| Abstract: | The effect of 0.6 wt.% yttrium addition on the oxidation behaviour of the coating material Ni-23Co-19Cr-12Al was studied under isothermal and thermal cycling conditions in air at 1373 and 1473 K. The reaction was followed thermogravimetrically while the SEM, EDX, EPMA and X-ray diffraction techniques were used to characterise the starting materials and the oxidized samples. Intensive spalling and the formation of a deep internal oxidation zone were observed in the case of the yttrium-free alloy. Yttrium strongly improved the oxidation resistance by substantial suppression of scale spalling and considerable reduction of internal oxidation. |
