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.

Modeling Smart Materials Using Hysteretic Recurrent Neural Networks

2009 ◽  
Author(s):  
Arun Veeramani ◽  
John Crews ◽  
Gregory D. Buckner
Keyword(s):  
Shape Memory Alloys ◽  
Shape Memory ◽  
Smart Materials ◽  
Real Time Control ◽  
Ferromagnetic Shape Memory Alloys ◽  
Two Phase ◽  
Time Control ◽  
Novel Approach ◽  
Three Phase ◽  
Ferromagnetic Shape Memory

This paper describes a novel approach to modeling hysteresis using a Hysteretic Recurrent Neural Network (HRNN). The HRNN utilizes weighted recurrent neurons, each composed of conjoined sigmoid activation functions to capture the directional dependencies typical of hysteretic smart materials (piezoelectrics, ferromagnetic, shape memory alloys, etc.) Network weights are included on the output layer to facilitate training and provide statistical model information such as phase fraction probabilities. This paper demonstrates HRNN-based modeling of two- and three-phase transformations in hysteretic materials (shape memory alloys) with experimental validation. A two-phase network is constructed to model the displacement characteristics of a shape memory alloy (SMA) wire under constant stress. To capture the more general thermo-mechanical behavior of SMAs, a three-phase HRNN model (which accounts for detwinned Martensite, twinned Martensite, and Austensite phases) is developed and experimentally validated. The HRNN modeling approach described in this paper readily lends itself to other hysteretic materials and may be used for developing real-time control algorithms.

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.

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 Study of the martensitic transition in Ni-Mn-Sn-Ti ferromagnetic shape memory alloys

2018 ◽  
Vol 23 (2) ◽  
Author(s):  
Federico Guillermo Bonifacich ◽  
Osvaldo Agustín Lambri ◽  
José Ignacio Pérez-Landazábal ◽  
Vicente Recarte ◽  
Damián Gargicevich ◽  
...  
Keyword(s):  
Shape Memory Alloys ◽  
Shape Memory ◽  
Martensitic Transition ◽  
Ferromagnetic Shape Memory Alloys ◽  
Ferromagnetic Shape Memory

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 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

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