Super-hard refractory high entropy alloy film with spinodal decomposition

Unsatisfactory hardness and wear resistance severely limit the application of the single-phase high entropy alloy films. Here, the NbMoWTa films with the alternating nano-multilayered structure were prepared based on spinodal decomposition by magnetron sputtering. The hybrid MC/MD simulation offers a thermodynamic origin for the alternating distribution of Ta-rich and W-rich nanolayers. This unique nano-multilayered structure with a characteristic periodicity of ∼7 nm exhibits intricate coherent alternating stress fields, thereby constraining the motion of dislocations. As a result, the prepared NbMoWTa film shows a hardness up to ∼21.9 GPa and a low wear rate at an order of 10^–5 mm³/(N m), even surpassing that of some high entropy ceramic coatings. This work provides a new perspective for the design and preparation of high-performance high entropy alloy films.