INVESTIGATION OF THE INTERFACE STRUCTURE OF CU/OXIDE PRECIPITATES IN AN INTERNALLY OXIDIZED CU-AL ALLOY

Theta-Al2O3, alpha-Al2O3 and CuAlO2 precipitates were found in an internally oxidized Cu-2.6wt.% Al alloy. The orientation relationships between these oxides and the matrix Cu were deter-mined from the selected area diffraction technique. The theta-Al2O3 has a monoclinic structure and the orientation relationship between the matrix Cu and theta-Al2O3 was determined to be [211]Cu//[132BAR]theta and (113BAR)Cu//(201BAR)theta. The CuAlO2 is a hexagonal crystal structure. The orientation relationship between Cu and CuAlO2 was determined to be [110]Cu//[1100BAR]CuAlO2 and (113)Cu// (0001)CuAlO2. The interphase boundary plane between matrix Cu and both oxides are near (113)Cu. An alphaAl2O3 oxide observed within a CuAlO2 precipitate had the orientation relationships [1100]CuAlO2//[2110BAR]alpha and (0001)CuAlO2//(0001)alpha. The high resolution imaging technique was applied to study the atomic structure of a Cu/CuAlO2 interface. The image simulation suggests that the terminated plane of CuAlO2 in the interphase boundary is an oxygen plane. The Cu atoms in (113BAR)Cu are all in 'lock-in' position in the interface.