Anisotropy of martensitic transformations in modeling of shape memory alloy polycrystals

Šittner, Petr; Novák, V.

doi:10.1016/s0749-6419(00)00009-7

Cited by 140 publications

(81 citation statements)

References 19 publications

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“…In single crystals, the first two issues are quite well understood (see for example [15,22,24]) while Figure 1: The phenomenon of superelasticity a framework for the third is emerging [25]. However, the understanding of polycrystals lags behind, and motivates this current work.…”

Section: Introductionmentioning

confidence: 93%

“…Thus the transformation in polycrystalline media is a complex phenomenon. Yet, remarkably,Šittner and Novák [24] as well as Lexcellent et al [18] observed that models based on the postulate of uniform stress in the polycrystal reasonably describe the experimental observation of the transformation yield surface. In this paper, we provide some rationale for this in the context of elastic energy minimization and nonlinear homogenization.…”

Section: Introductionmentioning

confidence: 97%

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Stress-Induced Phase Transformations in Shape-Memory Polycrystals

Bhattacharya

Schlömerkemper

2009

Arch Rational Mech Anal

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Shape-memory alloys undergo a solid-to-solid phase transformation involving a change of crystal structure. We examine model problems in the scalar setting motivated by the situation when this transformation is induced by the application of stress in a polycrystalline material made of numerous grains of the same crystalline solid with varying orientations. We show that the onset of transformation in a granular polycrystal with homogeneous elasticity is in fact predicted accurately by the so-called Sachs bound based on the ansatz of uniform stress. We also present a simple example where the onset of phase transformation is given by the Sachs bound, and the extent of phase transformation is given by the constant strain Taylor bound. Finally we discuss the stress-strain relations of the general problem using Milton-Serkov bounds.

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Section: Introductionmentioning

confidence: 93%

Section: Introductionmentioning

confidence: 97%

Stress-Induced Phase Transformations in Shape-Memory Polycrystals

Bhattacharya

Schlömerkemper

2009

Arch Rational Mech Anal

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“…[5] However, in a polycrystalline material, the interaction between grains, precipitation effects, or preferred orientations can play an important role in this sense and modify considerably these values. Sittner and Novák [17] have calculated the deformation for a B2 : B19Ј transformation in a polycrystalline NiTi by means of simulations taking into account only an "average" of different orientations, obtaining values between 8.6 and 5.7 pct. Moreover, a high dispersion of experimental results exists for near-equiatomic polycrystalline NiTi *The thermodynamical magnitudes used for calculations are also included.…”

Section: A Niti Ribbonsmentioning

confidence: 99%

Shape memory properties of Ni-Ti based melt-spun ribbons

Santamarta¹,

Cesari²,

Pons³

et al. 2004

Metall Mater Trans A

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Shape-memory properties of equiatomic NiTi, Ni 45 Ti 50 Cu 5 , and Ni 25 Ti 50 Cu 25 ribbons made by melt spinning have been studied by temperature inducing the martensitic transformation under constant tensile loads. Recoverable strains above 4 pct can be obtained under ϳ100 MPa loads for the NiTi and Ni 45 Ti 50 Cu 5 ribbons, transforming to B19Ј martensite. The B19 martensite is formed in the Ni 25 Ti 50 Cu 25 ribbon after crystallization, and according to the lowering in transformation strain as Cu content increases, the recoverable strain is close to 2.5 pct for ϳ150 MPa load. The transformation temperatures exhibit a linear dependence on the applied stress, which can be quantitatively described by means of a Clausius-Clapeyron type equation. The NiTi and Ni 45 Ti 50 Cu 5 ribbons exhibited some degree of two-way shape-memory effect (TWSME) after thermomechanical cycling. Texture analyses performed on the different ribbons allow us to better understand the transformation strains obtained in each ribbon. The amounts of shapememory effect (SME) and nonrecoverable strain shown by the studied ribbons are of the same order as those already observed in bulk materials, which makes melt spinning an ideal substitute to complicated manufacturing processes if really thin samples are needed. However, applicable stresses in melt-spun ribbons are limited by a relatively "premature" brittle fracture caused by irregularities in ribbon thickness.

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“…3) that /3/' preceded the yi' formation even in compression), for large strains and mainly in compression, formation of the yi' phase in polycrystals is equally probable and shall be considered. We have recently proposed a crystallographic model of SMA polycrystals [13] based on the theoretical calculation of the a-T diagrams that can deal with anisotropics and multiple martensite phase formation.…”

Section: Discussionmentioning

confidence: 99%

Martensitic transformations of Cu-Al-Ni single crystals in tension/compression

2001

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Abstract. Cu-AI-Ni alloys, similarly as other Cu-base shape memory alloys, transform into more martensitic structures c^' (6R), Pi' (18R) and y x ' (2H), depending on the temperature, stress, load axis orientation, sense of loading and composition. The transformation stress-temperature conditions at which individual transitions take place are beneficially represented in so called non-equilibrium stress-temperature phase diagrams. On the basis of the 363K) and comparison with our previous results obtained on alloys with higher Al content (T 0 <263K).

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Anisotropy of martensitic transformations in modeling of shape memory alloy polycrystals

Cited by 140 publications

References 19 publications

Stress-Induced Phase Transformations in Shape-Memory Polycrystals

Stress-Induced Phase Transformations in Shape-Memory Polycrystals

Shape memory properties of Ni-Ti based melt-spun ribbons

Martensitic transformations of Cu-Al-Ni single crystals in tension/compression

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