Microstructures and mechanical properties of multi-component (AlCrTaTiZr)NxCy nanocomposite coatings

Multi-component (AlCrTaTiZr)NxCy coatings with the incorporation of quinary metallic elements and different N and C contents were deposited by AlCrTaTiZr/C co-sputtering in an N2/Ar mixed atmosphere under an AlCrTaTiZr-alloy-target power of 150 W and different C-target powers (0-200 W). At a C-target power of 0 W, an (AlCrTaTiZr)N0.6 coating with a face-centered cubic solid-solution structure was deposited and exhibited a large columnar structure; its hardness and steady-stage creep strain rate were measured as about 20 GPa and 1.5 × 10−4 1/s, respectively. By applying a C-target power of 100 W, an (AlCrTaTiZr)N0.6C0.2 coating was formed with a fine columnar structure. Owing to the incorporated C atoms, the (111) interplanar spacing of the face-centered cubic structure was increased from 0.249 to 0.253 nm. The hardness increased to 32 GPa and the creep strain rate was lowered to 1.1 × 10−4 1/s attributed to the introduction of covalent-like bonds, grain refinement and the formation of an amorphous-like and nanocomposite structure. Furthermore, under a C-target power of 200 W, excess C atoms agglomerated to form clusters in the deposited (AlCrTaTiZr)N0.6C0.4 coating. Consequently, the hardness slightly decreased to 30 GPa and the creep strain rate increased to 2.4 × 10−4 1/s.