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Title: Atomic structures and compositions of internal interfaces

Technical Report ·
DOI:https://doi.org/10.2172/5347280· OSTI ID:5347280
 [1];  [2]
  1. Northwestern Univ., Evanston, IL (United States). Dept. of Materials Science and Engineering
  2. Argonne National Lab., IL (United States)

This research program addresses fundamental questions concerning the relationships between atomic structures and chemical compositions of metal/ceramic heterophase interfaces. The chemical composition profile across a Cu/MgO {l brace}111{r brace}-type heterophase interface, produced by the internal oxidation of a Cu(Mg) single phase alloy, is measured via atom-probe field-ion microscopy with a spatial resolution of 0.121 nm; this resolution is equal to the interplanar space of the {l brace}222{r brace} MgO planes. In particular, we demonstrate for the first time that the bonding across a Cu/MgO {l brace}111{r brace}-type heterophase interface, along a <111> direction common to both the Cu matrix and an MgO precipitate, has the sequence Cu{vert bar}O{vert bar}Mg{hor ellipsis} and not Cu{vert bar}Mg{vert bar}O{hor ellipsis}; this result is achieved without any deconvolution of the experimental data. Before determining this chemical sequence it was established, via high resolution electron microscopy, that the morphology of an MgO precipitate in a Cu matrix is an octahedron faceted on {l brace}111{r brace} planes with a cube-on-cube relationship between a precipitate and the matrix. First results are also presented for the Ni/Cr{sub 2}O{sub 4} interface; for this system selected area atom probe microscopy was used to analyze this interface; Cr{sub 2}O{sub 4} precipitates are located in a field-ion microscope tip and a precipitate is brought into the tip region via a highly controlled electropolishing technique.

Research Organization:
Northwestern Univ., Evanston, IL (United States). Dept. of Materials Science and Engineering
Sponsoring Organization:
USDOE; USDOE, Washington, DC (United States)
DOE Contract Number:
FG02-89ER45403
OSTI ID:
5347280
Report Number(s):
DOE/ER/45403-3; ON: DE92012136
Country of Publication:
United States
Language:
English