HRTEM study of a Cu/Al2O3interface

Abstract

The interface between Cu and faceted particles of a cubic Al₂O₃ phase in an internally oxidized CuAl alloy was studied by HRTEM. Image simulations indicate that the Al₂O₃ precipitates have a highly disordered spinel-type structure. The precipitates grow by ledge migration and possess internal defects, mainly coherent twin boundaries and stacking faults. At the Cu/Al₂O₃ interface, two orientation relationships were observed: ‘parallel topotaxy’ and ‘twin topotaxy’. The interface was always parallel to {111} planes of the Al₂O₃. No localized misfit dislocations were observed either by HRTEM or by weak beam dark field electron microscopy. The atomistic configuration at the interface is well described by a rigid lattice model assuming that a partially occupied oxygen layer terminates the Al₂O₃.