Fe-Ni-Al-Ta polycrystalline shape memory alloys showing excellent superelasticity

2019 ◽  
Vol 13 (01) ◽  
pp. 1950096
Author(s):  
Zhaoxia Chen ◽  
Wenyi Peng
Keyword(s):  
Shape Memory Alloys ◽  
Shape Memory ◽  
Room Temperature ◽  
High Strength ◽  
Polycrystalline Alloys

Fe-Ni-Co-Al-Ta polycrystalline shape memory alloys have received extensive attention due to their excellent properties such as huge superelasticity, high strength and high damping. We herein report that Fe-Ni-Al-Ta polycrystalline alloys also have excellent superelasticity, which can exhibit a large superelastic strain of more than 17% in compression at room temperature. This superelasticity has slim hysteresis and is greatly affected by the content of Ta in the alloys. In this work, Fe-Ni-Al-Ta shape memory alloys reveal some characteristics that are different from the reported Fe-Ni-Co-Al-based shape memory alloys.

Cold Bending a Ni-Ti Shape Memory Alloy Wire

2015 ◽  
Vol 661 ◽  
pp. 98-104 ◽  
Author(s):  
Kuang-Jau Fann ◽  
Pao Min Huang
Keyword(s):  
Shape Memory Alloy ◽  
Shape Memory Alloys ◽  
Shape Memory ◽  
Shape Memory Effect ◽  
Memory Effect ◽  
Room Temperature ◽  
Aging Treatment ◽  
Treatment Temperature ◽  
Bending Test ◽  
Solution Treatment Temperature

Because of being in possession of shape memory effect and superelasticity, Ni-Ti shape memory alloys have earned more intense gaze on the next generation applications. Conventionally, Ni-Ti shape memory alloys are manufactured by hot forming and constraint aging, which need a capital-intensive investment. To have a cost benefit getting rid of plenty of die sets, this study is aimed to form Ni-Ti shape memory alloys at room temperature and to age them at elevated temperature without any die sets. In this study, starting with solution treatments at various temperatures, which served as annealing process, Ni-rich Ni-Ti shape memory alloy wires were bent by V-shaped punches in different curvatures at room temperature. Subsequently, the wires were aged at different temperatures to have shape memory effect. As a result, springback was found after withdrawing the bending punch and further after the aging treatment as well. A higher solution treatment temperature or a smaller bending radius leads to a smaller springback, while a higher aging treatment temperature made a larger springback. This springback may be compensated by bending the wires in further larger curvatures to keep the shape accuracy as designed. To explore the shape memory effect, a reverse bending test was performed. It shows that all bent wires after aging had a shape recovery rate above 96.3% on average.

Development of High-Strength, Fine, and Ultrafine-Grained Shape Memory Alloys

2018 ◽  
Vol 119 (13) ◽  
pp. 1346-1349
Author(s):  
V. G. Pushin ◽  
N. N. Kuranova ◽  
A. V. Pushin
Keyword(s):  
Shape Memory Alloys ◽  
Shape Memory ◽  
High Strength ◽  
Ultrafine Grained

Investigation of Ageing Phenomena in CuAlNi Based Shape Memory Alloys

2007 ◽  
Vol 537-538 ◽  
pp. 129-136 ◽  
Author(s):  
Marton Benke ◽  
Valéria Mertinger ◽  
E. Nagy ◽  
Jan Van Humbeeck
Keyword(s):  
Martensitic Transformation ◽  
Shape Memory Alloys ◽  
Shape Memory ◽  
Ternary Alloy ◽  
Room Temperature ◽  
Beta Phase ◽  
Heat Treatments ◽  
Thermoelastic Martensitic Transformation ◽  
Transformation Temperatures ◽  
Exothermic Process

The ageing phenomena and its effect on the thermoelastic martensitic transformation was investigated in three Cu-base SMAs. The transformation temperatures shifted to higher temperatures due to aging in the beta-phase. To increase the alloy’s ductility, a definite amount of Mn (4 wt%) and Fe (2 wt%) were added to the ternary alloy. The thermoelastic martensitic transformation was found in the not-aged samples of the CuAlNiMn and CuAlNiMnFe alloys. This transformation was destroyed due to ageing heat treatments by a fairly unknown exothermic process. The thermoelastic martensitic transformation appeared again in the aged CuAlNiMn and CuAlNiMnFe samples after keeping them on room temperature for a few months. This phenomena was investigated by DSC, SEM, TEM, and XRD.

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.

In situ TEM study of irradiation-induced transformation in TiNi shape memory alloys

2003 ◽  
Vol 792 ◽  
Author(s):  
X. T. Zu ◽  
F.R. Wan ◽  
S. Zhu ◽  
L. M. Wang
Keyword(s):  
Phase Transformation ◽  
Martensitic Transformation ◽  
Shape Memory Alloys ◽  
Shape Memory ◽  
Electron Irradiation ◽  
Room Temperature ◽  
Critical Voltage ◽  
In Situ Tem ◽  
In Situ Observation

ABSTRACTTiNi shape memory alloy (SMA) has potential applications for nuclear reactors and its phase stability under irradiation is becoming an important topic. Some irradiation-induced diffusion-dependent phase transformations, such as amorphization, have been reported before. In the present work, the behavior of diffusion-independent phase transformation in TiNi SMA was studied by electron irradiation at room temperature. The effect of irradiation on the martensitic transformation of TiNi shape memory alloys was studied by Transmission Electron Microscopy (TEM) with in-situ observation and differential scanning calorimeter (DSC). The results of TEM and DSC measurements show that the microstructure of samples is R phase at room temperature. Electron irradiations were carried out using several different TEM with accelerating voltage of 200 kV, 300 kV, 400 kV and 1000 kV. Also the accelerating voltage in the same TEM was changed to investigate the critical voltage for the effect of irradiation on phase transformation. It was found that a phase transformation occurred under electron irradiation above 320 kV, but never appeared at 300 kV or lower accelerating voltage. Such phase transformation took place in a few seconds of irradiation and was independent of atom diffusion. The mechanism of Electron-irradiation-induced the martensitic transformation due to displacements of atoms from their lattice sites produced by the accelerated electrons.

Microstructural Irreversibilities under Thermal Cycling in Ni-Ti-Fe Shape Memory Alloys

2011 ◽  
Vol 702-703 ◽  
pp. 888-891 ◽  
Author(s):  
Ritwik Basu ◽  
Lokendra Jain ◽  
Bikas Maji ◽  
Madangopal Krishnan ◽  
Karri V. Mani Krishna ◽  
...  
Keyword(s):  
Shape Memory Alloys ◽  
Thermal Cycling ◽  
Shape Memory ◽  
Room Temperature ◽  
Residual Deformation ◽  
Austenite Grain Size ◽  
Reversible Transformation ◽  
Martensite Content ◽  
Austenite Grain ◽  
Grain Misorientation

The thermal cycling (quenching in liquid nitrogen and reverting back to room temperature: austenite martensite reversible transformation) response of Ni-Ti-Fe shape memory alloys has been investigated. It was clearly noted that residual deformation, estimated in terms of noticeable differences in austenite grain size, depend on the relative clustering of fine grains. During repeated thermal cycling, the residual deformation, in-grain misorientation developments and retained martensite content scaled together: bringing out a clear picture of microstructural irreversibility.

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.

Synthesis and Evaluation of Biocompatibility of Cu-Al-Mn Shape Memory Alloy

2019 ◽  
Vol 969 ◽  
pp. 380-385 ◽  
Author(s):  
Arunabha Majumder ◽  
Vybhavi Shivakumar ◽  
A.G. Shivasiddaramaiah ◽  
C. Shashishekar ◽  
U.S. Mallikarjun ◽  
...  
Keyword(s):  
Shape Memory Alloy ◽  
Shape Memory Alloys ◽  
Shape Memory ◽  
Room Temperature ◽  
Boiling Water ◽  
Ingot Metallurgy ◽  
Step Quenching

In recent days, it is being found that shape memory alloys can be used in the medicinal field which helps to alleviate numerous disabilities in people. The Shape memory alloy are evaluated for biocompatibility in present work. The objective is to determine the biocompatibility of Cu-Al-Mn SMAs using the alloy of composition 10-14 weight. % Aluminium (Al), 5-9 weight% Manganese (Mn) and rest copper (Cu) through ingot metallurgy in a constrained atmosphere. The casted samples were homogenisation at 900°C for one and half hours and then rolled at 900°C. The rolled specimens were betatized for half an hour at 900°C followed by Step quenching in boiling water (100°C) and quenching in water at room temperature (30°C). They are cut to the dimension of 10 mm * 10mm * 1mm (breadth*length*height) and then effect of shape memory on obtained alloy was assessed. In continuation, in order to understand the biocompatibility of obtained alloy, the samples were analysed for antibacterial movement by turbido-metric process. The microorganisms utilized for biocompatibility are S.aureus and E.coli. The outcomes showed remarkable biocompatibility with the inference that it can be employed for invitrouses.

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