MOLECULAR DYNAMICS APPROACH OF THE [001] TWIST GRAIN BOUNDARIES ENERGY IN Cu

Using the Molecular Dynamics technique the energy E vs the misorientation θ has been calculated for the CSL [001] twist grain boundaries in Cu. Two potentials have been used ; the Morse potential and a spline potential constructed by Englert and Tompa for Cu. In each case the low and high angle grain boundary regions have been clearly distinguished by using the relation E=E0θ(A-lnθ), valid for low angle grain boundaries. To this relation a polynomial has been added, in order to describe the energy vs misorientation dependence in the range (0,450)

GRAIN BOUNDARIES ANALYSIS IN POLYCRYSTALLINE SILICON BY TEM

Des interfaces de Si polycristallin ont été examinées en utilisant le modèle CSL. La relation de rotation de chaque bicristal a été analysée par la technique du système instrumental et la description du petit angle a été apliquée pour la caractérisation des CSL du Si. Le plus souvent, on observe des Σ = 3 joints de macles cohérents ou incohérents, les derniers étants cohérents dans le sens microscopique. Des cas des joints de grains multiples ont ete examinés également et des relations entre eux pour CSL avec Σ > 3 ont été établies. Un exemple intéressant est le Σ = 39 qui se forme par combinaison du Σ = 13b avec Σ = 3 et c'est un CSL triclinique sans opération de rotation de 180°. Les résultats qu'on présente ici justifient l'utilisation du modèle CSL à la description des interfaces du Si polycristallin.Polycrystalline Si interfaces were examined within the CSL's approach . The rotation relationship of every bicrystal has been analyzed with the technique of the instrumental system and the small angle description has been used for the CSL characterization.The most frequently occuring descriptions are CSL's Σ = 3 coherent and incoherent twins, the later being microscopically coherent. Cases of multiple boundaries were also examined and interelations were found between low or high angle boundaries for CSL's with Σ > 3. A special case of interest is a Σ = 39 CSL which i s formed from a combination of Σ = 13b and Σ = 3 and is a triclinic CSL lacking 180° rotational operations. The results presented indicate that for polycrystalline Si the CSL model could be used in describing the interfaces occuring

INTERFACE JUNCTIONS AND SIMMETRY

Des jonctions triples de haute symétrie sont examinées par MET dans le silicium. Les propriétés de symétrie des grains et de leurs interfaces sont étudiées sur base du modèle de CSL. Des jonctions de flexions suivant ˂110˃ de type Σ(3,3,9), Σ(3,9,27a), et Σ(3,27a,81d) sont examinées ; elles contiennent toutes une Σ=3 avec interface {111}. La relation des interfaces avec les CSL et la symétrie des jonctions triples est analysée en details.High symmetry triple junctions in polysilicon observed by TEM are presented. The symmetry properties of their grains and interfaces are studied with the use of the CSL model. The examples concern triple junctions of ˂110˃ tilt boundaries with the CSL configurations of Σ(3,3,9), Σ(3,9,27a) and Σ(3,27a,81d). In all the cases the Σ=3 twin with interface the {111} plane is at least one of the components. The connection of the interfaces with the CSLs and the symmetry of the triple junction is analytically discussed

INTERFACIAL DEFECTS IN NiO-ZrO2 (CaO) EUTECTIC

Des interfaces lamellaires dans l'eutectique obtenu par solidification dirigée (ESD) NiO-ZrO2(CaO) ont été étudiées par des techniques optiques électroniques. Plusieurs défauts caracteristiques à l'interface ont été analysés et interprétés à l'aide de considérations géometriques. Une attention particulière est portée aux défauts topographiques et à leurs caracteristiques structurales et fonctionnelles.Lamellar interfaces in the NiO-ZrO2(CaO) directionally solidified eutectic (DSE) have been investigated using electron optical techniques. Several characteristic interfacial defects have been analyzed and discussed invoking geometric arguments. Special attention is given to the topographical defects and their structural and functional characteristics

CUBIC [001] TWIST CSL GRAIN BOUNDARIES STUDY BY MEANS OF RANDOM WALK

The random walk procedure has been applied on some typical relaxed CSL twist grain boundaries. The relaxation has been achieved by means of the Molecular Dynamics method, applied on the CSL computational cells. Some of the random walk parameters are discussed and the information dimension is examined as a function of the rotation angle θ. The remarkable anisotropy observed in the parameters between the grain boundary and the bulk is common to many dynamical properties of the grain boundaries