Compressive response of NiTi single crystals

Şehitoğlu, Hüseyin; Караман, И.; Anderson, R.J.; Zhang, X.; Gall, Ken; Maier, Hans Jürgen; Chumlyakov, Yu. I.

doi:10.1016/s1359-6454(00)00153-1

Cited by 264 publications

(114 citation statements)

References 11 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The following in-situ TEM investigations were performed on this specimen. The shape of the compression test curves is in good agreement with results on NiTi single crystal compression testing reported earlier [12,13].…”

Section: Materials and Experimental Proceduressupporting

confidence: 89%

In-situ TEM cooling/heating experiments on deformed NiTi shape memory single crystals

Simon

Kröger

Somsen

et al. 2009

ESOMAT 2009 - 8th European Symposium on Martensitic Transformations

View full text Add to dashboard Cite

Abstract. In the present study we report about the influence of dislocations on martensitic transformations in NiTi single crystals. Microstructural investigations are performed on Ni 50.4 Ti 49.6 (at.%) single crystals using in-situ cooling and heating transmission electron microscopy (TEM). Solution heat-treated Ni 50.4 Ti 49.6 single crystals were oriented by electron backscatter diffraction (EBSD) and compressed in [111] B2 -direction to different strain levels. DSC measurements on undeformed and deformed material states reveal a two step transformation from B2 to R-phase and then from Rcrystal shows that mainly screw dislocations with [001] type burgers vectors are present. During cooling, the martensitic R-phase grows homogeneously. On further cooling in some regions a burst like growth of B19'-neddles can be observed in addition to B19'-regions that nucleate and grow promoted by the stress-fields of dislocations. Dislocation analysis after back transformation suggests that dislocations form as a result of the martensitic transformation.

show abstract

Section: Materials and Experimental Proceduressupporting

confidence: 89%

In-situ TEM cooling/heating experiments on deformed NiTi shape memory single crystals

Simon

Kröger

Somsen

et al. 2009

ESOMAT 2009 - 8th European Symposium on Martensitic Transformations

View full text Add to dashboard Cite

show abstract

“…First, a uniform temperature increase prior to the onset of the Liiders-like deformation [9] demonstrates that the transformation starts prior to the localisation. Second, this Luders-like behaviour is not observed in compression or shear tests of single-crystals or polycristalline NiTi [13][14][15][16], as shown in Figure 3(b) and Figure 5(a), or in tension-compression tests of Cu based SMAs [17][18][19], as shown in Figure 3(a). In tension tests of NiTi SMAs, this localisation is hindered when using bulk specimens [20].…”

Section: Non-homogeneity Of the Tensile Testmentioning

confidence: 99%

“…This causes mechanical anisotropy of textured polycristalline SMAs [43][44][45] due to anisotropy of superelastic deformation of SMA single crystals [38][39][40][41]. Third, superelastic SMAs single crystals display asymmetric tension-compression deformation behaviour [29][30]16]. This contributes to the asymmetric tension-compression deformation behaviour observed on isotropic as well as textured polycrystalline SMAs [32,43,47].…”

Section: Role Of "Micro"-mechanisms At the Martensite-variant Level Amentioning

confidence: 99%

“…Most of these models are based on the Phenomenological Theory of Martensite Crystallography (PTMC) and on self-consistent schemes [46][47]. For the present, none of them uses the more realistic micro-models developed recently [44,16]. Prediction of micro-macro models gives useful information to build macroscopic constitutive relationships.…”

Section: Role Of "Micro"-mechanisms At the Martensite-variant Level Amentioning

confidence: 99%

See 1 more Smart Citation

Stress state effect on mechanical behaviour of shape memory alloys : Experimental characterisation and modelling

Orgéas

Favier

2001

J. Phys. IV France

View full text Add to dashboard Cite

Abstract. As engineering components utilising the beneficial properties of shape memory alloys (SMA) become geometrically complex and as applications involve combinations of loading states, a full evaluation of the effects of stress state on stress-strain response of these materials becomes critical for the success of these applications. Such evaluation is required to establish reliable constitutive relationship to model the complex thermomechanical behaviour of SMAs. This paper is intended to present a non-exhaustive overview on studies and results dealing with experimental characterisation and modelling of the effects of stress state on mechanical behaviour of shape memory alloys. In that respect, our presentation is mainly focused on one hand on experimental results on superelastic and ferroelastic deformation of polycrystalline alloys and on the other hand on the modelling at the macroscopic level, yielding critical reorientation or transformation constitutive equations. INTRODUCTIONShape memory alloys (SMAs) are known to exhibit a range of novel thermomechanical properties due to thermoelastic martensitic transformations. The superelasticity is a quasi-elastic deformation far beyond the conventional elastic limit of the material when deformed at certain temperature above A p the finishing temperature of the reverse martensite-to-austenite transformation. This phenomenon is associated with stress-induced martensitic (SIM) transformation. If the temperature is lowered to below M p the finishing temperature of the forward austenite-to-martensite transformation, the deformation proceeds by martensite reorientation. Martensite may deformed by reorientation forth and back with alternating stresses in opposite directions. This deformation mode is known as the ferroelasticity, in recognition of its phenomenological similarity to ferromagnetism. The one-way shape memory effect is observed when a specimen deformed by martensite reorientation reverts to its original shape upon heating to above A f Numerous experimental works have been performed in the past three decades aiming at characterising the thermo-mechanical behaviour in order to provide experimental evidences for the establishment of constitutive models. These experimental studies have been devoted to both single-crystal and polycrystal specimens, mainly using Cu-based and NiTi SMAs. Most mechanical testing has been carried out in tension using wire specimens. Less work has been done to characterise properties under other stress states. As engineering components become geometrically complex and as applications involve combinations of loading states, it becomes important to characterise material properties in different stress states. This will allow the establishment of reliable constitutive equations to model the complex thermomechanical behaviour of SMAs.The present paper is intended to give a non-exhaustive overview on the studies and results dealing with experimental characterisation and modelling of the influence of stress state on mechanical behaviour of...

show abstract

“…* kochmann@caltech.edu Furthermore, solids undergoing phase transitions or domain switching display a similar instability on the microscale when the crystal lattice transforms from one energy-minimizing phase into another (or into a mixture of variants) under the action of external stimuli such as thermal [22,23] or electric fields [24,25] or under imposed deformation or applied loads [26,27]. In all systems, a negative curvature of the energy landscape implies a violation of positive definiteness of the incremental elastic modulus tensor, which has been referred to as (static) negative stiffness [28,29].…”

Section: Introductionmentioning

confidence: 99%

Dynamics of periodic mechanical structures containing bistable elastic elements: From elastic to solitary wave propagation

2014

View full text Add to dashboard Cite

We investigate the nonlinear dynamics of a periodic chain of bistable elements consisting of masses connected by elastic springs whose constraint arrangement gives rise to a large-deformation snap-through instability. We show that the resulting negative-stiffness effect produces three different regimes of (linear and nonlinear) wave propagation in the periodic medium, depending on the wave amplitude. At small amplitudes, linear elastic waves experience dispersion that is controllable by the geometry and by the level of precompression. At moderate to large amplitudes, solitary waves arise in the weakly and strongly nonlinear regime. For each case, we present closed-form analytical solutions and we confirm our theoretical findings by specific numerical examples. The precompression reveals a class of wave propagation for a partially positive and negative potential. The presented results highlight opportunities in the design of mechanical metamaterials based on negative-stiffness elements, which go beyond current concepts primarily based on linear elastic wave propagation. Our findings shed light on the rich effective dynamics achievable by nonlinear small-scale instabilities in solids and structures.

show abstract

Compressive response of NiTi single crystals

Cited by 264 publications

References 11 publications

In-situ TEM cooling/heating experiments on deformed NiTi shape memory single crystals

In-situ TEM cooling/heating experiments on deformed NiTi shape memory single crystals

Stress state effect on mechanical behaviour of shape memory alloys : Experimental characterisation and modelling

Dynamics of periodic mechanical structures containing bistable elastic elements: From elastic to solitary wave propagation

Contact Info

Product

Resources

About