Inconel 718 alloy, renowned for its outstanding high-temperature strength, oxidation resistance, and corrosion resistance, has found extensive applications across aerospace, energy, and other critical sectors. The advent of the additive manufacturing technology, particularly the laser powder bed fusion technology, has opened up novel avenues for the fabrication of Inconel 718 alloy and its composites. Nevertheless, the intricate microstructure of components produced by this technology gives rise to selective dissolution during subsequent electrochemical machining. This phenomenon not only deteriorates the surface quality but also restricts the further expansion of its applications.

In this study, laser powder bed fused Inconel 718 alloy and TiB?/Inconel 718 composite are used to innovatively address the surface quality problem faced by traditional electrolytic grinding. The core purpose of this research is to deeply explore the intrinsic relationship between the microscopic properties of materials and the processing technology, so as to optimize the processing quality and expand the application range of materials. Specifically, this research uses X-ray photoelectron spectroscopy (XPS) analysis technology to determine the chemical composition and elemental distribution of the superpassivation films of two materials. Through a detailed analysis of the composition of the superpassivation film, the aim is first to reveal its formation mechanism and the influence on the surface properties of the material during processing, and then to study the parameters of the electrolytic grinding process including different feed rates and rotational speeds and the relationship between the microstructure of materials and the electrolytic grinding surface quality . Scanning electron microscope (SEM) is used to observe the microstructural changes of materials under different process parameters in real time, and the surface quality parameters after electrolytic grinding can be accurately determined in combination with surface roughness measuring instruments and other equipment. Through comprehensive and detailed experimental data collection and analysis, the influence mechanism of microstructure on surface quality under different process conditions is deeply explored.

Compared to Inconel 718 alloy, TiB?/Inconel 718 composite can form a denser superpassivation film during electrolytic machining. The root cause of this phenomenon is that the addition of TiB₂ induces the formation of more homogeneous microstructures inside the material. At the microscopic level, the uniformly distributed TiB₂ particles act as a “backbone” and provide numerous stable attachment sites for the growth of superpassivation films. These sites make the superpassivation film more uniform in the formation process, and due to its strong interaction with the TiB₂ particles, the superpassivation film can be firmly attached to the TiB? particles, effectively avoiding being washed away by the electrolyte, thus ensuring the integrity and stability of the superpassivation film and improving the corrosion resistance of the material. Both materials are composed of Ni(OH)?, Fe(OOH), Fe?O?, Cr(OH)?, Cr?O?, TiO?, MoO?, Nb?O?, and other compounds. It is worth noting that the added TiB? does not participate in electrochemical dissolution throughout the electrochemical processing process, and mainly plays a role in enhancing the microstructural stability and promoting the formation of superpassivation films in the material. When it comes to the study of the effect of process parameters on surface quality, both Inconel 718 alloy and TiB?/Inconel 718 composite are available at a feed rate of 1.33 mm/s and a rotational speed of 1000 r/min, the surface quality is at its best, the surface is extremely flat, and there are no pits. At the same time, the gouge phenomenon caused by stray corrosion has been significantly improved, and the gouge amount has been greatly reduced.

Compared with Inconel 718 alloy, the nano-TiB₂ particles in the microstructure of TiB₂/Inconel 718 composite are diffusely distributed in the dendrite, which forms a denser superpassivation film in electrolytic machining, and the optimal parameters in electrolytic grinding are 1.33 mm/s and 1000 r/min, in which the volumetric electrochemical equivalent of Inconel 718 alloy is 1.727 mm³/(A?min), and the volumetric electrochemical equivalent of TiB₂/ Inconel 718 composite is 1.796 mm³/(A?min).