Reactive HiTUS TiNbVTaZrHf-N_x Coatings: Structure, Composition and Mechanical Properties

Area of Science:

• Materials Science
• Surface Engineering
• Coatings Technology

Background:

• High entropy metal sub-lattice stabilized nitride coatings offer superior thermal, mechanical, and corrosion resistance for extreme environments.
• Multicomponent refractory transition metals (Ti, Nb, V, Ta, Zr, Hf) are key constituents in these advanced materials.

Purpose of the Study:

• Investigate the High Target Utilization Sputtering (HiTUS) technique for reactive sputtering of TiNbVTaZrHf-xN coatings.
• Analyze hysteresis behavior, structure, composition, stoichiometry, and mechanical properties of the resulting coatings.

Main Methods:

• Employed the novel High Target Utilization Sputtering (HiTUS) technique for reactive sputtering.
• Investigated hysteresis during sputtering and characterized coating properties (structure, composition, mechanical).
• Varied nitrogen content to study its effect on coating characteristics.

Main Results:

• Coating structures evolved from amorphous to textured nano-columnar fcc with increasing nitrogen.
• Homogeneous, single-phase multicomponent nitrides were achieved, analogous to high entropy stabilized compounds.
• Mechanical properties, including hardness (up to ~33 GPa) and modulus (up to ~400 GPa), scaled with nitrogen content, peaking in sub-stoichiometric nitride (~42 at% N).
• Low fracture toughness (~1 MPa.m½) was observed.

Conclusions:

• Reactive HiTUS is effective for producing multicomponent nitrides.
• Stoichiometry and mechanical properties can be controlled by adjusting nitrogen additions.
• The developed coatings show promise for applications requiring high hardness and modulus, despite limited fracture toughness.