Akademik Məlumat İdarəetmə Sistemi
Journal of Materials Engineering and Performance, vol.34, no.4, pp.3172-3181, 2025 (SCI-Expanded, Scopus)
Deformable Austempered Ductile Iron (DADI) is a type of cast iron used as a substrate to deposit slurry coatings of Al and AlCr microsized particles. The goals were to obtain decent surface aluminization, to study the high-temperature behavior of aluminized layers received and highlight the microstructural aspects of the developed coatings as well as the formed oxides. The influence of slurry composition on the thickness of the formed intermetallic diffusion layers, their chemistry and microstructure were first studied. Post-coating annealing in the low-Al activity conditions for both pure aluminum and AlCr slurry coatings developed a distinctive layered structure of coatings and diffusion zones when applied onto the Fe rich DADI substrate. The Al slurry has formed a more defined and relatively wide diffusion layer of 20 µm, while the interdiffusion aluminized zone under it was profoundly thinner (4 µm) due to the low activity of Al. The slurry coating of AlCr composition formed a 10 µm thin diffusion zone with mostly unreacted Cr particles incorporated in it and the lightly aluminized layer under the latter were found to be of equal thickness. All the layers for both coatings were rich with Kirkendall voids once again proving the strong, predominantly outward-driven mechanism of diffusion. On the other hand, the latter is also supported by the enrichment of all the formed zones with the carbon sourced from the DADI substrate. Subsequent high-temperature oxidation of aluminized DADI specimens with pure Al and AlCr slurries at 650 °C for 500 hours in the laboratory air revealed a more protective nature of the former. This was confirmed by the kinetic data, which showed a reduction of oxide growth rate on the single- and double-component slurry-coated samples by factors of roughly 14 and 4, respectively, when compared with uncoated DADI.