Influence of Ni on martensitic phase transformations in NiTi shape memory alloys

Frenzel, J.; George, E.P.; Dlouhy, A.; Somsen, C.; Wagner, M.F.-X.; Eggeler, G.

doi:10.1016/j.actamat.2010.02.019

Influence of Ni on martensitic phase transformations in NiTi shape memory alloys (bibtex)

by J. Frenzel, E.P. George, A. Dlouhy, C. Somsen, M.F.-X. Wagner, G. Eggeler

Abstract:

High-precision data on phase transformation temperatures in NiTi, including numerical expressions for the effect of Ni on M_S, M_F, A_S, A_F and T₀, are obtained, and the reasons for the large experimental scatter observed in previous studies are discussed. Clear exper- imental evidence is provided confirming the predictions of Tang et al. 1999 [19] regarding deviations from a linear relation between the thermodynamic equilibrium temperature and Ni concentration. In addition to affecting the phase transition temperatures, increasing Ni contents are found to decrease the width of thermal hysteresis and the heat of transformation. These findings are rationalized on the basis of the crystallographic data of Prokoshkin et al. 2004 [68] and the theory of Ball and James [25]. The results show that it is important to document carefully the details of the arc-melting procedure used to make shape memory alloys and that, if the effects of processing are properly accounted for, precise values for the Ni concentration of the NiTi matrix can be obtained.

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Reference:

Frenzel, J., George, E.P., Dlouhy, A., Somsen, C., Wagner, M.F.-X., Eggeler, G.: Influence of Ni on martensitic phase transformations in NiTi shape memory alloys, Acta Materialia 58, 3444-3458, 2010.

Bibtex Entry:

@Article{Frenzel2010,
  author    = {Frenzel, J. and George, E.P. and Dlouhy, A. and Somsen, C. and Wagner, M.F.-X. and Eggeler, G.},
  journal   = {Acta Materialia},
  title     = {{Influence of Ni on martensitic phase transformations in {NiTi} shape memory alloys}},
  year      = {2010},
  issn      = {13596454},
  number    = {9},
  pages     = {3444--3458},
  volume    = {58},
  abstract  = {High-precision data on phase transformation temperatures in NiTi, including numerical expressions for the effect of Ni on M\textsubscript{S}, M\textsubscript{F}, A\textsubscript{S}, A\textsubscript{F} and T\textsubscript{0}, are obtained, and the reasons for the large experimental scatter observed in previous studies are discussed. Clear exper- imental evidence is provided confirming the predictions of Tang et al. 1999 [19] regarding deviations from a linear relation between the thermodynamic equilibrium temperature and Ni concentration. In addition to affecting the phase transition temperatures, increasing Ni contents are found to decrease the width of thermal hysteresis and the heat of transformation. These findings are rationalized on the basis of the crystallographic data of Prokoshkin et al. 2004 [68] and the theory of Ball and James [25]. The results show that it is important to document carefully the details of the arc-melting procedure used to make shape memory alloys and that, if the effects of processing are properly accounted for, precise values for the Ni concentration of the NiTi matrix can be obtained.},
  doi       = {10.1016/j.actamat.2010.02.019},
  keywords  = {Hysteresis width, NiTi shape memory alloys, Phase transformation temperatures, Thermodynamics, Vacuum arc melting},
  publisher = {Acta Materialia Inc.},
  url       = {http://linkinghub.elsevier.com/retrieve/pii/S1359645410001059},
}