Effects of orientation on the shape memory behavior of Ni51Ti49 single crystals

I. Kaya, H. E. Karaca, M. Souri, Y. Chumlyakov, H. Kurkcu

Research output: Contribution to journalArticlepeer-review

18 Scopus citations

Abstract

The orientation dependence of the shape memory responses of [001], [011] and [111]-oriented Ni51Ti49 single crystals and Ni50.8Ti49.2 polycrystals are systematically studied in compression. Thermal cycling under constant stress and superelasticity experiments were conducted on both homogenized and aged (1.5 h at 500 °C) samples to understand the effects of precipitation on their shape memory behavior. It has been found that recoverable strain, temperature and stress hysteresis, Classius-Clapeyron slopes, and critical stress for plastic deformation are highly orientation dependent. The recoverable strains were 3, 2.65 and 2.38% under 400 MPa in [001], [011] and [111] orientations, respectively. After aging, the recoverable strains were 3.19, 2.78 and 2.11% under 400 MPa in [001], [011] and [111] orientations, respectively. Above 400 MPa, irrecoverable strain increased considerably for [011] and [111]-oriented samples. In [001] orientation, very narrow temperature hysteresis of 10 °C, recoverable strain of 3.03% and total strain of 3.65% were observed under ultra high compressive stress level of 1500 MPa. Moreover, [001] orientation showed perfect superelasticity with total strain of 7% and a large superelastic window (∆T=140 °C). The transformation temperatures are lower in homogenized samples than the aged samples due to decreased Ni-concentration in matrix by the formation of Ni-rich precipitates.

Original languageEnglish
Pages (from-to)73-81
Number of pages9
JournalMaterials Science and Engineering A
Volume686
DOIs
StatePublished - Feb 16 2017

Bibliographical note

Funding Information:
This work was supported in part by the NASA EPSCOR:NNX11AQ31A, NSF CMMI- 1538665, RSF- 14-29-00012 and the Research Directorate Kuwait Foundation for Advancement Sciences with Grant No: KFAS: P114-16SM-02. I.K. acknowledges the support from Anadolu University (Grant No:1605F390).

Publisher Copyright:
© 2017 Elsevier B.V.

Keywords

  • Phase transformation
  • Shape memory alloy
  • Single crystal

ASJC Scopus subject areas

  • Materials Science (all)
  • Condensed Matter Physics
  • Mechanics of Materials
  • Mechanical Engineering

Fingerprint

Dive into the research topics of 'Effects of orientation on the shape memory behavior of Ni51Ti49 single crystals'. Together they form a unique fingerprint.

Cite this