Phase diagram features and solidification behaviour of CoCu2O3 at elevated oxygen pressure

A unique behaviour of the phase CoCu2O3 was found both from CALPHAD calculations and directional solidification experiments. For elevated oxygen partial pressure the solidification mode changed from double-peritectic to a congruent melting behaviour with respect to the metals (Cu, Co) and to the oxygen content. This transition predicted by the phase diagram calculations was confirmed by microstructure and phase analyses of samples solidified at oxygen pressures up to 60 bar. A DTA analysis has verified basic features of the phase diagram at normal pressures.