Shape memory behavior of high strength NiTiHfPd polycrystalline alloys

H. E. Karaca, E. Acar, G. S. Ded, B. Basaran, H. Tobe, R. D. Noebe, G. Bigelow, Y. I. Chumlyakov

Research output: Contribution to journalArticlepeer-review

77 Scopus citations


Systematic characterization of the shape memory properties of a quaternary Ni45.3-Ti29.7-Hf20-Pd5 (at.%) polycrystalline alloy was performed in compression after selected aging treatments. Precipitation characteristics were revealed by transmission electron microscopy. The effects of aging temperature and time on transformation temperatures, recoverable and residual strains, and temperature and stress hystereses were determined by differential scanning calorimetry, constant-load thermal cycling experiments and isothermal strain cycling (superelasticity) tests. The crystal structure and lattice parameters of the transforming phases were determined from X-ray diffraction analysis. It was revealed that precipitation hardening significantly improved the shape memory properties of the NiTiHfPd alloy. Under optimum aging conditions, shape memory strains of up to 4% under 1 GPa were possible, and superelasticity experiments resulted in full strain recovery without any plastic deformation, even at stress levels as high as 2 GPa. The NiTiHfPd polycrystalline alloy exhibited very high damping capacity/absorbed energy (30-34 J cm-3) and work output (30-35 J cm-3), which were attributed to the ability to operate at high stress levels without significant plastic deformation and to a high mechanical hysteresis (>900 MPa) at temperatures ranging from 20 C to 80 C.

Original languageEnglish
Pages (from-to)5036-5049
Number of pages14
JournalActa Materialia
Issue number13
StatePublished - Aug 2013

Bibliographical note

Funding Information:
This work was supported in part by the NASA Fundamental Aeronautics Program, Aeronautical Sciences Project and the NASA EPSCOR program under Grant No: NNX11AQ31A, KY EPSCoR RID program under Grant No. 3049024332 and RFBR project with Grant No. 10-03-0154-a.


  • High strength alloys
  • Mechanical characterization
  • Phase transformation
  • Precipitation
  • Shape memory alloys

ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials
  • Ceramics and Composites
  • Polymers and Plastics
  • Metals and Alloys


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