magnetic field up to 0.4 MA/m and decreases under magnetic field up to 0.8 MA/m and then increases again when the magnetic field becomes higher than 0.8 MA/m. (iv) The P-2M transformation temperature increases linearly with increasing applied magnetic field. (v) All transformation temperatures increase linearly with increasing hydrostatic pressure. The experimental results mentioned above (i)~(iv) under magnetic field can be well explained by using the Clausius-Clapeyron equation.

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Martensitic Transformation and Metamagnetic Transition in Co-V-(Si, Al) Heusler Alloys

Metals ◽

10.3390/met11020226 ◽

2021 ◽

Vol 11 (2) ◽

pp. 226

Author(s):

Kousuke Nakamura ◽

Atsushi Miyake ◽

Xiao Xu ◽

Toshihiro Omori ◽

Masashi Tokunaga ◽

...

Keyword(s):

Magnetic Field ◽

Martensitic Transformation ◽

Spontaneous Magnetization ◽

Heusler Alloys ◽

Parent Phase ◽

Entropy Change ◽

Ferromagnetic State ◽

Martensite Phase ◽

Reverse Martensitic Transformation ◽

Curie Temperatures

This study investigates the crystal structure, martensitic transformation behavior, magnetic properties, and magnetic-field-induced reverse martensitic transformation of Co64V15(Si21–xAlx) alloys. It was found that by increasing the Al composition, the microstructure changes from the martensite phase to the parent phase. The crystal structures of the martensite and parent phases were determined as D022 and L21, respectively. Thermoanalysis and thermomagnetization measurements were used to determine the martensitic transformation and Curie temperatures. Both the ferromagnetic state of the parent phase and that of the martensite phase were observed. With the increasing Al contents, the martensitic transformation temperatures decrease, whereas the Curie temperatures of both the martensite and parent phases increase. The spontaneous magnetization and its composition dependence were also determined. The magnetic-field-induced reverse martensitic transformation of a Co64V15Si7Al14 alloy under pulsed high magnetic fields was observed. Moreover, using the results of the DSC measurements and the pulsed high magnetization measurements, the temperature dependence of the transformation entropy change of the Co-V-Si-Al alloys was estimated.

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Martensite-austenite and Ferromagnetic-paramagnetic Transformations in Ni2-xAxMn1-yByGa1-zCz (A, B=Co; C=Al) Heusler Alloys

Revista de Chimie ◽

10.37358/rc.08.12.2058 ◽

2009 ◽

Vol 59 (12) ◽

Author(s):

Mihail-Liviu Craus ◽

Viorel Dobrea ◽

Mihai Lozovan

Keyword(s):

Magnetic Field ◽

Transition Temperature ◽

Martensitic Transformation ◽

Low Temperatures ◽

Room Temperature ◽

Heusler Alloys ◽

Partial Substitution ◽

Martensitic Transition ◽

Cscl Type ◽

Curie Temperatures

Ni2MnGa Heusler alloy is known as a potential smart material. At room temperature it has a L21 type structure, undergoing a martensitic transition (TM) at low temperatures. Some authors have classified Ni-Mn-Ga Heusler alloys on the values of martensitic transformation and Curie temperatures: first group formed by alloys with TM below room temperature and TC, second group with TM around room temperature and third group with TM]TC. The partial substitution of Ni with Mn leads to an increase of the transition temperature and a decrease of the Curie temperature. The Ni2-xMn1+xGa alloys have a complex tetragonal structure at room temperature. The substitution of Ga with Al can change the crystalline and magnetic structure of Heusler alloys: Ni2MnAl is antiferromagnetic for a B2 (CsCl type, with Mn and Al randomly distributed in the center of the cube) structure and ferromagnetic for a L21 (BiF3 type with Mn and Al ordered distributed in the cube center) structure. We intend to put in evidence a dependence between the applied magnetic field on a side, and the transition temperature, on other side, for the Ni2-xAxMn1-yByGa1-zCz (A, B=Co; C=Al) Heusler alloys.

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An Interpretation on Kinetics of Martensitic Transformation

Solid State Phenomena ◽

10.4028/www.scientific.net/ssp.172-174.90 ◽

2011 ◽

Vol 172-174 ◽

pp. 90-98 ◽

Cited By ~ 1

Author(s):

Tomoyuki Kakeshita ◽

Takashi Fukuda ◽

Yong-Hee Lee

Keyword(s):

Magnetic Field ◽

Hydrostatic Pressure ◽

Martensitic Transformation ◽

Magnetic Fields ◽

Martensitic Transformations ◽

Phenomenological Theory ◽

Time Dependent ◽

Isothermal Process ◽

Kinetics Of ◽

Transformation Processes

We have investigated athermal and isothermal martensitic transformations (typical displacive transformations) in Fe–Ni, Fe–Ni–Cr, and Ni-Co-Mn-In alloys under magnetic fields and hydrostatic pressures in order to understand the time-dependent nature of martensitic transformation, that is, the kinetics of martensitic transformation. We have confirmed that the two transformation processes are closely related to each other, that is, the athermal process changes to the isothermal process and the isothermal process changes to the athermal one under a hydrostatic pressure or a magnetic field. These findings can be explained by the phenomenological theory, which gives a unified explanation for the two transformation processes previously proposed by our group.

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