Multiscale TRIP-based investigation of low-cycle fatigue of polycrystalline NiTi shape memory alloys

Zhang, Yahui; Moumni, Ziad; You, Yajun; Zhang, Weihong; Zhu, Jihong; Anlaş, Günay

doi:10.1016/j.ijplas.2018.12.003

Cited by 51 publications

(16 citation statements)

References 62 publications

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“…An increasing number of works show that both functional and structural fatigue is initiated by transformation/orientation-induced plasticity [15,[17][18][19][20][21][22][23]. High local stress field resulting from the incompatible deformation at the austenite-martensite interfaces assists dislocation slip even when the macroscopic stress is below the yield strength.…”

Section: Introductionmentioning

confidence: 99%

Evolution of transformation characteristics of shape memory alloys during cyclic loading: transformation temperature hysteresis and residual martensite

Zhang

You

et al. 2020

Smart Mater. Struct.

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This paper investigates the evolutions of transformation temperatures and residual martensite of shape memory alloys during cyclic loading. Pseudoelastic NiTi specimens were firstly subjected to stress-controlled cyclic loading; then differential scanning calorimetry and x-ray diffraction characterizations were conducted on samples cut from specimens after different cycles as well as virgin one. Results show that (i) transformation temperatures rise while the transformation temperature hysteresis increases at initial cycles and then remarkably decreases when the SMA is highly distorted; (ii) due to the accumulation of residual martensite, the more fatigue cycles applied to the SMAs, the less latent heat absorbed/released during the transformation. Furthermore, residual martensite volume fraction was calculated with respect to plasticity and a linear character was observed.

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Section: Introductionmentioning

confidence: 99%

Evolution of transformation characteristics of shape memory alloys during cyclic loading: transformation temperature hysteresis and residual martensite

Zhang

You

et al. 2020

Smart Mater. Struct.

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“…This causes the formation of an interface between the newly formed martensitic phase and the already existing untransformed martensitic phase. This interface is also a potential crack nucleation site during thermomechanical cycling as the TRIP causes the low-cycle fatigue of shape memory alloys (Zhang and He, 2018; Zhang et al, 2019). Generally, the austenite/martensite interfaces and martensite/martensite interfaces undergo the plastic deformation to accommodate the strain energies arising from the incompatibility, whereby their energies are redirected to each other.…”

Section: Resultsmentioning

confidence: 99%

“…Generally, the austenite/martensite interfaces and martensite/martensite interfaces undergo the plastic deformation to accommodate the strain energies arising from the incompatibility, whereby their energies are redirected to each other. When there is an increase in the upper cycle temperature, the energy associated with the interfaces increases and causes the TRIP to accelerate, resulting in lower fatigue resistance of SMA (Zhang et al, 2019). Moreover, when the applied load level is increased, the propagation of the nucleated cracks increases, resulting in continuous permanent deformation, as observed in Figure 8.…”

Section: Resultsmentioning

confidence: 99%

Effect of operating parameters on functional fatigue characteristics of an Ni-Ti shape memory alloy on partial thermomechanical cycling

Swaminathan

Sampath

2022

Journal of Intelligent Material Systems and Structures

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In this study, the influence of upper cycle temperature (maximum temperature in a cycle) and the magnitude of applied stress on the functional properties of an SMA during partial thermomechanical cycling has been studied. A near-equiatomic NiTi SMA was chosen and tested under different upper cycle temperatures (between martensite finish (Mf) and austenite finish (Af) temperatures) and stress level (below and above the yield strength of the martensite). The upper cycle temperature was varied by controlling the magnitude of the current supply. The results show that a raise in the upper cycle temperature causes the permanent strain to increase and also lowers the stability. However, decreasing the stress imposed to a value lower than the yield strength of the martensite improves cyclic stability. The upper cycle temperature was found to influence the crack nucleation, whereas the applied stress level the crack propagation during partial thermomechanical cycling of SMAs. Therefore, decreasing the upper cycle temperature as well as the magnitude of stress applied to lower than the yield stress of martensite have been found to be suitable strategies for increasing the lifespan of SMA-based actuators during partial thermomechanical cycling.

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“…9). These experimental results, particularly to the {114} austenite twins in the microstructure of deformed wires, can be hardly explained considering the conventional dislocation slip based mechanisms of functional fatigue of NiTi proposed in the state of the art articles on this topic in the literature [3,[27][28][29][30][31].…”

Section: Mechanisms Of the Stress Induced B2 ) B19 0 ) B2 T Martensitic Transformationmentioning

confidence: 91%

B2 ⇒ B19′ ⇒ B2T Martensitic Transformation as a Mechanism of Plastic Deformation of NiTi

Šittner

Heller

Sedlák

et al. 2019

Shap. Mem. Superelasticity

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Deformation of superelastic NiTi wire with tailored microstructure was investigated in tensile loadingunloading tests up to the end of the stress plateau in wide temperature range from room temperature up to 200°C. Lattice defects left in the microstructure of deformed wires were investigated by transmission electron microscopy. Tensile deformation is localized up to the highest test temperatures, even if practically no martensite phase exists in the wire at the end of the stress plateau. In tensile tests at elevated temperatures around 100°C, at which the upper plateau stress approaches the yield stress for plastic deformation of martensite, upper plateau strains become unusually long, transformation strains become unrecoverable and deformation bands containing {114} austenite twins appear in the microstructure of deformed wires. These observations were rationalized by assuming activity of B2 ) B19 0 ) B2 T martensitic transformation into the austenite twins representing a new mechanism of plastic deformation of NiTi, additional to the dislocation slip in austenite and/or martensite. It is claimed that this transformation becomes activated in any thermomechanical load in which the oriented B19 0 martensite is exposed to high stress at high temperatures, as e.g., during shape setting or actuator cycling at high applied stress.Keywords Materials Á Stress-induced martensitic transformation Á Superelasticity Á Twinning This article is an invited submission to Shape Memory and Superelasticity selected from presentations at the Shape Memory and Superelastic Technology Conference and Exposition (SMST2019) held May 13-17, 2019 at The Bodensee Forum in Konstanz, Germany, and has been expanded from the original presentation.

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Multiscale TRIP-based investigation of low-cycle fatigue of polycrystalline NiTi shape memory alloys

Cited by 51 publications

References 62 publications

Evolution of transformation characteristics of shape memory alloys during cyclic loading: transformation temperature hysteresis and residual martensite

Evolution of transformation characteristics of shape memory alloys during cyclic loading: transformation temperature hysteresis and residual martensite

Effect of operating parameters on functional fatigue characteristics of an Ni-Ti shape memory alloy on partial thermomechanical cycling

B2 ⇒ B19′ ⇒ B2T Martensitic Transformation as a Mechanism of Plastic Deformation of NiTi

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