Atomic Scale Studies of Segregation at Ceramic/Metal Heterophase Interfaces

Atom-probe field-ion microscopy was used to measure quantitatively ${\gamma }_{\mathrm{Ag}}$, the absolute values of the Gibbsian interfacial excess of Ag, at semicoherent MgO/Cu(Ag) $\{222\}$ heterophase interfaces. Atomically clean metal oxide/metal heterophase interfaces were obtained by internal oxidation of a pure ternary Cu(Mg,Ag) single-phase alloy to produce octahedral-shaped MgO precipitates, 10 to 30 nm in diameter, in a single-phase Cu(Ag) matrix. The measured value of ${\gamma }_{\mathrm{Ag}}$ at 500 °C is $(2\pm 0.6)\times {10}^{15}$ atoms c${\mathrm{m}}^{–2}$.