Towards large area deposition of Cr2AlC on steel

Cr2AlC belongs to the MAX phases, which are promising materials for protective coatings on steel due to their unique combination of properties like corrosion and oxidation resistance, good electrical conductivity, low friction coefficient, damage tolerance, and high temperature stability. Here the deposition of Cr2AlC thin films has been carried out by magnetron sputtering of a Cr2AlC compound target. The effect of the substrate temperature on the constitution was investigated. It was found that the MAX phase structure is stable in a substrate temperature range between 1123 K and 723 K. At lower substrate temperatures, the structure of the film is X-ray amorphous. A temperature of approximately 870 K was determined for the transition from amorphous to crystalline Cr2AlC using differential scanning calorimetry. A phase purity of more than 90% MAX phase in the films was reached and the equilibrium volume is in excellent agreement with our ab initio calculations. The here presented deposition method provides a pathway towards large area deposition of MAX phase Cr2AlC coatings on steel.