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

D. Frankel; T. Jiang; G. B. Olson

doi:10.1016/j.matpr.2015.07.403

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

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

^*Corresponding author for this work

Materials Science and Engineering

Research output: Contribution to journal › Article › peer-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 language	English (US)
Pages (from-to)	S801-S804
Journal	Materials Today: Proceedings
Volume	2
DOIs	https://doi.org/10.1016/j.matpr.2015.07.403
State	Published - 2015

Keywords

Fatigue
Heusler phase
Medical devices
PdTi
Shape memory
Superelasticity
Systems design

ASJC Scopus subject areas

Materials Science(all)

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10.1016/j.matpr.2015.07.403

Cite this

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title = "Design of a Fatigue Resistant Ni-free PdTi-base SMA",

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.",

keywords = "Fatigue, Heusler phase, Medical devices, PdTi, Shape memory, Superelasticity, Systems design",

author = "D. Frankel and T. Jiang and Olson, {G. B.}",

note = "Funding Information: This material is based upon work supported by the Nat. Sci. Found. Grad. Res. Fellow. under Grant No. DGE-1324585. The work on low-Ni alloy development was made possible by funding from General Motors R&D center. LEAP measurements were performed at the Northwestern University Center for Atom Probe Tomography (NUCAPT). Funding from NSF-MRI (DMR-0420532) and ONR-DURIP (N00014-0400798, N00014-0610539, N00014-0910781) grants is also acknowledged. NUCAPT received support through the Initiative for Sustainability and Energy at Northwestern and the NSF{\textquoteright}s MRSEC program (DMR-0520513 and 1121262). Publisher Copyright: {\textcopyright} 2015 The Authors.",

year = "2015",

doi = "10.1016/j.matpr.2015.07.403",

language = "English (US)",

volume = "2",

pages = "S801--S804",

journal = "Materials Today: Proceedings",

issn = "2214-7853",

publisher = "Elsevier Limited",

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T1 - Design of a Fatigue Resistant Ni-free PdTi-base SMA

AU - Frankel, D.

AU - Jiang, T.

AU - Olson, G. B.

N1 - Funding Information: This material is based upon work supported by the Nat. Sci. Found. Grad. Res. Fellow. under Grant No. DGE-1324585. The work on low-Ni alloy development was made possible by funding from General Motors R&D center. LEAP measurements were performed at the Northwestern University Center for Atom Probe Tomography (NUCAPT). Funding from NSF-MRI (DMR-0420532) and ONR-DURIP (N00014-0400798, N00014-0610539, N00014-0910781) grants is also acknowledged. NUCAPT received support through the Initiative for Sustainability and Energy at Northwestern and the NSF’s MRSEC program (DMR-0520513 and 1121262). Publisher Copyright: © 2015 The Authors.

PY - 2015

Y1 - 2015

N2 - 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.

AB - 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.

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KW - Heusler phase

KW - Medical devices

KW - PdTi

KW - Shape memory

KW - Superelasticity

KW - Systems design

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ER -

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

Abstract

Keywords

ASJC Scopus subject areas

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