Superelastic behavior of aged and thermomechanical treated NiTi alloy at Af+10°C

Shahmir, Hamed; Nili‐Ahmadabadi, Mahmoud; Naghdi, F.

doi:10.1016/j.matdes.2010.06.022

Cited by 43 publications

(10 citation statements)

References 12 publications

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“…Several high remelting cycles for homogenization are reported in some works in the literature. In Lin et al [66], homogenization is performed at 1050 °C for 72 h, while in Shamir et al [67], hot forging and annealing are performed at 1000 °C for 12 h after several remelting cycles for homogenization. The high temperature and long duration of annealing can be considered as an important disadvantage of the VAR method.…”

Section: Bulk Micromachined Smamentioning

confidence: 99%

Micromachined Shape-Memory-Alloy Microactuators and Their Application in Biomedical Devices

2015

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Shape memory alloys (SMAs) are a class of smart materials characterized by shape memory effect and pseudo-elastic behavior. They have the capability to retain their original form when subjected to certain stimuli, such as heat or a magnetic field. These unique properties have attracted many researchers to seek their application in various fields including transportation, aerospace, and biomedical. The ease process adaption from semiconductor manufacturing technology provides many opportunities for designing micro-scale devices using this material. This paper gives an overview of the fabrication and manufacturing technique of thin-film and bulk micromachined SMAs. Key features such as material properties, transformation temperature, material composition, and actuation method are also presented. The application and micromechanism for both thin-film and bulk SMA are described. Finally, the microactuator devices emphasized for biomedical applications such as microgrippers and micropumps are highlighted. The presented review will provide information for researchers who are actively working on the development of SMA-based microscale biomedical devices.

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Section: Bulk Micromachined Smamentioning

confidence: 99%

Micromachined Shape-Memory-Alloy Microactuators and Their Application in Biomedical Devices

2015

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“…The low-temperature, stress-free phase is called martensite (Mphase), which has a lower symmetry based on a monoclinic structure (B19'). In some special situations, there is an intermediate rhombohedral phase, distortion of the B2 phase, known as the R-phase [6,10,17,[19][20][21][22][23]. Presence, or not, of this last phase is strongly influenced by heat treatment of the shape memory alloy [21,22,24].…”

Section: -2 -Differential Scanning Calorimetrymentioning

confidence: 99%

“…This study highlights that the presence of the R-phase is due to cycling. A lot of studies reveal that temperatures of each transition phase (Ms, Mf, As and Af) and the peak temperatures (Mp and Ap) were influenced by the heat treatment [10,17,19,25,26]. As the heat treatment, cyclic loading is now an important parameter which can disturb the phase transformation temperatures and may be at the origin of the intermediate phase (R-phase).…”

Section: -2 -Differential Scanning Calorimetrymentioning

confidence: 99%

Deformation mechanisms in a TiNi shape memory alloy during cyclic loading

Gloanec

Bilotta

Gerland

2013

Materials Science and Engineering: A

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Deformation mechanisms governing the cyclic stress-strain behaviour of a TiNi shape memory alloy are investigated in this work. In order to understand the implementation of these mechanisms during cyclic loading, three low cycle fatigue tests were performed and stopped at different stages. The first test was stopped after the first cycle, the second one after 40 cycles corresponding to the beginning of the stabilization of the cyclic strain-stress behaviour and the last one was carried out up to failure (3324 cycles). Submitted to fatigue loading, the response of the TiNi shape memory alloy presents a classical pseudoelastic response. Two deformation mechanisms, identified by TEM observations, are highlighted, the first one by twins and the second by dislocation slip and their interaction with precipitates. These two mechanisms evolve without competition during cyclic loading. In the same time, nanomechanical properties were also examined and an evolution of the microhardness or indentation modulus has been noticed.

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“…Due to simultaneous visualisation of several types of simulations in the GUI (superelasticity loops, pseudoplasticity loops, recovery strain cycles) and built-in parametrized functions, various sets of experiments can be used for parameters identification procedure. Since different chemical composition and processing (heat treatment, training) usually lead to very different transformation and detwinning/reorientation kinetics in NiTi [6][7][8], the GUI opens a wide space for simple, rapid and effective modeling of various types of NiTi wires. …”

Section: The Two-dimensional Modelmentioning

confidence: 99%

Modeling of Two-dimensional Thermomechanical Loading of NiTi Wires

Frost

Sedlák

2009

ESOMAT 2009 - 8th European Symposium on Martensitic Transformations

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Abstract. Results of simulations obtained by model iRLOOP for the Roundrobin SMA Modeling are briefly described and discussed. The Two-dimensional ModelThin wires from NiTi shape memory alloys exhibit outstanding thermomechanical properties which makes them suitable for a wide range of new medical and engineering applications. When these structures are mechanically loaded, multiple deformation modes involving tension, compression, torsion and bending usually occur. However, due to specific properties of thin wires the complex behavior can be effectively simulated by two-dimensional approach in many cases.The proposed model consists of two interlinked algorithms -the first simulating the tensioncompression response, the other simulating the shear mode -which are used simultaneously. The algorithms are twinned, i.e. the torsion algorithm was derived from the simple one-dimensional (tension-compression) model iRLOOP by reinterpretation of variables and parameters. Driving forces for martensitic transformation in the two algorithms are mutually independent (independent interface evolution concept) and simple assumptions on coupled strain evolution are made.The 1 Detailed description of model iRLOOP can be found in [3,4]. The two-dimensional extension including discussion of its physical motivation is described in [5]

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Superelastic behavior of aged and thermomechanical treated NiTi alloy at Af+10°C

Cited by 43 publications

References 12 publications

Micromachined Shape-Memory-Alloy Microactuators and Their Application in Biomedical Devices

Micromachined Shape-Memory-Alloy Microactuators and Their Application in Biomedical Devices

Deformation mechanisms in a TiNi shape memory alloy during cyclic loading

Modeling of Two-dimensional Thermomechanical Loading of NiTi Wires

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