Synthesizability of Sputtered Cr-Al-B and Ti-Al-B Coatings Studied by Theory and Experiment

The synthesizability of magnetron-sputtered Cr-Al-B and Ti-Al-B coatings is investigated by combining temperature-dependent Gibbs energy predictions with a critical experimental assessment. Experimental phase formation data are consistent with predictions that Cr2AlB2 formation is thermodynamically favored and Ti2AlB2 is prone to decomposition. The guided choice of synthesis temperatures ≤500 °C, substantially lower than those previously reported, yields significantly denser Cr2AlB2 coatings, enabling the first measurement of their mechanical properties. Hence, temperature-dependent Gibbs free energy predictions are valuable to assess the synthesizability of MAB phase coatings by magnetron sputtering provided diffusion is enabled.