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 Be₂C 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 Be₂C-C equilibrium at 1,573 ∼ 1,873 K and under the conditions of BeO-C equilibrium for normalized CO partial pressure π_CO = 0.01 and 1 at 1,423 ∼ 1,873 K. The activity coefficient of beryllium, γ_Be, 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 X_Be at 1,423 ∼ 1,873 K:
ln γ_Be = {[-1 582.1 (T / K) ^-1-1.9154 log (T / K) + 7.1103] × 10⁴ (±80)} · (1-X_Be)²
+ {[1 577.8 (T / K) ^-1 + 1.9154 log (T / K)-7.1089] × 10⁴ (±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.