scholarly journals Effect of aluminum alloying on the structure and properties of rapidly quenched TiNiCu alloy

2021 ◽  
Vol 2056 (1) ◽  
pp. 012042
Author(s):  
A V Shelyakov ◽  
N N Sitnikov ◽  
I A Zaletova ◽  
S A Eroshenkov ◽  
O N Sevryukov
Keyword(s):  
Liquid Phase ◽  
Shape Memory ◽  
Isothermal Annealing ◽  
Rapid Quenching ◽  
Significant Shift ◽  
Temperature Hysteresis ◽  
Structure And Properties ◽  
Recoverable Strain ◽  
Mems Technology ◽  
Micro Actuators

Abstract The efficiency of shape memory alloys for the MEMS technology has been recently demonstrated. Quasibinary intermetallic TiNi-TiCu alloys produced by rapid quenching from liquid phase in the form of thin (about 40 um) ribbons are an attractive material for the fabrication of micro-actuators due to their narrow temperature hysteresis of the shape memory effect (SME) and relatively large recoverable strain. In order to broaden the functionality of SME microdevices, in this work we have alloyed TiNiCu containing 25 at.% copper with aluminum. The results have shown that alloying with 0.6 at.% Al increases the cast characteristics of the composition and favors its amorphization. Upon crystallization by isothermal annealing or electropulse treatment the resultant microstructure and SME properties of the Al containing alloy change but slightly in comparison with the original alloy however there is a significant shift (by more than 15°C) of the SME temperature range toward lower temperatures.

Effect of Heat Treatments on the Damping Characteristics of TiNi-Based Shape Memory Alloys

2006 ◽  
Vol 319 ◽  
pp. 33-38 ◽  
Author(s):  
I. Yoshida ◽  
Kazuhiro Otsuka
Keyword(s):  
Internal Friction ◽  
Shape Memory Alloys ◽  
Shape Memory ◽  
Low Frequency ◽  
Heat Treatments ◽  
Damping Capacity ◽  
Temperature Hysteresis ◽  
Temperature Spectrum ◽  
Two Peaks ◽  
Very High

Low frequency internal friction of Ti49Ni51 binary and Ti50Ni40Cu10 ternary shape memory alloys has been measured. The effect of solution and aging heat treatments on the damping property was examined. The temperature spectrum of internal friction for TiNi binary alloy consists, in general, of two peaks; one is a transition peak which is associated with the parent-martensite transformation and is rather unstable in a sense that it strongly depends on the frequency and decreases considerably when held at a constant temperature. The other one is a very high peak of the order of 10-2, which appears at around 200K. It appears both on cooling and on heating with no temperature hysteresis, and is very stable. The behavior of the peak is strongly influenced by the heat treatments. The trial of two-stage aging with a purpose of improving the damping capacity has been proved unsatisfactory. TiNiCu has a very high damping, the highest internal friction reaching 0.2, but by quenching from very high temperature, say 1373K, the damping is remarkably lowered. For the realization of high damping the quenching from a certain temperature range around 1173K seems the most preferable condition.

Cyclic Behavior of Concrete Confined by Active and Passive Jackets

2010 ◽  
Author(s):  
Eunsoo Choi ◽  
Yeon-Wook Kim ◽  
Young-Soo Chung ◽  
Hong-Taek Kim ◽  
Baik-Soon Cho
Keyword(s):  
Shape Memory ◽  
Compressive Loading ◽  
Volumetric Strain ◽  
Confined Concrete ◽  
Cyclic Behavior ◽  
Temperature Hysteresis ◽  
Plastic Strains ◽  
Carbon Fiber Reinforce Polymer ◽  
Concrete Cylinders ◽  
Loading Tests

Shape memory alloy (SMA) wire jackets for concrete are distinct from the conventional jackets of steel or FRP since they provide active confinement that can be easily archived due to the shape memory effect of SMAs. This study uses NiTiNb SMA wires of 1.0 mm diameter to confine concrete cylinder with the dimension of 300 mm × 150 mm (L × D). The NiTiNb SMAs have a relative wider temperature hysteresis than NiTi SMAs and, thus, are more applicable for severe temperature-variation environment which civil structures are exposed to. Steel jackets of passive confinement are also prepared to compare the cyclic behavior of active and passive confined concrete cylinders. For this purpose, monotonic and cyclic compressive loading tests are conducted to obtain axial and circumferential strain. The both of strains are used to estimate volumetric strains of concrete cylinders. Also, plastic strains from cyclic behavior are also estimated. For the NiTiNb SMA jacketed cylinders, the monotonic axial behavior differs from the envelope of cyclic behavior; this should be studied in future. The plastic strains of the active confined concrete show a similar trend to those of the passive confinement. The trend of plastic strain of this study does not match with that of CFRP (Carbon Fiber Reinforce Polymer) jackets. For the volumetric strain, the active jackets of the NiTiNb SMA wires provide more energy dissipation than the passive jacket of steel.

scholarly journals Cu-Al-Zn system: Calculation of thermodynamic properties in liquid phase

2013 ◽  
Vol 67 (1) ◽  
pp. 157-164 ◽  
Author(s):  
Lidija Gomidzelovic ◽  
Ivan Mihajlovic ◽  
Ana Kostov ◽  
Dragana Zivkovic
Keyword(s):  
Mathematical Modeling ◽  
Liquid Phase ◽  
General Solution ◽  
Thermodynamic Properties ◽  
Ternary System ◽  
Shape Memory ◽  
Ternary Interaction ◽  
General Solution Model ◽  
Shape Memory Materials ◽  
System Calculation

In the paper are presented the results of thermodynamic analysis of Cu-Al-Zn ternary system, which belongs to a group of copper-based shape memory materials. General solution model was used for calculation of thermodynamic properties in the temperature interval from 1373 to 2173 K, in sections from Cu, Al and Zn corner, respectively, with following ratios of 1:3, 1:1 and 3:1. Also, on the basis of the obtained results, ternary interaction parameters were determined using Mathematical Modeling System (MLAB).

Experimental and numerical studies on a novel shape-memory alloy wire–woven trusses capable of undergoing large deformation

2019 ◽  
Vol 30 (15) ◽  
pp. 2283-2298
Author(s):  
Zhixiang Rao ◽  
Xiaojun Yan ◽  
Xiaoyong Zhang ◽  
Bin Zhang ◽  
Jun Jiang ◽  
...  
Keyword(s):  
Shape Memory Alloy ◽  
Shape Memory ◽  
Large Deformation ◽  
Residual Deformation ◽  
Shape Memory Alloy Wire ◽  
Static Compression ◽  
Recoverable Strain ◽  
Alloy Wire ◽  
Assembly Method ◽  
Finite Element Analysis Simulation

Currently, most wire-woven trusses are fabricated with traditional metals such as steel and aluminum, thus the deformation ability is constrained due to the low yield strain of common metals. Shape-memory alloy is a kind of smart material which can bear large recoverable strain while producing hysteresis. Due to the unique capacity of large deformation and remarkable damping property of the shape-memory alloy, a novel lattice trusses assembled by superelastic shape-memory alloy coil springs was proposed. Furthermore, the treatment processes to prepare the shape-memory alloy coil springs and the assembly method to fabricate the shape-memory alloy wire–woven trusses were also introduced. The quasi-static compression under different maximum deformation and temperatures was performed to investigate the mechanical and thermal responses of the proposed shape-memory alloy wire–woven trusses. Cyclic compression tests were also performed to study the functional fatigue of the shape-memory alloy wire–woven trusses. The proposed wire-woven trusses can undergo up to 80% deformation by compression and recover without evident residual deformation after unloading. Finite element analysis simulation of representative volume element under different deformation was presented. Analytical modeling of the stiffness of shape-memory alloy wire–woven trusses was also carried out. Both the numerical and analytical methods can predict the stiffness within a small deviation.

Quantitative phase transformation behavior in TiNi shape memory alloy thin films

2004 ◽  
Vol 19 (10) ◽  
pp. 2822-2833 ◽  
Author(s):  
Bo-Kuai Lai ◽  
H. Kahn ◽  
S.M. Phillips ◽  
Z. Akase ◽  
A.H. Heuer
Keyword(s):  
Thin Films ◽  
Shape Memory Alloy ◽  
Residual Stresses ◽  
Shape Memory ◽  
Microelectromechanical Systems ◽  
Rietveld Analysis ◽  
Phase Fraction ◽  
Temperature Hysteresis ◽  
Noticeable Effect ◽  
Heating And Cooling

Phase transformations in near-equiatomic TiNi shape memory alloy thin films were studied, and the phase fraction evolutions were quantitatively correlated to the stress and resistivity of the films. TiNi thin films with compositions of 50.1, 51.1, and 51.7 at.% Ti all exhibited transformation temperatures between 65 and 100 °C, low residual stresses at room temperature (RT), and high recoverable stresses, thus making them suitable for microactuators in microelectromechanical systems. Low residual stresses at RT, less than 50 MPa, can be obtained even when only a small quantity of martensite, less than 30%, is present. Phase fraction evolution during complete thermal cycles (heating and cooling) was studied using elevated temperature x-ray diffraction, combined with quantitative Rietveld analysis. R-phase always appeared in these near-equiatomic TiNi thin films during cooling but did not have a noticeable effect on the stress–temperature hysteresis curves, which mainly depend on the phase fraction evolution of martensite. On the other hand, the occurrence of R-phase determined the variation of film resistivity. Martensite, austenite, and R-phase coexisting within a single grain were observed using transmission electron microscopy.

scholarly journals Finite Element Studies of Triple Actuation of Shape Memory Alloy Wires for Surgical Tools

2018 ◽  
Author(s):  
Bardia Konh
Keyword(s):  
Shape Memory ◽  
Artificial Heart ◽  
Heart Valves ◽  
Engineering Systems ◽  
Design And Development ◽  
Orthodontic Wires ◽  
Recoverable Strain ◽  
Artificial Heart Valves ◽  
Innovative Products ◽  
Superelastic Behavior

Since the early discovery in 1951 [1], shape memory alloys (SMAs) have been used in design and development of several innovative engineering systems. SMAs’ unique characteristics have introduced unconventional alternatives in design and development of advanced devices. SMA’s field of applications has covered many areas from aerospace to auto industries, and medical devices [2]. During the past couple of decades, scientists have suggested material models to predict the SMA’s shape memory effect (SME) and its superelastic behavior. The superelastic characteristic of SMAs (its capability to exhibit a large recoverable strain) has been widely used to develop innovative products including biomedical implants such as stents, artificial heart valves, orthodontic wires, frames of indestructible spectacles, etc. However, its actuation capabilities, known as SME, hasn’t been thoroughly expanded. The number of products privileging from SMA’s SME behavior has been very limited. The reason relies on the SMA’s complex material properties that depend on the stress, strain and temperature at every stage of actuation as well as the material’s processing and the thermomechanical loading history.

Work Output Enhancement of Ferromagnetic Shape Memory Micro Actuators

2008 ◽  
Author(s):  
Yaniv Ganor ◽  
Doron Shilo
Keyword(s):  
Shape Memory ◽  
Structural Phase ◽  
Structural Phase Transformation ◽  
Comprehensive Information ◽  
Micro Actuators ◽  
Ferromagnetic Shape Memory ◽  
Alternating Magnetic Fields ◽  
Current Stage ◽  
Boundary Microstructure ◽  
Actuation Strain

Ferromagnetic shape memory (FSM) alloys are a class of materials which are both ferromagnetic and capable of undergoing a structural phase transformation. FSM alloys have significant advantage over conventional shape-memory temperature-based actuators because they can be remotly actuated by fast alternating magnetic fields. Therefore, FSM alloys attract keen attention as promising candidates for a variety of MEMS applications, as they can provide large strokes using small components. The most commonly used FSM alloy is Ni2MnGa and its off-stoichiometric alloys, which are used in commercial cm-scale FSM actuator. However, at the current stage, no experiments of the magneto-mechnical behavior of micro-scale actuators were conducted. Overall, the behavior of FSM alloys involves motion of twin boundaries and is significantly influenced by its microstructure. Based on a theoretical model, we have shown that down-scale specimens have finer twin boundary microstructure that consequently may increase the blocking stress characteristic such that it will enhance the output work for actuation. In light of this, a novel experimental method was realized to establish this conjecture and to provide comprehensive information on the behavior of small actuators. A series of tests demonstrated no actuation strain reduction up to extraordinary loads of 10MPa, and thus paves the route for engineering FSM high-power micro actuators by controlling their microstructure.

Self-Assembled Silicon Microdevices Driven by Muscle

2004 ◽  
Author(s):  
Jianzhong Xi ◽  
Jacob Schmidt ◽  
Carlo Montemagno
Keyword(s):  
Information Technology ◽  
Medical Research ◽  
Robotic Systems ◽  
Electromagnetic Actuators ◽  
Electrical Devices ◽  
Mems Technology ◽  
Micro Optics ◽  
Micro Actuators ◽  
Temporal And Spatial ◽  
Self Assembled

Over the last two decades, a variety of micro-robotic systems have been developed including electrothermal, electrostatic, electrochemical, piezoelectric, and electromagnetic actuators based on MEMS technology. The development of these micro-actuators promises a revolution in biological and medical research and applications analogous to that brought about by the miniaturization of electrical devices in information technology. For example, controllable manipulation of these tiny actuators may enable precise temporal and spatial delivery of chemicals, micro-optics or microelectronics to specific targeted sites.

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