JSME International Journal Series A Solid Mechanics and Material Engineering
Online ISSN : 1347-5363
Print ISSN : 1344-7912
ISSN-L : 1344-7912
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Molecular Dynamics Simulations of Shape-Memory Behavior Based on Martensite Transformation and Shear Deformation
Takuya UEHARATakato TAMAINobutada OHNO
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2006 Volume 49 Issue 3 Pages 300-306

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Abstract

Molecular dynamics simulations of the shape-memory effect are carried out to investigate the atomistic behavior during deformation and shape-recovery processes. The embedded-atom-method potential function and parameters for Ni-Al alloy are applied. The initial configurations of atoms are set on the lattice points of the martensite structure, in which the distribution of the variant orientation is limited to the two-dimensional direction for simplicity. When the shear load is imposed toward the x direction, parallel to the variant interface, the deformation of the variants occurs, and finally, all variants settle into the uniform orientation. The deformed state is maintained after the load is released, and the original shape is recovered through heating and cooling processes because of phase transformation to bcc and martensite. In the loading process, the stress-strain curve exhibits a zigzag shape consisting of repeated stress increase and abrupt release. The interval of the stress peaks is revealed to be smaller as the model size becomes larger. Deformation observed in variant layers seems to occur at the same time at every points in the layer for a small model. However, the simulation with a large model indicates a nucleation and propagation behavior in each layer.

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© 2006 by The Japan Society of Mechanical Engineers
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