The effects of various pre-oxidation treatments on the Type II (i.e., 700ºC) hot corrosion resistance of
novel Pt+Hf-modified ?'-Ni3Al + ?-Ni alloys and coatings were studied and compared to a state-of-theart
Pt-modified ß-NiAl coating. The pre-oxidation treatments were carried out in air and in Ar
atmospheres at temperatures of 700, 1080, and 1100oC and for times of 1, 6, and 24h. It was found that
pre-oxidation in air at higher temperatures and for a shorter period was quite beneficial in improving hot
corrosion resistance of the Pt+Hf-modified ?' + ? alloys and coatings. In fact, the results suggested that
the oxide scale formed with such a treatment was much more protective than the Ar and longer-term air
pre-oxidation treatments. It was also found that with an optimum pre-oxidation treatment, a Pt+Hfmodified
?'+? coating exhibited superior hot corrosion resistance compared to a Pt-modified ß coating.