Deposition and interfacial characterization of Fe-based amorphous coating deposited on AZ31B magnesium alloy

Abstract

This study investigated the microstructure, residual stress, and bonding performance of Fe-based amorphous coatings (AMCs) on AZ31B magnesium alloy substrates to elucidate the deposition mechanisms and interfacial characterization. The results demonstrate that the coatings possess a typical amorphous structure, with amorphous content exceeding 95 % in all cases. The impact of particles caused a molten layer on the surface of the magnesium alloy substrate, facilitating atomic diffusion and resulting in a localized metallurgical bonding at the coating-substrate interface. The internal lamellar interface of the coating primarily relies on mechanical and physical bonding due to oxidation. Additionally, the near-interface magnesium alloy substrate effectively reduces the strain mismatch at the coating-substrate interface and dissipates residual stresses in the coating through its own plastic deformation, resulting in near-zero residual stress. Nonetheless, due to stress release and the edge-loaded plate cracking model, weak bonding regions, approximately 50–170 μm, exist in the Fe-based AMCs on AZ31B magnesium alloy substrate. Beyond this range, the surface properties of the coating were significantly improved. These findings provide valuable insights for the design of coatings on magnesium alloy surfaces and the reduction of residual stresses in thermal spray coatings.