
Accession Number : ADA184808
Title : Study of Boundary Structures.
Descriptive Note : Final rept. 1 Apr 8331 Jul 87,
Corporate Author : WASHINGTON UNIV SEATTLE DEPT OF MATERIALS SCIENCE AND ENGINEERING
Personal Author(s) : Kikuchi, Ryoichi
PDF Url : ADA184808
Report Date : 31 Jul 1987
Pagination or Media Count : 17
Abstract : The project extends previous studies on structures of a 2D grain boundary (g.b.). The basic analytical tool is the cluster variation method (CVM) and the path probability method (PPM), both developed by the author. In the CVM, the free energy is minimized with respect to a large number of variables using a linear iteration method called the natural iteration method (NIM). A square lattice is chosen as the basic lattice (called the DSC lattice) of the analysis. The first, second, and third nearest neighbor pairs are excluded due to a large repulsion. The fourth and fifth neighbors contribute interaction potentials E(4,AB) and E(5,AB), and so on. In the DSC lattice the CVM is formulated using a cluster made of nine lattice points in the form of a quadruple square. The QS formulation leads to numerical results that are reliable compared with the MC method. In low temperatures, atoms hardly deviate from the skeletal stable crystalline structure. The pair method is found to give reliable numerical results practically the same as those of QS for low temperatures including the entire ordered phase in the work D. This result is significant because when the pair method is used, the two sides of the g.b. do not need to be oriented symmetrically as were done in the present report. Applications of this point of view for g.b. of different angle combinations and the 3D cases are now planned.
Descriptors : *GRAIN STRUCTURES(METALLURGY), *GRAIN BOUNDARIES, *LATTICE DYNAMICS, VARIATIONAL METHODS, MELTING, LOW TEMPERATURE, TOUGHNESS, STRENGTH(MECHANICS), DIFFUSION, STATISTICAL MECHANICS, ITERATIONS
Subject Categories : Metallurgy and Metallography
Distribution Statement : APPROVED FOR PUBLIC RELEASE