Defect processes of M3AlC2 (M = V, Zr, Ta, Ti) MAX phases

The interest on the Mn+1AXn phases (M = early transition metal; A = group 13-16 element and X = C and/or N) stems from their combination of advantageous metallic and ceramic properties. Aluminium containing 312 MAX phases in particular are deemed to enhance high-temperature oxidation resistance. In the present study, we use density functional theory calculations to study the intrinsic defect processes of M3AlC2 MAX phases (M = V, Zr, Ta, Ti). The calculations reveal that Ti3AlC2 is the more radiation tolerant 312 MAX phase considered here. In Ti3AlC2 the carbon Frenkel reaction is the lowest energy defect process with 3.17 eV. Results are discussed in view of recent experimental and theoretical results of related systems.