The effect of an Al2O3 dispersion on the adhesion of Al2O3 scales on aluminized Co-10% Cr alloys

The beneficial effect of dispersions of reactive-metal oxide particles on the adhesion of Cr₂O₃ and Al₂O₃ scales formed on heat-resisting alloys is wellknown. It has been shown that an Al₂O₃ dispersion in an alloy can improve the adhesion of a Cr₂O₃ scale, and it is of particular interest in assessing the various theoretical proposals for the effect to determine whether such a dispersion can affect the adhesion of an Al₂O₃ scale. In this investigation, a Co–10% Cr–1 % Al alloy was first internally oxidized to form an Al₂O₃ dispersion. This alloy was then aluminized so that on subsequent oxidation an Al₂O₃ scale developed. It was shown that the dispersion did indeed improve the scale adhesion. The implications of this result are discussed.