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

Jae Hoon Kim; Takashi Fukuda; Tomoyuki Kakeshita

doi:10.4028/www.scientific.net/MSF.512.189

Paper Titles

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Magnetization Chirality of Ni-Fe and Ni-Fe/Mn-Ir Asymmetric Ring Dots for High-Density Memory Cells
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Change of Interlayer Exchange Coupling between the Adjacent Magnetic Transition Metal Layers across a Rare-Earth Metal Layer by Hydrogenation
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Magnetic Phase Diagram in Layered Perovskite Manganite La_2-2xSr_1+2xMn₂O₇ (0.313≤x≤0.350)
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Martensitic Transformation of Ni-Mn-Ga Alloys under Magnetic Field and Hydrostatic Pressure
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Magnetocrystalline Anisotropy and Twinning Stress of 10M and 2M Martensites in Ni-Mn-Ga System
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Influence of Magnetic Field Direction and Temperature on Rearrangement of Martensite Variants in Fe-31.2at.%Pd
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Anodic Porous Zirconium Oxide Prepared in Sulfuric Acid Electrolytes
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Surface Properties of Ag-Cu-Zr Liquid Alloys in Relation to the Wettability of Boride Ceramics
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Martensitic Transformation of Ni-Mn-Ga Alloys under Magnetic Field and Hydrostatic Pressure

Abstract:

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.