Thermal cycling performance of NiPtAl-Hf coatings before and after laser shock peening treatment

This paper studies the influence of laser shock peening (LSP) on the high-temperature oxidation behavior of NiPtAl-Hf coatings and evaluates their performance under thermal cycling conditions. The surface morphology and microstructure of the coatings were characterized and analyzed. High-temperature service performance was evaluated by examining the phase transition of θ-Al ₂ O ₃ and α-Al₂O₃ and the evolution of the thermally grown oxide (TGO) through transient oxidation and thermal cycling tests. Results show that LSP significantly promotes the phase transition from θ-Al₂O₃ to α-Al₂O₃. The effect is attributed to the high-density dislocations and plastic deformation regions introduced by LSP, which provide abundant heterogeneous nucleation sites for α-Al₂O₃. Comparative cyclic oxidation experiments further show that LSP refines the grain structure and introduces dislocation networks, enhancing aluminum diffusion for selective oxidation and mitigating thermal stress generated during thermal cycling process. Consequently, the TGO exhibits more stable growth with reduced cracking. Additionally, dislocation-induced strengthening effect promotes the rapid formation of a uniform protective oxide layer and while suppressing undesirable phase transitions. These findings highlight the potential of LSP as an effective strategy to enhance the thermal cycling performance of NiPtAl-Hf coatings high-temperature applications.