Laser annealing of amorphous NiTi shape memory alloy thin films to locally induce shape memory properties

Wang, X Xi; Bellouard, Yves; Vlassak, JJ

doi:10.1016/j.actamat.2005.07.022

Cited by 76 publications

(41 citation statements)

References 21 publications

(27 reference statements)

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“…fabrication and performance. For fabrication, similar actuators could be reduced to millimeter feature sizes (26) using current methods or submillimeter scales using physical vapor deposition and patterning (27). For these actuator types, Joule heating becomes more effective at smaller scales, bandwidth will increase (mechanically as well as thermodynamically), and the energy density should remain constant.…”

Section: Discussionmentioning

confidence: 99%

Programmable matter by folding

Hawkes

Benbernou

et al. 2010

Proc. Natl. Acad. Sci. U.S.A.

579

474

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Programmable matter is a material whose properties can be programmed to achieve specific shapes or stiffnesses upon command. This concept requires constituent elements to interact and rearrange intelligently in order to meet the goal. This paper considers achieving programmable sheets that can form themselves in different shapes autonomously by folding. Past approaches to creating transforming machines have been limited by the small feature sizes, the large number of components, and the associated complexity of communication among the units. We seek to mitigate these difficulties through the unique concept of self-folding origami with universal crease patterns. This approach exploits a single sheet composed of interconnected triangular sections. The sheet is able to fold into a set of predetermined shapes using embedded actuation. To implement this self-folding origami concept, we have developed a scalable end-to-end planning and fabrication process. Given a set of desired objects, the system computes an optimized design for a single sheet and multiple controllers to achieve each of the desired objects. The material, called programmable matter by folding, is an example of a system capable of achieving multiple shapes for multiple functions.reconfigurable robotics | self-assembly | multifunctional materials | computational origami E very day, scientists and engineers design new devices to solve a current problem. Each device has a unique function and thus has a unique form. The geometry of a cup is designed to hold liquid and is therefore different from that of a knife which is meant to cut. Even if both are made of the same material (e.g., metal, ceramic, or plastic), neither can perform both tasks. Is this redundancy in material, yet limitation in tasks entirely necessary? Is it possible to create a programmable material that can reshape for multiple tasks?Programmable matter is a material whose properties can be programmed to achieve specific shapes or stiffnesses upon command. In this paper we consider the theory and design of programmable matter material that can assume multiple desired shapes on demand.We have developed a unique concept of self-folding origami with universal crease patterns that decreases the complexity in individual elements and is scalable in the number and size of elements. Instead of relying on many individual subunits, which may be complex and difficult to orient correctly, we utilize a single sheet with repeated triangular tiles connected by flexible creases. This sheet can fold with a certain crease pattern to create multiple three-dimensional shapes, depending on which creases fold, in which direction, and in which order. We build on a large body of prior work in self-reconfiguring robotics to realize machines with changing shapes. Self-reconfiguring robots are modular systems whose bodies consist of multiple modules that can communicate and move relative to each other to form different shapes. These shapes support the different locomotive, manipulative, or sensing needs of the robo...

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Section: Discussionmentioning

confidence: 99%

Programmable matter by folding

Hawkes

Benbernou

et al. 2010

Proc. Natl. Acad. Sci. U.S.A.

579

474

View full text Add to dashboard Cite

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“…On closer observation, these grains had thin alternating bands of white and dark contrast that are caused by the (0 0 1) compound twins of B19', as reported by Waitz et al [34] Additional reports on the twin martensitic structure in a Ni-Ti thin film suggests that these are <011> type II twins, which are observed frequently in bulk material, furnace, and laser annealed NiTi thin films. [35,36] The <011> type II twins band is much narrower because of the much smaller grain size in a thin film. Zhang et al [35] reported that in a Ti-Ni thin film the existence of <011> type II twinning is a consequence of lattice invariant shear in the cubic to monoclinic transformation.…”

Section: Microstructural Analysismentioning

confidence: 99%

An Investigation on Phase Formations and Microstructures of Ni-rich Ni-Ti Shape Memory Alloy Thin Films

Priyadarshini

Aich²,

Chakraborty³

2010

Metall Mater Trans A

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Ni-rich Ni-Ti alloy thin films were fabricated by radio frequency (RF)-direct-current (DC) magnetron sputtering using elemental Ni and Ti as sputter targets. Si (100) was chosen as a substrate that was either held at room temperature or at 573 K (300°C) during the depositions. The 380-nm-thick films were characterized by field emission scanning electron microscopy, energy dispersive spectroscopy, grazing incidence X-ray diffraction, atomic force microscopy, high-resolution transmission electron microscopy, and Vickers microhardness tester. The results suggests that because of the lack of surface mobility of the adatoms at the room temperature, the deposited films were smooth and amorphous, with a crystallite size of 15 nm accompanied with a porous morphology. At higher substrate temperatures, an increase in the surface diffusion leads to the formation of partially crystalline, rougher films with a denser, compact, fibrous grain microstructure. The formation of Ni-rich precipitates such as Ni 4 Ti 3 , Ni 2 Ti, and Ni 3 Ti along with small amount of the NiTi phase were attributed to the localized heating and cooling within the grains. Few grains exhibited band structures that are believed to be a result of<110> type II twins.

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“…It exhibits SE while the test temperature is close to the austenite finish temperature (A f ) [8][9][10][11][12][13][14]. A considerable body of experiments has been conducted on NiTi alloys to investigate its strain rate and temperature-dependent phase transformation behaviour [11,12,[14][15][16][17][18][19]. Nemat-Nasser et al [8,9] studied the dynamic behaviour of NiTi at various strain rates in a range of 10 −3 to about 2 × 10 4 s −1 and at temperatures in a range of 77-400 K. The results showed that the SE behaviour of NiTi was more sensitive to temperature than to strain rate.…”

Section: Introductionmentioning

confidence: 99%

Atomistic study of temperature and strain rate-dependent phase transformation behaviour of NiTi shape memory alloy under uniaxial compression

Yin

Huang

et al. 2015

Philosophical Magazine

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Molecular dynamics simulation was conducted to investigate the phase transformation behaviour of nickel-titanium (NiTi, 50%-50% at.%) nanopillar under uniaxial compression at loading rates varying from 3.30 × 10 7 to 3.30 × 10 9 s −1 and at temperatures varying from 325 to 600 K. The phase transformation of NiTi was observed to be sensitive to loading rates and temperatures. The phase transformation stress of B2 → B19 increased with increasing temperature while it was insensitive to loading rate. The phase transformation stress of B19 → B19′ → BCO increased with increasing strain rate and decreasing temperature. In addition, reverse phase transformation was observed during compression due to the interaction between the phase transformation of B19 → B19′ → BCO and the deformation twinning/dislocation slide-induced plasticity of the BCO phase, leading to different residual crystal structures after loading. Moreover, a diagram for the phase transformation behaviour of NiTi in the simulated ranges of strain rate and temperature was obtained, from which the contrary experimental observations on the phase transformation behaviour of NiTi from the studies of Nemat-Nasser et al. (Mech. Mater. 37 (2005) p.287) and Liao et al. (J. Appl. Phys. 112 (2012) p.033515) at various strain rates could be well explained.

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Laser annealing of amorphous NiTi shape memory alloy thin films to locally induce shape memory properties

Cited by 76 publications

References 21 publications

Programmable matter by folding

Programmable matter by folding

An Investigation on Phase Formations and Microstructures of Ni-rich Ni-Ti Shape Memory Alloy Thin Films

Atomistic study of temperature and strain rate-dependent phase transformation behaviour of NiTi shape memory alloy under uniaxial compression

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