Combined high-resolution electron microscopy and computer modeling of a ?=5 (210) [001] tilt boundary in AuCu3

Abstract

Combined high-resolution electron microscopy, computer modeling, and image simulations are used to study the structure of the 27 --5 (210) [001] tilt boundary in the ordered compound AuCu3. On the experimental side, we have prepared thin samples cut in a bulk bicrystal containing an interface close to the above (Otilt ~ 37~ The high-resolution images obtained at 400kV along the [001] tilt axis show that among possible configurations, the boundary adopted predominantly a symmetrical one. Theoretically, using the standard geometrical approach, we derived possible atomic configurations of the boundary and we identified some of the defects allowing for the coexistence between these variants. Finally, we performed energy minimizations using these geometrical models and an n-body potential adapted to this compound. In agreement with the experiment, one of the two possible symmetrical variants is associated to the lowest excess energy. Moreover, the computations show that large variations affect the spacing of (210) atomic planes near the boundary.