Thermodynamic Analysis of Copper-Beryllium Alloy Production.

Abstract

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 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] × 104 (±80)} · (1-XBe)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.