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Equilibrium Amorphous Silicon–Calcium–Oxygen Films at Interfaces in Copper–Alumina Composites Prepared by Melt Infiltration
Author(s) -
Scheu Christina,
Dehm Gerhard,
Kaplan Wayne D.
Publication year - 2001
Publication title -
journal of the american ceramic society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.9
H-Index - 196
eISSN - 1551-2916
pISSN - 0002-7820
DOI - 10.1111/j.1151-2916.2001.tb00710.x
Subject(s) - materials science , copper , transmission electron microscopy , amorphous solid , microstructure , composite material , silicon , porosity , phase (matter) , mineralogy , crystallography , metallurgy , nanotechnology , chemistry , organic chemistry
The microstructure of copper–alumina (Cu‐Al 2 O 3 ) composites that have been prepared via the melt infiltration of liquid copper into porous alumina preforms was studied in detail, using various transmission electron microscopy (TEM) techniques. Two different samples—with open pore diameters of 0.2 and 0.8 μm—were investigated. For both specimens, a single crystalline copper network that extended throughout the open porosity of the alumina preform was observed. An amorphous glass phase that contained silicon and calcium was observed at the Al 2 O 3 /Cu/Al 2 O 3 triple junctions. The diameters of these amorphous pockets, which were strongly faceted along the Al 2 O 3 grains, were up to 20 and 100 nm for the initial pore sizes of 0.2 and 0.8 μm, respectively. A glass phase that contained silicon and calcium also was present at the Cu/Al 2 O 3 interfaces, whereas the Al 2 O 3 boundaries remained dry. Detailed high‐resolution transmission electron microscopy investigations have shown that the interfacial glass phase at the Cu/Al 2 O 3 interfaces exhibited a uniform equilibrium film thickness along the interface region. However, the interfacial film thickness was dependent on the orientation of the Al 2 O 3 grain, and its value varied from 0.4 nm for Al 2 O 3 rhombohedral‐plane termination ((1¯012)) up to 1 nm for Al 2 O 3 basal‐plane termination ((0001)).