STRUCTURAL ANALYSIS AND PROPERTIES OF GRAIN BOUNDARIES IN HEXAGONAL CARBIDES

1 October 1988

journal article
Published by EDP Sciences in Le Journal de Physique Colloques

Vol. 49 (C5) , C5-271
https://doi.org/10.1051/jphyscol:1988531

Abstract

Grain boundaries in tungsten carbide crystals (hexagonal structure c/a = 0.976) show many coïncidence orientations. The most frequent orientation has a coïncidence index Σ = 2. H.R.E.M. images of such grain boundaries have been realized. These grain boundaries show a defect structure, only due to the mismatch of the a and c parameters. These defects consist of dissociated 1/61 or 1/2 2 dislocations regularly spaced. An atomic step is associated with each dislocation. This particular grain boundary can be described as a Σ = 2 (c/a = 1) grain boundary with a periodic structure of dislocations or as a Σ = 39 (c/a = 0.975) grain boundary with a 1°5 deviation to the exact coïncidence orientation

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