Grain Boundary Strengthening in Alumina by Rare Earth Impurities

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Science  13 Jan 2006:
Vol. 311, Issue 5758, pp. 212-215
DOI: 10.1126/science.1119839

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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.

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