![Sample our Physical Sciences journals, sign in here to start your FREE access for 14 days]({"type":"image" , "src" : "/sda/110819/TOC-Subject-Sample-2021-Physical-Sciences.jpg"})
Abstract
Interfacial defects, such as grain boundary dislocations, play an important role in the creep behavior of alumina. In the present work, interfacial defects are analyzed in detail using a Volterra approach without a reference to a near-coincidence description. We investigate disconnections (boundary steps with dislocation character) in a diffusion-bonded alumina bicrystal, with a misorientation close to the rhombohedral twin, by conventional and atomic resolution electron microscopy. The bicrystal contains two arrays of parallel disconnections with Burgers vectors that have alternating equal and opposite twist components, so there is no long-range stress field. This configuration is discussed in terms of the stability of different grain boundary disconnection arrangements. The complex core structure of the defects is revealed by high resolution electron microscopy using exit wave reconstruction. It is shown that the defects are dissociated into two partials that delimit grain boundary segments with alternating structure.
Acknowledgements
E.A. Stepantsov and A.L. Vasiliev from the Institute of Crystallography of Moscow are gratefully acknowledged for preparation of the bicrystals. The authors also thank U. Dahmen, R.C. Pond and J. Thibault for fruitful discussions and L. Priester for her critical reading of the manuscript. The National Center for Electron Microscopy is supported by the Director, Office of Science, Office of Basic Energy Sciences, Materials Sciences and Engineering Division of the US Department of Energy under Contract No. DE-AC02-05CH1123. A. Serra acknowledges funding from MCyT project *FIS2006-12436-C02-02.
