A Limit to Accelerated Free-Sintering: Nano-Phase Separation Interferes With Organic Debinding
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11661_2023_Article_7152.pdf
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2.39 MB
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Author(s)
Naunheim, Yannick
Perrin, Alice
Oliver, Christian E.
Stone, Katherine
Schuh, Christopher A.
Date Issued
August 10, 2023
Publisher
Springer US
Citation
Naunheim, Yannick, Perrin, Alice, Oliver, Christian E., Stone, Katherine and Schuh, Christopher A. 2023. "A Limit to Accelerated Free-Sintering: Nano-Phase Separation Interferes With Organic Debinding."
Version
Final published version
Abstract
Abstract
Nano-phase separating Ni–12 at. pct Ag powders are processed via high-energy ball milling and brought into a supersaturated state with a reduction of the grain size to the nanocrystalline scale, a combination that is designed to encourage rapid densification by phase separation upon heating. This unstable powder is then characterized by dilatometry, in-situ x-ray diffraction, thermogravimetry and microstructure analysis for sintering cycles up to 940 °C. However, these powder compacts exhibit excessive pore evolution and significant macroscopic swelling caused by removal of the organic process additives. This competition of organic removal with densification is known in nanocrystalline metals, but the present study adds an additional dimension of phase separation, which shifts the dominant swelling mechanism as the formation of the second phase traps the volatilizing organics and hinders the debinding process. The creep swelling and overall loss in relative density is then dominated by the creep deformation of the second Ag phase. The interference between organic removal and low-temperature onset of consolidation represents a new challenge to efforts aimed at rapid free sintering and should guide the design of rapidly sintering alloys; specifically, the present work emphasizes the need to select alloys that have their sintering-accelerating phase separation temperature above the range where gases are evolved.
MIT Department
Massachusetts Institute of Technology. Department of Materials Science and Engineering
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Creative Commons Attribution 4.0 International license
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DOI of Published Version
https://doi.org/10.1007/s11661-023-07152-3
