摘要
Laser shock processing(LSP),as a novel surface modification technology,exhibits tremendous potential to improve the oxidation resistance of alloys.In this paper,(γ’+β)two-phase Ni-34Al-0.1Dy coatings were prepared by electron beam physical vapor deposition(EB-PVD)and then treated by LSP with different pulse energy(4 and 5 J).Their oxidation behavior(including isothermal oxidation and cyclic oxidation)at 1150°C was compared.In the isothermal oxidation case,the LSP-treated samples exhibited good ox-idation resistance due to high dislocation density and refined grains caused by the LSP.For the cyclic oxidation,however,the LSP-treated samples were subjected to undesirable thermally grown oxide(TGO)spallation.In the early oxidation stage(within 30 min),the residual compressive stress introduced by the LSP rapidly released,resulting in a severe plastic deformation at the coating/TGO interface.As a result,the mismatch between coating and TGO gave rise to the TGO spallation.With the increase in the oxida-tion time,work hardening,which continuously limited the synchronous deformation of the TGO/coating interface,became the dominant mechanism controlling the TGO spallation of 5 J-treated coatings.The continuous TGO spallation affected the Al supply and thus deteriorated the cyclic oxidation behavior.
基金
sponsored by the Science Center for Gas Turbine Project(No.P2021-A-Ⅳ−002-002)
National Science and Technology Major Project(Grant No.2017-Ⅵ-0002-0072)
the fundamental research funds for central universities(No.YWF-22-l-1033)
the corresponding author(J.He)appreciates the support from Youth Talent Support Program of Beihang University.