Research paper

Results in Materials

Surface modification of Ni-based single crystal superalloys by energy-intensive multifunction cavitation with synchrotron X-ray irradiation at SPring-8

Toshihiko Yoshimura, Umi Sugitani, Eito Chikashige, Suguru Ito, Kentaro Uesugi

SSRN

１

36

Elsevier

A novel surface modification technique combining high-brilliance synchrotron X-rays generated at the SPring-8 facility with positron-assisted magnetic energy-intensive multifunction cavitation was applied to the nickel-based single-crystal superalloys SC610 and CMSX-4. Processing was carried out over the pressure range of 5–25 MPa using acetone/deuterated acetone or water/heavy water mixtures, and the effects of the working fluid and processing pressure on surface properties were systematically investigated. The hardness and surface roughness of the alloys were examined and these materials were further characterized using scanning electron microscopy (SEM) with energy dispersive X-ray spectroscopy (EDS) and laser microscopy. Processing with acetone produced significant hardness increases of approximately +100 to 150 HV, demonstrating a hardening capability comparable to or exceeding that of conventional shot peening. In contrast, processing with water increased the hardness of the CMSX-4 without a corresponding increase in surface roughness, whereas the SC610 showed only limited changes. Surface roughness tended to increase under low pressure conditions and decrease at higher pressures, and these conditions did not always provide maximum hardness. SEM observations and EDS analyses suggested that the formation of a reaction layer occurred at intermediate pressures, whereas uniform plastic deformation became dominant at higher pressures. These results indicate that the surface modification resulting from PXMEI-MFC processing occurs via different mechanisms that are determined by the pressure and working medium. The present technique is promising as a surface modification method capable of providing both surface hardening and smoothness and could be used to improve the performance of Ni-based superalloys.