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Ultra‐Uniform Nanocrystalline Materials via Two‐Step Sintering
Name
Dong20YangAFM.pdf
Description
Accepted version
Size
10.16 MB
Format
Adobe PDF
Checksum (MD5)
e362f1aa2b839fcc4617ca52a0d347fa
Author(s)
Dong, Yanhao
Yang, Hongbing
Zhang, Lin
Li, Xingyu
Ding, Dong
Wang, Xiaohui
Li, Ju
Li, Jiangong
Chen, I-Wei
Date Issued
2021
Journal
Advanced Functional Materials
Publisher
Wiley
Version
Author's final manuscript
Abstract
© 2020 Wiley-VCH GmbH Nanocrystalline materials with superior properties are of great interest. Much is discussed about obtaining nanograins, but little is known about maintaining grain-size uniformity that is critical for reliability. An especially intriguing question is whether it is possible to achieve a size distribution narrower than what Hillert theoretically predicted for normal grain growth, a possibility suggested—for growth with a higher growth exponent—by the generalized mean-field theory of Lifshitz, Slyozov, Wagner (LSW), and Hillert but never realized in practice. Following a rationally designed two-step sintering route, it has been made possible in bulk materials by taking advantage of the large growth exponent in the intermediate sintering stage to form a uniform microstructure despite residual porosity, and freezing the grain growth thereafter while continuing densification to reach full density. The bulk dense Al2O3 ceramic thus obtained has an average grain size of 34 nm and a size distribution much narrower than Hillert's prediction. Bulk Al2O3 with a grain-size distribution narrower than the particle-size distribution of starting powders is also demonstrated, as are highly uniform bulk engineering metals (refractory Mo and W-Re alloy) and complex functional ceramics (BaTiO3-based alloys with superior dielectric strength and energy capacity).
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DOI of Published Version
10.1002/ADFM.202007750
