Effect of Ni4Ti3 precipitation on martensitic transformation in Ti-Ni (bibtex)

by N. Zhou, C. Shen, M.F.-X. Wagner, G. Eggeler, M.J. Mills, Y. Wang

Abstract:
Precipitation of Ni4Ti3 plays a critical role in determining the martensitic transformation path and temperature in Ni-Ti shape memory alloys. In this study, the equilibrium shape of a coherent Ni4Ti3 precipitate and the concentration and stress fields around it are determined quantitatively using the phase field method. Most recent experimental data on lattice parameters, elastic constants, precipitate–matrix orientation relationship and thermodynamic database are used as model inputs. The effects of the concentration and stress fields on subsequent martensitic transformations are analyzed through interaction energy between a nucleating martensitic particle and the existing microstructure. Results indicate that R-phase formation prior to B19' phase could be attributed to both direct elastic interaction and stress-induced spatial variation in concentration near Ni4Ti3 precipitates. The preferred nucleation sites for the R-phase are close to the broad side of the lenticular-shaped Ni4Ti3 precipitates, where tension normal to the habit plane is highest, and Ni concentration is lowest.
Reference:
Zhou, N., Shen, C., Wagner, M.F.-X., Eggeler, G., Mills, M.J., Wang, Y.: Effect of Ni4Ti3 precipitation on martensitic transformation in Ti-Ni, Acta Materialia 58, 6685-6694, 2010.
Bibtex Entry:
@Article{Zhou2010a,
  author    = {Zhou, N. and Shen, C. and Wagner, M.F.-X. and Eggeler, G. and Mills, M.J. and Wang, Y.},
  journal   = {Acta Materialia},
  title     = {{Effect of Ni\textsubscript{4}Ti\textsubscript{3} precipitation on martensitic transformation in {Ti-Ni}}},
  year      = {2010},
  number    = {20},
  pages     = {6685--6694},
  volume    = {58},
  abstract  = {Precipitation of Ni\textsubscript{4}Ti\textsubscript{3} plays a critical role in determining the martensitic transformation path and temperature in Ni-Ti shape memory alloys. In this study, the equilibrium shape of a coherent Ni\textsubscript{4}Ti\textsubscript{3} precipitate and the concentration and stress fields around it are determined quantitatively using the phase field method. Most recent experimental data on lattice parameters, elastic constants, precipitate–matrix orientation relationship and thermodynamic database are used as model inputs. The effects of the concentration and stress fields on subsequent martensitic transformations are analyzed through interaction energy between a nucleating martensitic particle and the existing microstructure. Results indicate that R-phase formation prior to B19' phase could be attributed to both direct elastic interaction and stress-induced spatial variation in concentration near Ni\textsubscript{4}Ti\textsubscript{3} precipitates. The preferred nucleation sites for the R-phase are close to the broad side of the lenticular-shaped Ni\textsubscript{4}Ti\textsubscript{3} precipitates, where tension normal to the habit plane is highest, and Ni concentration is lowest.},
  doi       = {10.1016/j.actamat.2010.08.033},
  keywords  = {Heterogeneous nucleation of phase transformations, Internal stresses, Phase field models, Shape memory alloys, Simulation},
  publisher = {Elsevier {BV}},
}
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