Formation of 3D CrC through solid state reaction-mediated Al extraction within CrAlC/Cu thin films.

We report on the formation of the CrC compound using chemical etching-free methodology to extract Al from a CrAlC MAX phase thin film. CrAlC/Cu assemblies were deposited on sapphire substrates, using magnetron sputtering, and were subsequently annealed in vacuum. The Al from the MAX phase was shown to diffuse into Cu resulting in the formation of AlCu and causing the MAX phase to collapse into CrC grains. These carbide grains were characterized by transmission electron microscopy and the interatomic distances extracted were in good agreement with calculations predicting the equilibrium volume of the CrC phase.