NiTi superelasticity via atomistic simulations |
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Authors: | Piyas Chowdhury Guowu Ren |
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Affiliation: | 1. Department of Mechanical Science and Engineering, University of Illinois at Urbana-Champaign, 1206?W. Green St., Urbana, IL 61801, USA;2. Institute of Fluid Physics, China Academy of Engineering Physics, Mianyang 621999, China |
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Abstract: | The NiTi shape memory alloys (SMAs) are promising candidates for the next-generation multifunctional materials. These materials are superelastic i.e. they can fully recover their original shape even after fairly large inelastic deformations once the mechanical forces are removed. The superelasticity reportedly stems from atomic scale crystal transformations. However, very few computer simulations have emerged, elucidating the transformation mechanisms at the discrete lattice level, which underlie the extraordinary strain recoverability. Here, we conduct breakthrough molecular dynamics modelling on the superelastic behaviour of the NiTi single crystals, and unravel the atomistic genesis thereof. The deformation recovery is clearly traced to the reversible transformation between austenite and martensite crystals through simulations. We examine the mechanistic origin of the tension–compression asymmetries and the effects of pressure/temperature/strain rate variation isolatedly. Hence, this work essentially brings a new dimension to probing the NiTi performance based on the mesoscale physics under more complicated thermo-mechanical loading scenarios. |
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Keywords: | superelasticity phase transformation atomic structure molecular dynamics computer simulations |
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