High temperature shape memory behavior of Ni47.3Ti29.7Hf20Pd3 alloys

Emre Acar, Guher P. Toker, Harun Kurkcu, Haluk E. Karaca

Research output: Contribution to journalArticlepeer-review

13 Scopus citations

Abstract

The shape memory properties of Ni47.3Ti29.7Hf20Pd3 alloys were investigated through stress-free thermal cycling, constant-stress thermal cycling and constant-temperature stress cycling experiments. The alloys showed reversible phase transformations above 180 °C, which makes them suitable for high temperature shape memory applications. Constant-stress thermal cycling experiments revealed that recoverable strains of about 2% were possible under compressive stress levels higher than 700 MPa and both the recoverable strain and thermal hysteresis values were strong functions of applied stress. Additionally, two-way shape memory strain of 0.7% was observed. Unlike most of the shape memory alloys that have Class I transformation, Class II transformation was observed in these alloys and its relationship to the elastic energy storage was discussed through thermo-elastic martensitic transformation thermodynamics approach.

Original languageEnglish
Article number106518
JournalIntermetallics
Volume111
DOIs
StatePublished - Aug 2019

Bibliographical note

Publisher Copyright:
© 2019 Elsevier Ltd

Keywords

  • Class II transformation
  • High strength
  • High temperature shape memory alloys
  • NiTiHfPd
  • Shape memory alloys

ASJC Scopus subject areas

  • General Chemistry
  • Mechanics of Materials
  • Mechanical Engineering
  • Metals and Alloys
  • Materials Chemistry

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