AIR OXIDATION OF TWO-PHASE Cu-Co ALLOYS AT 600～800℃
双相Cu—Co合金在600—800℃空气中的氧化

The air oxidation of three -phase Cu-Co alloys namely Co-25 % , 50 % and 75 % GI was studied at 600 -800°C . The scaling kinetics follows only approximately the parabolic rate law, with rate constants isothemlly increasing with the Cu content. All the alloys fom ccmposite scales containing canplex mixtures of GI and Co oxides, where Cu concentrates preferentially in the external regions. Beneath the external scales there is in mt cases a region of a mixed Cooxide and Cu metal : for alloys containing up to 50 % GI this >k' ' one corresponds to the internal oxidation of Co, while for the alloy containing 25% GJ it is a Co oxide ma& "'"ctmtaining dispersion of isolated Cu particles. At variance with the behavior of solid-solution binaw alloys, Co is 'k~depleted in the alloy beneath this region in spite of its preferential local oxidation. The peculiar structure of tthe scales formed on these alloys is interpreted by considering their -phase nature.