Atomic structure of a tilt grain boundary in aluminum by HREM

Abstract

A knowledge of the atomic structure of grain boundaries is central to a better understanding of the properties of polycrystalline materials. Attempts to predict grain boundary structure have so far led to the development of various geometrical models for grain boundaries. The concepts of coincident site lattice (CSL) (1), displacement shift complete (DSC) lattice (2,3,4) and the 0-lattice model (2), based on geometrical constructions of adjoining crystals forming boundaries, have been found useful in characterizing the structure of ideal grain boundaries. These models give suggestions regarding the atomic relaxation that occurs at the core of the boundary in the form of dislocations. The 0-lattice model is particularly useful in describing the primary dislocation content of low angle grain boundaries. In this paper the authors present a high resolution electron microscopy investigation of the core structure of a 6[degree][001] symmetrical tilt grain boundary in aluminum. For the first time the atomic structure of such a grain boundary in an FCC metal is resolved. The boundary structure obtained from the HREM images is compared to the corresponding structure predicted by the 0-lattice model and found to be in excellent agreement.