Cyclic oxidation of an ultrafine-grained and CeO2-dispersed δ-Ni2Al3 coating

A novel ultrafine-grained and CeO2-dispersed δ-Ni2Al3 coating was fabricated through aluminizing a CeO2-nanoparticle-dispersed nanocrystalline Ni matrix film using an NH4Cl-activated pack cementation method at 600 °C. Two CeO2-free δ-Ni2Al3 coatings, one coarse-grained and the other ultrafine-grained, were also prepared. Compared with the later, the ultrafine-grained and CeO2-dispersed coating profoundly increased scale spalling resistance during cyclic oxidation in air at 1000 °C. The dispersed CeO2, together with the ultrafine-grained coating structure, helped prevent the formation of cavities at the scale/coating interface, which was proposed as a main cause for improvement of the cyclic oxidation resistance.