Microstructure and shape memory behavior of [111]-oriented NiTiHfPd alloys

E. Acar, H. Tobe, H. E. Karaca, R. D. Noebe, Y. I. Chumlyakov

Research output: Contribution to journalArticlepeer-review

9 Scopus citations

Abstract

The relationship between the microstructure and shape memory properties of [111]-oriented Ni45.3Ti29.7Hf20Pd5 (at%) single crystals was explored. In this precipitation-strengthened alloy, the size and volume fraction of precipitates and interparticle distances govern the martensite morphology and the ensuing shape memory responses. Aging of the solution-treated material, leading to a microstructure of fine, closely spaced precipitates, resulted in a material capable of a shape memory strain of 2.15% at 1000 MPa in compression. Larger precipitates formed after aging the as-grown single crystals (without a prior solution treatment) resulting in a shape memory strain of 2.5% at this same stress level in constant-stress thermal cycling experiments. Superelastic strains of 4% in compression without any residual strain were possible under various microstructural conditions and the stress hysteresis could be varied between nearly 500 and 1000 MPa depending on the microstructure.

Original languageEnglish
Article number035011
JournalSmart Materials and Structures
Volume25
Issue number3
DOIs
StatePublished - Feb 22 2016

Bibliographical note

Funding Information:
This work was supported in part by the NASA Transformative Aeronautics Concepts Program (TACP) under the Transformational Tools & Technologies Project, the NASA EPSCOR program under Grant NNX11AQ31A, KSEF-148- 502-15-355, NSF CMMI-1538665, RSF program under grant no. 14-29-00012 and Erciyes University.

Publisher Copyright:
© 2016 IOP Publishing Ltd.

Keywords

  • NiTiHfPd
  • elastic energy storage
  • microstructure
  • shape memory alloys
  • superelasticity

ASJC Scopus subject areas

  • Signal Processing
  • Civil and Structural Engineering
  • Atomic and Molecular Physics, and Optics
  • Materials Science (all)
  • Condensed Matter Physics
  • Mechanics of Materials
  • Electrical and Electronic Engineering

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