| About this Abstract |
| Meeting |
Materials Science & Technology 2020
|
| Symposium
|
Manufacturing and Processing of Advanced Ceramic Materials
|
| Presentation Title |
A Rational Design of Ultra-uniform Nanocrystalline Materials |
| Author(s) |
Yanhao Dong, Hongbing Yang, Jiangong Li, I-Wei Chen, Ju Li |
| On-Site Speaker (Planned) |
Yanhao Dong |
| Abstract Scope |
Nanocrystalline materials often show superior properties and are thus of great interest. Much has been discussed about ultrafine grain sizes, but little is known about ultra-uniformity, defined as grain size distribution narrower than predicted by the classical theory of Hillert. Here we provide a generalized growth theory unifying the mean-field solutions from Lifshitz, Slyozov, Wagner (LSW) and Hillert. For curvature driven grain growth, we find for growth exponent n >1 a steady-state size distribution that is analytically solvable and the distribution narrows with increasing n. Experimental validation of this prediction is found in porous Al2O3 ceramics at various stages of sintering and in dense Al2O3 nanoceramics produced by two-step sintering with an extremely uniform microstructure of 34 nm average grain size. The mechanism of two-step sintering shall be discussed, which is supported by sharp grain boundary mobility transitions experimentally observed in yttria stabilized zirconia and pure tungsten. |