Deformation mechanisms in a superelastic NiTi alloy: An in-situ high resolution digital image correlation study

E. Polatidis; M. Šmíd; I. Kuběna; W.-N. Hsu; G. Laplanche; H. Van Swygenhoven

Materials & Design (Jun 2020)

Deformation mechanisms in a superelastic NiTi alloy: An in-situ high resolution digital image correlation study

E. Polatidis,
M. Šmíd,
I. Kuběna,
W.-N. Hsu,
G. Laplanche,
H. Van Swygenhoven

Affiliations

E. Polatidis: Photons for Engineering and Manufacturing, Swiss Light Source, Paul Scherrer Institute, CH-5232 Villigen PSI, Switzerland
M. Šmíd: Photons for Engineering and Manufacturing, Swiss Light Source, Paul Scherrer Institute, CH-5232 Villigen PSI, Switzerland
I. Kuběna: Photons for Engineering and Manufacturing, Swiss Light Source, Paul Scherrer Institute, CH-5232 Villigen PSI, Switzerland; CEITEC IPM, Institute of Physics of Materials AS CR, v.v.i., Žižkova 22, 616 62 Brno, Czech Republic
W.-N. Hsu: Photons for Engineering and Manufacturing, Swiss Light Source, Paul Scherrer Institute, CH-5232 Villigen PSI, Switzerland; Neutrons and X-rays for Mechanics of Materials, IMX, École Polytechnique Féderale de Lausanne, CH-1015 Lausanne, Switzerland
G. Laplanche: Institut für Werkstoffe, Ruhr-Universität Bochum, Universitätsstr. 150, 44780 Bochum, Germany
H. Van Swygenhoven: Photons for Engineering and Manufacturing, Swiss Light Source, Paul Scherrer Institute, CH-5232 Villigen PSI, Switzerland; Neutrons and X-rays for Mechanics of Materials, IMX, École Polytechnique Féderale de Lausanne, CH-1015 Lausanne, Switzerland; Corresponding author at: Photons for Engineering and Manufacturing, Swiss Light Source, Paul Scherrer Institute, CH-5232 Villigen PSI, Switzerland.

Journal volume & issue: Vol. 191

Abstract

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An in-situ high resolution digital image correlation investigation during uniaxial tensile deformation reveals the recoverable and the non-recoverable strain mechanisms in a Ni51Ti49 alloy with a mean grain size of 35 μm. Recoverable strain is due to the martensitic transformation, for which more than one variant per grain can be activated. The majority of the activated variants exhibit high Schmid factor. The variant selection can be influenced by shear transmission across grain boundaries, when the geometrical compatibility between the neighboring habit plane variants is favourable; in these cases variants that do not have the highest Schmid factor, with respect to the macroscopically applied load, are activated. The experimentally determined transformation strains agree well with theoretical calculations for single crystals. The non-recoverable strain is due to deformation slip in austenite, twinning in martensite and residual martensite. The results are discussed in view of possible twinning modes that can occur in austenite resulting in significant non-recoverable strain.

Published in Materials & Design

ISSN: 0264-1275 (Print); 1873-4197 (Online)
Publisher: Elsevier
Country of publisher: United Kingdom
LCC subjects: Technology: Electrical engineering. Electronics. Nuclear engineering: Materials of engineering and construction. Mechanics of materials
Website: https://www.journals.elsevier.com/materials-and-design

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