Kirkendall pore evolution during interdiffusion and homogenization of titanium-coated nickel microwires

Arun J. Bhattacharjee; Aaron R. Yost; Dinc Erdeniz; David C. Dunand; Ashley E. Paz y Puente

doi:10.1016/j.intermet.2021.107199

Kirkendall pore evolution during interdiffusion and homogenization of titanium-coated nickel microwires

Arun J. Bhattacharjee, Aaron R. Yost, Dinc Erdeniz, David C. Dunand, Ashley E. Paz y Puente^*

^*Corresponding author for this work

Materials Science and Engineering

Research output: Contribution to journal › Article › peer-review

3 Scopus citations

Abstract

In-situ and ex-situ X-ray 3D-tomography is used to characterize the microstructure of Ni microwires, with wire diameters spanning 25–100 μm, (i) after vapor-phase deposition of Ti onto their surface and (ii) after subsequent homogenization to achieve the near-equiatomic NiTi composition desired for shape-memory or superelastic behavior. After Ti deposition at 925 °C, wires are partially homogenized, exhibiting a pure Ni core surrounded by concentric shells of Ni₃Ti, NiTi and NiTi₂ intermetallic phases. Because of the imbalanced Ni and Ti diffusive fluxes, Kirkendall porosity is formed near the center of the wire, which often merges into a single pore in cross-sections, due to spatial confinement of the wire geometry. During subsequent homogenization at 925 °C, these Kirkendall pores grow due to further Ni-Ti interdiffusion, and they coalesce into a single, hollow channel near the central axis of the wire, thus forming a NiTi microtube. In some cases, off-center pores form in addition to the central pore, but these off-center pores do not form continuous channels.

Original language	English (US)
Article number	107199
Journal	Intermetallics
Volume	134
DOIs	https://doi.org/10.1016/j.intermet.2021.107199
State	Published - Jul 2021

Funding

This research was supported by the National Science Foundation under award number DMR-1611308 (Dr. Judith Yang, program manager). The authors thank Mr. Ajith Achuthankutty (University of Cincinnati) for experimental assistance at the Advanced Photon Source, Prof. Ashwin Shahani (University of Michigan, Ann Arbor) for assistance with the MATLAB script for 3D visualization and measurement of pore volume fraction and Dr. Xianghui Xiao (currently staff scientist at Brookhaven National Laboratory) for assistance with operating the 2-BM beamline at the Advanced Photon Source. This research was supported by the National Science Foundation under award number DMR-1611308 (Dr. Judith Yang, program manager). The authors thank Mr. Ajith Achuthankutty (University of Cincinnati) for experimental assistance at the Advanced Photon Source, Prof. Ashwin Shahani (University of Michigan, Ann Arbor) for assistance with the MATLAB script for 3D visualization and measurement of pore volume fraction and Dr. Xianghui Xiao (currently staff scientist at Brookhaven National Laboratory) for assistance with operating the 2-BM beamline at the Advanced Photon Source.

Keywords

A. shape memory alloys
B. diffusion
C. coatings
D. point defect
F. x-ray tomography
in situ

ASJC Scopus subject areas

General Chemistry
Mechanics of Materials
Mechanical Engineering
Metals and Alloys
Materials Chemistry

Access to Document

10.1016/j.intermet.2021.107199

Cite this

@article{512b7bbc563d4babb0dcf974e3ec5116,

title = "Kirkendall pore evolution during interdiffusion and homogenization of titanium-coated nickel microwires",

abstract = "In-situ and ex-situ X-ray 3D-tomography is used to characterize the microstructure of Ni microwires, with wire diameters spanning 25–100 μm, (i) after vapor-phase deposition of Ti onto their surface and (ii) after subsequent homogenization to achieve the near-equiatomic NiTi composition desired for shape-memory or superelastic behavior. After Ti deposition at 925 °C, wires are partially homogenized, exhibiting a pure Ni core surrounded by concentric shells of Ni3Ti, NiTi and NiTi2 intermetallic phases. Because of the imbalanced Ni and Ti diffusive fluxes, Kirkendall porosity is formed near the center of the wire, which often merges into a single pore in cross-sections, due to spatial confinement of the wire geometry. During subsequent homogenization at 925 °C, these Kirkendall pores grow due to further Ni-Ti interdiffusion, and they coalesce into a single, hollow channel near the central axis of the wire, thus forming a NiTi microtube. In some cases, off-center pores form in addition to the central pore, but these off-center pores do not form continuous channels.",

keywords = "A. shape memory alloys, B. diffusion, C. coatings, D. point defect, F. x-ray tomography, in situ",

author = "Bhattacharjee, {Arun J.} and Yost, {Aaron R.} and Dinc Erdeniz and Dunand, {David C.} and {Paz y Puente}, {Ashley E.}",

note = "Publisher Copyright: {\textcopyright} 2021 Elsevier Ltd",

year = "2021",

month = jul,

doi = "10.1016/j.intermet.2021.107199",

language = "English (US)",

volume = "134",

journal = "Intermetallics",

issn = "0966-9795",

publisher = "Elsevier Ltd",

}

TY - JOUR

T1 - Kirkendall pore evolution during interdiffusion and homogenization of titanium-coated nickel microwires

AU - Bhattacharjee, Arun J.

AU - Yost, Aaron R.

AU - Erdeniz, Dinc

AU - Dunand, David C.

AU - Paz y Puente, Ashley E.

PY - 2021/7

Y1 - 2021/7

N2 - In-situ and ex-situ X-ray 3D-tomography is used to characterize the microstructure of Ni microwires, with wire diameters spanning 25–100 μm, (i) after vapor-phase deposition of Ti onto their surface and (ii) after subsequent homogenization to achieve the near-equiatomic NiTi composition desired for shape-memory or superelastic behavior. After Ti deposition at 925 °C, wires are partially homogenized, exhibiting a pure Ni core surrounded by concentric shells of Ni3Ti, NiTi and NiTi2 intermetallic phases. Because of the imbalanced Ni and Ti diffusive fluxes, Kirkendall porosity is formed near the center of the wire, which often merges into a single pore in cross-sections, due to spatial confinement of the wire geometry. During subsequent homogenization at 925 °C, these Kirkendall pores grow due to further Ni-Ti interdiffusion, and they coalesce into a single, hollow channel near the central axis of the wire, thus forming a NiTi microtube. In some cases, off-center pores form in addition to the central pore, but these off-center pores do not form continuous channels.

AB - In-situ and ex-situ X-ray 3D-tomography is used to characterize the microstructure of Ni microwires, with wire diameters spanning 25–100 μm, (i) after vapor-phase deposition of Ti onto their surface and (ii) after subsequent homogenization to achieve the near-equiatomic NiTi composition desired for shape-memory or superelastic behavior. After Ti deposition at 925 °C, wires are partially homogenized, exhibiting a pure Ni core surrounded by concentric shells of Ni3Ti, NiTi and NiTi2 intermetallic phases. Because of the imbalanced Ni and Ti diffusive fluxes, Kirkendall porosity is formed near the center of the wire, which often merges into a single pore in cross-sections, due to spatial confinement of the wire geometry. During subsequent homogenization at 925 °C, these Kirkendall pores grow due to further Ni-Ti interdiffusion, and they coalesce into a single, hollow channel near the central axis of the wire, thus forming a NiTi microtube. In some cases, off-center pores form in addition to the central pore, but these off-center pores do not form continuous channels.

KW - A. shape memory alloys

KW - B. diffusion

KW - C. coatings

KW - D. point defect

KW - F. x-ray tomography

KW - in situ

UR - http://www.scopus.com/inward/record.url?scp=85103696304&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=85103696304&partnerID=8YFLogxK

U2 - 10.1016/j.intermet.2021.107199

DO - 10.1016/j.intermet.2021.107199

M3 - Article

AN - SCOPUS:85103696304

SN - 0966-9795

VL - 134

JO - Intermetallics

JF - Intermetallics

M1 - 107199

ER -

Kirkendall pore evolution during interdiffusion and homogenization of titanium-coated nickel microwires

Abstract

Funding

Keywords

ASJC Scopus subject areas

Access to Document

Other files and links

Fingerprint

Cite this