The Microstructure and High‐temperature Cycle Oxidation Mechanism of the Nickel‐Based Superalloy Surface Treated by Laser Shock Processing and Ion Implantation at 1100 °C

Abstract The microstructure and high‐temperature cycle oxidation mechanism of a nickel‐based superalloy subjected to hafnium (Hf) ion surface implantation and laser shock processing (LSP) at 1100 °C are investigated. The phases, microstructures, and morphologies of the superalloy subjected to LSP and ion implantation before and after high‐temperature cycle oxidation are characterized using various technologies, including X‐ray photoelectron spectroscopy, high‐temperature cycle oxidation, scanning electron microscopy, and transmission electron microscopy. A distinct amorphous HfO 2 layer, with a thickness of ≈30 nm, forms on the alloy's surface. Under the dual action of LSP and ion implantation, a large number of crystal defects, such as dislocation tangles, dislocation pile‐ups, twins and subgrains, are induced, and they provide channels for the rapid formation of protective oxide films through the diffusion of metal cations. At the initial stage of high‐temperature oxidation, the nucleation of oxides began at the dislocation sites. The higher the dislocation density is, the greater the formation density is. A different oxidation mechanism, in which titanium ions are preferential diffused, occurred in samples after Hf ion implantation. Compared with samples only treated by Hf ion implantation, those undergoing both LSP and ion implantation displayed oxide particles that are significantly smaller, more densely packed, and adhered more strongly to the substrate. This refined oxide layer effectively acts as a barrier, hindering the infiltration of oxygen ions into the underlying substrate.