The microstructure and linear superelasticity of cold-drawn TiNi alloy

Zheng, Yufeng; Huang, Bowen; Zhang, J.X; Zhao, Liancheng

doi:10.1016/s0921-5093(99)00632-2

Cited by 70 publications

(24 citation statements)

References 16 publications

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“…We refer to the associated shape recovery as twinning-induced elasticity (TIE). In the literature, TIE was referred to as ''linear superelasticity'' [24][25][26] or ''twinning pseudoelasticity'' [23]. Figure 1b shows examples of stress/strain curves from a NiTi SMA in the TIE state.…”

Section: Introductionmentioning

confidence: 99%

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Twinning-Induced Elasticity in NiTi Shape Memory Alloys

Birk

Biswas

Frenzel

et al. 2016

Shap. Mem. Superelasticity

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Pseudoelasticity (PE) in shape memory alloys relies on the formation of stress-induced martensite during loading and on the reverse transformation during unloading. PE yields reversible strains of up to 8 % and is applied in applications such as medical implants, flexible eye glass frames, damping elements, and others. Unfortunately, PE shows a strong temperature dependence and thus can only be exploited within a relatively narrow temperature window. The present work focuses on a related process, which we refer to as twinning-induced elasticity (TIE). It involves the growth and shrinkage of martensite variants which are stabilized by dislocations, which are introduced by appropriate cold work. TIE yields reversible strains of the order of 3 %. The TIE effect does not suffer from the strong temperature dependence of PE. The weak temperature dependence of mechanical TIE properties makes TIE attractive for applications where temperature fluctuations are large. In the present work, we study the TIE effect focusing on Ni 50 Ti 50 shape memory alloy wires. The degree of plastic pre-deformation of the initial material represents a key parameter of the ingot metallurgy processing route. It governs the exploitable recoverable strain, the apparent Young's modulus, and the widths of the mechanical hysteresis. Dynamic mechanical analysis is used to study the effects of pre-deformation on elementary microstructural processes which govern TIE.

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Section: Introductionmentioning

confidence: 99%

“…1a is not observed. However, TIE is known to provide lower reversible strains as compared to PE SMAs [23,24,27,28]. Typically, strains of the order of 3 % can be fully recovered.…”

Section: Introductionmentioning

confidence: 99%

Twinning-Induced Elasticity in NiTi Shape Memory Alloys

Birk

Biswas

Frenzel

et al. 2016

Shap. Mem. Superelasticity

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“…It has been confirmed that the properties of TiNi SMAs can be affected by various thermal mechanical treatments such as aging in Ni-rich TiNi alloys, [1][2][3] cold rolling 4) and thermal cycling, 5) moreover, the addition of a third element to replace Ni and/or Ti has a substantial effect on phase transformation behavior of TiNi binary alloys. It is well known that the Ms temperature decreases with the addition of V, Fe, Co, but increases remarkably with element such as Au, Pd, Pt, and Hf.…”

Section: Introductionmentioning

confidence: 99%

Effects of Cerium Addition on Martensitic Transformation and Microstructure of Ti<SUB>49.3</SUB>Ni<SUB>50.7</SUB> Alloy

et al. 2006

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In order to study the effect of Cerium on martensitic transformation and microstructure of Ti 49:3 Ni 50:7 alloy, a group of TiNiCe alloys with different content of Ce addition were prepared. The microstructure and the martensitic transformation behavior of TiNiCe ternary alloys were investigated by optical microscopy, scanning electron microscopy (SEM), X-ray diffraction (XRD) and differential scanning calorimetry (DSC). The results show that the microstructure of Ti 49:3 Ni 50:7 alloy is changed obviously by Ce addition, and there are many Ce-rich phases dispersing in the TiNi matrix. One step martensitic transformation due to B2 $ B19 0 transformation occurs during the cooling and heating processes of the TiNiCe ternary alloys. The phase transformation temperatures increase remarkably when the content of Ce is less than 2 at%. However, when the content of Ce is further increasing, the phase transformation temperatures increase slowly and tend to stable.

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“…It was shown [2][3][4] that this alloy system possesses a high pseudoelastic, also called superelastic effect. However, all previously studied stress strain loops showing pseudoelastic behaviour in these alloys, as well as in most SMA systems such as Ti-Pd-Ni [5], Ni-Ti [6,7], Fe-Pt [8], Cu-Al-X where X is Mn, Zn, Ni [9,10] etc. are due to the stress induced martensite transformation (i.e.…”

Section: Introductionmentioning

confidence: 99%

“…: highly nonlinear hysteretic behaviour, strongly dependent on the stress or deformation rates [12,13], not stable with stress cycling, and with strong temperature dependence of the superelastic loop and critical stress values [4,10,11]. While the Ti-Ni [6] seems attractive having 100% recovery and a quasilinear behaviour, though it possesses small elastic strain values (4%) at very high stress values above 1GPa. On the other hand, in the 20% compressive strain in the martensite phase of single crystalline Ni-Mn-Ga alloy was obtained [14].…”

Section: Introductionmentioning

confidence: 99%

Giant elasticity in the Ni-Mn-Ga single crystalline FSMA martensites

Glavatskyy

Glavatska

2009

ESOMAT 2009 - 8th European Symposium on Martensitic Transformations

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Abstract. The phenomenon of the giant elastic completely reversible linear strain is found at constant temperatures in Ni-Mn-Ga martensites. Single crystals of some off-stoichiometric Ni-Mn-Ga compositions possess rubber-like behavior in the martensite phase with completely elastic strain reaching over 10% at some 90MPa compressive stress at room temperature. The observed phenomenon is different from the conventional (two-phase) superelasticity, since it is found completely in the martensite phase and no intermartensitic reaction is observed during the load-unload cycling. The main features of the observed rubber-like behavior are: 1) complete elasticity and giant values of the strains achieved; 2) the linear character of stress-strain dependence; 3) excellent stability to the mechanical cycling, stress rate and temperature variation, in contrast to the conventional two-phase superelasticity due to the stress induced martensite transformation. Current work is directed to study the structural mechanisms of the found phenomenon by means of the neutron diffraction in-situ under compressive stress cycling.

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The microstructure and linear superelasticity of cold-drawn TiNi alloy

Cited by 70 publications

References 16 publications

Twinning-Induced Elasticity in NiTi Shape Memory Alloys

Twinning-Induced Elasticity in NiTi Shape Memory Alloys

Effects of Cerium Addition on Martensitic Transformation and Microstructure of Ti<SUB>49.3</SUB>Ni<SUB>50.7</SUB> Alloy

Giant elasticity in the Ni-Mn-Ga single crystalline FSMA martensites

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