The thermodynamics of the Cu-Be-C-O system was studied in wide ranges of temperature and alloy composition, considering the importance of the minimization of Be
2C and BeO formation in Cu-Be alloy production.
The equilibrium relation of molten Cu-Be-C-O system was determined by conducting the following experiments: the solubility measurements of beryllium in molten copper under the conditions of Be
2C-C equilibrium at 1,573 ∼ 1,873 K and under the conditions of BeO-C equilibrium for normalized CO partial pressure
πCO = 0.01 and 1 at 1,423 ∼ 1,873 K. The activity coefficient of beryllium,
γBe, in liquid Cu-Be alloys with respect to pure liquid beryllium as the standard state was also determined as a function of temperature
T and mole fraction of beryllium
XBe at 1,423 ∼ 1,873 K:
ln
γBe = {[-1 582.1 (
T / K)
-1-1.9154 log (
T / K) + 7.1103] × 10
4 (±80)} · (1-
XBe)
2+ {[1 577.8 (
T / K)
-1 + 1.9154 log (
T / K)-7.1089] × 10
4 (±80)}
Additionally, the activity of beryllium in solid Cu-Be alloys was determined by an EMF method at 973 ∼ 1,073 K to establish a partial stability diagram of the solid Cu-Be-O system.
Based on the results obtained, the operational conditions of the current Cu-Be alloy production process were also examined from a thermodynamic viewpoint. At the same time, several methods for improving the process were proposed.
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