title: Subnanometer three-dimensional atom-probe investigation of segregation at MgO/Cu ceramic/metal heterophase interfaces.
abstract: Three-dimensional atom-probe (3DAP) microscopy has been applied to the study of segregation at ceramic/metal (C/M) interfaces. In this article, results on the MgO/Cu(X) (where X = Ag or Sb) systems are summarized. Nanometer-size MgO precipitates with atomically clean and atomically sharp interfaces were prepared in these systems by internal oxidation. Segregation of the ternary component (Ag or Sb) at the MgO/Cu heterophase interface was enhanced by extended low-temperature anneals. Magnesia precipitates in the 3DAP reconstructions were delineated as isoconcentration surfaces, and segregation of each ternary component at the C/M interfaces was analyzed with the proximity histogram method developed at Northwestern University. This method allows the direct extraction of the Gibbsian interfacial excess of solute at the C/M interfaces from the experimental data. A value of (3.2+/-2.0) x 10(17)m(-2) at 500 degrees C is obtained for the segregation of Ag at a MgO/Cu(Ag) interface, while a value of (2.9+/-0.9) x 10(18) m(-2) at 500 degrees C is obtained for the segregation of Sb at a MgO/Cu(Sb) interface. The larger Gibbsian excess for Sb segregation at this ceramic/metal heterophase interface is most likely due to the so-called pdeltaV effect.
authors.affiliation: Department of Material Science and Engineering, Northwestern University, Evanston, IL, USA. j-sebastian@northwestern.edu
authors.forename: J T
authors.initials: JT
authors.lastname: Sebastian
authors.forename: J
authors.initials: J
authors.lastname: Rüsing
authors.forename: O C
authors.initials: OC
authors.lastname: Hellman
authors.forename: D N
authors.initials: DN
authors.lastname: Seidman
authors.forename: W
authors.initials: W
authors.lastname: Vriesendorp
authors.forename: B J
authors.initials: BJ
authors.lastname: Kooi
authors.lastname: De Hosson JTh