T. Takasugi et al., HIGH-RESOLUTION ELECTRON-MICROSCOPY OF GRAIN-BOUNDARIES IN NI-3(AL0.8TI0.2) BICRYSTALS .2. COINCIDENCE SITE LATTICE BOUNDARIES, Philosophical magazine. A. Physics of condensed matter. Structure, defects and mechanical properties, 75(5), 1997, pp. 1417-1434
The grain-boundary structure of Sigma = 5, [001] (36.8 degrees), Sigma
= 25, [001] (16.26 degrees) and Sigma = 3, [011] (109.47 degrees) coi
ncidence site lattice (CSL) tilt boundaries in the Ll(2)Ni(3)(Al0.8Ti0
.2) bicrystals prepared by hot pressing were investigated by high-reso
lution transmission electron microscopy with the help of image simulat
ion. An atomic arrangement in the Sigma = 5, [001] (36.8 degrees) boun
dary is asymmetric with a small quantity of rigid-body translation; ac
commodation of atoms is small and is localized on a near-grain-boundar
y plane. An atomic arrangement in the Sigma = 25, [001] (16.26 degrees
) boundary is asymmetric without appreciable rigid-body translation; s
ome atoms are withdrawn and it is interpreted as an array of dissociat
ed (a/2)(110) superpartials. An atomic arrangement in the Sigma = 3, [
011] (109.47 degrees) boundary is primarily symmetric, and local accom
modation of atoms and rigid body translation vary with deviation from
the grain-boundary plane. In the three CSL boundaries observed in this
study, atomic-size cavities are commonly observed.