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Article
Shape Memory Alloys via Halide-Activated Pack Equilibration
Advanced Engineering Materials
  • Andrew S. King
  • Ryan D. Dempsey
  • David W. Lipke, Missouri University of Science and Technology
Abstract

Fabrication of shape memory alloy (SMA) components based on NiTi is challenging due to the precision with which elemental composition and microstructure must be controlled during processing to achieve desired shape memory behavior. Herein, a method to control chemistry in an NiTi SMA via halide-activated pack equilibration (SHAPE) against a constant chemical potential reservoir is described. To demonstrate the efficacy of the SHAPE process, an initially titanium-deficient specimen (pure nickel foam) has been equilibrated against an excess of an intimately mixed two-phase pack (NiTi + Ti2Ni) in the presence of a vapor phase transport agent (iodine). The two-phase pack regulates chemical potentials in this two-component system in accordance with Gibbs' phase rule. Ti-rich NiTi foams thus produced exhibit reproducible and well-defined phase transformation behaviors. The SHAPE process is advantageous for the fabrication of shape memory components of varying areal dimension, shape, and/or complexity owing to independence of the equilibrium state of the system from either the initial state of the specimen or the details of the process kinetics. Current limitations and prospects for the application of this method to improve the quality of SMA components are briefly discussed.

Department(s)
Materials Science and Engineering
Publication Status
Early View: Online Version of Record before inclusion in an issue
Keywords and Phrases
  • Chemical Vapor Transport,
  • NiTi,
  • Reaction Processing,
  • Shape Memory Alloy
Document Type
Article - Journal
Document Version
Citation
File Type
text
Language(s)
English
Rights
© 2022 Wiley, All rights reserved.
Publication Date
2-3-2022
Publication Date
03 Feb 2022
Citation Information
Andrew S. King, Ryan D. Dempsey and David W. Lipke. "Shape Memory Alloys via Halide-Activated Pack Equilibration" Advanced Engineering Materials (2022) ISSN: 1527-2648; 1438-1656
Available at: http://works.bepress.com/david-lipke/7/