Microstructure degradation of simple, Pt- and Pt + Pd-modified aluminide coatings on CMSX-4 superalloy under cyclic oxidation conditions

► Microstructural aspects of high temperature oxidation degradation are analyzed. ► Three types of oxides formed on the coatings during cyclic oxidation tests ► Pt and Pt-Pd incorporation significantly increases the stability of the β-NiAl phase. ► Pt and Pt-Pd modified aluminide coatings maintain more stable α-alumina oxide layer. ► Considerable stresses form in the Al-depleted β-NiAl phase due to Pt and Pd incorporation.