Grain Boundary Strengthening in Alumina by Rare Earth Impurities
J. P. Buban,1
K. Matsunaga,1*
J. Chen,2
N. Shibata,1
W. Y. Ching,2
T. Yamamoto,3
Y. Ikuhara1
Impurity doping often alters or improves the properties of materials. In alumina, grain boundaries play a key role in deformation mechanisms, particularly in the phenomenon of grain boundary sliding during creep at high temperatures. We elucidated the atomic-scale structure in alumina grain boundaries and its relationship to the suppression of creep upon doping with yttrium by using atomic resolution microscopy and high-precision calculations. We find that the yttrium segregates to very localized regions along the grain boundary and alters the local bonding environment, thereby strengthening the boundary against mechanical creep.
1 Institute of Engineering Innovation, University of Tokyo, 2-11-16, Yayoi, Bunkyo, Tokyo 113–8656, Japan.
2 Department of Physics, University of Missouri–Kansas City, 5100 Rockhill Road, Kansas City, MO 64110–2499, USA.
3 Department of Advanced Materials Science, University of Tokyo, 5-1-5, Kashiwanoha, Kashiwa, Chiba 277–8561, Japan.
* Present address: Department of Materials Science and Engineering, Kyoto University, Yoshida-Honmachi, Sakyo, Kyoto 606–8501, Japan.
To whom correspondence should be addressed. E-mail: ikuhara{at}sigma.t.u-tokyo.ac.jp
