Effects of High Magnetic Field and Tensile Stress on Martensitic Transformation Behavior and Microstructure At 4 K in Fe-Ni-C Alloys

1995 ◽  
Vol 398 ◽  
Author(s):  
H. Ohtsuka ◽  
K. Nagai ◽  
S. Kajiwara ◽  
H. Kitaguchi ◽  
M. Uehara
Keyword(s):  
Magnetic Field ◽  
Martensitic Transformation ◽  
Tensile Stress ◽  
Shape Memory Alloys ◽  
Shape Memory ◽  
High Magnetic Field ◽  
Constant Magnetic Field ◽  
Critical Magnetic Field ◽  
Transformation Behavior ◽  
The Magnetic Field

ABSTRACTEffects of high magnetic field and tensile stress on martensitic transformation behavior and microstructure at 4 K have been studied in Fe-31Ni-0.4C and Fe-27Ni-0.8C shape memory alloys. It was found that the critical magnetic field to induce martensitic transformation is between 7.5 T and 10 T. In the case of Fe-27Ni-0.8C, martensitic transformation is stress-induced at lower level of stress in magnetic field than in the case when no magnetic Field is applied. The amount of martensite formed by increasing the magnetic field under constant stress is larger than that formed by increasing the stress in the constant magnetic field.

scholarly journals Effects of High Magnetic Field and Tensile Stress on Martensitic Transformation Behavior and Microstructure at 4.2 K in Fe–Ni–C Alloys

1996 ◽  
Vol 37 (5) ◽  
pp. 1044-1049 ◽  
Author(s):  
Hideyuki Ohtsuka ◽  
Kotobu Nagai ◽  
Setsuo Kajiwara ◽  
Hitoshi Kitaguchi ◽  
Mitsuru Uehara
Keyword(s):  
Magnetic Field ◽  
Martensitic Transformation ◽  
Tensile Stress ◽  
High Magnetic Field ◽  
Transformation Behavior

scholarly journals Microstructure and Phase Transformation Analysis of Ni50−xTi50Lax Shape Memory Alloys

Crystals ◽  
2018 ◽  
Vol 8 (9) ◽  
pp. 345 ◽  
Author(s):  
Weiya Li ◽  
Chunwang Zhao
Keyword(s):  
Phase Transformation ◽  
Martensitic Transformation ◽  
Shape Memory Alloys ◽  
Shape Memory ◽  
Martensite Transformation ◽  
Transformation Behavior ◽  
Ni Content ◽  
Start Temperature

The microstructure and martensitic transformation behavior of Ni50−xTi50Lax (x = 0.1, 0.3, 0.5, 0.7) shape memory alloys were investigated experimentally. Results show that the microstructure of Ni50−xTi50Lax alloys consists of a near-equiatomic TiNi matrix, LaNi precipitates, and Ti2Ni precipitates. With increasing La content, the amounts of LaNi and Ti2Ni precipitates demonstrate an increasing tendency. The martensitic transformation start temperature increases gradually with increasing La content. The Ni content is mainly responsible for the change in martensite transformation behavior in Ni50−xTi50Lax alloys.

Effects of Surface Pinning, Locking and Adaption of Twins on the Performance of Magnetic Shape-Memory Alloys

2011 ◽  
Vol 684 ◽  
pp. 177-201 ◽  
Author(s):  
Markus Chmielus ◽  
Peter Müllner
Keyword(s):  
Magnetic Field ◽  
Shape Memory Alloys ◽  
Shape Memory ◽  
Surface Damage ◽  
Magnetic Shape Memory ◽  
Magnetic Shape Memory Alloys ◽  
Fatigue Lifetime ◽  
Twin Density ◽  
External Constraints ◽  
The Magnetic Field

We study the effect of surface modifications and constraints on the mechanical properties of Ni-Mn- Ga single crystals, which are imposed by (i) structural modifications near the surface, (ii) mounting to a solid surface, and (iii) guiding the stroke. Spark eroded samples were electropolished and characterized before and after each polishing treatment. Surface damage was then produced with spark erosion and abrasive wearing. Surface damage stabilizes and pins a dense twin-microstructure and prevents twins from coarsening. The density of twins increases with increasing degree of surface deformation. Twinning stress and hardening rate during mechanical loading increase with increasing surface damage and twin density. In contrast, when a damaged surface layer is removed, twinning stresses, hardening rate, and twin density decrease. Constraining the sample by mounting and guiding reduces the magnetic-field-induced strain by locking twins at the constrained surfaces. . For single-domain crystals and for hard magnetic shape-memory alloys, external constraints strongly reduce the magnetic-field-induced strain and the fatigue lifetime is short. In contrast, for selfaccommodated martensite and for soft magnetic shape-memory alloys, the twin-microstructure adapts well to external constraints and the fatigue lifetime is long. The performance of devices with MSMA transducers requires managing stress distributions through design and control of surface properties, microstructure, and constraints.

scholarly journals Training of the Ni–Mn–Fe–Ga ferromagnetic shape-memory alloys due cycling in high magnetic field

2003 ◽  
Vol 258-259 ◽  
pp. 523-525 ◽  
Author(s):  
A.A. Cherechukin ◽  
V.V. Khovailo ◽  
R.V. Koposov ◽  
E.P. Krasnoperov ◽  
T. Takagi ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Shape Memory Alloys ◽  
Shape Memory ◽  
High Magnetic Field ◽  
Ferromagnetic Shape Memory Alloys ◽  
Ferromagnetic Shape Memory

Hysteresis effects in the magnetic-field-induced reverse martensitic transition in magnetic shape-memory alloys

2010 ◽  
Vol 108 (4) ◽  
pp. 043914 ◽  
Author(s):  
Thorsten Krenke ◽  
Seda Aksoy ◽  
Eyüp Duman ◽  
Mehmet Acet ◽  
Xavier Moya ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Shape Memory Alloys ◽  
Shape Memory ◽  
Martensitic Transition ◽  
Magnetic Shape Memory ◽  
Magnetic Shape Memory Alloys ◽  
The Magnetic Field
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