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Deformation and Degradation of Superelastic NiTi Under Multiaxial Loading

40 Pages Posted: 13 Dec 2018 First Look: Under Review

See all articles by Wei-Neng Hsu

Wei-Neng Hsu

Paul Scherrer Institute (PSI) - Photons for Engineering and Manufacturing Group; Ecole Polytechnique Fédérale de Lausanne - Neutrons and X-rays for Mechanics of Materials

Efthymios Polatidis

Paul Scherrer Institute (PSI) - Photons for Engineering and Manufacturing Group

Miroslav Šmíd

Paul Scherrer Institute (PSI) - Photons for Engineering and Manufacturing Group

Steven Van Petegem

Paul Scherrer Institute (PSI) - Photons for Engineering and Manufacturing Group

Nicola Casati

Paul Scherrer Institute (PSI) - Materials Science Group

Helena Van Swygenhoven

Paul Scherrer Institute (PSI) - Photons for Engineering and Manufacturing Group; Ecole Polytechnique Fédérale de Lausanne - Neutrons and X-rays for Mechanics of Materials

Abstract

The degradation of the superelastic properties of a commercial NiTi alloy are studied during uniaxial, biaxial and load-path-change cycling performed in-situ with synchrotron X-ray diffraction. Careful examination of the diffraction pattern during uniaxial loading shows the R-phase as a transition between the austenite and the B19' martensite. Degradation of the superelasticity is found to depend strongly on the loading and unloading path followed, and it is discussed in terms the B19' martensitic variant selection, the accumulation of dislocations, and the residual R-Phase and B19' martensite. Cycling biaxially leads to faster degradation than uniaxially due to a larger accumulation of dislocations. If the deformation cycle contains a load path change, dislocation accumulation increases further and more martensite is retained.

Keywords: superelastic NiTi, multiaxial, load path change, martensitic transformation, functional fatigue

Suggested Citation

Hsu, Wei-Neng and Polatidis, Efthymios and Šmíd, Miroslav and Petegem, Steven Van and Casati, Nicola and Swygenhoven, Helena Van, Deformation and Degradation of Superelastic NiTi Under Multiaxial Loading (December 13, 2018). Available at SSRN: https://ssrn.com/abstract=3300686 or http://dx.doi.org/10.2139/ssrn.3300686

Wei-Neng Hsu (Contact Author)

Paul Scherrer Institute (PSI) - Photons for Engineering and Manufacturing Group

5232 Villigen PSI
Switzerland

Ecole Polytechnique Fédérale de Lausanne - Neutrons and X-rays for Mechanics of Materials

Station 5
Odyssea 1.04
1015 Lausanne, CH-1015
Switzerland

Efthymios Polatidis

Paul Scherrer Institute (PSI) - Photons for Engineering and Manufacturing Group

5232 Villigen PSI
Switzerland

Miroslav Šmíd

Paul Scherrer Institute (PSI) - Photons for Engineering and Manufacturing Group

5232 Villigen PSI
Switzerland

Steven Van Petegem

Paul Scherrer Institute (PSI) - Photons for Engineering and Manufacturing Group

5232 Villigen PSI
Switzerland

Nicola Casati

Paul Scherrer Institute (PSI) - Materials Science Group

5232 Villigen PSI
Switzerland

Helena Van Swygenhoven

Paul Scherrer Institute (PSI) - Photons for Engineering and Manufacturing Group ( email )

5232 Villigen PSI
Switzerland

Ecole Polytechnique Fédérale de Lausanne - Neutrons and X-rays for Mechanics of Materials ( email )

Station 5
Odyssea 1.04
1015 Lausanne, CH-1015
Switzerland

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