Thermodynamic analysis of internal oxidation of Cu-Al alloy

Thermodynamic requirements of internal oxidation of Cu-Al alloy were systematically analyzed, and the area chart of internal oxidation thermodynamics was drawn at the same time. Results indicate that the preferential oxidation area is quite large in the area chart, which is determined by the maximum and minimum partial pressure of oxygen, where 1g P-O1(max) = (-17 611/7)+12.91, 1g P-O2(min) = (-55 830/T)-(4/3)1g[%Al]+19.95. But the practical internal oxidation area is a small part of the preferential oxidation area below the maximum partial pressure of oxygen. The volume concentration product K,, and concentration of residual aluminum are such extreme minimum values that the internal oxidation can be proceeded completely. Temperature and partial pressure of oxygen should be adjusted synchronously during the control of internal oxidation. The optimum technology of internal oxidation is the adoption of high temperature of about 1 223 K, and high partial pressure of oxygen that should approach to or even be equal to the upper limit of oxygen partial pressure. Cold snap in hydrogen should be used to prevent the oxidation of copper during cooling.