Nitrogen pressure significantly impacts microstructures and mechanical properties of CrAlN coatings prepared by pulsed laser deposition

The effect of nitrogen pressure on the crystalline phase, composition, microstructure, and mechanical properties of chromium aluminum nitride (CrAlN) coatings prepared by pulsed laser deposition (PLD) and the underlying mechanism are clarified. All coatings exhibited a single-phase face-centered cubic crystal structure. Nitrogen pressure significantly impacts microstructures and mechanical properties of CrAlN coatings. As the nitrogen pressure increased, the coatings transitioned from a (200)-preferred orientation to a (111)-preferred orientation. The nitrogen content increase with increasing nitrogen pressure while the Cr/Al ratio of the coatings remains almost constant of 7:3. The coating fabricated at 10 Pa exhibits the highest hardness, modulus, elastic strain failure strength, plastic deformation strength, elastic recovery ratio/rate, adhesion force, and wear rate because of finer grain and denser structure. Particularly, its hardness (30.6 GPa) is higher than CrAlN coatings with the same Cr/Al ratio of 7:3 fabricated by other methods.