ORIENTATION AND POSITION ACCURACY OF ELECTRON DIFFRACTION.

Abstract

The misorientations existing between subgrains are of critical importance in understanding the nucleation and growth of recrystallised grains. In this paper it is demonstrated that, because of spherical aberration and focus error in the objective of a conventional 100 kV electron microscope, the accuracy of beam direction determination is a function of the size of the area selected, when this area is small. For beam direction determination to within 2 degree accuracy over the whole unit triangle using a modern 100 kV microscope, the minimum area must be greater than 1. 5 mu m diameter. The implications of this on previous conventional Selected Area Diffraction deformation textures studies, where the subgrain size is typically about 2,500 A, are discussed.