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.

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.

Neutron diffraction study on crystal structure and phase transformation in Ni-Mn-Ga ferromagnetic shape memory alloys

2007 ◽  
Vol 22 (4) ◽  
pp. 307-311 ◽  
Author(s):  
D. Y. Cong ◽  
Y. D. Wang ◽  
J. Z. Xu ◽  
L. Zuo ◽  
P. Zetterström ◽  
...  
Keyword(s):  
Crystal Structure ◽  
Phase Transformation ◽  
Neutron Diffraction ◽  
Shape Memory Alloys ◽  
Shape Memory ◽  
Neutron Diffraction Study ◽  
Martensitic Structure ◽  
Ferromagnetic Shape Memory Alloys ◽  
Structure Changes ◽  
Ferromagnetic Shape Memory

Crystal structure and phase transformation behaviors in two Ni-Mn-Ga ferromagnetic shape memory alloys (FSMAs) with compositions of Ni48Mn30Ga22 and Ni53Mn25Ga22 (at. %) as a function of temperature were investigated by in situ neutron diffraction experiments. Neutron diffraction technique proves to be highly efficient in characterizing structural transformation in Ni-Mn-Ga FSMAs, which consist of nearby elements in the periodic table. Our neutron results show that Ni48Mn30Ga22 has a cubic, L21 Heusler structure from 373 to 293 K. Its crystal structure changes into a seven-layered orthorhombic martensitic structure when cooled to 243 K, and no further transformation is observed upon cooling to 19 K. Neutron diffraction results also show that Ni53Mn25Ga22 has a tetragonal I4/mmm martensitic structure from 20 to 403 K. A pre-transformation around room temperature is observed from an abrupt jump in unit-cell volume of Ni53Mn25Ga22, which corresponds with an endothermic peak detected in a heated DSC curve.

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

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.

Structure and Phase Stability of NiMnGa Ferromagnetic Shape Memory Alloys by Experimental and Ab Initio Techniques

2010 ◽  
Vol 638-642 ◽  
pp. 2040-2045 ◽  
Author(s):  
Claude Esling ◽  
Dao Yong Cong ◽  
Jing Bai ◽  
Yu Dong Zhang ◽  
Jean Marc Raulot ◽  
...  
Keyword(s):  
Crystal Structure ◽  
Orientation Relationship ◽  
Room Temperature ◽  
Phenomenological Theory ◽  
Shear Angle ◽  
Martensitic Structure ◽  
Ferromagnetic Shape Memory Alloys ◽  
Austenite Grain ◽  
Ferromagnetic Shape Memory ◽  
Martensitic Variants

This paper summarizes some of our recent results on crystal structure, microstructure, orientation relationship between martensitic variants and crystallographic features of martensitic transformation in Ni-Mn-Ga FSMAs. It was shown that Ni53Mn25Ga22 has a tetragonal I4/mmm martensitic structure at room temperature. The neighboring martensitic variants in Ni53Mn25Ga22 have a compound twinning relationship with the twinning elements K1={112}, K2={11-2}, η1=<11-1>, η2=<111>, P={1-10} and s=0.379. The ratio of the relative amounts of twins within the same initial austenite grain is ~1.70. The main orientation relationship between austenite and martensite is Kurdjumov-Sachs (K-S) relationship. Based on the crystallographic phenomenological theory, the calculated habit plane is {0.690 -0.102 0.716}A (5.95° from {101}A), and the magnitude, direction and shear angle of the macroscopic transformation shear are 0.121, <-0.709 0.105 0.698>A (6.04° from <-101>A) and 6.88°, respectively.

Aging Response to Microstructure and Properties of Ferromagnetic Shape Memory Alloys

2011 ◽  
Vol 326 ◽  
pp. 81-87
Author(s):  
M.B. Bhatty ◽  
Zameer Abbas ◽  
Fazal Ahmad Khalid
Keyword(s):  
Shape Memory Alloys ◽  
Shape Memory ◽  
Aging Treatment ◽  
Dual Phase ◽  
Magnetic Shape Memory ◽  
Ferromagnetic Shape Memory Alloys ◽  
Polycrystalline Alloys ◽  
Different Temperatures ◽  
Ferromagnetic Shape Memory ◽  
The Cost

Ni-Mn-Ga magnetic shape memory alloys are employed for applications in actuators and sensing devices. Ni-Mn-Ga single crystalline alloys exhibit ferromagnetic shape memory effect with large reproducible strains in moderate magnetic fields. The cost for producing single crystals is high and there is a requirement to investigate the polycrystalline Ni-Mn-Ga alloys for similar applications. This work presents a study of the effect of composition and heat treatment on the microstructure, in polycrystalline off-stoichiometric compositions of high Ni, Ni-Mn-Ga alloys. Cast polycrystalline alloys were homogenized and analysed using optical microscopy, X-ray diffraction, and thermal analysis. Stability of the martensitic transformation temperature was studied by aging the alloys at different temperatures. Martensitic structure was found in both the alloys (~ 54at% and 58 at%). The alloy with high Ni~58 at% content was found to be having a dual phase structure (martensite and FCC γ). Single phase Ni-Mn-Ga alloy has shown transformation at temperature >400K while the dual phase alloy with Ni ~58at% has transformed at temperature >700K thus making it suitable for high temperature applications. Martensitic stabilization effect was observed in alloy with Ni ~54 at% after aging treatment while it was absent in alloy with ~58at% Ni.

Fe-Mn-Si/6.5wt%Si-Fe Bilayer Ribbons produced by Using Melt Spinning Technique

2012 ◽  
Vol 721 ◽  
pp. 53-58 ◽  
Author(s):  
Daisuke Imamuara ◽  
Takashi Todaka ◽  
Masato Enokizono
Keyword(s):  
Shape Memory Alloys ◽  
Shape Memory ◽  
Melt Spinning ◽  
Magnetic Layer ◽  
Magnetic Shape Memory ◽  
Ferromagnetic Shape Memory Alloys ◽  
Application Range ◽  
The Common ◽  
Ferromagnetic Shape Memory ◽  
Melt Spinning Technique

Recently, progress of the intelligent materials plays a big role in development of science and technology. We have ever tried to develop ferromagnetic shape memory alloys to expand application range of the common non-magnetic shape memory alloys, which are typical intelligent material. However the saturation magnetization and the shape memory effect were in a relation of trade-off, so we couldn’t get a good result. In this research, we tried to develop ferromagnetic shape-memory alloys as a composite material by using the single-roll melt spinning technique. They are bilayer ribbons, which have both shape memory layer and magnetic layer.

scholarly journals Tunable Martensitic Transformation and Magnetic Properties of Sm-Doped NiMnSn Ferromagnetic Shape Memory Alloys

Crystals ◽  
2021 ◽  
Vol 11 (9) ◽  
pp. 1115
Author(s):  
Najam ul Hassan ◽  
Mohsan Jelani ◽  
Ishfaq Ahmad Shah ◽  
Khalil Ur Rehman ◽  
Abdul Qayyum Khan ◽  
...  
Keyword(s):  
Magnetic Properties ◽  
Martensitic Transformation ◽  
Shape Memory Alloys ◽  
Shape Memory ◽  
Transformation Temperature ◽  
Room Temperature ◽  
Field Variation ◽  
Martensitic Transformation Temperature ◽  
Ferromagnetic Shape Memory Alloys ◽  
Ferromagnetic Shape Memory

NiMnSn ferromagnetic shape memory alloys exhibit martensitic transformation at low temperatures, restricting their applications. Therefore, this is a key factor in improving the martensitic transformation temperature, which is effectively carried out by proper element doping. In this research, we investigated the martensitic transformation and magnetic properties of Ni43Mn46-x SmxSn11 (x = 0, 1, 2, 3) alloys on the basis of structural and magnetic measurements. X-ray diffraction showed that the crystal structure transforms from the cubic L21 to the orthorhombic martensite and gamma (γ) phases. The reverse martensitic and martensitic transformations were indicated by exothermic and endothermic peaks in differential scanning calorimetry. The martensitic transformation temperature increased considerably with Sm doping and exceeded room temperature for Sm = 3 at. %. The Ni43Mn45SmSn11 alloy exhibited magnetostructural transformation, leading to a large magnetocaloric effect near room temperature. The existence of thermal hysteresis and the metamagnetic behavior of Ni43Mn45SmSn11 confirm the first-order magnetostructural transition. The magnetic entropy change reached 20 J·kg−1·K−1 at 266 K, and the refrigeration capacity reached ~162 J·Kg−1, for Ni43Mn45SmSn11 under a magnetic field variation of 0–5 T.

scholarly journals Crystallographic insights into diamond-shaped 7M martensite in Ni–Mn–Ga ferromagnetic shape-memory alloys

IUCrJ ◽  
2019 ◽  
Vol 6 (5) ◽  
pp. 909-920 ◽  
Author(s):  
Zong-Bin Li ◽  
Bo Yang ◽  
Yu-Dong Zhang ◽  
Claude Esling ◽  
Xiang Zhao ◽  
...  
Keyword(s):  
Martensitic Transformation ◽  
Shape Memory Alloys ◽  
Shape Memory ◽  
Electron Backscatter Diffraction ◽  
Deformation Gradient ◽  
Type I ◽  
Magnetic Shape Memory ◽  
Ferromagnetic Shape Memory Alloys ◽  
Ferromagnetic Shape Memory ◽  
Habit Planes

For Heusler-type Ni–Mn–Ga ferromagnetic shape-memory alloys, the configuration of the martensite variants is a decisive factor in achieving a large magnetic shape-memory effect through field-induced variant reorientation. Based upon the spatially resolved electron backscatter diffraction technique, the microstructural evolution associated with the martensitic transformation from austenite to seven-layered modulated (7M) martensite was investigated on a polycrystalline Ni53Mn22Ga25 alloy. It was clearly shown that grain interior nucleation led to the formation of diamond-shaped 7M martensite within the parent austenite matrix. This diamond microstructure underwent further growth through an isotropic expansion with the coordinated outward movement of four side habit planes, followed by an anisotropic elongation with the forward extension of a type-I twin pair. A two-step growth model is proposed to describe the specific morphology and crystallography of 7M martensite. In addition, the habit planes were revealed to possess a stepped structure, with the {1 0 1}A plane as the terrace and the {0 1 0}A plane as the step. The characteristic combination of martensite variants and the underlying mechanism of self-accommodation in the martensitic transformation have been analysed in terms of the minimum total transformation strain, where the deformation gradient matrix was constructed according to the experimentally determined orientation relationship between the two phases. The present results may deepen the understanding of special martensite microstructures during the martensitic transformation in ferromagnetic shape-memory alloys.

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