HREM study of dispersoids in cryomilled oxide dispersion strengthened materials

Abstract
Thin platelets (dispersoids) only a few atomic layers thick formed in cryomilled oxide dispersion strengthened aluminium, have been investigated by high-resolution electron microscopy (HREM). In order to interpret the experimental images, computer simulations of HREM images based on different structure models have been carried out. The image simulations have been used to determine the composition and the structure of the dispersoids. Two types of dispersoids have been found: one type consists of a single layer of nitrogen with the nitrogen atoms in tetrahedral positions in aluminium, the other type consists of one single layer of oxygen with the oxygen atoms in octahedral positions in aluminium.