Synergistic effects of ultrasonic surface rolling and multilayer coatings on hot salt corrosion fatigue behavior of TC11 alloy

The underlying mechanisms of a sequential combined treatment—combining ultrasonic surface rolling process (USRP) pretreatment with TiAlTaSiN/TiAlTaSi multilayer coating—on the hot salt corrosion fatigue (HSCF) properties of TC11 alloy are explored. The sequential combined treated sample has superior HSCF resistance, with an HSCF limit 35.9% higher than the untreated substrate and 2.4% higher than the substrate without NaCl film. The diffusion of corrosive species is effectively inhibited by the multilayer coating, which consequently suppresses hot salt corrosion and delays the initiation of fatigue cracks. Meanwhile, the double nanocrystal interface formed by the USRP-induced nanograined surface and the nanocrystalline Ti transition layer promotes coordinated deformation between the coating and substrate under cyclic loading. In addition, the stabilized compressive residual stress field and the strength-toughness matched structure further inhibit crack propagation. These synergistic effects collectively improve HSCF resistance of the TC11 alloy.