Taming the Pseudoelastic Response of Nitinol Using Ion Implantation

Alejandro Hinojos, Daniel Hong, Hariharan Sriram, Longsheng Feng, Chao Yang, Janelle P. Wharry, Xuesong Gao, Khalid Hattar, Nan Li, Jeremy E. Schaffer, Yunzhi Wang, Michael J. Mills, Peter M. Anderson

Research output: Contribution to journalArticlepeer-review

Abstract

Implantation of Ni50.5Ti49.5 wire with 30 MeV Ni6+ ions at doses (< 0.1 DPA) typically smaller than employed in the literature is shown to systematically alter the pseudoelastic response, with extrema in Berkovich nanoindentation load (+50%), hysteresis (−60%), and recoverable displacement (−19%) occurring at ∼ 3.6 μm below the implantation surface. These extraordinary values are attributed to ∼ 10 to 20 nm amorphous clusters that constrain the stress-induced B2-B19′ phase transformation. This is substantiated by phase field simulations of crystalline-amorphous composites and molecular dynamics simulations of crystalline-vacancy cluster composites showing the spatial refinement of martensite caused by nm-scale defects. The results suggest that ion implantation may potentially expand the processing and performance space for NiTi, by creating amorphous defects at smaller length scales than dislocation substructures produced by conventional deformation processing.

Original languageEnglish (US)
Article number115261
JournalScripta Materialia
Volume226
DOIs
StatePublished - Mar 15 2023
Externally publishedYes

Keywords

  • Ion implantation
  • Molecular dynamics
  • Nanoindentation
  • Phase field
  • Pseudoelastic
  • Shape memory alloy

ASJC Scopus subject areas

  • General Materials Science
  • Condensed Matter Physics
  • Mechanics of Materials
  • Mechanical Engineering
  • Metals and Alloys

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