Field ion microscopy investigations of grain boundary topography

Abstract

Abstract Field ion microscopy in conjunction with computer graphics has been used to study the topography of a number of grain boundaries. Nearly all of the boundaries observed showed a tendency toward the existence of relatively wide expanses of planar regions. In some cases, hills connecting planar regions appeared. Also, in some cases, small ridges, valleys, pits, and protrusions were superimposed on the planar regions. In at least one case the ridge-valley structure seemed to be periodic. Stereographic pole plots were also obtained for each boundary. These confirmed the tendency toward planarity, in that clustering of poles about particular orientations occurred. The characteristics observed were analysed in terms of lattice coincidence at the boundary. It was found that in three out of four cases examined there was correlation with the coincidence model. In the fourth case the boundary planes were planes of low coincidence and were low-index planes in the crystal lattice.