Growth and properties of multi-layer nano CrAlN/TiAlN composite coating on the cermets with CrFeCoNiMo, CrFeCoNiMn, CrFeCoNiAl high entropy alloy phase

Abstract In the work, multi-layer nano CrAlN/TiAlN composite coating was deposited on the cermets with CrFeCoNiMo, CrFeCoNiMn, CrFeCoNiAl high entropy alloy phase. Growth and properties of the coating were systematically investigated. The results showed that CrAlN, TiAlN and Ti(C,N) possessed same crystal plane spacing as well as diffraction angles. Thus, higher possibility for crystallization of CrAlN (2 0 0), TiAlN (2 0 0) plane on Ti(C,N) phase were obtained rather than on the binder phase. For cermets with CrFeCoNiAl, little white binder phase and smallest grains attributed to the densest and thinnest coatings on the cermets with CrFeCoNiAl. TEM revealed that columnar CrAlN monolayer exhibited a thickness of 23.4 nm and TiAlN showed thickness of 1.2 nm. Crystal planes of (0–2 0) for CrAlN was exactly parallel to (0–2 0) of core-rim phase, showing an epitaxial growth characteristic. The domain-matching epitaxy took place when the CrAlN layer was deposited on the Ti(C,N) phase, where lattice planes matched across the interface to release the mismatch strain. Besides, the multi-layer nano CrAlN/TiAlN coating deposited on the cermets with CrFeCoNiAl achieved the highest average nano-hardness of 33.4 Gpa, Young’s modulus of 445.3 Gpa and best adhesion strength of 68.11 N due to the dense and smooth coating microstructure.