Distribution of grain boundaries in magnesia as a function of five macroscopic parameters

A semi-automated method has been used to measure all five macroscopically observable parameters of 4.1 x 10(6) boundary plane segments making up 5.4 mm(2) of boundary area in a hot-pressed magnesia polycrystal. The observations allow a complete description of the distribution of crystal orientations, grain boundary misorientations, and the crystallographic orientations of grain boundary planes. Among the low misorientation angle grain boundaries, there is a preference for tilt boundaries, especially those with boundary plane normals in the <110> direction. At all fixed misorientations, there is a preference for boundaries with a boundary plane normal in the <100> direction. These boundaries are generally asymmetric and occur at least twice as frequently as the average boundary for each fixed misorientation. (C) 2003 Acta Materialia Inc. Published by Elsevier Science Ltd. All rights reserved.