Mechanical and surface properties of Aluminum-Copper-Iron quasicrystal thin films

Highlights: • Growing Al-Cu-Fe thin film quasicrystals using a multilayer structure by sputtering. • The effects of annealing time on the mechanical properties in Al-Cu-Fe thin films quasicrystal. • Understanding the phase transitions of the Al-Cu-Fe multilayers to quasicrystal phase. • The highest contact angle (127°) on record was achieved for a thin film quasicrystal with high hardness. We show quasicrystal formation by annealing multilayers of Al, Cu and Fe. The mechanical and surface properties of quasicrystals are affected by the parameters of annealing process. Here, multilayer Al-Cu-Fe thin film samples with different compositions were sputtered on Si/SiO₂ substrates and subjected to a two-step annealing process for different durations (5, 10 and 15 h). X-ray diffraction analyses indicated that the 15-h annealed sample had a sharper quasicrystal peak, which was more stable than any other phases. From the XRD data, the amount of each phase was calculated; the sample with longer annealing duration revealed a high amount of ψ-phase (84.3% crystallinity of quasicrystal) with a small amount of cubic Al₅₀ (CuFe) ₅₀ phase. Nanoindentation tests and contact angle measurements showed that this sample also had the greatest hardness (∼11 GPa) and the highest contact angle (127°), respectively.