Interatomic potential for the NiTi alloy and its application

Ren, Guowu; Şehitoğlu, Hüseyin

doi:10.1016/j.commatsci.2016.06.012

Cited by 49 publications

(14 citation statements)

References 32 publications

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“…It is evident that the obtained volumes for the austenitic and martensitic structures at room temperature (∼300 K) are 13.64Å 3 and 13.73Å 3 , respectively, which are in good accordance with those of experiment values (13.70Å 3 and 13.80Å 3 ) [31]. From this figure, it is distinctly demonstrated that the martensite start temperature ( ) is 270 K from the discrete positive change, which yield a closer fit to the experimental data when performing a comparison with the previous study [20]. Besides, the discrete decrease during the reheating process marks that the martensite phase transforms back into the austenite at the temperature of 390 K. It is obvious that both martensitic and reverse transformation (i.e., austenite) occur in the process of cooling and heating.…”

Section: Simulationssupporting

confidence: 88%

“…In this work, the computed energy is 5.05 eV corresponding to an equilibrium lattice constant of 0 = 2.999Å, and these values conform to other potentials [20]. Some other calculated physical properties of equiatomic NiTi compounds are presented in Table 1.…”

Section: Nn Meam Potentialsupporting

confidence: 78%

“…Due to the Stress (GPa) Figure 7: Snapshots of the nano-NiTi during the compressive loading and the unloading process. The color of the atoms is scaled according to the common neighbor analysis (CNA) pattern [20]. In each snapshot, blue atoms correspond to the B2 structure and gray atoms to the B19 structure.…”

Section: Simulationsmentioning

confidence: 99%

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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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Section: Simulationssupporting

confidence: 88%

Section: Nn Meam Potentialsupporting

confidence: 78%

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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 Eshelby tensor corresponding to this geometry can be obtained from [76]. The material constants employed for NiTi are taken from [73,77]. It must be noted that these constants were obtained from experiments on polycrystalline NiTi but are quite effective for the spirit in which this model is employed.…”

Section: Modeling Methodology and Resultsmentioning

confidence: 99%

Unraveling Frequency Effects in Shape Memory Alloys: NiTi and FeMnAlNi

Sidharth

Mohammed

Abuzaid

et al. 2021

Shap. Mem. Superelasticity

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With the presence of internal interfaces such as the austenite-martensite interface and the internal twin boundaries in the martensite, shape memory alloys (SMAs) can be employed in passive/active damping applications. Due to the latent heat of transformation, a temperature rise/drop during a load/unload cycle is expected to dynamically couple with the mechanical response of the SMA and influence the stress levels of forward/reverse transformation and thus the hysteretic area (i.e. the dissipated energy). Additionally, the temperature change per cycle is a function of loading frequency due to momentary heat transfer effects. To this end, for the first time, we demonstrate a rate insensitive shape memory alloy system, Fe 43.5 Mn 34 Al 15 Ni 7.5 which also exhibits near-zero temperature dependent stress-strain response. Contrastingly, we show that Ni 50.8 Ti, which is widely used commercially, is highly rate sensitive. With straightforward in situ experiments, complemented with thermomechanical modelling, we pinpoint the key material parameter which dictates frequency sensitivity. The corresponding results are then discussed in the light of different mechanisms contributing to the damping capacity of SMAs.

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“…However, certain phases and mechanical responses predicted by the FS potential were not in good accordance with those reported in the literature. On the other hand, the 2NN MEAM potential was modified from a many-body potential [9,13]. The potential of this type further considered the second nearest-neighbor interactions and the angular related terms [14], and thus, it may provide a more accurate stress- or temperature-induced phase transformation in NiTi alloys [10].…”

Section: Introductionmentioning

confidence: 99%

The Analysis of Superelasticity and Microstructural Evolution in NiTi Single Crystals by Molecular Dynamics

Chen

Tsou

2018

Materials

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Superelasticity in shape memory alloys is an important feature for actuators and medical devices. However, the function of the devices is typically limited by mechanical bandwidth and fatigue, which are dominated by the microstructures. Thus, in order to correlate the mechanical response and the microstructures, the microstructural evolution in NiTi single crystals under the compression, tensile, and shearing tests is simulated by molecular dynamics (MD) in the current study. Then, the martensite variant identification method, which identifies the crystal variants/phases of each lattice based on the transformation matrix, is used to post-process the MD results. The results with the detailed information of variants and phases reveal many features that have good agreement with those reported in the literature, such as X-interfaces and the transitional orthorhombic phase between the austenite and monoclinic phases. A new twin structure consisting of diamond and wedge-shaped patterns is also discovered. The macroscopic behavior, such as stress-strain curves and the total energy profile, is linked with the distribution of dislocation and twin patterns. The results suggest that the loading cases of shear and compression allow a low critical strain for the onset of martensitic transformation and a better superelasticity behavior. Therefore, the two loading cases are suitable to apply to the NiTi actuators. The current work is expected to provide insight into the mechanical responses and design guideline for NiTi shape memory alloy actuators.

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Interatomic potential for the NiTi alloy and its application

Cited by 49 publications

References 32 publications

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

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

Unraveling Frequency Effects in Shape Memory Alloys: NiTi and FeMnAlNi

The Analysis of Superelasticity and Microstructural Evolution in NiTi Single Crystals by Molecular Dynamics

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