Strengthening of Ni-based superalloys using energy-intensive multifunction cavitation processing systems incorporating ionic liquids

This work developed an energy-intensive multifunction cavitation technology involving ionic liquids (ILs). This technology was used to process a single crystal of the Ni-based superalloy SC610, employing a mixture of the IL 1-butyl-3-methylimidazolium tetrafluoroborate ([BMIM][BF₄]) and pure water. The intensity of this process was found to result in the formation of surface cracks and new chemical compounds that were deposited on the alloy surface. The application of this treatment to a columnar crystal of the Ni-based superalloy CM186LC provided a more uniform surface structure than that obtained from the same process without the IL. Incorporating the IL also reduced the processing time and increased the hardness that could be obtained. The ions comprising the IL were found to be incorporated into the cavitation bubbles. Multiphoton ionization was promoted by laser irradiation and collisions between bubbles were made more forceful by the Lorentz force associated with a magnetic field. These factors increased the number of bubbles available for processing.