Abstract
To study the effect of alloying elements on the growth stress of an oxide scale, a two side oxidation bending method has been developed, which has advantages over the one side oxidation bending method. Using the new method, the effect of yttrium on the growth stress of an Al2O3 scale formed during the oxidation of Co–30Cr–6Al sputtered coatings at 900°C in air has been studied. The results indicate that an ion implantation dose of 2×1017 Y+ cm−2 decreases the stress in the oxide scale by 1–2–GN–m−2. It is proposed that yttrium can promote plasticity in the oxide by mechanisms such as diffusion creep, so that the stress becomes lower due to relaxation. In the initial stages of oxidation, a transient change of stress is accounted for by the influence of yttrium on the oxidation of the coating.
MST/1589
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