Accession Number : AD0756884

Title :   Coincidence Structural Unit Models for Grain Boundaries in HCP Metals.

Descriptive Note : Technical rept.,

Corporate Author : ARMY MATERIALS AND MECHANICS RESEARCH CENTER WATERTOWN MASS

Personal Author(s) : Bruggeman,Gordon A. ; Bishop,George H. , Jr. ; Hartt,William H. , III

Report Date : FEB 1972

Pagination or Media Count : 46

Abstract : CUPY EXACT COINCIDENCE SITES BUT INSTEAD OCCUPY COMPROMISE POSITIONS BETWEEN TWO NEARLY COINCIDENT LATTICE SITES. This extension allows one to define near-coincidence-site lattices (near-CSL's) from which are derived short-period near-coincidence structural units. Exact and near-CSL's in the common hcp metals are tabulated for rotations about (0001), <1,0,-1,0>, and <1,1,-2,0>, and short-period coincidence structural units are presented. Geometric models of a variety of symmetric and asymmetric <1,0,-1,0> tilt boundaries are developed as examples to show how a relatively few coincidence structural units are combined in the structures of both simple and complex boundaries. Although hcp boundaries are treated here, the approach is quite general and can be applied to any crystal structure. (Author)

Descriptors :   (*GRAIN BOUNDARIES, METALS), DISLOCATIONS, CRYSTAL LATTICES, TITANIUM

Subject Categories : Metallurgy and Metallography
      Crystallography

Distribution Statement : APPROVED FOR PUBLIC RELEASE