Atomistic study of nanotwins in NiTi shape memory alloys

Zhong, Yuan; Gall, Ken; Zhu, Ting

doi:10.1063/1.3621429

Cited by 95 publications

(90 citation statements)

References 58 publications

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“…Of course, the martensite phase fraction used in the constitutive model is obtained from the present study, noting that in [74] it is assumed that the thermally induced martensite phase fraction varies linearly with temperature. However, as demonstrated herein, based on experimental studies [43], phase field simulations [31,33,34] and molecular dynamics simulations [25,27] the martensite phase fraction varies exponentially with temperature. The total free energy is expressed as a function of the total martensite phase fraction, thus the dependency of the phase fraction on temperature does not influence the free energy and thermodynamics laws [74].…”

Section: Figure-5mentioning

confidence: 62%

“…This difference is mainly due to size effects and consideration of the single crystal (in the simulations) vs. the polycrystalline (in the experiment) NiTi SMA samples; this is addressed in detail in the following sections. Significant size effects have been reported extensively, [25,27,28,30,61] where it is also demonstrated that the presence of defects such as free surfaces can appreciably alter the martensite transformation start Size effects are demonstrated in Figure 3 and some relevant results (evolution of microstructure at different temperatures and sizes) are documented in the supplementary material. Figure 3 shows the variation of martensite phase fraction with respect to temperature for different size of NiTi films.…”

Section: Figure-2mentioning

confidence: 82%

“…Recently the many-body interaction part of Lai and Liu potential has been modified by Zhong et al [25,28], where the terms in (1) are expressed as In (2) and (3), i and j denote atoms, and β α , denote type of atoms (Ni or Ti). A detailed description of the parameters involved is provided in Zhong et al [25].…”

Section: Molecular Dynamics (Md) Simulationsmentioning

confidence: 99%

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Linking simulations and experiments for the multiscale tracking of thermally induced martensitic phase transformation in NiTi SMA

Gur

Frantziskonis

2016

Modelling Simul. Mater. Sci. Eng.

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Martensitic phase transformation in NiTi shape memory alloys (SMA) occurs over a hierarchy of spatial scales, as evidenced from observed multiscale patterns of the martensitic phase fraction, which depend on the material microstructure and on the size of the SMA specimen. This paper presents a methodology for the multiscale tracking of the thermally induced martensitic phase transformation process in NiTi SMA. Fine scale stochastic phase field simulations are coupled to macroscale experimental measurements through the compound wavelet matrix method (CWM). A novel process for obtaining CWM fine scale wavelet coefficients is used that enhances the effectiveness of the method in transferring uncertainties from fine to coarse scales, and also ensures the preservation of spatial correlations in the phase fraction pattern. Size effects, well-documented in the literature, play an important role in designing the multiscale tracking methodology. Molecular dynamics (MD) simulations are employed to verify the phase field simulations in terms of different statistical measures and to demonstrate size effects at the nanometer scale. The effects of thermally induced martensite phase fraction uncertainties on the constitutive response of NiTi SMA is demonstrated.

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Section: Figure-5mentioning

confidence: 62%

Section: Figure-2mentioning

confidence: 82%

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Linking simulations and experiments for the multiscale tracking of thermally induced martensitic phase transformation in NiTi SMA

Gur

Frantziskonis

2016

Modelling Simul. Mater. Sci. Eng.

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“…The study by Wu et al [20] showed that dislocation nucleation started from surfaces during torsional deformation of NiTi nanowires. The study by Zhong et al [13,21] showed that complex phase transformation behaviour including the super-elasticity and the shape memory effects of NiTi nanostructures was observed during compressive loading and unloading. Tomohiro et al [22] studied the microscopic mechanism of stress-induced martensitic transformation of NiTi alloys.…”

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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“…Some reports claimed that the stress-induced martensite transformation would occur accompanied with deformation twinning when the alloy was subjected to plastic deformation in the austenite state [18]. Zhong et al performed an in-depth study on the structure and geometrical limit of nanoscale twins in NiTi by combining the crystallographic theory with atomistic simulations [19]. However, the role of atomic interactions involved during structural transformations, such as twinning and size effect as well as the temperature-dependent behavior, is not yet well understood.…”

Section: Introductionmentioning

confidence: 99%

Molecular Dynamics Modeling of the Effect of Nanotwins on the Superelasticity of Single-Crystalline NiTi Alloys

Guo

Zeng

Chen

et al. 2017

Advances in Materials Science and Engineering

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The objective of this work is to simulate the superelasticity and shape-memory effect in a single-crystalline nickel-titanium (NiTi) alloy through a molecular dynamics (MD) study. Cooling and heating processes for this material are reproduced to investigate the temperature-induced phase transformation in its microstructure. It is found that the martensitic transformation and its reverse process occur accompanied by an abrupt volume change, and the transformed variants lead to the appearance of the (001) type compound twin. In addition, the transform temperatures for martensite start ( ) and austenite finish ( ) are determined, respectively. The results indicate that when the temperature is beyond during the compressive loadingunloading, the superelastic behavior becomes pronounced, which is attributed to the role of nanotwins on the transformation from the austenitic phase (B2) to martensitic phase (B19 ). Compared to existing experimental data, a reasonable agreement is achieved through the modeling results, highlighting the importance of the compound twins for dominating the superelasticity of nanostructured NiTi alloys.

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Atomistic study of nanotwins in NiTi shape memory alloys

Cited by 95 publications

References 58 publications

Linking simulations and experiments for the multiscale tracking of thermally induced martensitic phase transformation in NiTi SMA

Linking simulations and experiments for the multiscale tracking of thermally induced martensitic phase transformation in NiTi SMA

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

Molecular Dynamics Modeling of the Effect of Nanotwins on the Superelasticity of Single-Crystalline NiTi Alloys

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