Preparation and nanoscopic plastic deformation of toughened Al-Cu-Fe-based quasicrystal/vanadium multilayered coatings

Abstract Ductile vanadium layers were alternately deposited with brittle aluminum-copper-iron-based quasicrystal-alloy layers to form multilayered coatings. The in-situ transmission electron microscopic observations of nanopillar compression revealed that the as-deposited single-layered amorphous aluminum-copper-iron alloy slightly deformed via shear banding. After annealing at 800 °C, brittle quasicrystal and intermetallic compounds were formed, so the single-layered coating cracked and peeled. In comparison, the multilayered coatings were effectively toughened. The multilayered nanopillars plastically deformed via dislocation activities and were work hardened owing to confined dislocation gliding. The as-deposited multilayered structure (amorphous alloy/crystalline vanadium) had a low 10% flow stress of 1.72 GPa, while the annealed multilayered structure (quasicrystal/vanadium) presented a high flow stress of 2.58 GPa owing to quasicrystal strengthening. Dislocation clusters were in-situ observed to glide laterally in the crystalline vanadium layers and move vertically through the vanadium and quasicrystal layers, yielding an improved plasticity.