Abstract
The refractory high-entropy TaNbHfZr films with various microstructures have been synthesized by magnetron sputtering via tuning different deposition temperature from 25 °C to 700 °C. At 25 °C, a complete amorphous structure with featureless surface morphology is formed. With the increase of deposition temperature, the precipitation of crystallites is observed at 500 °C and a nanocrystalline bcc structure high-entropy TaNbHfZr alloy film with the surface morphology of needle-like islands at 700 °C due to the significantly improved atom diffusion ability. Nanoindentation results also indicate that the hardness and reduced elastic modulus of the films are strongly dependent on their distinct microstructures. For amorphous dominated films, the hardness increases with the elevated temperature accompanied with enhanced modulus. The bcc TaNbHfZr high-entropy alloy film displays superior hardness of ∼15.3 GPa. The strengthening mechanism can be attributed to the distortion induced solid-solution strengthening and the grain boundary strengthening in the nanocrystalline microstructure.
| Original language | English |
|---|---|
| Pages (from-to) | 1025-1030 |
| Number of pages | 6 |
| Journal | Journal of Alloys and Compounds |
| Volume | 797 |
| DOIs | |
| State | Published - 15 Aug 2019 |
Keywords
- High entropy films
- Magnetron sputtering
- Nanoindentation
- Substrate temperature
- TaNbHfZr