DFT-supported phase-field study on the effect of mechanically driven fluxes in Ni sub(4)Ti sub(3) precipitation

Formation of the Ni sub(4)Ti sub(3) precipitate has a strong effect on the shape memory properties of NiTi alloys. In this work, growth of this precipitate is studied using phase-field modelling and density functional theory (DFT) calculations. Using first-principles calculations, the composition-de...

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Bibliographic Details
Published in:Modelling and simulation in materials science and engineering 2014-04, Vol.22 (3), p.1-14
Main Authors: Kamachali, Reza Darvishi, Borukhovich, Efim, Hatcher, Nicholas, Steinbach, Ingo
Format: Article
Language:English
Subjects:
Computer simulation
Elastic constants
Intermetallic compounds
Intermetallics
Mathematical models
Modelling
Precipitates
Precipitation
Shape memory alloys
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Summary:Formation of the Ni sub(4)Ti sub(3) precipitate has a strong effect on the shape memory properties of NiTi alloys. In this work, growth of this precipitate is studied using phase-field modelling and density functional theory (DFT) calculations. Using first-principles calculations, the composition-dependent stability and elastic properties of the B2 phase are obtained. Composition-dependent elastic constants are incorporated into our phase-field model to investigate the interplay between stress and concentration fields around the precipitate. The model introduces a source of diffusion due to mechanical relaxation which is accompanied by local softening/hardening of the B2 phase. The results are discussed in light of previous experimental and simulation studies.
ISSN:0965-0393
1361-651X
DOI:10.1088/0965-0393/22/3/034003