High-throughput preparation and characterization of early hot-corrosion behaviors of compositional gradient Al–Cr complex coatings on a novel Co–Al–W-based alloy

High-throughput characterization of early hot-corrosion behaviors of compositional gradient Al–Cr complex coatings on a novel Co–Al–W alloy prepared by multi-arc ion plating technology at 1000–1100 °C for 10–30 min was conducted for the first time. As deposited, the coatings showed a laminate microstructure composed of various Al–Cr compounds. After corrosion, a three-layer structure formed between the coating and the substrate, with an outermost layer composed of α-Al₂O₃ + α-Cr₂O₃, an inter-diffusion layer, and an innermost reaction layer containing B₂-CoAl + μ-Co₇(W_0.8Cr_0.2)₆. Finally, the early hot-corrosion mechanism of the gradient Al–Cr complex coatings was discussed.