Effect of substrate temperature on AlCoCrCuFeNiTi film synthesized by magnetron co-sputtering

Abstract High entropy alloys (HEAs) have attracted significant interest in recent years due to their exceptional structural and mechanical properties, yet their film behaviour is underexplored. The AlCoCrCuFeNiTi HEA has been studied for bulk, but has not been studied for film synthesis via magnetron sputtering and the role of substrate temperature on the HEA. In this study, films of AlCoCrCuFeNiTi have been synthesized via magnetron co-sputtering at different substrate temperatures (room temperature, 250 °C and 500 °C) on Si substrates. The study investigates the effect of substrate temperature on phases, composition, microstructure, and mechanical properties of AlCoCrCuFeNiTi films. The film synthesized at room temperature was amorphous, and the film synthesized at high temperature showed crystallinity. The 250 °C film had a mix of face-centered cubic and body-centered cubic phases, and the 500 °C film had primary face-centered cubic and B2 phases. The films had columnar cross sections and the 500 °C film had equiaxed grains and prominent grain boundaries. The 500 °C film had the highest average surface roughness of 5.02 nm, driven by grain growth. A maximum contact angle of 117.67° was achieved for the 500 °C film. At higher substrate temperatures, the film had better mechanical properties than the film at room temperature. The 250 °C film had the highest hardness of 4.82 GPa, and the 500 °C film had the highest reduced Young’s modulus of 103.92 GPa. The higher mechanical properties at higher substrate temperatures were due to the improved mobility of atoms at higher substrate temperatures, which allowed for compact, dense films. The substrate temperature has been found to have a strong impact on the phase, microstructure and mechanical properties of AlCoCrCuFeNiTi films. The study outcomes offer valuable insights for designing AlCoCrCuFeNiTi HEA films. Further study can be done on the effect of substrate bias on the behaviour of AlCoCrCuFeNiTi films.