Micromechanical Modeling of Precipitation Hardened NiTiHf Conference Paper uri icon

abstract

  • © 2018 Trans Tech Publications, Switzerland. Actuation response of NiTiHf high temperature SMAs can be enhanced by means of suitable heat treatment on the material through precipitation hardening. Heat treatments can be chosen carefully to improve the performance of the NiTiHf SMAs in order to meet the requirements of targeted applications to design more robust and efficient high temperature solid-state actuator systems. The present work aims to develop a novel approach to model and predict the behavior of heat-treated NiTiHf SMAs. The predictions of the thermomechanical response of NiTiHf SMAs are based on Representative Volume Elements (RVEs). The precipitated NiTiHf SMA is modeled as a composite consist of of thermo-elastic non-transforming precipitates and a polycrystalline SMA matrix. The structural effect of precipitates and the effect of Hf-concentration gradient resulted from Hf depletion during precipitation are included. The composition distribution resulting from the elemental depletion and the transformation temperature distributions in the SMA matrix are related. In the present work, these relations are developed from experimental measurements on several NiTiHf compositions. Thermo-mechanical responses of Ni50.3 Ti29.7 Hf20 heat-treated at 500°C for 48h at different loading conditions are predicted and the correlations with experimental results demonstrate the validity of the proposed framework.

author list (cited authors)

  • Joy, J. K., Solomou, A., Baxevanis, T., Karaman, I., & Lagoudas, D. C.

citation count

  • 1

publication date

  • March 2018