Stress-Strain-Temperature Behavior Due to B2-R-B19′ Transformation in NiTi Polycrystals

Thermomechanical behavior of superelastic NiTi wires undergoing sequential B2-R-B19′ martensitic transformation was investigated by two recently developed in-situ experimental methods (in-situ neutron diffraction and combined ultrasonic and electric resistance measurements) capable of detecting and recognizing the activity of various deformation/transformation processes in NiTi and theoretically by micromechanical modeling. An earlier model of SMA polycrystal transformation is further developed, so it accounts for the strains due to the R-phase related deformation processes in activated NiTi. A continuous variation of the rhombohedral distortion angle α of the R-phase structure with temperature and stress is newly introduced as a legitimate deformation mechanism. Simulation results for NiTi bars and wires exposed to three types of thermomechanical tests—mechanical loading at constant temperature, cooling under constant stress, and recovery stress tests are presented and confronted with results.

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In situ experimental evidence on R-phase related deformation processes in activated NiTi wires

Materials Science and Engineering A ◽

10.1016/j.msea.2006.02.200 ◽

2006 ◽

Vol 438-440 ◽

pp. 579-584 ◽

Cited By ~ 19

Author(s):

P. Šittner ◽

P. Sedlák ◽

M. Landa ◽

V. Novák ◽

P. Lukáš

Keyword(s):

Experimental Evidence ◽

Deformation Processes ◽

Niti Wires

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In Situ Experimental Methods for Characterization of Deformation Processes in SMAs

Advances in Science and Technology ◽

10.4028/www.scientific.net/ast.59.47 ◽

2008 ◽

Vol 59 ◽

pp. 47-56

Author(s):

Petr Šittner ◽

J. Pilch ◽

P. Lukas ◽

Michal Landa ◽

H. Seiner ◽

...

Keyword(s):

Shape Memory ◽

Martensitic Transformations ◽

Experimental Methods ◽

Smart Structure ◽

Functional Responses ◽

Modeling Tools ◽

Deformation Processes ◽

Transformation Processes

In order to better understand the unique functional responses of shape memory alloys, improve the currently existing SMA modeling tools and used them beneficially in smart structure applications, it is desirable to investigate the deformation/transformation processes in these materials in action – i.e. under stress and temperature variation. In this work, an overview is presented on the applications of various recently developed or originally employed in-situ experimental methods and approaches to martensitic transformations in SMAs.

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Influence of Volume Fraction of Long-Period Stacking Ordered Structure Phase on the Deformation Processes during Cyclic Deformation of Mg-Y-Zn Alloys

Crystals ◽

10.3390/cryst11010011 ◽

2020 ◽

Vol 11 (1) ◽

pp. 11

Author(s):

Daria Drozdenko ◽

Gergely Farkas ◽

Pavol Šimko ◽

Klaudia Fekete ◽

Jan Čapek ◽

...

Keyword(s):

Path Dependence ◽

Volume Fraction ◽

Deformation Mechanisms ◽

Electron Backscattered Diffraction ◽

Long Period ◽

Lpso Structure ◽

Deformation Processes ◽

In Situ Neutron Diffraction ◽

Zn Alloys

Deformation mechanisms in extruded Mg-Y-Zn alloys with different volume fractions of the long-period stacking ordered (LPSO) structure have been investigated during cyclic loading, i.e., compression followed by unloading and reverse tensile loading. Electron backscattered diffraction (EBSD) and in situ neutron diffraction (ND) techniques are used to determine strain path dependence of the deformation mechanisms. The twinning-detwinning mechanism operated in the α-Mg phase is of key importance for the subsequent hardening behavior of alloys with complex microstructures, consisting of α-Mg and LPSO phases. Besides the detailed analysis of the lattice strain development as a function of the applied stress, the dislocation density evolution in particular alloys is determined.

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Deformation processes in functional materials studied by in situ neutron diffraction and ultrasonic techniques

Materials Science and Engineering A ◽

10.1016/j.msea.2006.01.181 ◽

2007 ◽

Vol 462 (1-2) ◽

pp. 12-22 ◽

Cited By ~ 6

Author(s):

P. Šittner ◽

V. Novák ◽

M. Landa ◽

P. Lukáš

Keyword(s):

Neutron Diffraction ◽

Functional Materials ◽

Deformation Processes ◽

Ultrasonic Techniques ◽

In Situ Neutron Diffraction

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Test method recommendations of RILEM TC 177-MDT 'Masonry durability and on-site testing' - D.4: In-situ stress tests based on the flat jack

Materials and Structures ◽

10.1617/14119 ◽

2004 ◽

Vol 37 (271) ◽

pp. 491-496 ◽

Cited By ~ 6

Author(s):

Keyword(s):

In Situ Stress ◽

Test Method ◽

Stress Tests ◽

Site Testing

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Evaluating the Mechanical Behavior of 316 Stainless Steel at the Microscale Using Finite Element Modelling and In-Situ Neutron Scattering

ASME 2010 Pressure Vessels and Piping Conference: Volume 6, Parts A and B ◽

10.1115/pvp2010-25599 ◽

2010 ◽

Cited By ~ 3

Author(s):

Dong-Feng Li ◽

Noel P. O’Dowd ◽

Catrin M. Davies ◽

Shu-Yan Zhang

Keyword(s):

Finite Element ◽

Stainless Steel ◽

Finite Element Modelling ◽

Mechanical Response ◽

Fe Model ◽

Lattice Strains ◽

Crystallographic Slip ◽

In Situ Neutron Diffraction ◽

Elastic Lattice

In this study, the deformation behavior of an austenitic stainless steel is investigated at the microscale by means of in-situ neutron diffraction (ND) measurements in conjunction with finite-element (FE) simulations. Results are presented in terms of (elastic) lattice strains for selected grain (crystallite) families. The FE model is based on a crystallographic (slip system based) representation of the deformation at the microscale. The present study indicates that combined in-situ ND measurement and micromechanical modelling provides an enhanced understanding of the mechanical response at the microscale in engineering steels.

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