Design of a Fatigue Resistant Ni-free PdTi-base SMA

D. Frankel*, T. Jiang, G. B. Olson

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

Abstract

Two main challenges in the design of reliable shape memory alloys for medical devices are improving fatigue life and addressing biocompatibility issues such as Ni hypersensitivity. This study presents the optimized design of a low-Ni (Pd, Ni)50(Ti, Al)50 alloy and the characterization of a peak-strengthened Ni-free (Pd, Fe)50(Ti, Al)50 superelastic alloy. Precipitate size, phase fraction, and phase composition are measured using Atom Probe Tomography (APT). From this data, thermodynamic and kinetic descriptions of the 2-phase field containing coherent L21 Heusler precipitates in a B2 matrix are developed. The optimum radius for precipitation strengthening in these systems is determined via experimentally calibrated strengthening models to be 2.3nm. Enhanced fatigue resistance of a peak-strengthened Ni-free alloy design is validated via thermal and mechanical cycling.

Original languageEnglish (US)
Pages (from-to)S801-S804
JournalMaterials Today: Proceedings
Volume2
DOIs
StatePublished - 2015

Keywords

  • Fatigue
  • Heusler phase
  • Medical devices
  • PdTi
  • Shape memory
  • Superelasticity
  • Systems design

ASJC Scopus subject areas

  • Materials Science(all)

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