Cr2AlC and metals reactivity: Sintering and oxidation

Cr2AlC-20 wt% (Sn; Cu; Co; Fe; Ag) powder mixtures were hot isostatically pressed at 1000 degrees C for 4 h under 150 MPa to investigate the possible alloying behaviour of the metals with the MAX phase. The as-synthesized bulk materials were further oxidized at 1000 and 1200 degrees C for 10 h under dry air flux to study the effect of the alloying on the oxidation performance of the MAX phase. The metallic elements did not dissolve into the MAX phase grains: they mainly acted as oxidizing agents on the MAX phase grains, draining the aluminum from it to form intermetallic phases. The oxidation tests resulted in the formation of an alumina scale for most of the samples. The oxidation kinetic study shows no improvement of the oxidation behaviour of the Cr2AlC-metal composites as compared to pure bulk Cr2AlC. Sn spheres embedded in an alumina layer and empty alumina shells are respectively observed on the surface of the oxidized Cr2AlC-Sn and Cr2AlC-Ag composites.