Evolution of microstructure and thermomechanical properties during superelastic compression cycling in Cu–Al–Ni single crystals

Ibarra, Andoni; Juan, J. San; Bocanegra, E.H.; Nó, M.L.

doi:10.1016/j.actamat.2007.05.012

Cited by 72 publications

(32 citation statements)

References 33 publications

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“…Based on Figure 1c, we find r c ≈ 187 MPa, which agrees to within ± 18 MPa with the values measured in compression tests on bulk single crystals of similar composition. [25] In addition, [ 26] Another interesting point to be remarked upon in Figure 1c concerns the transformation speed during the stress plateaus upon loading and unloading. These microcompression experiments have millisecond resolution, and during the phase transformation a substantial amount of strain can accumulate in that time interval.…”

Section: Gies Enabling a New Generation Of Smart Mems (Smems)mentioning

confidence: 99%

Superelasticity and Shape Memory in Micro‐ and Nanometer‐scale Pillars

2007

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Micro-and nanoelectromechanical systems (MEMS and NEMS, respectively) are being developed intensively and constitute a new paradigm of technological development for the present century. With a growing world-wide market in excess of one hundred billion dollars, MEMS and NEMS pose a challenge for the science and technology of microfabrication [1] and have already found usage as sensors and actuators across numerous industrial sectors, [2] from automotive, aerospace, and telecommunications [3] to emerging biomedical technologies. [4] In parallel, the development of multifunctional and smart materials [5] is converging with miniaturization technologies, enabling a new generation of smart MEMS (SMEMS). Among the different smart materials targeted for use in SMEMS, shape memory alloys have attracted considerable interest [6,7] because they offer the highest output work density (about 10 7 J m -3 ), and exhibit specific desirable thermomechanical effects owing to the reversibility of their thermoelastic martensitic transformation. [8] In particular, integrating into MEMS components that exhibit superelasticity, or one-way or two-way shape memory, would enable a new generation of functional microdevices. In the last decade, great effort has been devoted to the production of shape memory thin films, which could be integrated into the planar technology of microsystems. Shape memory thin films have been mainly produced by sputtering, and exhibit both superelastic and shape memory properties. The effort has largely been focused on the Ti-Ni system (reviewed by Miyazaki and Ishida [9] ), and combinatorial methods are also being applied to develop new compositions not presently used in bulk shape memory applications.[10] However, although such sputtered films are often made with thicknesses between 0.5 and 15 lm, the desirable thermomechanical effects of superelasticity and shape memory have only been tested and exploited for applications using their largest dimensions above millimeter size. [6,7,9] Thus, there remain important unanswered questions about the nature of these thermomechanical effects at the scales relevant to MEMS and NEMS applications. In the present work the first objective is to design and produce simple shape memory alloy features of micro-and nanometer-scale dimensions, smaller in every dimension than a typical thin film thickness currently obtained by sputtering-around 5 lm. The second objective is to demonstrate on such features the thermomechanical properties of superelasticity and shape memory at the nanometer scale. We report that stress-induced or thermal martensitic transformation can take place at the nanometer scale in a reversible way; individual martensite variants below 25 nm thick appear in these experiments. The presented results demonstrate that in Cu-Al-Ni shape memory alloys, completely recoverable superelasticity, in a high number of cycles, is achievable at the very fine scales pertinent to MEMS devices. From a practical perspective, a first issue to consider is how we can demonstrate an...

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Section: Gies Enabling a New Generation Of Smart Mems (Smems)mentioning

confidence: 99%

Superelasticity and Shape Memory in Micro‐ and Nanometer‐scale Pillars

2007

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“…The technique has also been employed to study the morphological evolution of martensite plates as they nucleate and grow and how this evolution is affected by dislocations [37,38] grain boundaries [39] and precipitates [40][41][42]. Lastly, in situ studies have been used to study interfaces [43], determining selection rules for stress-induced martensite phases and variants [44][45][46][47] and observing dislocation substructure evolution during cycling [48][49][50][51].…”

Section: Introductionmentioning

confidence: 99%

Transition from many domain to single domain martensite morphology in small-scale shape memory alloys

Ueland

Schuh

2013

Acta Materialia

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“…The plastic deformation induced during the thermo-mechanical cycling leads to a change of microstructure of SMA wire. Lattice defects, dislocations and nano-scaled precipitates are introduced into the matrix and they cause significant changes in transformation temperature and in the capability of the material to recover a deformation [28][29][30], as depicted in Figure 4. In most cases, SMA wires used as actuator, are heated by means of an electrical pulse (Joule effect) and cooled by natural air convection.…”

Section: Sma Linear Actuatorsmentioning

confidence: 99%