Nano-Crystallization of High-Entropy Amorphous NbTiAlSiWxNy Films Prepared by Magnetron Sputtering

High-entropy amorphous NbTiAlSiWxNy films (x = 0 or 1, i.e., NbTiAlSiNy and NbTiAlSiWNy) were prepared by magnetron sputtering method in the atmosphere of a mixture of N-2 + Ar (N-2 + Ar = 24 standard cubic centimeter per minute (sccm)), where N-2 = 0, 4, and 8 sccm). All the as-deposited films present amorphous structures, which remain stable at 700 degrees C for over 24 h. After heat treatment at 1000 degrees C the films began to crystalize, and while the NbTiAlSiNy films (N-2 = 4, 8 sccm) exhibit a face-centered cubic (FCC) structure, the NbTiAlSiW metallic films show a body-centered cubic (BCC) structure and then transit into a FCC structure composed of nanoscaled particles with increasing nitrogen flow rate. The hardness and modulus of the as-deposited NbTiAlSiNy films reach maximum values of 20.5 GPa and 206.8 GPa, respectively. For the as-deposited NbTiAlSiWNy films, both modulus and hardness increased to maximum values of 13.6 GPa and 154.4 GPa, respectively, and then decrease as the N-2 flow rate is increased. Both films could be potential candidates for protective coatings at high temperature.