Environmental Engineering Reference
In-Depth Information
Formation of Mutually Insoluble Oxides
For some alloy systems, the oxides, AO and BO, may for all practical purposes
be considered immiscible. However, under equilibrium conditions, the oxides
will be mutually doped with the other cation. Classic examples of such binary
alloy systems are Cu-Zn (forming Cu
2
O/CuO and ZnO), Cu-Ni (forming Cu
2
O/
CuO and NiO), Cu-Be (forming Cu
2
O/CuO and BeO), etc. As an illustration,
the behavior of Cu-Be alloys is discussed. The scale morphologies developed
for different concentrations of Be and the oxidation mechanism are presented
schematically in Fig. 6.13. Maak [29] studied the oxidation behavior of a number
of Cu-Be alloys in air with 0.08-12.6 at. % Be at 1123 K. Alloys containing up
to 6.7 at. % Be were found to oxidize at the same rate as pure copper. The oxide
(a)
(b)
Figure 6.13
(a) Schematic presentation of the scale morphologies developed in differ-
ent Cu-Be alloys oxidized in air at 1123 K. (b) Schematic illustration of oxidation mecha-
nism in Cu-Be alloys [2].
