The oxidation behavior of the bond coat is improved using a HVOF
nanostructured NiCrAlY coating. NiCrAlY powder is mechanically cryomilled
and HVOF sprayed onto Ni-based alloy to form a nanocrystalline bond coat.
Oxidation is performed on the coating to form the thermally grown oxide
layer (thermally grown oxide). After heat treatment at 1000.degree. C.
for 24 and 95 hour, a homogeneous .alpha.-Al.sub.2O.sub.3 layer is formed
on top of the bond coat. The nanostructured characteristic of the coating
and the presence of Al.sub.2O.sub.3 within the cryomilled powders
(oxidation occurred during cryomilling process) affects the nucleation of
the alumina layer on the top of the coating. The formation of a
continuous thermally grown oxide layer protects the coating from further
oxidation and avoids the formation of mixed oxide protrusions, such as
those presented in the coating sprayed using the as-received powder.