Part II. Oxidation of yttrium doped Cr2AlC films in temperature range between 700 and 1200 degree C

The isothermal oxidation behaviour of Cr2AlC films deposited with 0.1-0.3 at.%Y addition on alumina substrates was investigated at temperatures between 700 and 1200 degree C for hold times of 1 to 30 h. It was found that the Y atoms impede the bulk diffusion of Al and Cr atoms and, thus, the initial transformation of the disordered solid solution (Cr, Al)2Cx to the ordered Cr2AlC-MAX phase. It also reduces the oxidation rate of the ordered Cr2AlC-MAX phase and promotes the alpha -Al2O3 phase formation relative to the other alumina on the surface and leads to better adhesion of the layers. 0.3 at.%Y was found to promote the formation of alpha -Al2O3 relative to the other possible phases most strongly for 700-900 degree C. However, 0.2 at.%Y addition was found to cause the best oxidation resistance at 1200 degree C. The model introduced in part I was developed further.