Synergistic effect of Pt and Hf on the early-stage oxidation behaviour of NiAl coating at 1000 °C
Y.F. Yang, Shuai Ren, Changguang Deng, Peng Ren, Pimin Zhang, Ru Lin Peng, Zebin Bao, W. Li
Abstract
The initial-stage oxidation behaviours of unmodified, Pt and Pt+Hf modified NiAl coating are systematically investigated by employing the photo-stimulated luminescence spectroscopy (PSLS) and transmission electron microscopy (TEM) technique. Both Pt and Hf additions can retard the θ- to α- Al2O3 phase transformation. The oxidation rates of the modified NiAl coatings are initially higher than that of the unmodified NiAl coating due to the longer presence of θ-Al2O3. However, they decrease drastically when the oxide in the scale turns to be α-Al2O3 dominantly. The delayed phase transformation in the modified coatings results in lower residual stress within the oxide scale.